JP4840955B2 - Static eliminator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a static eliminator for static elimination, that is, static elimination, for controlling static electricity in air.
[0002]
[Prior art]
Static electricity removal (static elimination) is performed to control static electricity in the air, such as cleaning in a clean room and preventing static charge of airborne particles. For this non-contact static elimination, a corona discharge ionizer, that is, a static elimination device, It is used a lot.
[0003]
In order to ensure static elimination by the static eliminator, that is, a desired effect, it is necessary to balance the positive and negative ion generation amounts due to the discharge of the electrode needle or the discharge electrode included in the static eliminator equally.
[0004]
In the invention disclosed in Japanese Patent Laid-Open No. 3-266398, a current detection electrode is disposed between a positive-side discharge electrode and a negative-side discharge electrode, and the difference between the positive ion generation amount and the negative ion generation amount is It is proposed to maintain the ion balance by detecting the ionic current generated by.
[0005]
Japanese Patent Application Laid-Open No. 8-78183 detects an effective static elimination current that generates ions that can substantially contribute to static elimination of a workpiece among currents flowing between a positive discharge electrode and a negative discharge electrode. Therefore, it has been proposed to control the amount of positive and negative ions that can substantially participate in static elimination.
[0006]
[Problems to be solved by the invention]
However, it is known that it becomes difficult to maintain ion balance when the discharge electrode is contaminated by discharge.
Accordingly, an object of the present invention is to provide a static eliminator capable of preventing the discharge electrode from being contaminated and maintaining a good ion balance over a long period of time.
Another object of the present invention is to provide a static eliminator capable of reducing wear of a discharge electrode in addition to maintaining a good ion balance by preventing contamination of the discharge electrode.
[0007]
[Means for Solving the Problems]
According to the present invention, such a technical problem is
As a voltage applied to the common discharge electrode, positive and negative ions are generated from the common discharge electrode by alternately generating high voltages having different polarities in the positive high voltage generation circuit and the negative high voltage generation circuit. In a static eliminator that generates ions alternately,
Between the period for applying and discharging a positive voltage to the common discharge electrode and the period for discharging by applying a negative voltage and the period of applying and discharging the negative voltage and then the positive voltage In each of the periods of applying and discharging, an interval period in which no voltage is applied to the common discharge electrode is provided,
After applying the positive voltage to the common discharge electrode to generate positive ions, before entering the interval period, the negative voltage is applied so that the common discharge electrode is substantially neutralized. The negative voltage is applied to the common discharge electrode generated by the high voltage generation circuit on the side,
After applying the negative voltage to the common discharge electrode to generate negative ions, before entering the interval period, the positive voltage is applied so that the common discharge electrode is substantially neutralized. This is achieved by providing a static eliminator which is generated by a high voltage generating circuit on the side and applies the positive voltage to the common discharge electrode .
[0008]
The above and other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments of the present invention.
[0009]
【Example】
FIG. 1 shows a pulse AC type static eliminator 1, which generates high voltages with different polarities in positive and negative high voltage generation circuits 2 and 3, and supplies them to a discharge electrode 4. Ions having different polarities, that is, positive and negative ions are alternately generated from the discharge electrode 4.
[0010]
Tungsten may be employed as the material of the discharge electrode 4, but silicon is preferably employed because of its excellent wear resistance.
[0011]
Both the positive and negative high voltage generation circuits 2 and 3 include a self-excited oscillation circuit 7 connected to the primary coil of the transformers 5 and 6 and a booster circuit 8 connected to the secondary coil, such as a double rectifier circuit. Including. A protective resistor 9 is provided between the high voltage generation circuits 2 and 3 and the discharge electrode 4.
[0012]
A ground (GND) plate 10 is provided near or around the discharge electrode 4, and the GND plate 10 is connected to a work-side ground, that is, a frame ground FG through a conductor 11. Second resistors R ₁ and R ₂ are provided in series. Specifically, the first resistor _{R 1} is provided on the GND plate 10 side, a second resistor _{R 2} is provided on the frame ground FG side. A conductor 12 connects between the first resistor R ₁ and the second resistor R ₂ and the ground side ends of the secondary coils of the positive and negative transformers 5 and 6.
[0013]
The current I ₁ between the discharge electrode 4 and the GND plate 10 can be indirectly detected by the potential difference V ₁ of the first resistor R ₁ . The difference in the amount of work side of the frame ground FG to reach the positive and negative ions, indirectly detected by the potential difference V ₂ of the current I _2, that the second resistor R ₂ through the second resistor R ₂ be able to.
[0014]
Therefore, the degree of discharge by the discharge electrode 4, that is, the amount of ions generated by the discharge electrode 4 can be detected by the potential difference V _{1 of} the first resistor R ₁ , thereby reducing the performance of the discharge electrode 4 or Not only can the efficiency decrease be grasped, but also the balance between the positive and negative ion generation amounts generated by the discharge electrode 4 can be known. On the other hand, the ion balance in the vicinity of the workpiece can be known from the potential difference V _{2 of} the second resistor R ₂ .
[0015]
For example, the potential difference V ₁ of the first resistor R ₁ is detected by the ion current detection circuit 14, and this detection data is input to the CPU 15, and the potential difference V ₁ becomes extremely small or decreases with time. If it becomes smaller than the value, it is sufficient to notify the operator by the alarm means or the display means 16 that the discharge is abnormal. Examples of this type of discharge abnormality include a case where dust accumulates on the discharge electrode 4.
[0016]
In addition, for example, the potential difference V ₂ of the second resistor R ₂ is detected by the ion current detection circuit 14, and this detection data is input to the CPU 15 so that the ion balance in the vicinity of the workpiece can be maintained. The positive and / or negative supply voltage to 4 may be changed or the pulse width may be changed. At the same time, the fact that the ion balance is not maintained may be notified to the operator through the alarm means or the display means 16.
[0017]
Further, for example, when the potential difference _{V 2} of the first resistor _{R 1} of the potential difference _{V 1} and / or the second resistor _{R 2} is extremely large, this is detected by the abnormal discharge current detection circuit 17 is input to the CPU 15, For example, when an abnormal discharge is generated due to a short circuit between the discharge electrode 4 and the GND plate 10 or between the discharge electrode 4 and the workpiece, the alarm means or the display means 16 turns on the emergency light. Or an alarm sound may be issued to the user or the worker.
[0018]
By detecting the potential difference V ₁ of the first resistor R ₁ by the ion current detection circuit 14, the following can be monitored. FIG. 2A is a monitor of the potential difference V _{1 of} the first resistor R ₁ , that is, the change in the current I ₁ between the discharge electrode 4 and the GND plate 10. In FIG. 2A, the part indicated by the arrow B is an inductive component.
[0019]
The current value of the point indicated by the arrow A the influence of the inductance component gone uptake by A / D converter as I _1, as shown in FIG. 2 (b) by tracking a current value I ₁ over time sometimes larger decrease in the current value I _1, the contamination or soiling of the discharge electrode 4 has progressed, the display LED16 as described later can be displayed to that effect.
[0020]
Further, the ion balance of the ion generation amount can be known by comparing the positive current value I ₁ or I ₂ with the negative current value I ₁ or I ₂ . When there is a difference between the positive current value I ₁ or I ₂ and the negative current value I ₁ or I ₂ , the CPU 15 applies the positive high voltage generation circuit 2 and / or the negative high voltage generation circuit 3 to the CPU 15. A feedback control signal is output so as to maintain the ion balance of the ion generation amount.
[0021]
FIG. 3A shows basic control signals supplied from the CPU 15 to the high voltage generation circuits 2 and 3. This basic control is performed when the ion balance near the workpiece and the ion balance around the discharge electrode 4 are zero, that is, when it is detected that the detected positive ions and negative ions are in a balanced state. It is.
[0022]
As can be understood from the figure, pulse signals 20 and 21 are alternately supplied to the high voltage generating circuit 2 on the positive side and the high voltage generating circuit 3 on the negative side. The positive and negative high voltage generation circuits 2 and 3 alternately generate a positive voltage or a negative voltage in response to the pulse signals 20 and 21, and supply this to the discharge electrode 4. Therefore, it can be said that FIG. 3A substantially illustrates the control of the voltage applied to the discharge electrode 4.
[0023]
The basic control illustrated in FIG. 3A will be described. A pause period, that is, an interval period Ti is provided between the positive pulse signal 20 and the next negative pulse signal 21, and the positive pulse signal 20 The reverse pulses 22 and 23 are supplied to the high voltage generation circuits 2 and 3 immediately after the end of the negative pulse signal and immediately after the end of the negative pulse signal.
[0024]
That is, immediately after the positive pulse signal 20 for driving the positive high voltage generation circuit 2 is finished, the reverse pulse signal, that is, the negative pulse signal 22 is supplied to the negative high voltage generation circuit 3. The reverse pulse signal 22 ends in a very short period, and thereafter, after passing through the interval period Ti, a negative pulse signal 21 for driving the negative high voltage generating circuit 3 is supplied.
[0025]
More specifically, the reverse pulse signal 22 is a period necessary for making the electric charge (voltage) remaining in the discharge electrode 4 and the high-voltage generating circuit 2 on the plus side substantially neutral by the positive pulse signal 20. Is determined experimentally, and the generation period is determined based on the experimental result. The substantially neutral state here means a state in which ions are not generated from the discharge electrode 4, and specifically, means that the discharge electrode 4 is in a charged state within ± 3 kV. Further, during the generation period of the reverse pulse signal 22, only the voltage necessary for making the electric charge (voltage) remaining in the plus side high voltage generation circuit 2 substantially neutralized is transferred by the minus side high voltage generation circuit 3. Therefore, ion discharge from the discharge electrode 4 is not performed.
[0026]
Next, when the supply of the pulse signal 21 for driving the minus-side high voltage generation circuit 3 is finished, a reverse pulse signal, that is, a positive pulse signal 22 is supplied to the plus-side high voltage generation circuit 2 immediately after that. The reverse pulse signal 23 ends in a very short period, and then the next cycle starts after an interval period Ti. The generation period of the reverse pulse signal 23 here is also set based on the same concept as the reverse pulse signal 22 described above, and specifically, the generation period same as that of the reverse pulse signal 22 is set.
[0027]
The above will be described with reference to the voltage value applied to the discharge electrode 4. A positive high voltage is supplied to the discharge electrode 4 to cause discharge (generation of positive ions). When the application of the positive high voltage is completed, immediately after that, that is, in synchronization with the completion of the application of the positive voltage, a reverse voltage, that is, a negative high voltage is generated in the negative high voltage generation circuit 3 for the period described above, and discharge is performed. The working electrode 4 is brought into a substantially neutral state.
[0028]
When the application of the reverse voltage is completed, the interval period Ti is reached. During the interval period Ti, the electric charge of the discharge electrode 4 is maintained in a substantially neutral state, and no ion discharge is performed.
[0029]
Next, when the interval period Ti ends, a negative high voltage is applied to the discharge electrode 4 to discharge (generate negative ions). When the application of the negative high voltage is completed, a reverse voltage, that is, a positive high voltage is supplied for a short period immediately after that. When the application of the reverse voltage is completed, the interval period Ti, that is, the rest period of the discharge electrode 4 is reached. When the interval period Ti ends, the next cycle starts.
[0030]
In the basic control when the ion balance is in an equilibrium state, the period (T ₀ ) during which positive or negative high voltage is applied to discharge the discharge electrode 4 and alternately generate positive ions and negative ions is The same. Therefore, theoretically, the amount of positive ions produced is equal to the amount of negative ions produced.
[0031]
For comparison, a conventional voltage application method is shown in FIG. FIG. 4 shows a pulse signal supplied to the positive high voltage generation circuit 2 and the negative high voltage generation circuit 3 when it is determined that the positive ion generation amount is equal to the negative ion generation amount. 20 and 21 are shown.
[0032]
As can be seen from FIG. 4, according to the conventional high voltage application method, positive or negative high voltage was alternately and continuously supplied to the discharge electrode 4. On the other hand, the high voltage application method according to the present invention applies a positive high voltage and then applies a negative high voltage and applies a negative high voltage and then applies a positive high voltage. A feature is that an interval period Ti in which no voltage is applied to the discharge electrode 4 is provided.
[0033]
Another feature of the high voltage application method according to the present invention is that, as shown in FIG. 3 (a), the discharge electrode 4 is applied in a short period immediately after applying a positive high voltage to generate positive ions. In addition, a reverse voltage (negative voltage) necessary for making the electric charge (voltage) remaining in the plus-side high-voltage generating circuit 2 substantially neutralized is generated by the minus-side high-voltage generating circuit 3, and similarly In order to make the charge (voltage) remaining in the discharge electrode 4 and the high-voltage generating circuit 3 on the negative side almost neutral after a negative high voltage is applied to generate negative ions. The high voltage generation circuit 2 on the plus side generates the reverse voltage (positive voltage) necessary for the above. In other words, in the high voltage application method according to the present invention, the discharge electrode 4 that has generated ions does not generate the reverse ions of the generated ions, and before entering the interval period Ti, this interval. The high-voltage generating circuit and the discharge electrode 4 that have been started prior to the above are brought into a substantially neutralized state.
[0034]
Prior to the interval period Ti, the high voltage generation circuit and discharge electrode 4 started prior to the interval period Ti are substantially neutralized, and for comparison, the high voltage generation circuit and discharge electrode started prior to the interval. A high voltage application method when 4 is not substantially neutralized, in other words, when the high voltage generation circuit and the discharge electrode 4 have residual charges will be described with reference to FIG. That is, according to the high voltage application method shown in FIG. 5 (a), the positive pulse signal 20 is supplied from the CPU to the high voltage generation circuit to generate positive ions, and immediately thereafter, the interval period Ti is entered. When the interval period Ti ends, the negative pulse signal 21 is supplied next to generate negative ions. When this pulse signal 21 ends, the next interval period Ti immediately starts.
[0035]
When an actual experiment was performed using the high voltage application method illustrated in FIG. 5A, the effect of preventing the discharge electrode 4 from being contaminated was not expected. The reason is considered as follows.
[0036]
That is, during the interval period Ti, even if the drive signal is turned off from the CPU to the high voltage generation circuit, charges remain in the discharge electrode 4 and the discharge electrode 4 is in a discharged state due to the remaining charges. It is believed that there is.
[0037]
That is, as shown in FIG. 5B, the discharge electrode 4 continues to generate positive ions or negative ions. FIG. 5 (b) is a diagram showing measured values of the voltage applied to the discharge electrode 4.
[0038]
Therefore, even if the high voltage application method shown in FIG. 5A is used, the discharge electrode 4 continues to be discharged, and the problem of contamination and wear of the discharge electrode 4 remains.
[0039]
On the other hand, according to the high voltage application method according to the present invention illustrated in FIG. 3 (a), the application of the positive high voltage is completed, and the reverse voltage, that is, the negative voltage is applied before the subsequent interval period Ti. A high voltage is generated in the minus side high voltage generation circuit 3 only for a period necessary to bring the plus side high voltage generation circuit 2 and the discharge electrode 4 into a substantially neutralized state. Similarly, before the application of the negative high voltage is completed and before the subsequent interval period Ti, the reverse high voltage, that is, the positive high voltage is generated by the high voltage generation circuit 2 on the positive side. The circuit 3 and the discharge electrode 4 are generated only for a period required to make the circuit 3 and the discharge electrode 4 substantially neutralized.
[0040]
Therefore, the charge remaining in the discharge electrode 4 is neutralized by the application of the reverse voltage, thereby preventing the discharge in the interval period Ti.
[0041]
That is, as shown in FIG. 3B, after the discharge electrode 4 generates positive ions or negative ions, it does not discharge during the interval period Ti and is in a resting state. FIG. 3B is a diagram showing measured values of the voltage applied to the discharge electrode 4.
[0042]
Thus, according to the high voltage application method according to the present invention, it is possible to set a period during which the discharge electrode 4 is completely rested, so that the discharge electrode 4 can be prevented from being soiled and wear can be reduced. The ion balance regarding ion generation can be maintained over a long period of time, and therefore the period during which maintenance is required can be prolonged. Such an effect was not only confirmed by experiments but also a very remarkable effect.
[0043]
The reverse voltage applied before the interval period Ti only needs to have a constant absolute value, and can be easily controlled by setting the voltage value to the same absolute value as the positive or negative high voltage to be applied for discharge. become.
[0044]
As described above, the basic principle of the high voltage application method according to the present invention is that the ion balance around the discharge electrode 4 and the ion balance near the workpiece are zero, that is, the amount of positive ions and negative ions around the discharge electrode 4 is the same. The case where there is an ion balance in the vicinity of the workpiece is described as an example. However, when the detected ion balance is biased to either the positive ion side or the negative ion side, control is performed to return it to zero. This control will be described with reference to FIGS.
[0045]
6 (a) to 10 (a) show the control contents when the ion balance is detected to be zero, that is, in an equilibrium state, which is the same as FIG. 3 (a). When the ion balance is zero, the output period of the positive pulse signal 20 and the negative pulse signal 21, that is, the positive ion generation period and the negative ion generation period are both indicated by T ₀ , and the rest period, that is, the interval period is indicated by Ti.
[0046]
FIG. 6B shows the control content when it is detected that, for example, the ion balance in the vicinity of the workpiece is biased to the negative side. This control is based on the premise that the generated voltage per unit time of the positive and negative high voltage generation circuits 2 and 3 is controlled to be constant.
[0047]
In the example shown in FIG. 6B, in order to increase the positive ion generation ratio in one cycle, the period of the positive pulse signal 20, that is, the positive ion generation period T (+) is extended by Δt (+), Other parameters, that is, the interval period Ti and the period of the negative pulse signal 21, that is, the negative ion generation period T (-) are fixed. Needless to say, the extension period Δt (+) of the positive pulse signal 20 changes depending on the amount of deviation of the ion balance.
[0048]
FIG. 7B shows the contents of control when it is detected that the ion balance in the vicinity of the workpiece is biased to the plus side in the same control method as shown in FIG.
[0049]
In the example illustrated in FIG. 7B, the period T (+) of the positive pulse signal 20 is set to the basic pulse generation period (T ₀ ) in order to increase the negative ion generation ratio in one cycle. Δt (+) is reduced, and other parameters, ie, the interval period Ti and the negative pulse period T (−) are fixed. Thereby, the production | generation ratio of the negative ion in one period will increase relatively.
[0050]
FIG. 8 (b) shows the contents of control as a second embodiment different from those shown in FIGS. 6 and 7 described above. As a premise of control, the time of one cycle of control is made constant and The length of two interval periods Ti existing in the cycle is fixed.
[0051]
Specifically, FIG. 8 (b) shows the control contents when it is detected that the ion balance in the vicinity of the workpiece is biased to the negative side under such preconditions. In order to increase the positive ion generation ratio, the positive pulse signal 20 is set to a period T (+) by adding Δt to the basic pulse generation period (T ₀ ), and the negative pulse signal 21 is changed to By controlling the basic pulse generation period (T ₀ ) by Δt, the period T (−) is controlled.
[0052]
Since the additional generation period Δt of the positive pulse signal 20 and the decrease period Δt of the negative pulse signal 21 have the same amount, the one-period period Tc can always be kept constant.
[0053]
In FIG. 8B, the control content when the ion balance in the vicinity of the workpiece is detected to be biased to the minus side has been described. However, the ion balance in the vicinity of the workpiece has been detected to be biased to the plus side. In this case, the positive pulse signal 20 is reduced by Δt with respect to the basic pulse generation period (T ₀ ), and the negative pulse signal 21 is added with Δt with respect to the basic pulse generation period (T ₀ ). Become. Further, it goes without saying that the increase / decrease Δt with respect to the positive and negative basic pulse periods (T ₀ ) described above is changed according to the degree of ion balance deviation in the vicinity of the workpiece.
[0054]
FIG. 9 (b) shows the control contents as a third embodiment different from the above-described FIGS. 6 to 8. As a premise of the control, while the time of one cycle of control is made constant, In this embodiment, the length of the negative ion generation period T _{0 and} two reverse pulse generation periods existing in one cycle is fixed.
[0055]
Specifically, FIG. 9 (b) shows the control contents when it is detected that the ion balance in the vicinity of the workpiece is biased to the negative side under such preconditions. In order to increase the positive ion generation ratio, Δt is added to the positive pulse signal 20 with respect to the basic pulse generation period T ₀ , and ½ of this increase Δt is subtracted from each interval period Ti. Therefore, Ti (−) and Ti (+) are controlled.
[0056]
FIG. 9B illustrates the control content when it is detected that the ion balance in the vicinity of the workpiece is biased to the minus side. However, the detection is performed if the ion balance in the vicinity of the workpiece is biased to the plus side. In this case, Δt is subtracted from the positive pulse signal 20 with respect to the basic pulse generation period T ₀ , and ½ of this decrease Δt is added to each interval period Ti. It goes without saying that the increase / decrease Δt with respect to the positive and negative basic pulse generation period T ₀ described above changes according to the degree of ion balance deviation in the vicinity of the workpiece. In contrast to the above embodiment, the positive ion generation period may be fixed, and the negative ion generation period and the interval period may be variable.
[0057]
Even in this control, Δt (+) and Δti are increased or decreased depending on the degree of ion balance. However, excessively shortening the interval period Ti impairs the original purpose of setting the interval period Ti. Therefore, it is preferable to set a certain limit on the amount of reduction Δti of the interval period Ti.
[0058]
FIG. 10B shows the control content when it is detected that the ion balance is biased to the minus side. This control fixes the positive ion generation period T (+) and the negative ion generation period T (−) (T (+) = T ₀ , T (−) = T ₀ ), and also fixes the interval period Tc. In addition, while the absolute values and periods of the reverse pulses 22 and 23 are also fixed, the absolute value of the positive pulse signal 20 is increased, and conversely, the absolute value of the negative pulse signal 21 is decreased. .
[0059]
In this control, ΔV is increased or decreased according to the degree of ion balance. As a modification, the absolute value of the negative pulse signal 21 may be fixed and only the absolute value of the positive pulse signal 20 may be increased. Conversely, the absolute value of the positive pulse signal 20 may be fixed and negative. Only the absolute value of the pulse signal 21 may be reduced.
[0060]
If necessary, a certain limit may be set to the value of ΔV in order to limit the maximum value of the voltage applied to the discharge electrode 4.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram of a pulse AC type static eliminator according to the present invention.
FIG. 2A is a diagram illustrating a state of a current flowing through a first resistor, and FIG. 2B is a diagram in which positive and negative detection values are plotted with time as a horizontal axis.
FIG. 3 is a diagram for explaining basic control of the discharge electrode when the ion balance is balanced according to the present invention.
FIG. 4 is a diagram for explaining basic control of a conventional discharge electrode.
FIG. 5 is a diagram for explaining control without applying a reverse voltage in order to understand the operation effect of the basic control of the present invention.
FIG. 6 is a diagram for explaining an example of feedback control of the discharge electrode according to the present invention when the ion balance is biased to the negative side.
FIG. 7 is a diagram for explaining an example of feedback control of the discharge electrode according to the present invention when the ion balance is biased to the plus side.
FIG. 8 is a diagram for explaining another example of feedback control of the discharge electrode according to the present invention when the ion balance is biased to the negative side.
FIG. 9 is a diagram for explaining another example of feedback control of the discharge electrode according to the present invention when the ion balance is biased to the negative side.
FIG. 10 is a diagram for explaining still another example of feedback control of the discharge electrode according to the present invention when the ion balance is biased to the negative side.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pulse AC type static elimination apparatus 2 Positive side high voltage generation circuit 3 Negative side high voltage generation circuit 4 Discharge electrode 10 GND plate 14 arrange | positioned in the vicinity of the discharge electrode Ion current detection circuit 15 CPU
FG Work Field Ground

Claims (3)

As a voltage applied to the common discharge electrode, positive and negative ions are generated from the common discharge electrode by alternately generating high voltages having different polarities in the positive high voltage generation circuit and the negative high voltage generation circuit. In a static eliminator that generates ions alternately,
Between the period for applying and discharging a positive voltage to the common discharge electrode and the period for discharging by applying a negative voltage and the period of applying and discharging the negative voltage and then the positive voltage In each of the periods of applying and discharging, an interval period in which no voltage is applied to the common discharge electrode is provided,
After applying the positive voltage to the common discharge electrode to generate positive ions, before entering the interval period, the negative voltage is applied so that the common discharge electrode is substantially neutralized. The negative voltage is applied to the common discharge electrode generated by the high voltage generation circuit on the side,
After applying the negative voltage to the common discharge electrode to generate negative ions, before entering the interval period, the positive voltage is applied so that the common discharge electrode is substantially neutralized. A static elimination device characterized in that the positive voltage is generated by a high voltage generation circuit on the side and applied to the common discharge electrode . A discharge electrode side ion balance detection means for detecting a current flowing between the GND plate and the discharge electrode, and having a GND plate in the vicinity of the discharge electrode;
And a control means for receiving a signal from the ion balance detection means and feedback-controlling the positive side and / or the negative side high voltage generation circuit so as to maintain the ion balance around the discharge electrode. The static eliminator of Claim 1 characterized by these. A workpiece-side ion balance detection means for detecting the ion balance in the vicinity of the workpiece;
Feedback control means for receiving the signal from the work side ion balance detection means and controlling the positive side and / or the negative side high voltage generation circuit so as to maintain the ion balance in the vicinity of the work. The static eliminator of Claim 1 or 2 characterized by the above-mentioned.

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