JP2012079530A - Static eliminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a static eliminator capable of excellently detecting a current affected by discharge even if a pulse for discharge has high frequency.SOLUTION: The static eliminator comprises a high voltage generator for applying high-voltage pulses (PL1 and PL2) to an ignition electrode, a current detector for detecting currents (Ii and It) generated by the application of the high-voltage pulses to the ignition electrode at a prescribed detection interval, and a controller for controlling the high voltage generator. The controller controls the high voltage generator to generate high-voltage pulses having detection pulse widths (PW3 and PW4) wider than normal pulse widths (PW1 and PW2) when the currents are detected. The detection pulse widths (PW3 and PW4) cause the currents a steady-state period K2 after a transient period K1 caused by the application of high-voltage pulses having the detection pulse widths, and the currents (Ii and It) are detected during the steady-state period K2.

Description

  The present invention relates to a static eliminator, and more particularly to a technique for detecting a current related to a discharge in a static eliminator that discharges ions from a discharge toward an object to neutralize the object.

  Conventionally, as a technique for detecting a current related to discharge in the static eliminator, for example, Patent Document 1 discloses a technique for providing a detection resistor for detecting an ion current related to discharge between a power supply control device and a ground line. Has been.

JP 2009-53422 A

  In the static eliminator disclosed in the above-described prior art document, the generation amount of positive and negative ions can be detected by the detection resistance, and the ion balance of the static eliminator can be taken. However, if the frequency of the discharge pulse is increased in order to shorten the charge removal time of the work (object) by the charge removal device, the voltage change of the discharge pulse and the parasitic formed in the discharge pulse application path. Due to the capacity and the like, a transient state occurs in the ion current and the like, and there is a disadvantage that the current cannot be detected suitably.

  The present invention has been completed based on the above situation, and provides a static eliminator capable of suitably detecting a current related to discharge even when the frequency of a pulse for discharge is increased. With the goal.

  As a means for achieving the above object, a static eliminator according to a first invention is a static eliminator that discharges ions toward an object to neutralize the object, and discharges the ions by discharge. An electrode, a high voltage generator for generating a high voltage pulse for generating the ions, applying the high voltage pulse to the discharge electrode, and a current generated by applying the high voltage pulse to the discharge electrode A current detection unit that detects a detection cycle; and a control unit that controls generation of the high-voltage pulse by the high-voltage generation unit, wherein the control unit detects the high current during normal static elimination when the current is detected. The high voltage generator is controlled so as to generate a high voltage pulse having a detection pulse width that is wider than a normal pulse width that is a pulse width of the voltage pulse. Has been set to the pulse width so as to have a constant period after a transient period by applying a high voltage pulse width, the current detection unit detects the current in the steady period of the current.

  According to this configuration, when a current generated by applying a high voltage pulse to the discharge electrode is detected, a high voltage pulse having a detection pulse width wider than the normal pulse width is applied to the discharge electrode. The detection pulse width is set to a pulse width such that the current has a steady period after the transient period due to the application of the high voltage pulse having the detection pulse width, and the current is detected in the steady period of the current. Therefore, even when the frequency of the high voltage pulse (discharge pulse) during normal charge removal is increased, the current related to the discharge can be suitably detected.

According to a second aspect of the present invention, in the static eliminator of the first aspect, the high-voltage generation unit includes a positive high-voltage generation unit that generates a positive high-voltage pulse for generating positive ions, and a negative high level for generating negative ions. A negative high voltage generator that generates a voltage pulse, and the control unit includes the positive high voltage generator and the negative high voltage so that the positive high voltage pulse and the negative high voltage pulse are alternately applied to the discharge electrode. The high voltage generators are controlled so as to generate the plus high voltage pulse and the minus high voltage pulse having the detection pulse width when switching the generation unit and detecting the current by the current detection unit.
According to this configuration, even when the frequency of the high voltage pulse is increased in the device that generates positive ions and negative ions to neutralize the object, the discharge current of the high voltage pulse (discharge pulse) is preferably used. Can be detected.

According to a third aspect of the present invention, in the static eliminator of the first or second aspect, the current is an ionic current that returns to the high-voltage generation unit through the ground by the emission of the ions, and the current detection unit is the object An ion current detection resistor that detects the ion current when adjusting the ion balance at the time of static electricity removal, the control unit is based on the ion current detected by the ion current detection resistor, by the high voltage generation unit Control the generation of the high voltage pulse.
According to this configuration, since the ion current is appropriately detected when adjusting the ion balance, the ion balance can be adjusted accurately.

According to a fourth aspect of the present invention, in the static eliminator of the second or third aspect of the invention, the control unit has a detection pulse width of the plus high voltage pulse and a detection pulse width of the minus high voltage pulse. Each high pressure generator is controlled to be equal.
According to this configuration, when each current is detected corresponding to the plus high voltage pulse and the minus high voltage pulse, each current can be detected under the same conditions as the high voltage pulse.

According to a fifth aspect of the present invention, in the static eliminator of the third or fourth aspect of the present invention, the device further includes a counter electrode facing the discharge electrode, and the current detection unit detects the deterioration level of the discharge electrode. A cycle for detecting the discharge current, further comprising a discharge current detection resistor that detects a discharge current that is a sum of a counter electrode current flowing through the counter electrode and the ion current when a voltage pulse is applied to the discharge electrode; Is a period longer than the period for detecting the ion current.
According to this configuration, since the detection frequency of the discharge current for detecting the deterioration degree of the discharge electrode is optimized, the delay of the static elimination time due to the current detection is suppressed.

  According to the static eliminator of the present invention, it is possible to suitably detect the current related to the discharge even when the frequency of the discharge pulse is increased.

The block diagram which shows schematically the electric constitution of the static elimination apparatus which concerns on one Embodiment Time chart schematically showing each signal related to current detection

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
The static eliminator of this embodiment applies a positive high voltage pulse for generating positive ions and a negative high voltage pulse for generating negative ions alternately to a discharge electrode at a predetermined cycle.

1. FIG. 1 is a configuration diagram schematically showing the electrical configuration of the static eliminator 10, and FIG. 2 is a schematic time chart of signals according to the present embodiment.

  As shown in FIG. 1, the static eliminator 10 includes a discharge needle 2, a counter electrode 3, a reactive current feedback shield 4, a control circuit 5, a current detection circuit 6, a high voltage generation unit 20, and the like. In addition, the static eliminator 10 includes a rectifier circuit that generates a positive DC voltage (+ DC) to be supplied to the high voltage generator 20, but is omitted in FIG. 1.

  The discharge needle (an example of a discharge electrode) 2 generates positive ions or maonous ions by discharging to the counter electrode 3 by applying a high voltage pulse PL, and discharges the ions to the work (object to be neutralized).

  The current detection circuit (an example of a current detection unit) 6 detects an ion current detection resistor 6A for detecting the ion currents Ipi and Ini and a degree of deterioration of the discharge needle 2 in order to adjust the ion balance. And a discharge current detection resistor 6B for detecting the discharge current Ih. Here, the discharge current Ih is the sum of the counter electrode current It and the ion current Ii flowing through the counter electrode 3 when the high voltage pulse PL is applied to the discharge needle 2. Here, the ion currents Ipi and Ini are currents that return to the high-voltage generation unit 20 through the ground due to the release of ions from the discharge needle 2 by the application of the high voltage pulse PL.

  The ion balance is adjusted by comparing the ionic current Ipi when the plus high voltage pulse PL1 is applied with the ionic current Ini when the minus high voltage pulse PL2 is applied, and adding a high value so that the difference is zero. This is performed by adjusting the pulse width PW1 of the voltage pulse PL1 and the pulse width PW2 of the minus high voltage pulse PL2 (see FIG. 2).

  On the other hand, the degree of deterioration (wear / deterioration) of the discharge needle 2 is detected by, for example, storing the initial detection value of the discharge current Ih when the plus high voltage pulse PL1 or the minus high voltage pulse PL2 is applied. This is done when the difference between the current values exceeds a predetermined level.

  Here, the cycle Th for detecting the discharge current Ih for detecting the degree of deterioration of the discharge needle 2 is a cycle equal to or longer than the cycle Ti for detecting the ion current Ii for adjusting the ion balance when discharging the work. It is said. This is because, since it takes time to degrade the discharge needle 2 as compared with the ion balance adjustment interval, the detection frequency of the discharge current Ih may be less than or equal to the detection frequency of the ion current Ii. Here, for convenience of detection, for example, both the discharge current detection cycle Th and the ion current detection cycle Ti are set to 1 s (seconds) (see FIG. 2).

  The ion current detection resistor 6A is a resistor for detecting the ion currents Ipi and Ini generated by applying the high voltage pulses PL1 and PL2 to the discharge needle 2, and the detection value (voltage value) is a control circuit (of the current detection unit). Example) is supplied to 5. The control circuit 5 detects the ion currents Ipi and Ini at the predetermined detection cycle Ti (1 s) based on the detection value.

  The discharge current detection resistor 6B is a resistor for detecting the discharge current Ih, and the detection value (voltage value) is supplied to the control circuit 5. The control circuit 5 detects the discharge current Ih in the predetermined detection cycle Th based on the detection value.

  The high voltage generation unit 20 generates high voltage pulses PL1 and PL2 for generating positive ions or negative ions, and applies the high voltage pulses PL1 and PL2 to the discharge needle 2. Specifically, the high voltage generation unit 20 includes a plus high voltage generation unit 20A that generates a plus high voltage pulse PL1 for generating plus ions, and a minus high voltage generation unit that generates a minus high voltage pulse PL2 for generating minus ions. 20B.

  The configuration of the plus high voltage generation unit 20A is a configuration of a generally known high voltage generation circuit, and includes a changeover switch 21A, a plus side oscillation circuit 22A, a boosting transformer 23A, a voltage doubler generation circuit 24A, and an output resistor 25A. Similarly, the minus high voltage generator 20B includes a changeover switch 21B, a minus side oscillation circuit 22B, a boosting transformer 23B, a voltage doubler generation circuit 24B, and an output resistor 25B. Here, the plus high voltage generator 20A and the minus high voltage generator 20B are controlled by the control circuit 5 so as to control the switching time of the changeover switch 21A and changeover switch 21B. A high voltage pulse PL2 is generated. Here, the voltage of the plus high voltage pulse PL1 is, for example, +7 kV, and the voltage of the minus high voltage pulse PL2 is, for example, −7 kV. In addition, the structure which produces | generates plus high voltage pulse PL1, PL2 is not restricted to the structure of each plus high voltage production | generation part 20A, 20B.

  The reactive current feedback shield 4 is connected to the low voltage side terminal of the secondary coil of the step-up transformer 23A of the plus high voltage generator 20A, and the current flowing through the parasitic capacitance is supplied to the secondary side coil of the step-up transformer 23A. Return to.

The control circuit (an example of the control unit) 5 controls the generation of the high voltage pulse PL by the high voltage generation unit 20 based on the current detected by the current detection circuit 6.
Specifically, the control circuit 5 performs switching control of the plus high voltage generator 20A and the minus high voltage generator 20B so that the plus high voltage pulse PL1 and the minus high voltage pulse PL2 are alternately applied to the discharge needle 2. Specifically, as described above, the control circuit 5 controls the pulse widths PW1 and PW2 of the plus high voltage pulse PL1 and the minus high voltage pulse PL2 by controlling the switching time of the changeover switch 21A and the changeover switch 21B.

  When adjusting the ion balance, the control circuit 5 detects the ionic current Ipi when the plus high voltage pulse PL1 is applied and the ionic current Ini when the minus high voltage pulse PL2 is applied. As described above, the ion balance of the static eliminator is obtained by controlling the pulse widths PW1 and PW2.

  When detecting each ion current Ipi, Ini, as shown in FIG. 2, the control circuit 5 detects the pulse width of each high voltage pulse PL1, PL2 when each ion current Ipi, Ini is detected. The pulse widths PW3 and PW4 are set to be wider than the normal pulse widths PW1 and PW2, which are the pulse widths of the high-voltage pulses PL1 and PL2 at the time of normal static elimination. That is, each changeover switch 21A and changeover switch 21B are controlled so that the detection pulse widths PW3 and PW4 are wider than the normal pulse widths PW1 and PW2.

Here, the detected pulse widths PW3 and PW4 are set such that the detected ion currents Ipi and Ini have a steady state period K2 after the transient period K1 due to the application of the high voltage pulses PL1 and PL2. The control circuit (an example of a current detection unit) 5 detects each ion current Ipi, Ini at the timing of the steady period K2.
Here, the “steady period” means, for example, a period in which the amount of change in current per 1 ms is 1% or less of the maximum current value (maximum value of the transient current). The specific transient period K1 and steady period K2 are determined in advance by experiments or the like.

  In the present embodiment, the detection pulse widths PW3 and PW4 are set to, for example, 50 ms, which is five times the detection pulse widths PW3 and PW4, assuming that the normal pulse widths PW1 and PW2 are 10 ms, for example. That is, even when the plus high voltage pulse PL1 and the minus high voltage pulse PL2 are switched at a high frequency of 50 Hz (period T1 = 20 ms), the detection pulse widths PW3 and PW4 are set to 50 ms at the time of current detection. Thus, the control circuit (an example of the current detection unit) 5 can detect the current in the steady state period K2 of each of the ion currents Ipi and Ini. Therefore, each ion current Ipi, Ini can be accurately detected even when the frequency of the discharge pulses PL1, PL2 is increased from 10 Hz to 50 Hz, for example.

Note that the detection pulse widths PW3 and PW4 are set to 50 ms here is an example confirmed by experiments or the like in consideration of the transient period K1 (effect of transient current) and the steady period K2. Not.
Here, the ion current detection cycle Ti is preferably, for example, 10 times or more as long as the time obtained by adding the detection pulse widths PW3 and PW4 in order to suppress the influence of the current detection on the static elimination operation. Here, since the time obtained by adding the detection pulse widths PW3 and PW4 is 100 ms, the ion current detection cycle Ti is set to 1 s as described above.

  In the present embodiment, the control circuit 5 switches the selector switches 21A and 21B so that the detection pulse width PW3 of the plus high voltage pulse PL1 is equal to the detection pulse width PW4 of the minus high voltage pulse PL2. Control timing. Therefore, each ion current Ipi, Ini can be detected under the same conditions as the applied pulse. Note that the detection pulse width PW3 and the detection pulse width PW4 are not necessarily equal. In short, the detection pulse widths PW3 and PW4 may be pulse widths that can ensure the steady period K2 for detecting the current.

Also, when detecting the discharge current Ih when detecting the degree of deterioration (wear / deterioration) of the discharge needle 2, the control circuit 5 detects the ion currents Ipi and Ini as shown in FIG. Similarly, the detection pulse widths PW3 and PW4 that are the pulse widths of the high-voltage pulses PL1 and PL2 when the discharge current Ih is detected are set to the normal pulse widths of the high-voltage pulses PL1 and PL2 at the time of normal discharge. The pulse width is wider than the pulse widths PW1 and PW2.
In addition, although the magnitude | sizes of the ion current Ii and the discharge current Ih differ, the waveform of the current Ii and the waveform of the discharge current Ih become a waveform substantially the same (refer FIG. 2).

2. Effects of the Embodiment When detecting each ion current Ipi, Ini or discharge current Ih for adjusting the ion balance or detecting the deterioration degree of the discharge needle 2, the detection pulse width PW3, which is a pulse width wider than the normal pulse widths PW1, PW2, is detected. High voltage pulses PL1 and PL2 of PW4 are applied to the discharge needle 2. At that time, the detection pulse widths PW3 and PW4 are set to pulse widths such that the currents Ipi, Ini and Ih have a steady period K2 after the transition period K1 due to application of the high voltage pulses PL1 and PL2 having the detection pulse widths PW3 and PW4. The currents Ipi, Ini, and Ih are detected during the stationary period K2. Therefore, even when the frequency of the high voltage pulse (discharge pulse) at the time of normal charge removal is increased, the currents Ipi, Ini, and Ih related to the discharge can be suitably detected. In particular, when the ion balance is adjusted, the ion currents Ipi and Ini are appropriately detected, so that the ion balance can be adjusted accurately.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the above embodiment, as the static eliminator 10, the discharge needle (discharge electrode) 2 is provided with a plus high voltage pulse PL1 for generating plus ions and a minus high voltage pulse PL2 for generating minus ions. Although an example of alternately applying at a predetermined cycle has been shown, the present invention is not limited to this. The present invention provides, for example, a static eliminator that generates only a plus high voltage pulse PL1 or only a minus high voltage pulse PL2 and applies only a plus high voltage pulse PL2 or only a minus high voltage pulse PL2 to the discharge electrode 2. Is also applicable.

2 ... discharge needle (discharge electrode)
3 ... Counter electrode 5 ... Control circuit (control unit, current detection unit)
6 ... Current detection circuit (current detection unit)
6A ... Ion current detection resistor 6B ... Discharge current detection resistor 10 ... Static eliminator 20 ... High voltage generator 20A ... Plus high voltage generator 20B ... Minus high voltage generator

Claims (5)

A static eliminator that discharges ions toward an object to neutralize the object,
A discharge electrode for discharging the ions by discharge;
Generating a high voltage pulse for generating the ions, and applying a high voltage pulse to the discharge electrode;
A current detector for detecting a current generated by application of the high voltage pulse to the discharge electrode at a predetermined detection period;
A control unit that controls generation of the high-voltage pulse by the high-voltage generation unit,
When the current is detected, the control unit generates the high voltage pulse having a detection pulse width that is wider than a normal pulse width that is a pulse width of the high voltage pulse at the time of normal discharge. Control the generator,
The detection pulse width is set to a pulse width such that the current has a stationary period after a transient period due to application of a high voltage pulse of the detection pulse width,
The current detection unit is a static eliminator that detects the current during a steady period of the current. The high-pressure generator is
A plus high voltage generator for generating a plus high voltage pulse for generating plus ions, and a minus high voltage generator for generating a minus high voltage pulse for generating minus ions,
The controller is
The plus high voltage generator and the minus high voltage generator are switched and controlled so that the plus high voltage pulse and the minus high voltage pulse are alternately applied to the discharge electrode,
2. The static eliminator according to claim 1, wherein when detecting the current by the current detection unit, each high-voltage generation unit is controlled to generate the plus high voltage pulse and the minus high voltage pulse having the detection pulse width. . The current is an ion current that returns to the high-voltage generation unit through the ground by the emission of the ions,
The current detection unit includes an ion current detection resistor that detects the ion current when adjusting the ion balance when neutralizing the object,
3. The static eliminator according to claim 1, wherein the control unit controls generation of the high voltage pulse by the high voltage generation unit based on an ion current detected by the ion current detection resistor.   The charge removal unit according to claim 2 or 3, wherein the control unit controls each high-voltage generation unit so that a detection pulse width of the plus high voltage pulse is equal to a detection pulse width of the minus high voltage pulse. apparatus. A counter electrode facing the discharge electrode;
The current detection unit is a sum of a counter electrode current flowing through the counter electrode and the ion current when the high voltage pulse is applied to the discharge electrode in order to detect a deterioration degree of the discharge electrode. A discharge current detecting resistor for detecting the discharge current;
5. The static eliminator according to claim 3, wherein a period for detecting the discharge current is a period equal to or longer than a period for detecting the ion current.

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