WO2013187383A1

WO2013187383A1 - Charge-neutralizing device

Info

Publication number: WO2013187383A1
Application number: PCT/JP2013/066011
Authority: WO
Inventors: 田中　幸一
Original assignee: シャープ株式会社
Priority date: 2012-06-11
Filing date: 2013-06-11
Publication date: 2013-12-19
Also published as: JP2013257952A

Abstract

A charge-neutralizing device imparts positive/negative ions generated by a discharge electrode to an object to be neutralized via a metal mesh plate, and is equipped with an ion monitor for detecting a positive/negative-ion-generation state, and a control means for adjusting the voltage of the metal mesh plate on the basis of the detection information detected by the ion monitor.

Description

Static eliminator

The present invention relates to a static eliminator that generates positive ions and negative ions and removes the charge of an object charged by the ions.

In the liquid crystal manufacturing process and semiconductor manufacturing process, the static eliminator plays an important role as an effective anti-static device against static electricity failure in the clean room. However, in accordance with the recent high integration and high speed response of semiconductors, it is necessary to miniaturize circuits and reduce the capacity, and electronic devices are becoming more sensitive to static electricity.

Along with this, the demand for static eliminators has been increasing year by year, and the demand for stability and low potential for ion balance of static eliminators has been increasing. Recently, in the semiconductor industry, ion balance control within ± 25V to ± 10V is required. Furthermore, it has been required to perform ion balance control in an area where the static eliminator performs static elimination.

Generally, the static eliminator generates air ions by forcibly ionizing surrounding air molecules to the positive electrode or the negative electrode. The generated air ions are struck against charged objects to neutralize static electricity. One method of ionizing air molecules is to generate a discharge phenomenon called corona discharge and ionize the air molecules by the generated discharge energy, and is widely used in ionization apparatuses.

In order to obtain the maximum effect of static elimination, it is necessary to adjust the balance so that the positive and negative ion generation amounts by the discharge of the discharge electrode included in the static elimination device are equal. However, the amount of positive and negative ions generated from the discharge electrode varies even when the same voltage is applied to the discharge electrode depending on conditions such as the temperature around the discharge electrode and the distance to the object to be discharged. In some cases, there is a problem that the object to be discharged is charged either positively or negatively.

FIG. 10 is a schematic diagram of the static eliminator 90 disclosed in Patent Document 1. The static eliminator 90 reduces the unevenness of static elimination by applying positive and negative ions generated between the discharge electrode 91 and the discharge ground electrode 92 to the static elimination object 94 through the mesh electrode 93 that is grounded or biased. ing.

Japanese Patent Laid-Open No. 2000-10056 (published April 7, 2000)

However, since the method of Patent Document 1 only applies grounding or bias to the mesh electrode, it does not finely adjust the ion balance, but changes in the surrounding environment over time, particularly temperature or humidity. The amount of positive and negative ions could not be controlled correctly with respect to the change of.

This invention is made | formed in view of said subject, The objective is to provide the static elimination apparatus which can adjust positive and negative ion amount appropriately.

A static eliminator according to the present invention is a static eliminator that applies positive and negative ions generated by a discharge electrode to a static eliminator through a mesh metal plate, the static eliminator comprising an ion monitor that detects the positive and negative ion generation state, and And a control means for adjusting the voltage of the mesh metal plate based on detection information detected by the ion monitor.

Further, the control means performs control so that a voltage having a polarity opposite to the ion polarity indicated by the detection information is applied to the mesh metal plate.

Further, the static eliminator may include switching means for selectively switching between positive and negative voltages applied to the mesh metal plate.

The voltage applied to the mesh metal plate may be a positive or negative DC voltage.

The static eliminator may include a fan that blows air from behind the discharge electrode and blows positive and negative ions together with air toward the mesh metal plate.

According to the present invention, it is possible to realize a static eliminator that can appropriately adjust the amount of positive and negative ions.

It is a schematic diagram of the static elimination apparatus which concerns on this invention. It is a circuit diagram of the positive / negative DC voltage generation circuit and ion balance control circuit of the static elimination apparatus which concerns on this invention. It is a conceptual diagram which shows an ion generation state and ion balance. It is a conceptual diagram which shows an ion generation state and ion balance. It is a conceptual diagram which shows the ion generation state and ion balance when adjusting ion balance. It is a conceptual diagram which shows an ion generation state and ion balance. It is a conceptual diagram which shows the ion generation state and ion balance when adjusting ion balance. It is a block diagram when the ion balance of the positive / negative ion generated from a static elimination apparatus is evaluated. It is a graph which shows the evaluation result of a static elimination apparatus. It is the schematic which shows a prior art.

Hereinafter, an example of an embodiment of the present invention will be described in detail. The following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention.

FIG. 1 is a schematic diagram of a static eliminator 100 according to an embodiment of the present invention. 1 includes an ion generation control circuit 10, a high voltage pulse generation circuit 11, a minus (−) discharge electrode 12, a plus (+) discharge electrode 13, a mesh metal plate 14, a changeover switch 15, a positive / negative DC voltage. The generating circuit 16, the ion balance control circuit 17, and the ion monitor 18 are comprised.

Using the drive pulse generated from the high voltage pulse generation circuit 11 under the control of the ion generation control circuit 10, negative ions from the negative (−) discharge electrode 12 and positive ions from the positive (+) discharge electrode 13 are generated. Generated. The generated positive and negative ions are sent to the object to be neutralized by a blower such as a fan.

On the other hand, a mesh metal plate 14 is installed in the vicinity of the discharge electrode between the minus (−) discharge electrode 12 and the plus (+) discharge electrode 13 and the object to be discharged. The mesh metal plate 14 is connected to a positive / negative DC voltage generation circuit 16 via a changeover switch 15, and the positive / negative DC voltage generation circuit 16 is connected to an ion balance control circuit 17. The ground line of the positive / negative DC voltage generation circuit 16 is connected to the earth line.

The ion monitor 18 is arranged in the vicinity of the mesh metal plate 14, detects ion information indicating an ion generation state such as ion concentration and ion polarity that has passed through the mesh metal plate 14, and transmits the detection information to the ion balance control circuit 17. To do. In the ion balance control circuit 17, optimal ion balance conditions are set in advance, and based on the detection information of the ion monitor 18, positive DC voltage value setting, negative DC voltage value setting, and which one is meshed It has a control function of determining whether to apply to the metal plate 14 and controlling the changeover switch.

Thus, based on the detection information of the ion monitor 18, the optimum ion balance can be maintained by the control of the ion balance control circuit. In addition, you may provide the fan 19 which ventilates from the back of a discharge electrode and blows out positive / negative ion to the mesh metal plate 14 side with air.

FIG. 2 shows details of the positive / negative DC voltage generation circuit 16 and the ion balance control circuit 17 shown in FIG. The positive / negative DC voltage generation circuit 16 is a voltage DC generation circuit using a Cockcroft-Walton circuit. The ion balance control circuit 17 is a boost chopper circuit configured using, for example, an LMC555 timer IC manufactured by National Semiconductor as the timer IC 26 and using, for example, a field effect transistor 2SK2232 manufactured by Toshiba as the MOSFET 28. A DC voltage can be generated from the pulse waveform by the Cockcroft-Walton circuit from a pulse waveform having a constant period (amplitude of 60 V when 2SK2232 is used) obtained by the step-up chopper circuit. The Cockcroft-Walton circuit is an ideal booster circuit consisting of only capacitors and diodes and operating without switching.

In the positive / negative DC voltage generation circuit 16 shown in FIG. 2, the capacitor 21 ′ connected to the right side of the capacitor 21 connected to the drain terminal 20 of the MOSFET 28 of the ion balance control circuit 17 is supplied to the capacitor 21 ′ every time the direction of the power supply voltage is reversed. A DC voltage twice the power supply amplitude is sequentially accumulated, and as a result, a boosted DC output is obtained in a direction in which these capacitors are connected in a daisy chain.

The output obtained can be made higher as the ladder made up of a plurality of capacitors is piled up horizontally. The positive / negative DC voltage generation circuit 16 has a negative (−) voltage generation circuit that can be amplified in five stages in the upper stage portion 24, and can generate a potential of 60V × 5 = 300V when a 60V pulse is used. I can do it. In the lower stage 25, a capacitor 21 'connected to the source terminal 22 of the MOSFET 28 is arranged in the direction opposite to the negative (-) voltage generator in the upper stage so that a positive (+) DC voltage can be generated. These outputs can be switched by the changeover switch 15.

Further, by controlling the applied voltage adjustment volume 23 connected to the sixth terminal 27 of the timer IC 26 in the ion balance control circuit 17, the pulse waveform cycle output to the drain terminal 20 of the MOSTFET 28 can be changed, and accordingly, The voltage value generated by the positive / negative DC voltage generation circuit 16 can be arbitrarily changed. Here, the effect of the positive / negative DC voltage generation circuit 16 and the ion balance control circuit 17 will be described using a conceptual diagram showing an ion generation state and ion balance.

FIG. 3 shows an example in which the ion balance is good when no potential is applied to the mesh metal plate 14. The ion generation control circuit 10, the high voltage pulse generation circuit 11, and the minus in the static eliminator 100 according to the present embodiment. In a state where positive or negative ions generated from a general ion generator 30 including the (−) discharge electrode 12 and the plus (+) discharge electrode 13 are uniformly generated, the balance is maintained near zero. Yes.

FIG. 4 shows a state in which the ion balance amount is shifted to the positive side because ions generated from the ion generator 30 are biased positively without applying a potential to the mesh metal plate 14. is there. In this state, the charge removal object cannot be correctly discharged.

FIG. 5 shows a state in which a minus (−) DC voltage is applied to the mesh metal plate 14 when the ions shown in FIG. 4 are biased to the plus (+) side and the ion balance is poor. When ions that are biased to plus (+) are attracted and reduced according to the strength of the DC voltage applied, the ion bias is reduced and the ion balance potential can be made close to zero. Thus, the ion balance potential can be adjusted by applying a DC voltage having a polarity opposite to the biased polarity to the mesh metal plate 14.

On the other hand, as shown in FIG. 6, when ions are biased to the minus (−) side and the ion balance is poor, as shown in FIG. 7, if a positive (+) DC voltage is applied to the mesh metal plate 14, the minus When ions that are biased toward (−) are attracted and reduced according to the strength of the DC voltage applied, the ion bias is reduced and the ion balance potential can be made close to zero.

FIG. 8 is a configuration diagram when the ion balance of positive and negative ions generated from the static eliminator 100 is evaluated in order to confirm the effect of the present invention. Using the drive pulse generated from the high voltage pulse generation circuit 11 by the ion generation control circuit 10, negative ions are generated from the minus (−) discharge electrode 12 and positive ions are generated from the plus (+) discharge electrode 13. The The generated positive and negative ions are sent to the object to be discharged by a blower such as a fan (not shown).

On the other hand, a mesh metal plate 14 is installed in the vicinity of the discharge electrode between the minus (−) discharge electrode 12 and the plus (+) discharge electrode 13 and the object to be discharged. Based on the detection information of the ion monitor 18, a control signal generated from the ion balance control circuit 17 is sent to the positive / negative DC voltage generation circuit 16.

The DC voltage generating circuit 16 generates a positive DC voltage and a negative DC voltage based on the setting of the positive DC voltage value and the setting of the negative DC voltage value, which are control contents of the control signal. The generated positive / negative DC voltage is sent to the changeover switch 15. In the changeover switch 15, the switch is switched based on which of positive and negative DC voltages, which is the control content of the control signal generated from the ion balance control circuit 17, is applied to the mesh metal plate 14. Apply a positive or negative DC voltage. Alternatively, a method of directly controlling each of the positive DC voltage and the negative DC voltage without providing the changeover switch 15 may be used.

As a method for evaluating the charge removal performance of the charge removal apparatus 100, a charge plate is generally used. In the present embodiment, a charge plate 80 manufactured by TRECK having a capacitance of 25 p and a capacitance of 2 pF is used, the charge plate 80 is once connected to the ground, the voltage of the charge plate 80 is once set to 0 V, and then the ion of the static elimination device 100 is used. Wind is applied to the charge plate 80. The potential amount is measured by measuring the potential of the charge plate 80 at that time with a surface potentiometer 81 connected to the charge plate 80. At this time, the distance between the positive and negative discharge electrodes of the charge removal apparatus 100 and the charge plate 80 was set to 300 mm.

In the measurement, it was confirmed that each of the two types of static elimination devices 100a and 100b was effective. Regarding the two types of static eliminators, the static eliminator 100a uses a conductive wire diameter of 0.5 mmφ in the mesh metal plate 14, and the static eliminator 100b uses a conductive wire diameter of 1.5 mmφ in the mesh metal plate 14. .

FIG. 9 is a graph showing the evaluation results of the static eliminators 100a and 100b. The horizontal axis represents the DC voltage value applied to the mesh metal plate 14 by the positive / negative DC voltage generation circuit 16, and the voltage was applied in the range of -300V to + 200V. The charge plate potential amount shown on the vertical axis indicates the average value of the potential amount when a predetermined voltage is applied to the mesh metal plate 14, and this is the ion balance potential amount. Further, the points indicated by circles in the graph are measurement point data of the static eliminator 100a and the points indicated by square marks are the measurement point data of the static eliminator 100b, and a linear straight line passing through them is drawn.

According to the measurement data of the static eliminator 100a in FIG. 9, the voltage applied to the metal mesh plate is around 0V, and the ion balance potential amount can be -8V to + 9V. In the case of the static eliminator 100b, the voltage applied to the metal mesh plate was around -200V, and the ion balance potential amount could be 0V to 18V. Further, as shown by the linear straight line shown in this graph, it can be seen that the ion balance potential amount is linearly proportional to the applied voltage value.

For example, when -200V is applied to the static eliminator 100a, the ion balance is stabilized around -25V. On the other hand, when + 200V is applied, it stabilizes near + 45V. For other measurement points, for example, an ion balance potential exists on a line that linearly connects the two points. The same applies to the static eliminator 100b, and when -300V is applied, it stabilizes in the vicinity of -26V. Moreover, when + 150V is applied, it stabilizes around + 145V. For other measurement points, for example, there is an ion balance potential on a line that linearly connects the above two points. From this, by controlling the applied voltage, the ion balance potential can be set to any value other than zero balance It becomes possible to easily control numerical values.

Here, the ion monitor 18 will be described. The ion monitor 18 is disposed in the vicinity of the mesh metal plate 14, detects ion information indicating an ion generation state such as the concentration and ion polarity of ions that have passed through the mesh metal plate 14, and transmits the detection information to the ion balance control circuit 17. To do. In the ion balance control circuit 17, optimum ion balance conditions are set in advance, and based on detection information from the ion monitor 18, positive DC voltage values and negative DC voltage values generated by the positive / negative DC voltage generation circuit 16. , And which one is applied to the mesh metal plate 14.

As described above, even when the ion balance is lost based on the detection information from the ion monitor 18, the optimum ion balance can be maintained by fine control of the ion balance control circuit based on the detection information from the ion monitor 18. .

In addition, the wire diameters constituting the mesh metal plate 14 are 0.5 mmφ and 1.5 mmφ conductive materials this time, but in the case of the 0.5 mmφ neutralization device 100 a having a small wire diameter, for example, ion balance is used. When controlling to ± 20V or less, the DC voltage applied to the mesh metal plate 14 can be 200V at the maximum. However, in the case of the static eliminator 100b having a wire diameter of about 3 times 1.5 mmφ, a higher voltage of 300V must be applied to the metal plate in order to obtain the same ion balance. If the conductivity of the wire is k, the resistance is R (Ω), the length is L (cm), and the cross-sectional area of the wire is S (cm ² ),
This is because, as indicated by k = (1 / R) × (L / S), the conductivity k of the wire constituting the mesh metal plate 14 is inversely proportional to the cross-sectional area S of the wire. That is, when the wire diameter increases, the circuit scale of the DC voltage generation circuit 16 increases, so that the apparatus becomes large and the cost of the apparatus itself increases. That is, the smaller the wire diameter, the higher the conductivity, so that the same effect can be obtained with a small voltage.

As described above, it was possible to finely adjust the ion balance by appropriately applying positive or negative DC voltage to the mesh metal plate installed in the vicinity of the discharge electrode based on the detection information of the ion monitor. In this embodiment, an example in which the positive / negative ion generation circuit has a common configuration in the static elimination device having a common configuration has been described, but the positive / negative ion generation circuit has a separate configuration. It is possible to apply also to.

The static eliminator and the balance adjustment circuit according to the present invention are widely applicable to static eliminators that generate positive ions and negative ions and remove the charge of an object charged by the ions.

DESCRIPTION OF SYMBOLS 10 Ion generation control circuit 11 High voltage pulse generation circuit 12 Minus (-) discharge electrode 13 Plus (+) discharge electrode 14 Mesh metal plate 15 Changeover switch 16 Positive / negative DC voltage generation circuit 17 Ion balance control circuit 18 Ion monitor 19 Fan 20 Drain Terminal 21, 21 'Capacitor 22 Drain terminal 23 Applied voltage adjustment volume 26 Timer IC
28 MOSFET
30 Ion generator 80 Charge plate 81 Surface potential meter 100, 100a, 100b Static neutralizer

Claims

A static elimination device that applies positive and negative ions generated by a discharge electrode to a static elimination object through a mesh metal plate,
The static eliminator includes an ion monitor that detects the positive / negative ion generation state,
Based on the detection information detected by the ion monitor,
A static eliminator comprising control means for adjusting the voltage of the mesh metal plate.
The control means includes
The static eliminator of Claim 1 which controls so that the voltage of the polarity opposite to the ion polarity which the said detection information shows may be applied to the said mesh metal plate.
3. The static eliminator according to claim 1 or 2, further comprising switching means for selectively switching between positive and negative voltages applied to the mesh metal plate.
3. The static eliminator according to claim 1 or 2, wherein the voltage applied to the mesh metal plate is a positive or negative DC voltage.
The static eliminator according to claim 1 or 2, further comprising a fan that blows air from behind the discharge electrode and blows positive and negative ions together with air toward the mesh metal plate.