JPH11345697A - Static eliminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely eliminate static by variably controlling strength of discharge in compliance with a capacitance size of an object to be statically eliminated and a static eliminating condition. SOLUTION: A surface potential of an object 1 to be statically eliminated is measured by a surface potentiometer sensor 2. An output signal is inputted to a recorder 9 and an A/D converting part 4. The measured value converted to a digital signal by the A/D converting part 4 is inputted to an arithmetic processing part 5. In the arithmetic processing part 5, a size of an applied voltage to apply (in a direction of attenuating the charge) to a discharge electrode needle 8 is determined from the surface potential value inputted, by using a specific table, functions or the like. A voltage outputted from a D/A converting part 6 is amplified to a determined applied voltage by using an amplifier 7, and is applied to the discharge electrode needle 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static eliminator used in fields requiring precise static elimination, such as IC and liquid crystal panel production.

[0002]

2. Description of the Related Art Generally, a static eliminator is of a type in which a high voltage is applied to a needle provided in the device and a charge is released by corona discharge from the needle tip, and a type in which air molecules are excited by irradiation with soft X-rays or the like. They are roughly divided into Those that use radiation
Since strict shielding is required for safety, a high voltage application type is widely used. For the high voltage application type,
Simultaneously or alternately generate negative discharges to remove electricity, but if the balance of discharge of either polarity is lost,
Since the object to be neutralized is reversely charged, many attempts have been made to keep the discharge amount constant. Further, in order to shorten the charge elimination time, some devices have been devised to measure the surface potential of the charge removal target and to prolong the discharge time of a polarity effective for charge elimination when alternately discharging.

[0003]

In a conventional high-voltage applying type static eliminator, if the output is adjusted with reference to the static elimination object having a large capacitance, when the static elimination object having a small capacitance comes, ,
The surface potential of the object greatly fluctuated, and the charge could not be accurately removed. Conversely, if the output is adjusted based on the object to be neutralized having a small capacitance, when an object having a large capacitance comes, the static elimination time becomes longer, which is not practical. Further, for an object having a large charge amount, the charge elimination time can be shortened by increasing the discharge time of the polarity for canceling the charge. However, because the intensity of the discharge cannot be varied,
For an object having a small capacitance, the surface potential greatly fluctuates, and precise static elimination cannot be performed. Further, in the conventional technology, since the static elimination state of the static elimination object when static elimination is performed cannot be confirmed, if the static elimination state changes due to some state change, the static elimination object is not sufficiently neutralized, or the reverse. In some cases, the battery may be charged, thereby deteriorating the production yield and stability.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a static eliminator capable of performing precise static elimination by variably controlling the intensity of discharge in accordance with the capacitance of the object to be neutralized and the static elimination state. .

[0005]

According to the first aspect of the present invention, at least one discharge electrode needle for generating a corona discharge to an object to be neutralized by applying an applied voltage, and a surface potential of the object to be neutralized is reduced. A surface voltmeter for continuously measuring, an arithmetic processing means for calculating the applied voltage for converging the surface potential of the object to be removed to zero according to the measured surface potential, and the discharge electrode needle for calculating the applied voltage obtained by the calculation. And a voltage output means for outputting a voltage to the discharge electrode needle by feeding back a measurement result of the surface voltmeter to the arithmetic processing means.

According to a second aspect of the present invention, there is provided the static eliminator according to the first aspect, wherein the arithmetic processing means calculates the capacitance of the object to be neutralized from the fluctuation of the measured surface potential and applies the surface potential in advance. A reference function indicating a voltage relationship is set for each of the capacitance ranges, and the calculation is performed by switching to the reference function corresponding to the capacitance.

According to a third aspect of the present invention, there is provided the static eliminator according to the first aspect, further comprising capacitance sensing means for sensing the magnitude of the capacitance of the object to be neutralized, and the arithmetic processing means. ,
A reference function indicating the relationship between the surface potential and the applied voltage is set in advance for each of the capacitance ranges, and the calculation is performed by switching to the reference function corresponding to the capacitance.

According to a fourth aspect of the present invention, in the static eliminator according to the third aspect, the capacitance sensing means continuously senses and calculates the capacitance value of the object to be neutralized by the arithmetic processing means. Feedback.

According to a fifth aspect of the present invention, there is provided the static eliminator according to any one of the first to third aspects, further comprising a monitoring means for monitoring a state of a surface potential of the object to be neutralized.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a static eliminator according to the present invention. As shown in FIG. 1, the static eliminator includes a surface voltmeter sensor 2, a surface voltmeter 3, an A / D converter 4, an arithmetic processing unit 5, a D / A converter 6, an amplifier 7, a discharge electrode needle 8, It comprises a recorder 9.

The object to be neutralized 1 is placed under a static eliminator, and the surface potential of the object to be neutralized is measured by a surface voltmeter sensor 2.
The measurement signal is output from the surface electrometer 3 as an analog signal. The output signal is input to the recorder 9 and the A / D converter 4. Since the recorder 9 is used as monitoring means for monitoring the measured value from the outside, the recorder 9
Alternatively, a meter or a digital display may be used. The measured value converted into a digital signal by the A / D converter 4 is input to the arithmetic processing unit 5. Here, the arithmetic processing unit 5
May be a personal computer or a one-chip microcomputer.

The arithmetic processing unit 5 determines the magnitude of the applied voltage (polar direction for attenuating the charge) to be applied to the discharge electrode needle 8 from a prescribed table or a function from the input surface potential value. In the present embodiment, the arithmetic processing unit 5
The voltage applied to the discharge needle 8 corresponding to the measured surface potential is determined based on the function 2-1 shown in FIG. The determined applied voltage value is input to the D / A converter 6 and converted into an analog signal. In general, the D / A converter 6 does not generate a high voltage (in the order of ± several kV or more) at which the discharge electrode needle can sufficiently discharge, so that the analog signal is amplified using the amplifier 7 up to the determined applied voltage. It is output and applied to the discharge electrode needle 8. Here, the output voltage of the amplifier 7 can output both positive and negative poles.
Outputs a voltage of the opposite polarity to the surface potential. The discharge electrode needle 8 is
Although a single needle has been described, a plurality of needles may be used. In addition, the discharge electrode needle 8 may be a thin metal wire of a scorotron type removing machine. The discharge electrode needle 8 to which the high voltage is applied generates a corona discharge at the tip to release electric charges, and attenuates the surface potential of the object 1 to be converged to zero. The surface potential of the object to be neutralized 1 is continuously measured by the surface voltmeter 3, and the surface potential after decay is similarly A / D converted and fed back to the arithmetic processing unit 5. Thus, the surface potential of the object 1 is further attenuated so as to converge to zero.

Further, the arithmetic processing unit 5 obtains a difference (variation amount) between the surface potential before attenuation and the surface potential after attenuation. The case where this fluctuation amount is small is the case where the capacitance of the object 1 is large. The charge removal target 1 having a large capacitance requires a large amount of charge to attenuate the surface potential. for that reason,
By increasing the applied voltage with respect to the surface potential (increasing the amount of discharge), the charge elimination time can be reduced.

Therefore, when the capacitance is large, the function 2-1 (see FIG. 2B) in which the applied voltage is increased is switched from the previously used function 2-1 of the surface potential and the applied voltage to the function 2-1. Perform the operation. Conversely, when the fluctuation amount is large, the capacitance of the object to be removed is small. If the same function 2-1 is continuously used, the fluctuation of the surface potential due to static elimination is large, and it is difficult to control the surface potential to converge to zero. Therefore, as shown in a function 2-3 (see FIG. 2C), the function is switched to a function that reduces the applied voltage. In the explanation, three types of functions are shown: one for reference, one for low capacitance, and one for high capacitance. However, it is also possible to perform more detailed cases and increase the number of functions. Although the function is shown as a linear function, a function that changes in a curved or stepwise manner may be used. The switching of the reference function by the capacitance may be performed first and fixed as it is, or the capacitance may always be calculated and switched together with the measurement of the surface potential. If the capacitance of the object to be neutralized is known to be constant beforehand, the reference function 2-
If 1 is set so as to be optimal for the capacitance, no switching operation occurs and no time is wasted.

In this manner, the applied voltage function is switched according to the capacitance of the object 1 to be removed, and the charge removal is continued. The surface potential of the object 1 is measured, the applied voltage is determined by comparing the surface potential with the function, the voltage is amplified, and the operation of discharging from the discharge electrode needle 8 is repeated. No discharge occurs. When the surface potential is near zero, almost no discharge occurs, so that even if the surface potential goes beyond zero, reverse charging does not occur, and as a result, static elimination on the order of several volts is possible. Further, if the surface potential of the object to be neutralized 1 rises due to some external influence after the surface potential has been attenuated to near zero, the discharge electrode needle 8 is discharged again in accordance with the surface potential, and the static elimination is performed. Is performed.

In this embodiment, an A / D converter is provided in the input unit. However, an analog signal may be directly used without using the A / D converter in the input unit. When determining the applied voltage to the discharge electrode needle 8, instead of using the graph of the applied voltage function, a table showing the relationship between the surface potential and the applied voltage can be used. Also, if it is known in advance that the capacitance of the object to be neutralized is constant,
A table, a function, or the like corresponding to the capacitance may be registered. Further, the capacitance of the object to be neutralized has been obtained by the arithmetic processing unit, but may be measured by using a capacitance measuring device. In this case, the measuring device always (continuously) measures the capacitance of the object to be neutralized and feeds it back to the arithmetic processing unit.

[0017]

According to the present invention, the surface potential of the object to be neutralized is constantly measured during static elimination, and the measurement result of the surface voltmeter is fed back to the arithmetic processing means to vary the voltage applied to the discharge electrode needle. Therefore, precise static elimination is possible. Also,
Since the capacitance of the object to be neutralized is calculated and calculated according to a predetermined reference function for the magnitude of the capacitance,
Furthermore, static elimination can be performed with high accuracy, and the static elimination time can be shortened. By feeding back the capacitance to the arithmetic processing means, a change in the capacitance of the object to be neutralized is also sensed, and more precise static elimination becomes possible. In addition, since the charged state of the surface potential of the object to be neutralized and the state of static elimination can be monitored, it is possible to contribute to stable production operation and product stability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a static eliminator according to the present invention.

FIG. 2 is a graph showing a reference function of an applied voltage with respect to a capacitance of an object to be neutralized.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 object to be removed 2 surface voltmeter sensor 3 surface voltmeter 4 A / D converter 5 arithmetic processing unit 6 D / A converter 7 amplifier 8 discharge electrode needle 9 recorder

Claims (5)

[Claims] At least one discharge electrode needle for generating a corona discharge to an object to be neutralized by applying an applied voltage, a surface potentiometer for continuously measuring the surface potential of the object to be neutralized, and a measurement Computing processing means for calculating the applied voltage for converging the surface potential of the object to be removed to zero according to the surface potential, and voltage output means for outputting the applied voltage obtained by the calculation to the discharge electrode needle, A static eliminator, wherein a measurement result of the surface voltmeter is fed back to the arithmetic processing means to vary a voltage applied to a discharge electrode needle. 2. The arithmetic processing means calculates an electrostatic capacity of an object to be neutralized from a variation in a measured surface potential value, and a reference function indicating a relationship between a surface potential and an applied voltage is set in advance for each of the electrostatic capacity ranges. The static eliminator according to claim 1, wherein the calculation is performed by switching to the reference function corresponding to the capacitance. 3. The apparatus according to claim 2, further comprising: capacitance sensing means for sensing the magnitude of the capacitance of the object to be neutralized, wherein the arithmetic processing means determines in advance that the reference function indicating the relationship between the surface potential and the applied voltage is the static function. The static eliminator according to claim 1, wherein the static elimination device is set for each capacitance range and is operated by switching to the reference function corresponding to the capacitance. 4. The static eliminator according to claim 3, wherein the capacitance sensing unit continuously performs sensing and feeds back a value of the capacitance of the object to be neutralized to the arithmetic processing unit. 5. A monitoring device for monitoring a state of a surface potential of an object to be neutralized is provided.
The static eliminator according to 2, 3, or 4.