JP2002025791A - Ac power source type ionizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electric charging of a destaticized object by electrostatic induction voltage caused by a corona discharge, and dispense with cleaning for discharge needles. SOLUTION: In this AC power source type ionizer, the plural discharge needles 17 are installed along the longitudinal direction of a bar-shaped insulative support body 18, an AC voltage is applied between the discharge needles 17 and a ground electrode (a counter ground plate 19) to generate positive and negative ions by the corona discharge, and the positive and negative ions are jetted to the static-destaticized object by high-pressure air to discharge the discharged object. The ionizer has an insulative casing 20 surrounding the discharge needles 17, the support body 18 and the ground electrode 19, and a grounded metal shield plate 11 installed, such that the shield plate 11 surrounds the casing 20. The discharge needles 17 are disposed inside the casing 20, while the positive and negative ions generated by the corona discharge are jetted from minute-diameter ion jet ports 12 formed in the casing 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor wafer or T
More specifically, the present invention relates to an ionizer such as an FT liquid crystal glass substrate, an MR head, and a GMR head for neutralizing a charged charge. Specifically, a plurality of discharge needles are arranged along the length direction of an insulating bar-shaped support. The present invention relates to a bar-shaped AC power supply type ionizer in which positive and negative ions are generated and ejected by applying a AC voltage to generate corona discharge.

[0002]

2. Description of the Related Art Conventionally, this type of ionizer has a large number of discharge needles arranged in an exposed state, and ions generated in the vicinity of these discharge needles are diffused by repulsive force of ions of the same polarity, or a discharge needle is used. In general, a method of injecting high-pressure air from near to diffuse ions. Especially A
In the C power supply type ionizer, since the positive and negative ions generated in the cycle of the AC power supply are present at a short distance, the recombination rate between the ions is high. For this reason, in order to obtain a sufficient neutralizing effect on the object to be neutralized moving directly below the ionizer, it is usual to arrange the ionizer at an interval of about 50 mm or less with respect to the object to be neutralized.

[0003]

As described above, in order to prevent recombination of positive and negative ions, the shorter the distance between the ionizer (discharge needle) and the object to be neutralized, the better. However, if the distance between the two is too short. An electrostatic induction voltage is generated in the object to be neutralized under the influence of the electric field formed by the discharge needle to which the high voltage is applied. When a high voltage of a commercial frequency is applied, the polarity of the electrostatic induction voltage changes 50 or 60 times per second, so that complete ionization is not performed by ions generated by the ionizer, and the surface of the object to be neutralized is not discharged. A voltage varying at 50 Hz or 60 Hz appears. This phenomenon cannot be observed with a charged plate monitor, which is an evaluation measuring instrument for an ionizer, due to the high frequency. In addition, when the object to be neutralized is a product that is weak in charging, such as a semiconductor wafer, a TFT liquid crystal glass substrate, an MR head, and a GMR head, the above-described effects of the electrostatic induction voltage cannot be ignored.

[0004] For example, when a positive electrostatic induction voltage is generated on the surface of a liquid crystal glass substrate moving on a transport line immediately below an ionizer, the positive and negative ions generated near a discharge needle are generated. Only negative ions are adsorbed on the surface of the glass substrate, and apparently the surface of the glass substrate is destaticized. However, when the glass substrate is separated from the discharge needle of the ionizer and the influence of the electrostatic induction is eliminated, the glass substrate remains negatively charged due to the negative ions adsorbed on the surface of the glass substrate.

As described above, when the charging phenomenon due to the electrostatic induction occurs, even if it appears that the charge is removed by the ionizer for a certain period of time, when the influence of the electrostatic induction is removed, the charged state is returned to complete the charge removal. Can not do.

Further, in the conventional bar-shaped ionizer, since a large number of discharge needles are arranged in an exposed state, dust around the discharge needles easily adheres to the discharge needles by electrostatic attraction, and a great amount of labor is required for cleaning. Is needed. Specifically, the discharge needles must be periodically cleaned using a cotton swab-shaped jig, which is an enormous operation when a large number of ionizers are installed. In particular, this type of ionizer is provided in a manufacturing apparatus of a manufacturing line for a semiconductor wafer, a liquid crystal or the like, and in order to clean the discharge needles, it is inevitable to stop the manufacturing line and clean the inside of the apparatus. These operations have instead led to the generation of dust, causing contamination of the inside of the apparatus and the object to be neutralized.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an AC power supply type ionizer which prevents charging of an object to be neutralized due to electrostatic induction and reduces labor, labor and cost of cleaning a discharge needle. .

[0008]

According to a first aspect of the present invention, a plurality of discharge needles are attached along a length direction of a bar-shaped insulating support member. An AC power supply type ionizer in which positive and negative ions are generated by corona discharge by applying an AC voltage between the ground electrode and the ground electrode, and the positive and negative ions are ejected to the object to be neutralized by high-pressure air to discharge the object. An insulating housing surrounding the discharge needle, the support and the ground electrode;
A metal shield plate attached to and surrounding the housing and grounded, wherein the discharge needle is disposed inside the housing and positive and negative ions generated by corona discharge are provided in the housing. Is injected from the small-diameter ion injection port formed on the substrate.

The invention according to claim 2 is the invention according to claim 1,
In a C power supply type ionizer, an ion level sensor made of a conductor is disposed in the internal space of the housing, and an ion current generated by positive and negative ions generated in the internal space and an induction current generated by electrostatic induction of the discharge needle are measured by the ion level sensor. This can be detected by a sensor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 is a perspective view showing the appearance of an ionizer according to the embodiment. In FIG. 1, this ionizer is formed in a substantially rectangular tube shape as a whole, and a grounded metal shield plate 11 covers a rectangular tube-shaped insulating casing 20 described later. A large number of ion injection ports 12 are arranged on the lower surface of the shield plate 11 along the length direction, and discharge needles (not shown) are respectively arranged above the inside of the ion injection ports 12.

A shielded high-voltage cable 13 is attached to one end of the ionizer in the length direction, so that a high AC voltage can be applied to the discharge needle inside the ionizer. An air inlet 14 is disposed below the high-pressure cable 13 so that high-pressure air can be introduced into the ionizer.

The ionizer is formed to have an arbitrary length of a few cm to about 200 cm so as to be applicable from a semiconductor wafer having a diameter of several cm to a wide liquid crystal glass substrate.

FIG. 2 is a longitudinal sectional view of FIG. In FIG. 2, reference numeral 15 denotes a high-voltage unit electrically connected to the high-voltage cable 13, to which an AC voltage of, for example, 5.3 kV is applied. A discharge needle 17 is attached to a lower end of the high-pressure part 15 via a discharge needle socket 16, and the ion injection port 12 is located immediately below the needle tip.

The high-pressure portion 15 and the discharge needle socket 16
A bar-shaped insulating support 18 is formed so as to surround the discharge needle 17. An opposing earth plate (earth electrode) 19 having a U-shaped cross section is disposed outside the support 18, and an insulating and rectangular cylindrical housing 20 surrounds the outside thereof. The ion injection port 12 described above is formed in the bottom plate 20A of the housing 20.
Are formed such that the diameter decreases along the ion injection direction, that is, downward. Also,
A through hole 11B is formed at a position of the bottom plate 11A of the shield plate 11 that matches the ion injection port 12.

Here, for example, the diameter of the outlet of the ion injection port 12 is 1 mm, the diameter of the through hole 11B is 8 mm, and the angle θ of the ion injection port 12 in the drawing is 15 °. The discharge needle 17 is disposed at a position deeper than the inner surface of the housing bottom plate 20A, and the distance L from the tip of the discharge needle 17 to the inner surface of the bottom plate 20A is 4.5 mm.

Further, an ion level sensor 21 made of a wire-like conductor is arranged at the inner corner of the casing 20 over the entire length of the casing 20. This ion level sensor 21
Is for detecting the ion current generated in the internal space of the ionizer and the induced current due to the electrostatic induction of the discharge needle 17. These ionic currents and induced currents are
Since the amount of deposits on the surface is small and the sharpness of the needle tip is large, the level sensor 21 constantly measures the ionic current and the induced current and compares them with a predetermined set value. It is possible to detect and display a decrease in ion level due to abrasion of the tip caused by adhesion or sputtering.

Next, the operation of the present embodiment will be described. FIG.
When a predetermined high voltage is applied to the high voltage portion 15 of the
An electric field is generated between the discharge needle 17 and the opposite ground plate 19.
A corona discharge is generated in the space around the tip of, and positive and negative ions are generated. These positive and negative ions are supplied to the air inlet 14.
Is injected from the ion injection port 12 to the object to be neutralized by the high-pressure air introduced from the nozzle.

At this time, since the outside of the opposing ground plate 19 is surrounded by the insulating casing 20, the electric field intensity outside the ionizer becomes small, and the electric charge to be removed is reduced as compared with the conventional structure in which the discharge needle is exposed. The influence of the electrostatic induction on the object can be considerably suppressed. However, with such a structure, ions existing in the housing 20 are not
As a result, the amount of ions is reduced, and the amount of ions ejected from the ion injection port 12 is reduced, resulting in a decrease in the static elimination effect. There is a risk of doing it.

Therefore, in this embodiment, the outer surface of the housing 20 is surrounded by the shield plate 11, and the shield plate 11 is grounded. As a result, the lines of electric force due to the ions adhering to the inner wall of the housing 20 terminate toward the shield plate 11, and apparently no charge is generated inside the housing 20. The rate at which the positive and negative ions generated in step (1) are neutralized with ions of the opposite polarity and disappear is reduced, and the amount of generated ions can be prevented from decreasing.

As described above, in the present embodiment, the ion injection efficiency can be increased, so that it is not necessary to arrange the discharge needle near the outlet of the ion injection port or to increase the diameter of the ion injection port as in the related art. As shown in FIG.
Is disposed inside the housing 20 and the diameter of the outlet of the ion injection port 12 is formed to be very small. According to the experiment of the inventor, the tip of the discharge needle 17 is arranged several mm inside from the injection port 12 and the diameter of the outlet of the injection port 12 is reduced to a small diameter of about 0.5 mm to 1.0 mm. The time required to attenuate the charge value of the object to be neutralized from ± 1000 V to ± 100 V when the object to be neutralized located at a position 50 mm below is neutralized is approximately 1 second or less.
It has been confirmed that sufficient performance can be exhibited.

FIGS. 3 to 8 are diagrams for comparing the effects of the prior art (an AC power supply type ionizer in which the discharge needle is exposed) and the present embodiment. In these figures,
The horizontal axis indicates time, and the vertical axis indicates voltage. That is, FIG. 3 is a diagram showing the electrostatic induction voltage on the surface of the object to be neutralized according to the prior art, and FIG.
Is -1000 when the charged object is neutralized.
FIG. 5 is a diagram showing a measurement of a required time (static elimination time) from V to -100 V, and FIG.
It is the figure which measured the time required until it becomes. FIG.
FIG. 7 is a diagram showing the electrostatic induction voltage on the surface of the object to be neutralized according to the embodiment of the present invention, and FIG. 7 is a diagram showing a measurement of the time required to change from −1000 V to −100 V when the object to be electrostatically charged is eliminated. FIG. 8 is also from + 1000V to +100
It is the figure which measured the time required until it becomes V. In any case, the distance from the ion injection port to the object to be neutralized is 50.
mm.

When FIG. 3 is compared with FIG. 6, according to the present embodiment, the electrostatic induction voltage of the object to be neutralized, which is remarkable in the prior art, is almost zero. Incidentally, the electrostatic induction voltage (large AC voltage on the positive side) according to the conventional technique shown in FIG. 3 cannot be observed by the charged plate monitor. Also, comparing FIGS. 4 and 7 and FIGS. 5 and 8, it can be seen that there is no significant difference in the static elimination time between the present embodiment and the prior art.

However, as shown in FIG. 3, in the prior art, charging due to an electrostatic induction voltage is generated on an object to be neutralized, and ions having the opposite polarity (mainly negative ions) are adsorbed on the charged charges to neutralize the charged objects. As a result, as shown in FIGS. 4 and 5, it is apparent that static elimination has been performed. However, since the static induction voltage decreases as the static elimination object moves away from the ionizer, the static elimination voltage decreases. The charged state due to the previously absorbed negative ions remains on the surface of the object. That is, the static elimination action shown in FIGS. 4 and 5 is apparent, and after a certain period of time, a negative voltage appears on the object to be neutralized, and it is clear that static elimination is not completely performed. .

On the other hand, in the present embodiment, as shown in FIG. 6, the electrostatic induction voltage is almost zero, and most of the ions generated by the corona discharge contribute to the neutralization of the object to be neutralized. It can be seen that the static elimination action shown in FIGS. 7 and 8 is reliable.

In this embodiment, the discharge needle 17 is not exposed, and the ion injection port 12 serving as an entrance for dust from outside has a very small diameter. As described above, if the ion current and the induced current are monitored by the ion level sensor 21, contamination and wear of the discharge needle 17 can be detected and displayed, so that appropriate cleaning of the discharge needle 17 can be performed. We can know time and exchange time.

[0026]

As described above, according to the present invention, the support for supporting the discharge needle is surrounded by the housing via the opposing ground plate, and the outside thereof is covered by the housing and the shield plate, and the shield plate is grounded. It has a unique structure. For this reason, the electrostatic induction voltage with respect to the object to be neutralized can be almost zero, and even if the discharge needle is arranged inside the housing and the ion injection port has a small diameter, the object to be neutralized can be reliably eliminated. Ionizer can be obtained. Further, since the effect of preventing contamination and wear of the discharge needle is great, the labor, labor, and cost required for cleaning or replacing the discharge needle can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external appearance of an ionizer according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of FIG.

FIG. 3 is a diagram showing an electrostatic induction voltage on the surface of an object to be neutralized according to a conventional technique.

FIG. 4 is a diagram illustrating a static elimination time according to the related art.

FIG. 5 is a diagram showing a static elimination time according to the related art.

FIG. 6 is a diagram showing an electrostatic induction voltage on the surface of an object to be neutralized according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating a static elimination time according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating a static elimination time according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Shield plate 11A Shield plate bottom plate 11B Through-hole 12 Ion injection port 13 High voltage cable 14 Air introduction port 15 High voltage part 16 Discharge needle socket 17 Discharge needle 18 Supporting body 19 Opposite earth plate (earth electrode) 20 Case 20A Case bottom plate 21 Ion level sensor

Claims (2)

[Claims] 1. A plurality of discharge needles are attached along the length of a bar-shaped insulating support, and an alternating voltage is applied between the discharge needles and a ground electrode to generate positive and negative ions by corona discharge. AC that generates and discharges the positive and negative ions to the object to be neutralized by high-pressure air
A power supply type ionizer, comprising: an insulating housing surrounding the discharge needle, the support, and the ground electrode; and a metal shield plate attached to surround the housing and grounded. An AC power supply type ionizer, wherein a discharge needle is disposed inside the casing and positive and negative ions generated by corona discharge are ejected from a small-diameter ion ejection port formed in the casing. 2. The ionizer according to claim 1, wherein an ion level sensor made of a conductor is disposed in an internal space of the housing, and an ion current generated by positive and negative ions generated in the internal space and a static electricity of the discharge needle. An AC power supply type ionizer, wherein an induced current due to electric induction can be detected by the ion level sensor.