Patent Description:
It has been conventionally known that in a step of processing or handling a semiconductor substrate, a liquid crystal substrate, or an organic EL substrate in a semiconductor, liquid crystal, or organic EL manufacturing process, static electricity is charged on a surface of the substrate and the static electricity causes a trouble that a circuit of the semiconductor substrate, liquid crystal substrate, or organic EL substrate breaks. In addition, electric charging on each substrate also causes a trouble that dust adheres to its surface.

As measures against such troubles, a static electricity removal apparatus that generates ions for preventing electric charging and removing static electricity on a substrate surface is installed in semiconductor, liquid crystal, and organic EL manufacturing apparatuses. As the static electricity removal apparatus, a corona discharge static electricity removal apparatus that ionizes air by high voltage and a soft X-ray static electricity removal apparatus that irradiates air with a soft X ray to ionize air are provided.

In the corona discharge static electricity removal apparatus, particles from an electrode are generated at the time of discharge; while in the soft X-ray static electricity removal apparatus, particles do not occur but leakage of soft X-rays affects human bodies. Thus, both have their respective demerits.

Under the circumstances, a soft X-ray static electricity removal apparatus that takes out only ionized air and does not allow leakage of a soft X-ray to the outside has been developed; however, its structure is complicated. Therefore, one of the inventors has previously proposed a soft X-ray shielding sheet that can prevent leakage of soft X rays from a discharge port with a simple structure by allowing soft X-rays that enter from a supply port to hit a passage at least three or more times before reaching the discharge port so that their travel in a straight line is prevented to make the soft X-rays attenuated or disappear (see Patent Literature <NUM>).

Document <CIT> discloses a soft X-ray shielding sheet that includes a first external layer sheet having a supply opening for supplying ionized air, an intermediate layer sheet having an ionized air flow-in opening communicating with the supply opening; and a second external layer sheet having a discharge opening communicating with the ionized air passage. The sheets are overlaid on one another and boded. One or more ionized air passages <NUM> are provided to communicate with the supply opening, the ionized air passage, and the discharge opening.

Document <CIT> discloses an ion gas generator including a cylindrical body containing an inlet and a gas blowoff port of the gas, the cylindrical body, inlet a gas supply means for flowing gas from, provided on the air outlet of the tubular body, and a perforated plate having a plurality of fine through holes, the radiation and the gas of X-ray in the desired region of the tubular body inside which the gas has flowed, comprising an X-ray generating tube to ionize.

Patent Literature <NUM>
International Publication No. <CIT>.

However, as semiconductors and the like are increasingly miniaturized, a demand for further increasing the amount of ionized air discharged and in addition, a demand for adjusting the amount of positive ions/negative ions have been arising. Therefore, it is an object of the present invention to provide a soft X-ray static electricity removal apparatus that achieves a further increase in the amount of ionized air discharged with a simple structure. Furthermore, it is an object of the present invention to provide a soft X-ray static electricity removal apparatus that can adjust the amount of positive ions/negative ions discharged.

To solve the above problem, a soft X-ray static electricity removal apparatus <NUM> according to a first aspect of the present invention includes, as illustrated in <FIG> for example, a soft X-ray generation device <NUM>, a container <NUM>, a soft X-ray shielding sheet <NUM>, and an insulating layer <NUM>. The soft X-ray generation device <NUM> generates soft X-rays <NUM> for ionizing air <NUM>. The container <NUM> has an outlet <NUM> from which ionized air <NUM> that has been ionized by the soft X-rays <NUM> flows out. The soft X-ray shielding sheet <NUM> is used at the outlet <NUM> of the container <NUM> and includes a first outer sheet <NUM> that is formed of a material opaque to the soft X-rays <NUM>, an interlayer sheet <NUM> that is formed of a material opaque to the soft X-rays <NUM>, and a second outer sheet <NUM> that is formed of a material opaque to the soft X-rays <NUM>. The first outer sheet <NUM> has supply ports <NUM> for the ionized air <NUM> formed therein. The interlayer sheet <NUM> has an ionized air passage <NUM> including ionized air inlet openings <NUM>, which communicate with the supply ports <NUM>, formed therein. The second outer sheet <NUM> has a discharge port <NUM>, which communicates with the ionized air passage <NUM>, formed therein. The first outer sheet <NUM>, the interlayer sheet <NUM>, and the second outer sheet <NUM> are stacked and adhered. The supply ports, the ionized air passage, and the discharge port communicate with each other to provide an ionized air transmission portion <NUM>. The insulating layer <NUM> insulates the soft X-ray shielding sheet <NUM> and the container <NUM> from each other.

In this configuration, air can be ionized by soft X-rays, the soft X-rays can be shielded while allowing passage of the ionized air with the soft X-ray shielding sheet, and further the soft X-ray shielding sheet is insulated from the container. Thus, the ionized air is not trapped by the soft X-ray shielding sheet and the amount of ionized air discharged increases.

In a soft X-ray static electricity removal apparatus <NUM> according to a second aspect of the present invention, as illustrated in <FIG> for example, the ionized air passage <NUM> extending from the supply ports <NUM> to the discharge port <NUM> has a bent portion <NUM>. In this configuration, the ionized air passage through which ionized air flows has the bent portions and this increases the number of times soft X-rays hit the ionized air passage during passing through the passage, thereby making the soft X-rays difficult to pass.

In a soft X-ray static electricity removal apparatus <NUM> according to the present invention, as illustrated in <FIG> for example, the insulating layer <NUM> is formed of ceramic. In this configuration, the insulating layer is formed of ceramic and this prevents deterioration due to soft X-rays.

In a soft X-ray static electricity removal apparatus <NUM> according to the present invention, as illustrated in <FIG> for example: the soft X-ray shielding sheet <NUM> has a circular cross section; and the insulating layer <NUM> has a plurality of arc-shaped ceramics <NUM> which are arranged so as to surround an outer periphery of the soft X-ray shielding sheet <NUM>. The insulating layer has a plurality of arc shaped ceramics and this prevents deterioration due to soft X-rays and prevents cracks at both the time of manufacture and the time of use.

A soft X-ray static electricity removal apparatus <NUM> according to an embodiment further includes, as illustrated in <FIG> for example, a power supply device <NUM> that applies a potential difference to the container <NUM> and the soft X-ray shielding sheet <NUM>. In this configuration, a potential difference can be applied to the container and the soft X-ray shielding sheet and this allows adjustment of the amount of positive ions/negative ions.

A soft X-ray static electricity removal apparatus <NUM> according to an embodiment further includes, as illustrated in <FIG> and <FIG> for example, a casing <NUM> that holds the insulating layer <NUM> at the outlet <NUM> of the container <NUM> so as to have the insulating layer <NUM> and the soft X-ray shielding sheet <NUM> arranged at the outlet <NUM> and that has a gap <NUM> between itself and the soft X-ray shielding sheet <NUM>. In this configuration, soft x-rays are prevented from leaking from between the casing and the soft X-ray shielding sheet.

According to the soft X-ray static electricity removal apparatus of the present invention, air can be ionized by soft X-rays, the soft X-rays can be shielded while allowing passage of the ionized air with the soft X-ray shielding sheet, and further the soft X-ray shielding sheet is insulated from the container. Thus, the amount of ionized air discharged can be increased. In addition, by applying a potential difference to the container and the soft X-ray shielding sheet, the amount of positive ions/negative ions discharged can be adjusted.

This application is based on <CIT> in Japan.

The present invention will also be more fully understood from the following detailed description. However, the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given for illustrative purposes only. From this detailed description, various changes and modifications will be apparent to those skilled in the art.

The use of the terms "a" and "an" and "the" and similar referents in the context herein or the context of the claims are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of any examples, or exemplary language (e. , "such as") provided herein, is intended merely to better illustrate the present invention and does not pose a limitation on the scope of the invention unless otherwise claimed.

Hereinafter, an embodiment of the present invention will be described with reference to drawings. It should be noted that in the drawings, the same or corresponding devices are denoted by the same reference numerals, thereby omitting redundant descriptions thereof. First, with reference to <FIG>, a soft X-ray static electricity removal apparatus <NUM> of the present invention will be described.

The soft X-ray static electricity removal apparatus <NUM> includes a container <NUM> that provides a space in which air is ionized and through which ionized air <NUM>, which has been ionized, flows. The container <NUM> has an air inlet <NUM> that takes air <NUM> into the container <NUM>. The air inlet <NUM> may include a fan to forcibly take the air <NUM> outside the container <NUM> into the container <NUM>. In the container <NUM>, a soft X-ray generation device <NUM> is arranged near a position where the air inlet <NUM> is provided. Soft X-rays <NUM> are generated from the soft X-ray generation device <NUM> and air is irradiated therewith within the container <NUM>; thereby the air is ionized. The soft X-ray generation device <NUM> may be a known soft X-ray device and thus, detailed description thereof is omitted. On the container <NUM>, an outlet <NUM> for the ionized air <NUM> is formed at a position away from a position where the air inlet <NUM> is provided. By providing the soft X-ray generation device <NUM> near the air inlet <NUM> and providing the outlet <NUM> at a position away from the air inlet <NUM>, air is caused to flow from the air inlet <NUM> to the outlet <NUM>, the air can be ionized by the soft X-rays <NUM> from the soft X-ray generation device <NUM>, and the ionized air <NUM> is discharged from the outlet in a short period of time. Thus, this arrangement is preferable; but other arrangements are acceptable. In general, the container <NUM> is formed by stainless steel or other metal.

At the outlet <NUM>, a soft X-ray shielding sheet <NUM> is arranged. That is, the ionized air <NUM> is discharged from the container <NUM> by passing through the soft X-ray shielding sheet <NUM>.

Here, with reference to <FIG> and <FIG>, an ionized air transmission portion <NUM> of the soft X-ray shielding sheet <NUM> through which the ionized air <NUM> passes is described. <FIG> is a cross-sectional view in the vicinity of the ionized air transmission portion <NUM> of the soft X-ray shielding sheet <NUM>; and <FIG> is an exploded perspective view thereof. The soft X-ray shielding sheet <NUM> is formed by stacking and adhering three sheets of: a first outer sheet <NUM> that is formed of a material opaque to the soft X-rays <NUM>, an interlayer sheet <NUM> that is formed of a material opaque to the soft X-rays <NUM>, and a second outer sheet that is formed of a material opaque to the soft X-rays <NUM>. Here, the material opaque to soft X-rays is typically a metal such as lead, iron, or aluminum, but is not limited to the metal. Metal can block the transmission of soft X-rays <NUM> even if it is thin and in addition, it is easily formed to be thin, so it is suitable for the soft X-ray shielding sheet <NUM>. Furthermore, a method for stacking and adhering them is not particularly limited. In the first outer sheet <NUM>, supply ports <NUM> through which the ionized air <NUM> in the container <NUM> enters the soft X-ray shielding sheet <NUM> are formed. In the interlayer sheet <NUM>, an ionized air passage <NUM> that has an ionized air inlet opening <NUM> at both end parts thereof is formed. In the second outer sheet <NUM>, a discharge port <NUM> through which the ionized air <NUM> is discharged to the outside of the container <NUM> is formed.

In the present example, two supply ports <NUM> in the first outer sheet <NUM> are formed so as to provide spacing between them on the first outer sheet <NUM>. The ionized air passage <NUM> in the interlayer sheet <NUM> includes the ionized air inlet openings <NUM> which are respectively formed at positions where communication with the supply ports <NUM> in the first outer sheet <NUM> is performed; and is formed so as to communicate with each of the ionized air inlet openings <NUM>. The discharge port <NUM> in the second outer sheet <NUM> is formed at a position where communication with the ionized air passage <NUM> is performed in the interlayer sheet <NUM>.

By stacking and adhering the first outer sheet <NUM>, the interlayer sheet <NUM>, and the second outer sheet <NUM>, which are formed as described above, the supply ports <NUM> in the first outer sheet <NUM> and the ionized air inlet openings <NUM> in the interlayer sheet <NUM> are made to communicate with each other, respectively and furthermore, at the center of the ionized air passage <NUM> in the interlayer sheet <NUM>, the ionized air passage <NUM> and the discharge port <NUM> in the second outer sheet <NUM> communicate with each other; thereby forming an ionized air transmission portion <NUM>. In the soft X-ray shielding sheet <NUM>, one ionized air transmission portion <NUM> may be formed; however, a plurality of ionized air transmission portions <NUM> may be formed.

In the ionized air passage <NUM>, bent portions <NUM> that bend at <NUM> degrees on a plane are provided so that the number of times the soft X-rays <NUM> hit an inner surface <NUM> of the second outer sheet <NUM> and an inner surface <NUM> of the first outer sheet <NUM> while entering from the supply ports <NUM> and reaching the discharge port <NUM> increases and the soft X-rays <NUM> are attenuated or disappear.

In addition, in order that a fluid resistance of the ionized air <NUM>, which has been ionized, is controlled so as to allow the ionized air to reach the discharge port <NUM> in a short period of time and so as to prevent recombination of positive ions and negative ions, each of the bent portions <NUM> of the ionized air passage <NUM> is formed to have a curved face <NUM> that is to reduce the fluid resistance of the ionized air. That is, the ionized air passage <NUM> has at least one or more bent portions <NUM> that bend at <NUM> degrees on a plane and thereby allows the soft X-rays <NUM> to disappear due to its hit on an inner surface, that is, the passage. It should be noted that the shape of the ionized air passage <NUM> may be other shapes. The shape is preferably such that the fluid resistance of the ionized air <NUM> is controlled while the number of times the soft X-rays <NUM> hit the passage is increased.

The operation of the soft X-ray shielding sheet <NUM> which is used in the soft X-ray static electricity removal apparatus <NUM> of the present invention according to the above configuration will be described with reference to <FIG>. In the container <NUM> that is on an upstream side of the soft X-ray shielding sheet <NUM>, the ionized air <NUM> which has been ionized into positive ions and negative ions by the soft X-rays <NUM> is in a pressurized state which is caused by feeding the air <NUM> into the container <NUM>. Therefore, the ionized air <NUM> flows from the supply ports <NUM> through the ionized air inlet openings <NUM> and the ionized air passage <NUM> and is discharged from the discharge port <NUM> to a downstream side of the soft X-ray shielding sheet <NUM>.

The soft X-rays <NUM> are incident from each of the supply ports <NUM> and go straight, pass the ionized air passage <NUM> through the ionized air inlet openings <NUM>, and reach the discharge port <NUM>; during which as illustrated in <FIG>, they hit the inner surface <NUM> of the second outer sheet <NUM>, the inner surface <NUM> of the first outer sheet <NUM>, the curved faces <NUM> of the bent portions <NUM>, or the like, thereby preventing their travel in a straight line. By the hits on the inner surfaces <NUM> and <NUM>, and the like, the soft X-rays <NUM> are attenuated and eventually almost disappear, so that the dangerous soft X-rays <NUM> are prevented from leaking from the discharge port <NUM>. In order to make the soft X-rays <NUM> attenuated and almost disappear, it is preferable that there should be three times or more hits on the inner surfaces <NUM> and <NUM>, and the like. For that purpose, the size and length of a cross section of the ionized air transmission portion <NUM> and the number of bent portions <NUM>, that is, a path of the ionized air passage <NUM> and the like are designed. It should be noted that the number of sheets constituting the soft X-ray shielding sheet <NUM> may be not three but four or more.

The ionized air <NUM> introduced from the supply ports <NUM> passes through the ionized air passage <NUM> and reaches the discharge port <NUM>. Since the bent portions <NUM> of the ionized air passage <NUM>, which are provided from the viewpoint of preventing leakage of the soft X-rays <NUM>, are formed to have the curved face <NUM>, the fluid resistance is reduced, allowing the ionized air <NUM> to reach the discharge port <NUM> in a short period of time. In particular, it is preferable that the ionized air <NUM> should pass through the soft X-ray shielding sheet <NUM> in a short period of time so as to prevent recombination of positive ions and negative ions; and thus, the path of the ionized air transmission portion <NUM> is shortened. Therefore, a large amount of ions are discharged to a downstream side of the discharge port <NUM>.

In the case of the soft X-ray shielding sheet <NUM> illustrated in <FIG> and <FIG>, two supply ports <NUM> and one discharge port <NUM> are provided, where the ionized air <NUM> passes the ionized air passage <NUM> and two flows of it collide at the discharge port <NUM> and thereby, the ionized air <NUM> from the discharge port <NUM> can be made to blow out vertically.

However, as illustrated in <FIG>, in a conventional soft X-ray static electricity removal apparatus <NUM>, the container <NUM> and the soft X-ray shielding sheet <NUM> are conducted to each other. A grounding wire <NUM> is connected to the container <NUM> so that a potential <NUM> from the container <NUM> and the soft X-ray shielding sheet <NUM> is passed to the ground. For this reason, the ionized air <NUM> is trapped in the soft X-ray shielding sheet <NUM> and the amount of ionized air <NUM> that passes through the soft X-ray shielding sheet <NUM> is apt to decrease.

Then, as illustrated in <FIG> and <FIG>, in the soft X-ray static electricity removal apparatus <NUM>, the container <NUM> and the soft X-ray shielding sheet <NUM> are insulated from each other by the insulating layer <NUM>. The soft X-ray shielding sheet <NUM> illustrated in <FIG> has a circular cross section and has a number of ionized air transmission portions <NUM> formed therein. On a circular outer periphery thereof, the insulating layer <NUM> is arranged.

<FIG> illustrates one example of the insulating layer <NUM>. On the circular outer periphery of the soft X-ray shielding sheet <NUM>, three arc-shaped ceramics <NUM> are arranged. Although there are insulating materials such as plastic and the like other than ceramic, they deteriorate by being irradiated with soft X-rays and generate powders. Ceramic does not deteriorate even when being irradiated with soft X-rays and is therefore preferable. In addition, an annular-shaped ceramic that covers the outer periphery of the soft X-ray shielding sheet <NUM> is acceptable; however, ceramic is a fragile material and therefore, may be broken at the time of manufacture or use. Therefore, instead of covering the entire perimeter with one annular-shaped member, a plurality of divided arc-shaped ceramics <NUM> are used. Furthermore, the soft X rays <NUM> pass through ceramic. Therefore, in order to prevent the soft X-rays <NUM> from passing through the annular-shaped insulating layer <NUM>, which covers the outer periphery of the soft X-ray shielding sheet <NUM>, and from leaking, the annular-shaped insulating layer <NUM> is covered by a casing <NUM> (see <FIG>) of the soft X-ray shielding sheet <NUM>. The casing <NUM> is commonly formed with the same material as that of the container <NUM>, such as stainless steel. Here, the casing <NUM> is structured so as to cover the soft X-ray shielding sheet <NUM> with a narrow gap <NUM> (for example, a clearance of <NUM> and a radial-direction width of <NUM>). By this gap <NUM>, the soft X-ray shielding sheet <NUM> and the casing <NUM> are insulated from each other. In addition, the gap <NUM> is made narrow and long, that is, the width in a radial direction is made larger than the clearance; and thereby, the soft X-rays <NUM> are prevented from passing through a space between the soft X-ray shielding sheet <NUM> and the casing <NUM>. More specifically, the gap <NUM> is shaped so that, when the soft X-rays <NUM> pass through the gap <NUM>, they hit the soft X-ray shielding sheet <NUM> and the casing <NUM> three times or more. Thus, the soft X-rays <NUM> are prevented from traveling in a straight line and hit the casing <NUM> and around the outer periphery of the soft X-ray shielding sheet <NUM>, thereby being attenuated and disappearing. The casing <NUM> of the soft X-ray shielding sheet <NUM> preferably, as illustrated in <FIG>, is a circular ring having a cross section of a U shape and is configured to store the arc-shaped ceramics <NUM> within the U shape, which facilitates handling the insulating layer <NUM>. In <FIG>, the arc-shaped ceramics <NUM> obtained by dividing its circumference into three equal parts are used; however, the number thereof is freely selected.

The container <NUM> and the soft X-ray shielding sheet <NUM> are insulated from each other by the insulating layer <NUM> and thereby when ions are trapped in the soft X-ray shielding sheet <NUM> in an initial stage of operation, the soft X-ray shielding sheet <NUM> gets the potential of trapped ions (positive or negative) and thereafter, ions of the same potential are not trapped and are transmitted through the soft X-ray shielding sheet <NUM>. Therefore, the ionized air <NUM> that is discharged through the soft X-ray shielding sheet <NUM> increases.

Furthermore, since insulation is made with the insulating layer <NUM>, a potential difference can be applied to the container <NUM> and the soft X-ray shielding sheet <NUM>. As illustrated in <FIG>, a power supply device <NUM> is provided, the positive or negative electrode of which is connected to the soft X-ray shielding sheet <NUM> with a soft X-ray shielding sheet cable <NUM>, and the other electrode of which is connected to the container <NUM> with a container cable <NUM>. Then, the soft X-ray shielding sheet <NUM> is positively or negatively charged and the container <NUM> is charged with a positive or negative voltage that is opposite thereto. It is estimated that when the container <NUM> is charged, dispersion of the ions of the same polarity in the container <NUM> (positive ions when positively charged, or negative ions when negatively charged) decreases, the ions of the same polarity in the container <NUM> increase, and the ions of the same polarity that pass through the soft X-ray shielding sheet <NUM> increase. That is, the amount of positive/negative ions discharge can be adjusted. Since the container <NUM> and the soft X-ray shielding sheet <NUM> are small and a potential to be applied may be low, a current flowing from the power supply device <NUM> may be as extremely small as several nA to several pA and the power supply device <NUM> may be a battery with low power.

As described so far, according to the soft X-ray static electricity removal apparatus <NUM> of the present invention, the soft X-ray shielding sheet <NUM> is insulated and thereby the amount of ionized air <NUM> discharged can be increased. In addition, a potential difference is applied to the container <NUM> and the soft X-ray shielding sheet <NUM> and thereby, the amount of positive/negative ions discharged can be adjusted.

Here, an experiment for confirming the effects of the insulating layer of the soft X-ray static electricity removal apparatus is described. Here, the effects of the insulating layer were confirmed by measuring the time taken to remove static electricity from a charge plate by using a soft X-ray static electricity removal apparatus with an insulating layer and a soft X-rays static electricity removal apparatus without an insulating layer. The soft X-ray static electricity removal apparatus used in the experiment is C-IGB-CA-<NUM> manufactured by Kondoh Industries, Ltd. and its outer shape is illustrated in <FIG>. The charge plate is H0601 manufactured by Shishido electrostatic, Ltd. and the dimensions of the plate are <NUM> x <NUM>. While the distance from the discharge port of the soft X-ray static electricity removal apparatus to the charge plate was changed to <NUM>, <NUM>, <NUM>, and <NUM> and the flowrate of air was changed to <NUM>, <NUM>, and <NUM>/min, the time for removing static electricity from +<NUM> V to +<NUM> V and the time for removing static electricity from -<NUM> V to -<NUM> V were measured in accordance with JIS C61340-<NUM>-<NUM> "charge plate. " The results are shown in Table <NUM>.

The results shown in Table <NUM> are averages of three actual measurements. Items indicated by "***" in Table <NUM> indicate results that static electricity was not removed (not lowered to <NUM> V) after <NUM> seconds had passed.

As is obvious from the results in Table <NUM>, it was found that by providing an insulating layer, the static electricity removal time is shortened except with some exceptions. Especially, in the case where the static electricity removal time was long without an insulating layer at the distance of <NUM> or <NUM>, the static electricity removal time was significantly shortened. This is considered to be a result of discharging a large amount of ionized air and thereby removing static electricity from the charge plate.

Next, described will be an experiment in which it was confirmed that the amount of positive/negative ions discharged can be adjusted by applying a potential difference to the container <NUM> and the soft X-ray shielding sheet <NUM> (see <FIG>). By using the same soft X-ray static electricity removal apparatus (with an insulating layer) as used in the Example <NUM>, a potential difference was applied to the container <NUM> and the soft X-ray shielding sheet <NUM> and the time for removing static electricity from the charge plate was measured. The distance from the discharge port of the soft X-ray static electricity removal apparatus to the charge plate was set to <NUM> and the flowrate of air was set to <NUM>/min; and then, the static electricity removal time in the cases of setting the potential differences between the soft X-ray shielding sheet <NUM> and the container <NUM> to ±<NUM> V, +<NUM> V, and -<NUM> V was measured. The results are shown in Table <NUM>.

The results shown in Table <NUM> are averages of three actual measurements. A difference in the results in the voltage applied of ±<NUM> V from those in Table <NUM> is estimated to be because measurement dates were different and the static electricity removal time, which is greatly influenced by atmospheric conditions (humidity, temperature, and the like), was changed due to the influence of a different atmosphere.

When a potential difference of +<NUM> V was applied to the soft X-ray shielding sheet (conversely, -<NUM> V to the container), the time for removing a positive voltage became short in comparison with a case where the potential difference was not applied, that is, the discharge of negative ions increased; and the time for removing a negative voltage became long, that is, the discharge of positive ions decreased. In addition, when a potential difference of -<NUM> V was applied to the soft X-ray shielding sheet (conversely, +<NUM> V to the container), the time for removing a positive voltage became long in comparison with a case where the potential difference was not applied, that is, the discharge of negative ions decreased; and the time for removing a negative voltage became short, that is, the discharge of positive ions increased. In short, when a positive voltage was applied to the soft X-ray shielding sheet and a negative voltage was applied to the container, dispersion of negative ions on an inner wall of the container decreased and negative ions in the container increased. As a result, it is estimated that the amount of negative ions discharged increased and the time for removing a positive voltage became short. Conversely, it is estimated that when a negative voltage and a positive voltage were applied to the soft X-ray shielding sheet and the container, respectively, positive ions in the container increased and thereby the amount of positive ions discharged increased and the time for removing a negative voltage became short.

As is also obvious from Table <NUM>, by applying a potential difference to the container and the soft X-ray shielding sheet, the amount of positive/negative ions discharged can be adjusted.

Claim 1:
A soft X-ray static electricity removal apparatus (<NUM>) comprising:
a soft X-ray generation device (<NUM>) that generates soft X-rays (<NUM>) for ionizing air;
a container (<NUM>) having an outlet (<NUM>), ionized air (<NUM>) flowing out from the outlet (<NUM>), the ionized air (<NUM>) having been ionized with the soft X-rays;
a soft X-ray shielding sheet (<NUM>) that is used at the outlet (<NUM>) of the container (<NUM>) and includes:
a first outer sheet (<NUM>) formed of a material opaque to the soft X-rays (<NUM>);
an interlayer sheet (<NUM>) formed of a material opaque to the soft X-rays (<NUM>); and
a second outer sheet (<NUM>) formed of a material opaque to the soft X-rays (<NUM>);
wherein the first outer sheet (<NUM>) has a supply port (<NUM>) for the ionized air formed therein;
the interlayer sheet (<NUM>) has an ionized air passage formed therein, the ionized air passage (<NUM>) having an ionized air inlet opening (<NUM>), the ionized air inlet opening (<NUM>) communicating with the supply port (<NUM>); and
the second outer sheet (<NUM>) having a discharge port (<NUM>) formed therein, the discharge port (<NUM>) communicating with the ionized air passage (<NUM>); and
and wherein the first outer sheet (<NUM>), the interlayer sheet (<NUM>), and the second outer sheet (<NUM>) are stacked and adhered, and the supply port (<NUM>), the ionized air passage (<NUM>), and the discharge port (<NUM>) communicate with each other to provide an ionized air transmission portion;
characterized in that it further comprising an insulating layer (<NUM>) formed of ceramic that insulates the soft X-ray shielding sheet (<NUM>) and the container (<NUM>) from each other;
wherein the soft X-ray shielding sheet (<NUM>) has a circular cross section, and has a number of ionized air transmission portions (<NUM>) formed therein, and
the insulating layer (<NUM>) is annular shaped and has a plurality of arc-shaped ceramics (<NUM>), the ceramics being arranged so as to surround an outer periphery of the soft X-ray shielding sheet (<NUM>), and the insulating layer (<NUM>) is arranged on a circular outer periphery thereof.