Soft X-ray static electricity removal apparatus

Abstract

Provided is a soft X-ray static electricity removal apparatus that has achieved an increase in the amount of ionized air discharged, with a simple structure. A soft X-ray static electricity removal apparatus (1) includes a soft X-ray generation device (90), a container (10), a soft X-ray shielding sheet (20), and an insulating layer (50). The soft X-ray generation device generates soft X-rays (92). The container (10) has an outlet (12) from which ionized air (100) that has been ionized with the soft X-rays flows out. The soft X-ray shielding sheet (20) is used at the outlet of the container and includes a first outer sheet (30), an interlayer sheet (34), and a second outer sheet (40) which are formed of a material opaque to the soft X-rays. The first outer sheet has supply ports (32) for the ionized air formed therein; the interlayer sheet has an ionized air passage (38) formed therein, which includes ionized air inlet openings (36) that communicate with the supply ports; and the second outer sheet has a discharge port (42) formed therein, which communicates with the ionized air passage. The supply ports, the ionized air passage, and the discharge port communicate with each other to provide an ionized air transmission portion (44). The insulating layer insulates the soft X-ray shielding sheet and the container from each other.

Claims

1. A soft X-ray static electricity removal apparatus comprising: a soft X-ray generation device that generates soft X-rays for ionizing air; a container having an outlet, ionized air flowing out from the outlet, the ionized air having been ionized with the soft X-rays; a soft X-ray shielding sheet that is used at the outlet of the container and includes: a first outer sheet formed of a material opaque to the soft X-rays; an interlayer sheet formed of a material opaque to the soft X-rays; and a second outer sheet formed of a material opaque to the soft X-rays; wherein the first outer sheet has a supply port for the ionized air formed therein; the interlayer sheet has an ionized air passage formed therein, the ionized air passage having an ionized air inlet opening, the ionized air inlet opening communicating with the supply port; and the second outer sheet having a discharge port formed therein, the discharge port communicating with the ionized air passage; and wherein the first outer sheet, the interlayer sheet, and the second outer sheet are stacked and adhered, and the supply port, the ionized air passage, and the discharge port communicate with each other to provide an ionized air transmission portion; and an insulating layer that insulates the soft X-ray shielding sheet and the container from each other.

2. The soft X-ray static electricity removal apparatus of claim 1, wherein the ionized air passage extending from the supply port to the discharge port has a bent portion.

3. The soft X-ray static electricity removal apparatus of claim 1, wherein the insulating layer is formed of ceramic.

4. The soft X-ray static electricity removal apparatus of claim 3, wherein the soft X-ray shielding sheet has a circular cross section, and the insulating layer has a plurality of arc-shaped ceramics, the ceramics being arranged so as to surround an outer periphery of the soft X-ray shielding sheet.

5. The soft X-ray static electricity removal apparatus of claim 1, further comprising: a power supply device that applies a potential difference to the container and the soft X-ray shielding sheet.

6. The soft X-ray static electricity removal apparatus of claim 1, further comprising: a casing that holds the insulating layer at the outlet of the container so as to have the insulating layer and the soft X-ray shielding sheet arranged at the outlet, the casing having a gap between itself and the soft X-ray shielding sheet.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a conceptual diagram for illustrating a soft X-ray static electricity removal apparatus of the present invention.

(2) FIG. 2 is a cross-sectional view for illustrating an ionized air transmission portion of a soft X-ray shielding sheet used in the soft X-ray static electricity removal apparatus.

(3) FIG. 3 is an exploded perspective view of the soft X-ray shielding sheet for illustrating the ionized air transmission portion of the soft X-ray shielding sheet used in the soft X-ray static electricity removal apparatus.

(4) FIG. 4 is a diagram for illustrating the soft X-ray shielding sheet and an insulating layer, which are used in the soft X-ray static electricity removal apparatus; (a) is a cross-sectional view in a plane orthogonal to a flow direction of ionized air and (b) is a side view seen from the flow direction of the ionized air.

(5) FIG. 5 is a diagram for illustrating an insulating layer of an embodiment; (a) is a cross-sectional view in a plane orthogonal to a flow direction of ionized air and (b) is a cross-sectional view on A-A.

(6) FIG. 6 is a diagram illustrating a soft X-ray static electricity removal apparatus used for experimenting with effects of an insulating layer of the soft X-ray static electricity removal apparatus.

(7) FIG. 7 is a conceptual diagram for illustrating a conventional soft X-ray static electricity removal apparatus.

DESCRIPTION OF EMBODIMENT

(8) 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. 1, a soft X-ray static electricity removal apparatus 1 of the present invention will be described.

(9) The soft X-ray static electricity removal apparatus 1 includes a container 10 that provides a space in which air is ionized and through which ionized air 100, which has been ionized, flows. The container 10 has an air inlet 14 that takes air 102 into the container 10. The air inlet 14 may include a fan to forcibly take the air 102 outside the container 10 into the container 10. In the container 10, a soft X-ray generation device 90 is arranged near a position where the air inlet 14 is provided. Soft X-rays 92 are generated from the soft X-ray generation device 90 and air is irradiated therewith within the container 10; thereby the air is ionized. The soft X-ray generation device 90 may be a known soft X-ray device and thus, detailed description thereof is omitted. On the container 10, an outlet 12 for the ionized air 100 is formed at a position away from a position where the air inlet 14 is provided. By providing the soft X-ray generation device 90 near the air inlet 14 and providing the outlet 12 at a position away from the air inlet 14, air is caused to flow from the air inlet 14 to the outlet 12, the air can be ionized by the soft X-rays 92 from the soft X-ray generation device 90, and the ionized air 100 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 10 is formed by stainless steel or other metal.

(10) At the outlet 12, a soft X-ray shielding sheet 20 is arranged. That is, the ionized air 100 is discharged from the container 10 by passing through the soft X-ray shielding sheet 20.

(11) Here, with reference to FIG. 2 and FIG. 3, an ionized air transmission portion 44 of the soft X-ray shielding sheet 20 through which the ionized air 100 passes is described. FIG. 2 is a cross-sectional view in the vicinity of the ionized air transmission portion 44 of the soft X-ray shielding sheet 20; and FIG. 3 is an exploded perspective view thereof. The soft X-ray shielding sheet 20 is formed by stacking and adhering three sheets of a first outer sheet 30 that is formed of a material opaque to the soft X-rays 92, an interlayer sheet 34 that is formed of a material opaque to the soft X-rays 92, and a second outer sheet that is formed of a material opaque to the soft X-rays 92. 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 92 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 20. Furthermore, a method for stacking and adhering them is not particularly limited. In the first outer sheet 30, supply ports 32 through which the ionized air 100 in the container 10 enters the soft X-ray shielding sheet 20 are formed. In the interlayer sheet 34, an ionized air passage 38 that has an ionized air inlet opening 36 at both end parts thereof is formed. In the second outer sheet 40, a discharge port 42 through which the ionized air 100 is discharged to the outside of the container 10 is formed.

(12) In the present example, two supply ports 32 in the first outer sheet 30 are formed so as to provide spacing between them on the first outer sheet 30. The ionized air passage 38 in the interlayer sheet 34 includes the ionized air inlet openings 36 which are respectively formed at positions where communication with the supply ports 32 in the first outer sheet 30 is performed; and is formed so as to communicate with each of the ionized air inlet openings 36. The discharge port 42 in the second outer sheet 40 is formed at a position where communication with the ionized air passage 38 is performed in the interlayer sheet 34.

(13) By stacking and adhering the first outer sheet 30, the interlayer sheet 34, and the second outer sheet 40, which are formed as described above, the supply ports 32 in the first outer sheet 30 and the ionized air inlet openings 36 in the interlayer sheet 34 are made to communicate with each other, respectively and furthermore, at the center of the ionized air passage 38 in the interlayer sheet 34, the ionized air passage 38 and the discharge port 42 in the second outer sheet 40 communicate with each other; thereby forming an ionized air transmission portion 44. In the soft X-ray shielding sheet 20, one ionized air transmission portion 44 may be formed; however, a plurality of ionized air transmission portions 44 may be formed.

(14) In the ionized air passage 38, bent portions 39 that bend at 90 degrees on a plane are provided so that the number of times the soft X-rays 92 hit an inner surface 41 of the second outer sheet 40 and an inner surface 31 of the first outer sheet 30 while entering from the supply ports 32 and reaching the discharge port 42 increases and the soft X-rays 92 are attenuated or disappear.

(15) In addition, in order that a fluid resistance of the ionized air 100, which has been ionized, is controlled so as to allow the ionized air to reach the discharge port 42 in a short period of time and so as to prevent recombination of positive ions and negative ions, each of the bent portions 39 of the ionized air passage 38 is formed to have a curved face 37 that is to reduce the fluid resistance of the ionized air. That is, the ionized air passage 38 has at least one or more bent portions 39 that bend at 90 degrees on a plane and thereby allows the soft X-rays 92 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 38 may be other shapes. The shape is preferably such that the fluid resistance of the ionized air 100 is controlled while the number of times the soft X-rays 92 hit the passage is increased.

(16) The operation of the soft X-ray shielding sheet 20 which is used in the soft X-ray static electricity removal apparatus 1 of the present invention according to the above configuration will be described with reference to FIG. 2. In the container 10 that is on an upstream side of the soft X-ray shielding sheet 20, the ionized air 100 which has been ionized into positive ions and negative ions by the soft X-rays 92 is in a pressurized state which is caused by feeding the air 102 into the container 10. Therefore, the ionized air 100 flows from the supply ports 32 through the ionized air inlet openings 36 and the ionized air passage 38 and is discharged from the discharge port 42 to a downstream side of the soft X-ray shielding sheet 20.

(17) The soft X-rays 92 are incident from each of the supply ports 32 and go straight, pass the ionized air passage 38 through the ionized air inlet openings 36, and reach the discharge port 42; during which as illustrated in FIG. 2, they hit the inner surface 41 of the second outer sheet 40, the inner surface 31 of the first outer sheet 30, the curved faces 37 of the bent portions 39, or the like, thereby preventing their travel in a straight line. By the hits on the inner surfaces 31 and 41, and the like, the soft X-rays 92 are attenuated and eventually almost disappear, so that the dangerous soft X-rays 92 are prevented from leaking from the discharge port 42. In order to make the soft X-rays 92 attenuated and almost disappear, it is preferable that there should be three times or more hits on the inner surfaces 31 and 41, and the like. For that purpose, the size and length of a cross section of the ionized air transmission portion 44 and the number of bent portions 39, that is, a path of the ionized air passage 38 and the like are designed. It should be noted that the number of sheets constituting the soft X-ray shielding sheet 20 may be not three but four or more.

(18) The ionized air 100 introduced from the supply ports 32 passes through the ionized air passage 38 and reaches the discharge port 42. Since the bent portions 39 of the ionized air passage 38, which are provided from the viewpoint of preventing leakage of the soft X-rays 92, are formed to have the curved face 37, the fluid resistance is reduced, allowing the ionized air 100 to reach the discharge port 42 in a short period of time. In particular, it is preferable that the ionized air 100 should pass through the soft X-ray shielding sheet 20 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 44 is shortened. Therefore, a large amount of ions are discharged to a downstream side of the discharge port 42.

(19) In the case of the soft X-ray shielding sheet 20 illustrated in FIG. 2 and FIG. 3, two supply ports 32 and one discharge port 42 are provided, where the ionized air 100 passes the ionized air passage 38 and two flows of it collide at the discharge port 42 and thereby, the ionized air 100 from the discharge port 42 can be made to blow out vertically.

(20) However, as illustrated in FIG. 7, in a conventional soft X-ray static electricity removal apparatus 201, the container 10 and the soft X-ray shielding sheet 20 are conducted to each other. A grounding wire 210 is connected to the container 10 so that a potential 212 from the container 10 and the soft X-ray shielding sheet 20 is passed to the ground. For this reason, the ionized air 100 is trapped in the soft X-ray shielding sheet 20 and the amount of ionized air 100 that passes through the soft X-ray shielding sheet 20 is apt to decrease.

(21) Then, as illustrated in FIG. 1 and FIG. 4, in the soft X-ray static electricity removal apparatus 1, the container 10 and the soft X-ray shielding sheet 20 are insulated from each other by the insulating layer 50. The soft X-ray shielding sheet 20 illustrated in FIG. 4 has a circular cross section and has a number of ionized air transmission portions 44 formed therein. On a circular outer periphery thereof, the insulating layer 50 is arranged.

(22) FIG. 5 illustrates one example of the insulating layer 50. On the circular outer periphery of the soft X-ray shielding sheet 20, three arc-shaped ceramics 52 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 20 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 52 are used. Furthermore, the soft X rays 92 pass through ceramic. Therefore, in order to prevent the soft X-rays 92 from passing through the annular-shaped insulating layer 50, which covers the outer periphery of the soft X-ray shielding sheet 20, and from leaking, the annular-shaped insulating layer 50 is covered by a casing 55 (see FIG. 6) of the soft X-ray shielding sheet 20. The casing 55 is commonly formed with the same material as that of the container 10, such as stainless steel. Here, the casing 55 is structured so as to cover the soft X-ray shielding sheet 20 with a narrow gap 56 (for example, a clearance of 0.5 mm and a radial-direction width of 2 mm). By this gap 56, the soft X-ray shielding sheet 20 and the casing 55 are insulated from each other. In addition, the gap 56 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 92 are prevented from passing through a space between the soft X-ray shielding sheet 20 and the casing 55. More specifically, the gap 56 is shaped so that, when the soft X-rays 92 pass through the gap 56, they hit the soft X-ray shielding sheet 20 and the casing 55 three times or more. Thus, the soft X-rays 92 are prevented from traveling in a straight line and hit the casing 55 and around the outer periphery of the soft X-ray shielding sheet 20, thereby being attenuated and disappearing. The casing 55 of the soft X-ray shielding sheet 20 preferably, as illustrated in FIG. 5 (a), is a circular ring having a cross section of a U shape and is configured to store the arc-shaped ceramics 52 within the U shape, which facilitates handling the insulating layer 50. In FIG. 5, the arc-shaped ceramics 52 obtained by dividing its circumference into three equal parts are used; however, the number thereof is freely selected.

(23) The container 10 and the soft X-ray shielding sheet 20 are insulated from each other by the insulating layer 50 and thereby when ions are trapped in the soft X-ray shielding sheet 20 in an initial stage of operation, the soft X-ray shielding sheet 20 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 20. Therefore, the ionized air 100 that is discharged through the soft X-ray shielding sheet 20 increases.

(24) Furthermore, since insulation is made with the insulating layer 50, a potential difference can be applied to the container 10 and the soft X-ray shielding sheet 20. As illustrated in FIG. 1, a power supply device 60 is provided, the positive or negative electrode of which is connected to the soft X-ray shielding sheet 20 with a soft X-ray shielding sheet cable 62, and the other electrode of which is connected to the container 10 with a container cable 64. Then, the soft X-ray shielding sheet 20 is positively or negatively charged and the container 10 is charged with a positive or negative voltage that is opposite thereto. It is estimated that when the container 10 is charged, dispersion of the ions of the same polarity in the container 10 (positive ions when positively charged, or negative ions when negatively charged) decreases, the ions of the same polarity in the container 10 increase, and the ions of the same polarity that pass through the soft X-ray shielding sheet 20 increase. That is, the amount of positive/negative ions discharge can be adjusted. Since the container 10 and the soft X-ray shielding sheet 20 are small and a potential to be applied may be low, a current flowing from the power supply device 60 may be as extremely small as several nA to several pA and the power supply device 60 may be a battery with low power.

(25) As described so far, according to the soft X-ray static electricity removal apparatus 1 of the present invention, the soft X-ray shielding sheet 20 is insulated and thereby the amount of ionized air 100 discharged can be increased. In addition, a potential difference is applied to the container 10 and the soft X-ray shielding sheet 20 and thereby, the amount of positive/negative ions discharged can be adjusted.

Example 1

(26) 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-100434 manufactured by Kondoh Industries, Ltd. and its outer shape is illustrated in FIG. 6. The charge plate is H0601 manufactured by Shishido electrostatic, Ltd. and the dimensions of the plate are 150 mm×150 mm. While the distance from the discharge port of the soft X-ray static electricity removal apparatus to the charge plate was changed to 50, 100, 150, and 200 mm and the flowrate of air was changed to 20, 30, and 40 L/min, the time for removing static electricity from +1000 V to +100 V and the time for removing static electricity from −1000 V to −100 V were measured in accordance with JIS C61340-4-7 “charge plate.” The results are shown in Table 1.

(27) TABLE-US-00001 TABLE 1 +1000 V.fwdarw.+100 V −1000 V.fwdarw.−100 V Without With Without With Air insulating insulating insulating insulating flowrate Distance layer layer layer layer 20 L/min 50 mm 8.3 sec 8.4 sec 8.1 sec 8.0 sec 100 mm 18.6 sec 16.4 sec 18.7 sec 17.1 sec 150 mm *** 59.1 sec 78.6 sec 99.9 sec 200 mm *** *** *** *** 30 L/min 50 mm 5.6 sec 5.5 sec 5.4 sec 5.1 sec 100 mm 9.7 sec 8.9 sec 9.6 sec 8.5 sec 150 mm 25.0 sec 15.0 sec 25.9 sec 13.5 sec 200 mm 115.2 sec 33.3 sec *** 38.8 sec 40 L/min 50 mm 4.3 sec 4.0 sec 4.1 sec 3.8 sec 100 mm 7.1 sec 6.2 sec 6.9 sec 6.1 sec 150 mm 12.4 sec 9.3 sec 12.3 sec 8.6 sec 200 mm 30.6 sec 14.3 sec 46.2 sec 15.6 sec

(28) The results shown in Table 1 are averages of three actual measurements. Items indicated by “***” in Table 1 indicate results that static electricity was not removed (not lowered to 100 V) after 200 seconds had passed.

(29) As is obvious from the results in Table 1, 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 150 mm or 200 mm, 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.

Example 2

(30) 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 10 and the soft X-ray shielding sheet 20 (see FIG. 1). By using the same soft X-ray static electricity removal apparatus (with an insulating layer) as used in the Example 1, a potential difference was applied to the container 10 and the soft X-ray shielding sheet 20 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 200 mm and the flowrate of air was set to 30 L/min; and then, the static electricity removal time in the cases of setting the potential differences between the soft X-ray shielding sheet 20 and the container 10 to ±0 V, +10 V, and −10 V was measured. The results are shown in Table 2.

(31) TABLE-US-00002 TABLE 2 Potential difference applied +1000 V.fwdarw.+100 V −1000 V.fwdarw.−100 V ±0 V 23.1 sec 19.5 sec +10 V to soft X-ray shielding 19.9 sec 23.4 sec sheet (−10 V to container) −10 V to soft X-ray shielding 26.4 sec 16.3 sec sheet (+10 V to container)

(32) The results shown in Table 2 are averages of three actual measurements. A difference in the results in the voltage applied of ±0 V from those in Table 1 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.

(33) When a potential difference of +10 V was applied to the soft X-ray shielding sheet (conversely, −10 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 −10 V was applied to the soft X-ray shielding sheet (conversely, +10 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.

(34) As is also obvious from Table 2, 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.

(35) The main reference numerals used in the description and drawings are listed below. 1 soft X-ray static electricity removal apparatus 10 container 12 outlet 20 soft X-ray shielding sheet 30 first outer sheet 31 inner surface of first outer sheet 32 supply port 34 interlayer sheet 36 ionized air inlet opening 37 curved face 38 ionized air passage 39 bent portion 40 second outer sheet 41 inner surface of second outer sheet 42 discharge port 44 ionized air transmission portion 50 insulating layer 52 arc-shaped ceramic 54 soft X-ray shielding plate 55 casing of soft X-ray shielding sheet 56 gap 60 power supply device 90 soft X-ray generation device 92 soft X-ray 100 ionized air 102 air 201 conventional soft X-ray static electricity removal apparatus 210 grounding wire 212 potential (flow thereof)