Patent Grant
7397647
The present invention relates to an ionizer which is used to eliminate static electricity, and more particularly relates to an ionized gas current emission type dust-free ionizer which is an ionizer of a type that emits an ionized gas current toward the object of static electricity removal, and which can be used in explosion-proof facilities and equipment.
In recent years, in explosion-proof facilities such as facilities where hazardous substances are handled or the like, clogging during the air feeding of combustible powders and clogging of sieves, as well as static charge build-up and discharge in the interiors of agitating tanks for organic solvents or the like whose inside surfaces are coated with Teflon, have become problems. Conventionally, in the case of static charge build-up and discharge inside such agitating tanks, the ignition of the organic solvents has been prevented by purging the air from the tanks with N2 gas, so that oxygen that might lead to ignition is eliminated. In the case of such de-charging methods, however, the initial costs and running costs of auxiliary facilities such as gas supply and exhaust facilities or the like are high, so that such methods are not desirable.
Meanwhile, air ionizing devices which neutralize electrical charges in charged bodies by means of ions have conventionally been used as devices for eliminating static electricity in production environments such as clean rooms or the like in which semiconductors, liquid crystal displays (hereafter referred to as “LCDs”) or the like are manufactured. Corona discharge type ionizers are commonly used as such air ionizing devices. In the case of such corona discharge type ionizers, a high positive or negative voltage is respectively applied to a positive or negative electrode, so that a corona discharge is generated, and the air surrounding the tip end of the abovementioned electrode is positively and negatively ionized; then, these ions are conveyed by air currents so that the charges on charged bodies are neutralized by ions of the opposite polarity.
However, semiconductor and liquid crystal manufacturing devices have become progressively smaller over the years, and in the case of conventional ionizers, it has become difficult to ensure an optimal installation space. Furthermore, the demand for static electricity countermeasures in narrow spaces such as the gaps between glass substrates inside cassettes and the like has also increased.
Accordingly, when the present inventors investigated the abovementioned reduction in size of air ionizing devices, and the application of such devices to explosion-proof facilities and equipment, the inventors found that the following problem points exist. Specifically, in the case of corona discharge type ionizers commonly used in the past, there is a considerable danger that the corona discharge itself will become an ignition source; accordingly, it has not been possible to use such ionizers in explosion-proof facilities such as facilities where hazardous substances are handled or the like.
Furthermore, in order to facilitate the generation of ions and prevent the consumption of generated ions, corona discharge type ionizers ionize the air in a state in which the electrodes are exposed in the vicinity of the object of de-charging. As a result, the following problems have also occurred.
(1) Generation of Ozone
Since the air in the vicinity of the object of de-charging is ionized by a corona discharge, a reaction which converts oxygen into ozone occurs besides the ionization of nitrogen and water vapor in the air. The surfaces of silicon wafers are oxidized by the oxidizing action of this ozone, and there are reactions with minute amounts of impurities in the air so that secondary particles are generated.
(2) Generation of Electromagnetic Noise
Irregular electromagnetic noise generated from the discharge electrode during the discharge may cause malfunctioning of precision instruments, computers or the like containing semiconductor elements.
(3) Generation of Dust from the Ion Generating Electrodes
The electrodes are consumed each time that a corona discharge is caused to occur, and the consumed electrode material is scattered. Furthermore, minute amounts of gas components in the air are converted into particles by the corona discharge, and are deposited on the ion generating electrodes, and when these particles reach a certain size, the particles are again scattered. As a result of such generation of dust, the yield drops.
In recent years, furthermore, ionizers which use soft X-rays as an ionization source have been developed. However, since the connecting parts between [such] ionizers and electrical cables, and the control devices for the ionization sources do not have explosion-proof specifications, it has been impossible to use such ionizers in explosion-proof facilities such as facilities handling hazardous substances or the like.
The present invention has been proposed in order to solve such problem points encountered in the prior art; it is an object of the present invention to provide an ionized gas current emission type dust-free ionizer which makes it possible to take countermeasures against static electricity in narrow spaces without causing the generation of ozone, electromagnetic noise, dust or the like, and which is also devised so that this ionizer can be used in explosion-proof facilities and equipment.
The present invention is an ionized gas current emission type dust-free ionizer which comprises a chamber having an ionization part that ionizes a portion of an ion carrier gas that is supplied to the interior of this chamber, and a blowing part that feeds the ion carrier gas toward a charged body, and in which the abovementioned ionization part is constructed from an ionization source that is contained in the abovementioned chamber, and a control device which is disposed outside the abovementioned chamber and which controls the quantity of ions generated by the abovementioned ionization source via a high-voltage cable, this ionizer being characterized in that the abovementioned ionization source is either the generating part of a soft X-ray generating device, the generating part of a low-energy electron beam generating device, or the generating part of an ultraviolet radiation generating device, and the abovementioned control device, the connecting part between the abovementioned control device and the high-voltage cable, and the connecting part between the abovementioned ionization source and the high-voltage cable, [all] have an explosion-proof structure.
In the ionized gas current emission type dust-free ionizer of the present invention, which has the abovementioned construction, since a corona discharge which might be a cause of ignition is not used as the ionization source, the ignition of combustible substances such as organic solvents or the like can be prevented. Furthermore, since the control device is formed with an explosion-proof structure, the ignition of combustible substances such as organic solvents or the like by the power supply or control board disposed inside the control device can be prevented.
Concrete embodiments of the present invention will be described below with reference to the attached figures.
(1-1) Construction
(1-1-1) Overall Construction
Furthermore, the ionized gas current emission type dust-free ionizer of the present invention has characterizing features in the construction of the control device 5, the construction of the connecting part (part A in
(1-1-2) Construction of Control Device
As is shown in
(1-1-3) Construction of Connecting Part Between High-Voltage Cable and Control Device
Specifically, a plug 61 is attached to the tip end portion of the high-voltage cable 6; thus, the high-voltage cable 6 is adapted so that this cable can be detachably connected to a socket 71 disposed in the side wall of the control device 5. Furthermore, the abovementioned plug 61 has a three-core structure, and electrodes 63 are attached to the tip ends of electrode supporting parts 62 that have a specified length “L”. Furthermore, a cap nut 65 which has a screw part 64 formed on the inside wall is attached to the outside of the base part 61a of the abovementioned plug 61 so that this nut can rotate.
Meanwhile, insertion holes 72 which engage with the electrode supporting parts 62 that are formed on the abovementioned plug 61 are formed in the socket 71 that is disposed in the side wall of the control device 5, and electrodes 73 that are connected with the electrodes 63 on the side of the abovementioned plug are formed in the deepest parts of these insertion holes 72. Furthermore, a screw part 74 is formed on the outer circumferential surface of the flange part 71a of the socket 71, and the device is adapted so that [this screw part 74] engages with the screw part 64 of the cap nut 65 attached to the abovementioned plug 61.
Furthermore, the length of the insertion holes 72 is set as “L” in correspondence to the electrode supporting parts 62 on the plug side, and this length “L” is set so that the attachment and detachment of both sets of electrodes can be performed in air-tight spaces constructed by the electrode supporting parts 62 of the plug 61 and the insertion holes 72 of the socket 71. Furthermore, as is shown in
(1-1-4) Construction of Connecting Part Between Ionization Source and High-Voltage Cable
As is shown in
(1-1-5) Construction of Ionization Part
As is shown in
Furthermore, an ionization source 4 is disposed near the installation position of the tube fitting 2 inside the chamber 1. Moreover, an ion generating device is formed by this ionization source 4 and the abovementioned control device 5.
Furthermore, the abovementioned ionization source 4 comprises the generating part of a soft X-ray generating device, the generating part of a low-energy electron beam generating device, the generating part of an ultraviolet radiation generating device or the like, and is adapted so that this ionization source ionizes the ion carrier gas that flows through the interior of the chamber 1.
(1-1-6) Construction of Shielding Part
In the present embodiment, as is shown in
(1-1-7) Construction of Blowing Part
The tip end portion of the chamber 1 is opened; this part is disposed in the vicinity of the charged body that is the object of de-charging, and is adapted so that the positive and negative ions generated in the abovementioned ion generating device are fed toward this charged body.
(1-1-8) Ionization Source
Next, the ionization source 4 will be described.
Soft X-rays are extremely weak X-rays with an energy of approximately 3 to 9.5 keV. Furthermore, a low-energy electron beam is an electron beam (soft electron beam) which is extracted at a low operating voltage of several tens of kilovolts by means of (for example) a super-compact electron beam irradiation tube manufactured by Ushio Denki K. K. or the like. This electron beam has a travel distance of only about 5 cm in air, and ionizes air or gases in this region.
Furthermore, in the case of a low-energy electron beam, since soft X-rays are also generated at the same time that ozone is generated in gases containing oxygen, shielding is necessary. Accordingly, in cases where a low-energy electron beam is used as an ionization source, it is desirable to use a non-reactive gas whose oxygen content is small enough that ozone is not generated, such as high-purity N2 gas or the like, as the ion carrier gas. Furthermore, the ultraviolet radiation generated by an ultraviolet radiation generating device is short-wavelength radiation with a wavelength of 400 nm or less, and an output power of approximately 30 W.
In cases where the ionization source 4 is a soft X-ray generating part, either air or a non-reactive gas may be used as the ion carrier gas that is supplied to the chamber 1; however, in cases where the ionization source 4 is a low-energy electron beam generating part or ultraviolet radiation generating part, it is desirable to a non-reactive gas whose oxygen content is small enough that ozone is not generated, such as high-purity N2 gas or the like, as the ion carrier gas.
(1-2) Effects and Merits
Next the effects and merits of the ionized gas current emission type dust-free ionizer of the present embodiment, which has the construction described above, will be described.
Since the ionized gas current emission type dust-free ionizer of the present embodiment uses the generating part of a soft X-ray generating device, the generating part of a low-energy electron beam generating device, the generating part of an ultraviolet radiation generating device or the like as an ionization source without using a corona discharge that might be a cause of ignition as this ionization source, the ignition of combustible substances such as organic solvents or the like can be prevented.
Furthermore, in the ionized gas current emission type dust-free ionizer of the present embodiment, a cooling device consisting of a Peltier element (thermoelectric cooling element) or the like is disposed inside the control device 5 that controls the quantity of ions generated by the abovementioned ionization source, so that heat radiating from the control board and heat sources disposed inside the control device, thus making it possible to control the interior of the device to a constant temperature; accordingly, the control device can be formed with an air-tight structure. As a result, the ignition of combustible substances such as organic solvents or the like by the control board and heat sources disposed inside the device can be prevented.
Furthermore, since the connecting part between the high-voltage cable 6 and the control device 5 has an explosion-proof structure of the type shown in
Furthermore, in the ionized gas current emission type dust-free ionizer of the present embodiment, the ion carrier gas that is supplied to the chamber 1 via a tube (not shown in the figures) and the tube fitting 2 is converted into positive and negative ions by irradiation with soft X-rays, a low-energy electron beam, ultraviolet radiation or the like by the ionization source 4 contained in the chamber 1. Furthermore, these positive and negative ions pass through the shielding part installed on the downstream side of the ionization part, and are supplied to the charged body that constitutes the object of de-charging from the tip end portion of the chamber 1, so that the positive and negative charges of opposite polarity on the charged body can be respectively neutralized.
Thus, in the ionized gas current emission type dust-free ionizer of the present embodiment, in cases where the ionization source 4 is a soft X-ray generating part, there is no generation of ozone, regardless of whether air or a non-reactive gas is used as the ion carrier gas. Furthermore, there is no generation of dust such as the scattering of electrode materials or deposition and re-scattering of impurities in the air, and there is likewise no generation of electromagnetic noise.
Furthermore, in cases where the ionization source 4 is a low-energy electron beam or ultraviolet radiation generating part, since a non-reactive gas whose oxygen content is small enough that there is no generation of ozone, such as high-purity N2 gas or the like, is used as the ion carrier gas, there is no generation of ozone, no generation of dust and no generation of electromagnetic noise during ionization.
Furthermore, soft X-rays or a low-energy electron beam can be sufficiently blocked by a thin polyvinyl chloride plate or the Like, so that there is almost no reflection; accordingly, shielding can be accomplished using a simple structure of the type shown in
Furthermore, as a result of the installation of the abovementioned shielding part, the disturbance of the gas current from the chamber blowing port can be reduced; accordingly, the following merit is also obtained: namely, the decrease in the quantity of ions caused by disturbance of the gas current can be ameliorated.
Furthermore, since the ionization source 4 and the control device 5 constituting the power supply part and control part of this ionization source 4 are installed separately with a high-voltage cable interposed, and since only the ionization source 4 is disposed inside the chamber 1, the internal diameter of the chamber 1 can be reduced; accordingly, the following merits can be obtained: namely, ions can be generated in an extremely narrow space, and de-charging can be performed even in the case of a narrow space such as (for example) the gaps between glass substrates accommodated inside a cassette.
Thus, the ionized gas current emission type dust-free ionizer of the present embodiment makes it possible to obtain an ionizer which allows countermeasures against static electricity to be taken in a narrow space without generating ozone, electromagnetic noise or dust, and which can be used in explosion-proof facilities and equipment.
The present embodiment is a modification in which the construction of the shielding part of the abovementioned first embodiment is altered.
In the present embodiment, as is shown in
The ionized gas current emission type dust-free ionizer of the present embodiment, which has the construction described above, has the same effects and merits as the abovementioned first embodiment; this ionizer can be used in explosion-proof facilities and equipment, and can form the area on the downstream side of the ionization part of the chamber 1 into a shielding structure by means of a simple construction.
The present embodiment is a modification in which the construction of the blowing part of the abovementioned first embodiment is altered. Furthermore, it goes without saying that the blowing part of the present embodiment can also be applied to the abovementioned second embodiment.
In the present embodiment, as is shown in
In the ionized gas current emission type dust-free ionizer of the present embodiment, which has the construction described above, the same effects and merits as those of the abovementioned first embodiment or second embodiment can be obtained; moreover, since a nozzle 20 which has a desired shape and size is attached to the blowing part, the ionized gas current can be blown onto the charged body at a high velocity, so that dirt or the like adhering to the charged body can be removed with a high efficiency while the charged body is de-charged. Furthermore, by selecting various types of nozzles 20, it is possible to broaden the ionized gas current at a wide angle in a conical shape, or to spread the ionized gas current into the form of an air curtain; accordingly, the ionized gas current can be controlled in accordance with the object of de-charging. Furthermore, by using a nozzle that allows adjustment of the degree of opening, it is easily possible to alter the jet velocity of the ionized gas current.
The present embodiment is a modification in which the construction of the blowing part of the abovementioned third embodiment is further altered.
In the present embodiment, as is shown in
In the ionized gas current emission type dust-free ionizer of the present embodiment, which has the construction described above, since a flexible hose 30 is attached to the blowing part and a nozzle 31 is further attached to the tip end of this flexible hose 30, not only can the same effects and merits as those of the abovementioned first through third embodiments be obtained, but it is also possible blow the ionized gas current onto the charged body at a high velocity, so that dirt or the like adhering to the charged body can be removed with a high efficiency while the charged body is de-charged. Furthermore, by selecting various types of nozzles 31, it is possible to broaden the ionized gas current at a wide angle in a conical shape, or to spread the ionized gas current into the form of an air curtain; accordingly, the ionized gas current can be controlled in accordance with the object of de-charging. Furthermore, by using a nozzle that allows adjustment of the degree of opening, it is easily possible to alter the jet velocity of the ionized gas current.
The present embodiment is an embodiment in which the shielding part and blowing part are constructed as an integral unit.
In the present embodiment, as is shown in
In the ionized gas current emission type dust-free ionizer of the present embodiment, which has the construction described above, since a plurality of openings which are of a size that can block X-rays are formed in a portion of the chamber on the downstream side of the ionization source 4, the jetting of an ionized gas current toward the object of de-charging can be accomplished simultaneously with shielding. Furthermore, as will be described below, the present embodiment is especially effective in cases where de-charging is performed by blowing an ionized gas current into the deep portions of narrow spaces such as the gaps between glass substrates in a cassette or the like.
The ionized gas current emission type dust-free ionizer of the present embodiment has characterizing features in the construction of the blowing port. Specifically, as is shown in
Furthermore, a shielding part 84 is disposed in the vicinity of the tip end portion of the abovementioned blowing port 81. As is shown (for example) in
Furthermore, an ion generating device is disposed in the side portion of the abovementioned blowing port 81. This ion generating device is constructed from an ionization source 4 which is disposed in the side portion of the blowing port 81, and a control device 5 which controls the quantity of ions generated by this ionization source 4. Furthermore, this control device 5 is disposed on the outside of the blowing port 81, and consists of a power supply part and control part which are used to generate soft X-rays or ultraviolet radiation from the ionization source; the control device 5 is connected to the ionization source 4 by a high-voltage cable 6.
Furthermore, the construction of this control device 5, the construction of the connecting part between the high-voltage cable 6 and the control device 5, and the construction of the connecting part between the ionization source 4 and the high-voltage cable 6, are the same as in the abovementioned first embodiment; accordingly, a description is omitted.
In the ionized gas current emission type dust-free ionizer of the present embodiment, which has the construction described above, this ionizer can be used in explosion-proof facilities and equipment; furthermore, since the ionization source 4 is contained internally in the vicinity of the outlet part of the blowing port 81, the ion carrier gas can be ionized in the vicinity of the blowing port 81, so that ionized air or the like can be supplied to the desired object of de-charging. Furthermore, since the ionization source 4 is contained internally in the side portion of the blowing port 81, and irradiation with radiation such as soft X-rays or the like is performed horizontally with the blowing port, a broad range can be covered by a single ionization source. Furthermore, since the ionization source 4 is contained internally in the vicinity of the outlet part of the blowing port 81, the distance from the ionization source 4 to the outlet of the blowing port is short, so that the following merit is also obtained: namely, there is little decrease in the ions due to the re-coupling of positive and negative ions.
This embodiment is a modification in which the installation position of the ionization source of the abovementioned sixth embodiment is altered. Specifically, in the present embodiment, as is shown in
In the ionized gas current emission type dust-free ionizer of the present embodiment, which has the construction described above, not only can the same effects and merits as in the abovementioned sixth embodiment be obtained, but it also possible to perform ionization over a broad range with a small ionization source in the case of an ionization source that can emit soft X-rays or the like over a broad angle. Accordingly, since the ionization efficiency is good, and the quantity of ions generated is increased, the de-charging performance is improved. Furthermore, the angle of incidence of the radiation on the shielding plates is greater than in cases where irradiation is performed horizontally in the vicinity of the shielding plates; accordingly, shielding is facilitated, and shielding plate with vertical holes or the like are unnecessary.
This embodiment is a modification of the abovementioned sixth embodiment, and indicates a case in which an HEPA filter or ULPA filter is disposed on the upstream side of the blowing port. Specifically, in the present embodiment, as is shown in
In the ionized gas current emission type dust-free ionizer of the present embodiment, which has the abovementioned construction, not only can the same effects and merits as those of the abovementioned sixth embodiment be obtained, but it is also possible to form the ion carrier gas that is fed in from the chamber 82 into a laminar flow, since a laminar flow forming filter 91 is disposed on the upstream side of the blowing port 81. As a result, in cases where a turbulent flow (jet) is supplied to the blowing port, the problem of a decrease in the quantity of ions and a drop in the de-charging efficiency due to the promotion of the re-coupling of positive and negative ions by the mixing effect can be prevented; accordingly, more efficient ionization can be accomplished, so that a superior de-charging performance can be obtained.
The ionized gas current emission type dust-free ionizer of the present embodiment is a modification of the abovementioned sixth embodiment. In this ionizer, as is shown in
In the ionized gas current emission type dust-free ionizer of the present embodiment, which has the abovementioned construction, the ionizer can be used in explosion-proof facilities and equipment; furthermore, since a laminar flow forming filter 91 is disposed on the upstream said of the blowing port 81, the ion carrier gas that is fed in from the chamber 82 can be formed into a laminar flow. As a result, in cases where a turbulent flow (jet) is supplied to the blowing port, the problem of a decrease in the quantity of ions and a drop in the de-charging efficiency due to the promotion of the re-coupling of positive and negative ions by the mixing effect can be prevented; accordingly, more efficient ionization can be accomplished, so that a superior de-charging performance can be obtained.
Furthermore, as is shown in
Furthermore, the present invention is not limited to the embodiments described above; various configurations such as those described below are possible. Specifically, the shapes or attachment positions and methods of respective concrete members may be appropriately altered. For example, the shape of the shielding part is not limited to the punched plates indicated in the respective embodiments described above; any shape that is capable of preventing the leakage of linearly advancing soft X-rays, low-energy electron beam electrons or the like to the outside, and that can carry the positive and negative ions that are generated, may be used.
Furthermore, the ionization source 4 is not limited to soft X-rays, a low-energy electron beam or ultraviolet radiation; other electromagnetic waves, beams or the like may be used as long as these sources do not generate ozone, dust or electromagnetic noise as a result of ionization. Moreover, as shown in
As was described above, the present invention can provide an ionized gas current emission type dust-free ionizer which makes it possible to take countermeasures against static electricity in a narrow space without causing the generation of ozone, electromagnetic noise, dust or the like, and which can also be used in explosion-proof facilities and equipment.
This is a divisional application of U.S. Ser. No. 10/479,353, filed on Jun. 1, 2004 and issued as U.S. Pat. No. 7,126,807.
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| Number | Date | Country | |
|---|---|---|---|
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| Number | Date | Country | |
|---|---|---|---|
| Parent | 10479353 | Jun 2004 | US |
| Child | 11507917 | US |
