JP4494082B2 - Static eliminator - Google Patents

Description

  The present invention relates to a static eliminator that generates air ions by ionizing air with radiation such as α rays and discharges a charged body with the air ions.

As a charge eliminating device that ionizes air in order to remove electricity from a charged body, a device using a radiation source such as α-ray is known as seen in, for example, Japanese Patent Application Laid-Open No. 7-45397. Yes. This static eliminator generates positive and negative air ions by ionizing air with radiation (mainly alpha rays) emitted from a radiation source containing a radioactive substance such as americium 241 ( ²⁴¹ Am), and the generated air ions Among these, the charged body is neutralized by air ions having a polarity opposite to that of the charged body.

  Thus, the static elimination apparatus which uses a radiation source has the advantage that an apparatus structure can be made small and simple. Also, like corona discharge type static eliminator, it is possible to avoid the generation of dust from the discharge needle and the occurrence of radio wave interference (such as malfunction of electrical equipment) to other electrical equipment due to radiation of high voltage electric field, etc. There is an advantage in terms of.

The radiation source used in this type of static eliminator is a sealed radioactive material, and is generally called a sealed radiation source.
JP 7-45397 A

  By the way, in the conventional static eliminator shown in the above-mentioned patent document 1, the charged body is neutralized simply by moving the charged body near the radiation source, or the radiation source and the charged body are placed in a storage room having a blower. It is accommodated so that the charged body is neutralized.

  However, positive and negative air ions generated by radiation from the radiation source simply diffuse spontaneously as they are, and their moving speed is very slow. For this reason, even if the charged body is simply moved in the vicinity of the radiation source, it is often impossible to sufficiently remove the charge from the charged body in a short time. Furthermore, α rays, which are radiation mainly used in this type of static eliminator, have a short range, and air ions are generated only at locations relatively close to the radiation source. In a situation where the distance cannot be shortened, it is difficult to remove the charged body.

  In addition, when a blower is provided, it is possible to forcibly blow the generated air ions toward the charged body, but there is a disadvantage that the apparatus configuration must be large. Also, not only air ions having the opposite polarity to the potential of the charged body, but also air ions having the same polarity as the charged body are supplied to the charged body, so that the charged body cannot be sufficiently discharged. There is also.

  The present invention has been made in view of such a background. Air ions generated by using radiation are effectively supplied to a charged body with a small and simple configuration, and the charge of the charged body can be eliminated in a short time. An object of the present invention is to provide a static eliminator that can be sufficiently performed.

Before describing the static eliminator of the present invention, reference inventions (first to fourth inventions) related to the present invention will be described. A first invention comprises a sealed source that emits radiation in a static eliminator that generates air ions for neutralizing charged bodies by its radiation, so as to expose the radiation-emitting surface of the sealed source by the A sealed radiation source holding member comprising a conductor for holding a sealed radiation source, and at least when the charged body is neutralized, the sealed radiation source holding member with the radiation emitting surface of the sealed radiation source facing the charged body Is electrically grounded.

  According to the static eliminator of the first invention, at least when the charged body is neutralized, the sealed radiation source holding member is electrically grounded with the radiation emitting surface of the sealed radiation source facing the charged body. Therefore, an electric field is formed between the sealed radiation source holding member and the charged body. For this reason, among the positive and negative air ions generated in the space in front of the radiation emitting surface (the space between the radiation emitting surface and the charged body) by the radiation from the radiation emitting surface of the sealed radiation source, the potential of the charged body Air ions of opposite polarity are forcibly moved toward the charged body by the action of the electric field (sucked by the charged body). The charged body is neutralized by the air ions having the opposite polarity that have moved to the charged body.

  Therefore, it is possible to quickly remove the charge from the charged body. In the first aspect of the invention, since the static electricity can be quickly removed from the charged body simply by electrically grounding the sealed radiation source holding member with a conducting wire or the like connected thereto, the structure of the static eliminator can be reduced in size. And can be simplified. In addition, as the charge removal of the charged body proceeds, the charged body potential approaches the ground potential, and the electric field between the charged body and the sealed radiation source holding member weakens. Ions are not excessively supplied to the charged body. Therefore, according to the first invention, air ions generated by using radiation can be effectively supplied to a charged body with a small and simple configuration, and the charge of the charged body can be sufficiently removed in a short time. it can.

  The sealed radiation source holding member does not have to be an integral structure, and may be an assembly in which two or more conductor members are connected to each other.

  In the first invention, it is desirable that the sealed radiation source holding member has an annular conductor portion around the radiation emitting surface of the sealed radiation source (second invention).

  According to the second aspect of the invention, since an electric field is formed between the sealed radiation source holding member and the charged body, around the radiation emitting surface of the sealed radiation source, the electric field reverses the potential of the charged body. Polar air ions can be efficiently moved to the charged body.

Further, a third invention as a reference invention includes a sealed radiation source that emits radiation, and in the static eliminator that generates air ions for neutralizing a charged body by the radiation, the radiation emitting surface of the sealed radiation source is covered. And a covering member made of a conductor provided with a plurality of holes through which the radiation emitted from the radiation emitting surface is transmitted, and at least the charged body is neutralized. At this time, the covering member positioned between the sealed radiation source and the charged body is electrically grounded with the radiation emitting surface of the sealed radiation source facing the charged body.

  According to the static eliminator of the third aspect of the invention, at least when neutralizing the charged body, the radiation emitting surface of the sealed radiation source is positioned between the sealed radiation source and the charged body with the radiation emitting surface facing the charged body. Since the covering member is electrically grounded, an electric field is formed between the covering member and the charged body. And this electric field is formed in the space ahead of the radiation emission surface of a sealed radiation source. For this reason, among the positive and negative air ions generated in the space between the covering member and the charged body by the radiation from the radiation emitting surface of the sealed radiation source, the majority of the air ions having the opposite polarity to the potential of the charged body are the electric field. As a result of this action, it is forcibly moved toward the charged body (sucked by the charged body). The charged body is neutralized by the air ions having the opposite polarity that have moved to the charged body.

  Therefore, it is possible to quickly remove the charge from the charged body. According to the first aspect of the present invention, since it is possible to quickly remove static electricity from the charged body simply by electrically grounding the covering member with a conducting wire or the like connected thereto, the structure of the static elimination device can be reduced in size and simplified. Can be. Also, as the charge removal of the charged body progresses, the potential of the charged body approaches the ground potential, and the electric field between the charged body and the covering member weakens. In other words, it is not supplied to the charged body. Therefore, according to the third invention, air ions generated using radiation can be effectively supplied to a charged body with a small and simple configuration, and the charged body can be sufficiently discharged in a short time. it can. Moreover, in 3rd invention, there exists an effect which protects the radiation | emission surface of a sealed radiation source holding member mechanically by providing a coating | coated member.

  In the third invention, the sealed radiation source holding member that holds the sealed radiation source is of course configured to expose the radiation emitting surface of the sealed radiation source to the space between the covering member, The material may be a conductor member or an insulating member. When the sealed radiation source holding member is made of a conductor member, the covering member and the sealed radiation source holding member may be electrically connected, and one of them may be grounded so that the other is grounded. In other words, the first invention or the second invention may be combined with the third invention.

  In the third aspect of the invention, it is desirable for the covering member to be disposed close to the radiation emitting surface within the range of the radiation from the radiation emitting surface of the sealed radiation source in order to reduce the size of the static eliminator. .

  In the third invention, it is preferable that the covering member is made of a net-like member (fourth invention).

  According to the fourth aspect of the present invention, since an electric field that is concentrated in front of the radiation emitting surface of the sealed radiation source can be formed between the charged body and the covering member, air ions having the opposite polarity are moved to the charged body. The effect can be enhanced. In the fourth aspect of the invention, the mesh portion of the mesh-like covering member is a hole that transmits radiation.

  By the way, in the first or second invention, in particular, if the distance between the sealed radiation source and the charged body is relatively large, the electric field between the charged body and the sealed radiation source becomes weak. The force to move polar air ions toward the charged body is weakened. Similarly, in the third or fourth aspect of the invention, if the distance between the covering member and the charging member is relatively large, the electric field between the charging member and the covering member becomes weak. The force to move ions toward the charged body is weakened.

Therefore, the static eliminator of the present invention employs the following configuration in order to achieve the above object. That is, in the first or second aspect of the invention, the potential detection means for detecting the potential of the charged body, and at least when the charge body is neutralized, between the charged body and the radiation emitting surface of the sealed radiation source. An ion accelerating electrode member made of a conductor provided to be positioned, and a DC voltage power source for selectively applying a positive or negative DC voltage to the ion accelerating electrode member, and removing the charged body When the voltage of the same polarity as the potential of the charged body detected by the potential detecting means is applied to the ion acceleration electrode member from the DC voltage power source, the ion acceleration electrode member is emitted from the radiation emitting surface of the sealed radiation source. Of the air ions generated by radiation, the ion accelerating electrode member and the sealed radiation source holding member are used to move an electric field having a polarity opposite to the electric potential of the charged body toward the charged body. And so as to form between the (fifth invention).

Similarly, in the third or fourth aspect of the invention , the potential detecting means for detecting the potential of the charged body, and at least when the charge body is neutralized, are positioned between the charged body and the covering member. An ion accelerating electrode member made of a conductor provided, and a DC voltage power source for selectively applying a positive or negative DC voltage to the ion accelerating electrode member, The acceleration electrode member is generated by the radiation emitted from the radiation emitting surface of the sealed radiation source by applying a voltage having the same polarity as the potential of the charged body detected by the potential detecting means from the DC voltage power source. that the electric field to move toward the air ions of potential polarity opposite to the charging of the charging member of the air ions to form between the ion acceleration electrode member and the covering member (A sixth aspect of the invention).

  According to these fifth and sixth inventions, when neutralizing the charged body, a voltage having a polarity opposite to the potential of the charged body detected by the potential detecting means is applied to the ion accelerating electrode member from the DC voltage power source. Accordingly, an electric field (in the case of the first or second invention) formed between the ion acceleration electrode member and the sealed radiation source holding member, or formed between the ion acceleration electrode member and the covering member. By the electric field (in the case of the third or fourth invention), air ions having a polarity opposite to the potential of the charged body can be forcibly moved toward the charged body. Therefore, even when the distance between the sealed radiation source holding member or the covering member and the charged body is relatively large, air ions having a polarity opposite to the potential of the charged body are efficiently moved to the charged body, and the charged body The charge removal can be performed, and a good charge removal effect of the charged body can be secured.

  In the fifth or sixth invention, the ion accelerating electrode member is constituted by, for example, an annular conductor member. In this case, the ion accelerating electrode member is charged between the sealed radiation source holding member and the charged body or charged with the covering member in a state in which the axial center thereof is oriented in the normal direction of the radiation emitting surface of the sealed radiation source. What is necessary is just to arrange | position between bodies.

  In the fifth or sixth invention, the magnitude of the voltage applied from the DC voltage power source to the ion accelerating electrode member is substantially equal to the magnitude of the potential of the charged body detected by the potential detecting means. It is preferable (the seventh invention).

  According to this, an electric field is hardly generated between the ion accelerating electrode member and the charged body, which prevents air ions having a polarity opposite to the potential of the charged body from moving toward the charged body. In addition, as the charge of the charged body becomes closer to 0 (ground potential) as the charge of the charged body progresses, the magnitude of the voltage applied to the ion acceleration electrode member also decreases. It is possible to avoid excessive supply of air ions having the opposite polarity to the potential to the charged body. Therefore, it is possible to quickly and sufficiently remove the charge from the charged body.

A first embodiment as a reference example related to the present invention will be described with reference to FIGS. FIG. 1 is an external perspective view of the static eliminator of the first embodiment, and FIG. 2 is a cross-sectional view of the static eliminator and the charged body shown by the section taken along the line II-II in FIG.

As shown in FIGS. 1 and 2, the static eliminator 1 of the present embodiment includes a sealed radiation source 2 as a radiation source and a sealed radiation source holding member 3 that holds the sealed radiation source 2. The sealed radiation source 2 is a plate-like material containing a radioactive substance, and its outer surface is coated with gold (Au). More specifically, the sealed radiation source 2 according to the present embodiment is a powder comprising a radioactive material Americium 241 ( ²⁴¹ Am) and Au on the upper surface of a 150 μm thick silver plate whose lower surface is coated with gold (Au). The body matrix is attached to a thickness of several μm, and the surface of the attached powder matrix is coated with 2 μm thick Au to form a plate. The radiation emitted from the sealed radiation source 2 is mainly α rays, and the upper surface of the sealed radiation source 2 is a radiation emitting surface 2a. Moreover, the radioactivity of the sealed radiation source 2 is, for example, less than 3.7 MBq.

In this embodiment, ²⁴¹ Am is used as the radioactive substance of the sealed radiation source 2, but polonium 210 ( ²¹⁰ Po), for example, may be used instead. However, the half-life of ²⁴¹ Am is 432.2 years, which is sufficiently longer than the half-life of 13 Po for ²¹⁰ Po. It is better to use ²⁴¹ Am to keep it.

  The sealed radiation source holding member 3 includes a main base 4 that directly holds the sealed radiation source 2 and a case base 5 that supports the main base 4.

  The main base 4 is a disk-shaped conductor member made of stainless steel, and the sealed radiation source 2 has its radiation emitting surface 2a outward (upward in FIG. 2) in a recess 4a formed in the center of the upper surface. It is fitted and fixed in a state of being opened.

  The case base 5 is a rectangular plate-like conductor member made of metal or conductive plastic, and the storage chamber 6 of the main base 4 is provided therein. In the storage chamber 6, the main base 4 to which the sealed radiation source 2 is fixed is accommodated with the radiation emission surface 2 a of the sealed radiation source 2 facing upward. In this case, the main base 4 and the case base 5 are electrically connected. An opening hole 7 having a diameter smaller than that of the main base 4 is provided in the center of the upper surface of the case base 5 so as to communicate with the storage chamber 6. The radiation of the sealed radiation source 2 is provided through the opening hole 7. The emission surface 2a and the peripheral portion (the peripheral portion of the radiation emission surface 2a) 4b of the main base 4 are exposed outward (upward in FIG. 2).

  With such a structure of the sealed radiation source holding member 3, the peripheral portion 4 b of the recess 4 a of the main base 4 and the peripheral portion 5 a of the opening hole 7 of the case base 5 are annular conductors around the sealed radiation source 2. Portions 4b and 5a are formed.

  Further, the case base 5 is grounded via a conducting wire 8 connected thereto. In this case, since the main base 4 and the case base 5 are electrically connected to each other, when the case base 5 is grounded, the main base 4 is also grounded.

  Next, the charge eliminating operation of the charged body X by the charge eliminating device 1 will be described with reference to FIG.

  When neutralizing the charged body X, the charged body X is made to face the radiation emitting surface 2 a of the sealed radiation source 2. At this time, the air in the space in front of the radiation emitting surface 2a (the space between the radiation emitting surface 2a and the charged body X) is caused by the radiation (mainly α rays) emitted from the radiation emitting surface 2a of the sealed radiation source 2. Ionization generates positive and negative air ions. This generation of air ions (air ionization) is mainly performed in a space within the range of the α ray range from the radiation emitting surface 2a, and the range is about 4 cm. The generated air ions diffuse in all directions due to concentration diffusion when there is no electric field in the space, but the movement speed of air ions due to the concentration diffusion is very slow.

  As described above, when the charged body X is opposed to the radiation emitting surface 2a of the sealed radiation source 2, the sealed radiation source holding member 3 is grounded, so that the charged body X and the sealed radiation source holding member 3 are In the meantime, an electric field is formed as illustrated by the electric lines of force indicated by the solid arrow Y1 in FIG. In FIG. 2, the lines of electric force are illustrated by taking the case where the charged body X is positively charged (the potential of the charged body X is positive) as an example. In this case, since the periphery of the radiation emitting surface 2a of the sealed radiation source 2 is the annular conductor portions 4b and 5a of the grounded sealed radiation source holding member 3, the electric field is accumulated around the radiation emitting surface 2a. Formed without. For this reason, among positive and negative air ions generated in the space between the radiation emitting surface 2 a and the charged body X, air ions having a polarity opposite to the potential of the charged body X are charged with the charged body X and the sealed radiation source holding member 3. Is smoothly moved toward the charged body X by the action of the electric field between and the charge of the charged body X is neutralized. Thereby, the charged body X is neutralized.

  Further, as the charge of the charged body X is neutralized, the electric field between the charged body X and the sealed radiation source holding member 3 is weakened, so that air ions having a polarity opposite to the potential of the charged body X are excessively charged. Moving to X is avoided. Therefore, it is avoided that the charged body X is charged to a reverse polarity.

  In addition, in this embodiment, although the main base 4 and the case base 5 which comprise the sealed radiation source holding member 3 were electrically connected, you may make it electrically insulate these. In this case, since the case base 5 is grounded, the case base 5 corresponds to the sealed radiation source holding member in the present invention.

Next, two embodiments as reference examples related to the present invention will be described with reference to FIGS. FIG. 3 is an external perspective view of the static eliminator of the present embodiment, and FIG. 4 is a cross-sectional view of the static eliminator and the charged body shown by a cross section taken along line IV-IV in FIG. In the description of the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted.

  In the static eliminator 11 of the present embodiment, the mesh-like (mesh) covering member 12 covers the opening end of the opening hole 7 of the case base 5 of the sealed radiation source holding member 3 (as a result, the sealed radiation source 2 is attached to the upper surface of the case base 5 so as to cover the radiation emission surface 2a. The covering member 12 is a conductor member made of metal or conductive plastic, and a peripheral portion thereof is electrically connected to the case base 5. The mesh of the covering member 12 is a hole through which the radiation emitted from the radiation emitting surface 2a is transmitted. In addition, the space | interval of the coating | coated member 12 and the radiation emission surface 2a is about several mm, and is a thing smaller than the range (about 4 cm) of the radiation (alpha ray) emitted from the radiation emission surface 2a. . Therefore, most of the radiation emitted from the sealed radiation source 2 passes through the mesh of the covering member 12.

  The static eliminator 11 of the present embodiment is the same as the static eliminator 1 of the first embodiment except for the structure described above. In this case, in this embodiment, the case base 5 and the covering member 12 of the sealed radiation source holding member 3 are electrically connected to each other, and the case base 5 is connected to the conductive wire 8 as in the first embodiment. Therefore, the covering member 12 is grounded via the case base 5.

  Note that a conductive wire may be connected to the covering member 12, and the covering member 12 may be directly grounded via the conductive wire. In the present embodiment, the case base 5 of the sealed radiation source holding member 3 is made of a conductor member. However, the case base 5 is made of an insulating member so that only the covering member 12 is grounded. Also good.

  Next, the charge eliminating operation of the charged body X by the charge eliminating device 11 will be described with reference to FIG.

  When neutralizing the charged body X, the charged body X is made to face the radiation emitting surface 2 a of the sealed radiation source 2. At this time, mainly in the space in front of the radiation emitting surface 2a (the space between the radiation emitting surface 2a and the charged body X) by the radiation (mainly α rays) emitted from the radiation emitting surface 2a of the sealed radiation source 2. The air in the space within the range of the α ray from the radiation emitting surface 2a is ionized, and positive and negative air ions are generated.

  As described above, since the covering member 12 and the sealed radiation source holding member 3 are grounded when the charged body X is opposed to the radiation emitting surface 2a of the sealed radiation source 2, the charged body X and the covering member 12 are grounded. In addition, an electric field is formed between the sealed radiation source holding member 3 (mainly the case base 5) as exemplified by the electric lines of force indicated by the solid arrow Y2 in FIG. In FIG. 4, the lines of electric force are illustrated by taking as an example the case where the charged body X is positively charged (the potential of the charged body X is positive). In this case, in particular, since the covering member 12 covers the front of the radiation emitting surface 2a of the sealed radiation source 2, the electric field between the covering member 12 and the charged body X is accumulated in the space in front of the radiation emitting surface 2a. Formed without. For this reason, out of positive and negative air ions generated in the space between the covering member 12 and the charged body X, air ions having a polarity opposite to the potential of the charged body X are mainly generated between the charged body X and the covering member 12. Due to the action of the electric field in between, it smoothly moves toward the charged body X and neutralizes the charge of the charged body X. Thereby, the charged body X is neutralized.

  Further, as the electric charge of the charged body X is neutralized, the electric field between the charged body X and the covering member 12 and the sealed radiation source holding member 3 is weakened. Excessive movement to the charged body X is avoided. Therefore, it is avoided that the charged body X is charged to a reverse polarity.

Next, a third embodiment as one embodiment of the present invention will be described with reference to FIGS. FIG. 5 is an external perspective view of the main part of the static eliminator of the present embodiment, and FIG. 6 is a cross-sectional view of the static eliminator and the charged body shown in the VI-VI line cross section of FIG. In the description of the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted.

  The static eliminator 21 according to the present embodiment includes an annular ion acceleration electrode member 22 disposed so as to face the opening end of the opening hole 7 of the case base 5 of the sealed radiation source holding member 3. The ion accelerating electrode member 22 is made of a metal conductor member, and its axis is directed in the normal direction of the radiation emitting surface 2a of the sealed radiation source 2, and its axis passes through the approximate center of the radiation emitting surface 2a. It is provided as follows. The ion accelerating electrode member 22 is connected to a DC voltage power source 23 that selectively generates positive and negative DC voltages via a connection lead 24 and is electrically insulated from the sealed line source holding member 3. Has been. The ion acceleration electrode member 22 and the sealed radiation source holding member 3 are fixedly supported on a base (not shown) made of an insulator.

  Further, as shown in FIG. 6, the static eliminator 21 includes an electrometer 25 as a potential detection unit that detects the potential of the charged body X. The electrometer 25 is arranged close to the charged body X, and outputs a voltage signal corresponding to the potential of the charged body X by electrostatic induction. The detection output of the electrometer 25 is input to a control device (not shown). The control device displays the potential of the charged body X and controls the voltage generated by the DC voltage power source 23. I have to. The static eliminator 21 of this embodiment is the same as that of the first embodiment except for the structure described above.

  Next, the charge eliminating operation of the charged body X by the charge eliminating device 21 will be described with reference to FIG.

  When neutralizing the charged body X, the charged body X is placed on the radiation emitting surface 2a of the sealed radiation source 2 such that the ion accelerating electrode member 22 is interposed between the charged body X and the sealed radiation source holding member 3. Make X face each other. At this time, the radiation (mainly α rays) emitted from the radiation emitting surface 2a is used to advance the space ahead of the radiation emitting surface 2a (in the space between the radiation emitting surface 2a and the charged body X, mainly the radiation emitting surface 2a). The air in the space within the range of the α ray from the ionization is ionized, and positive and negative air ions are generated.

  In addition, the electrometer 25 is disposed close to the charged body X, and the potential of the charged body X is detected by the electrometer 25. Then, a DC voltage is applied from the DC voltage power supply 23 to the ion acceleration electrode member 22 by a control device (not shown) according to the detected potential of the charged body X. In this case, the DC voltage applied to the ion accelerating electrode member 22 has the same polarity as the potential of the charged body X detected by the electrometer 25 and has a magnitude approximately equal to the magnitude (absolute value) of the potential. Voltage.

  At this time, an electric field is formed between the ion acceleration electrode member 22 and the grounded sealed radiation source holding member 3 as illustrated by the electric lines of force indicated by the solid line arrow Y3 in FIG. In FIG. 6, the lines of electric force are illustrated by taking as an example a case where the charged body X is positively charged and a positive DC voltage is applied to the ion acceleration electrode member 22. In this case, since the ion accelerating electrode member 22 is annular, the front surface of the radiation emitting surface 2a of the sealed radiation source 2 is open toward the charged body X. For this reason, among the air ions generated in the space in front of the radiation emitting surface 2a, most of the air ions having a polarity opposite to the polarity of the voltage of the ion acceleration electrode member 22 (= the polarity of the potential of the charged body X) are ions. After being accelerated toward the charged body X by the electric field between the acceleration electrode member 22 and the sealed radiation source holding member 3, it passes through the inside of the ion acceleration electrode member 22 and moves toward the charged body X. Then, the charge of the charged body X is neutralized. Thereby, the charged body X is neutralized.

  Further, as the charge removal of the charged body X proceeds, the potential of the charged body X detected by the electrometer 25 approaches zero. In accordance with this, the magnitude of the voltage generated by the DC voltage power source 23 (DC voltage applied to the ion acceleration electrode member 22) is substantially equal to the magnitude of the detected potential of the charged body X by a control device (not shown). Will be reduced. Accordingly, it is possible to prevent an electric field between the ion accelerating electrode member 22 and the charged body X from being generated so as to prevent air ions having a polarity opposite to the potential of the charged body X from moving toward the charged body X. The As a result, air ions having a polarity opposite to that of the charged body X move smoothly toward the charged body X until the charged body X is neutralized.

  In the present embodiment, the cover member is not provided in front of the radiation emitting surface 2a of the sealed radiation source 2. However, as in the static eliminator 11 of the second embodiment, the mesh-like cover member 12 is provided. It may be. In this case, mainly, air ions accelerated by the electric field formed between the ion accelerating electrode member 22 and the mesh covering member 12 move toward the charged body X, and the charged body X is neutralized. Will be.

  Next, the test result of the static elimination effect of the examples of the static eliminators 1, 11 and 21 of the first to third embodiments described above will be described with reference to FIG. FIG. 7 shows a device configuration for performing a test on the static elimination effect of the static elimination devices 1, 11 and 21 according to the first to third embodiments. In FIG. 7, for the sake of convenience, only the sealed radiation source 2 and the sealed radiation source holding member 3 which are main parts of the static eliminators 1, 11 and 21 of the embodiments are illustrated.

  In FIG. 7, reference numeral 31 denotes a charging plate monitor. The charging plate monitor 31 has a metal (conductor) charging plate 34 attached to an upper surface portion of a main body 32 via an insulating member 33. The charging plate 34 corresponds to a pseudo charged body. The main body 32 has a surface potential measuring device 35 that measures the potential of the charging plate 34, a high voltage power source 36 that applies a DC voltage to the charging plate 34, and charges the charging plate 34, and the potential attenuation of the charging plate 34. A timer 37 for measuring time is incorporated. The charging plate 34 of the charging plate monitor 31 used in the embodiment is 50 mm square, and its capacitance is 3.5 pF.

  Using the charging plate monitor 31, the following tests were performed on the static eliminators 1, 11, and 21 of the first to third embodiments.

  The sealed radiation source holding member 3 of the static eliminator 1 of the first embodiment is disposed at a distance of 20 mm from the charging plate 34, and the charging plate 34 is charged to a predetermined potential by the high voltage power source 36. There are two types of charging potential at this time: + 100V and -100V. From the state in which the charging plate 34 is charged in this way, the time required for the potential of the charging plate 34 measured by the surface potential measuring device 35 to attenuate from +100 V to +5 V, and the time required to attenuate from -100 V to -5 V, Was measured by the timer 37. Further, the surface potential measuring device 35 measured the potential of the charging plate 34 in a steady state (a state where the potential of the charging plate 34 was attenuated to a substantially constant value) as an offset voltage. This offset voltage serves as an index of the balance (ion balance) of the production amount of positive and negative air ions generated by the static eliminator. The closer the value is to 0, the more uniform the production amount of positive and negative air ions. It means that.

  The sealed radiation source holding member 3 of the static eliminator 11 of the second embodiment was disposed at a distance of 20 mm from the charging plate 34, and the potential decay time and the offset voltage of the charging plate 34 were measured in the same manner as in Example 1. In this case, the distance between the radiation emitting surface 2a of the sealed radiation source 2 and the covering member 12 was 2 mm and 10 mm, and the potential decay time and the offset voltage were measured for each.

[Comparative Example 1]
For comparison with Examples 1 and 2, the sealed radiation source holding member of the static eliminator having the same structure as the static eliminator 1 of the first embodiment is disposed at a distance of 20 mm from the charging plate 34 without being grounded. 1, the decay time of the potential of the charging plate 34 and the offset voltage were measured.

  The measurement results of Examples 1 and 2 and Comparative Example 1 are shown in Table 1 below.

  The sealed radiation source holding member 3 of the static eliminator 1 of the first embodiment was disposed at a distance of 40 mm from the charging plate 34, and the potential decay time and the offset voltage of the charging plate 34 were measured as in Example 1.

  The sealed radiation source holding member 3 of the static eliminator 11 of the second embodiment was disposed at a distance of 40 mm from the charging plate 34, and the potential decay time and the offset voltage of the charging plate 34 were measured in the same manner as in Example 1. In this case, the distance between the radiation emitting surface 2a of the sealed radiation source 2 and the covering member 12 was 2 mm and 10 mm, and the potential decay time and the offset voltage were measured for each.

[Comparative Example 2]
For comparison with Examples 3 and 4, the sealed radiation source holding member of the static eliminator having the same structure as the static eliminator 1 of the first embodiment is disposed at a distance of 40 mm from the charging plate 34 without being grounded. 1, the decay time of the potential of the charging plate 34 and the offset voltage were measured.

  The measurement results of Examples 3 and 4 and Comparative Example 2 are shown in Table 2 below.

前記表１および表２から明らかなように、帯電プレート３４の電位の減衰時間は、実施例１、２では、比較例１よりも大幅に短い時間となっており、実施例３、４では、比較例２よりも大幅に短い時間となっている。このことから、前記第１実施形態および第２実施形態の如く、密封線源保持部材３や被覆部材１２を接地することが、帯電体の除電を迅速に行なう上で効果的であることが判る。また、実施例２，４の試験結果を参照すると、第２実施形態の除電装置１１を用いた場合の帯電プレート３４の電位の減衰時間は、密封線源保持部材３と被覆部材１２との距離の影響をさほど受けないことが判る。従って、第２実施形態のように被覆部材１２を備える場合には、除電装置１１の小型化の観点から、該被覆部材１２はできるだけ密封線源２の放射線放出面２ａに近いことが望ましい。

As apparent from Table 1 and Table 2, the potential decay time of the charging plate 34 is much shorter in Examples 1 and 2 than in Comparative Example 1, and in Examples 3 and 4, The time is significantly shorter than that of Comparative Example 2. From this, it can be seen that grounding the sealed radiation source holding member 3 and the covering member 12 as in the first embodiment and the second embodiment is effective in quickly removing the charge from the charged body. . Further, referring to the test results of Examples 2 and 4, when the static eliminator 11 of the second embodiment is used, the potential decay time of the charging plate 34 is the distance between the sealed radiation source holding member 3 and the covering member 12. It is understood that it is not so affected by. Therefore, when the covering member 12 is provided as in the second embodiment, it is desirable that the covering member 12 is as close as possible to the radiation emitting surface 2a of the sealed radiation source 2 from the viewpoint of miniaturization of the static eliminator 11.

  Further, as is clear from comparison between Examples 1 and 2 in Table 1 and Examples 3 and 4 in Table 2, the decay time of the potential of the charging plate 34 is the sealed radiation source holding member of the static eliminators 1 and 11. 3 and the charging plate 34 have a shorter time when the distance is 20 mm than when the distance is 40 mm. Accordingly, when the charged body is neutralized by the neutralizing devices 1 and 11, it is desirable that the distance between the sealed radiation source holding member 3 and the charged body be close to about 20 mm in order to quickly perform the neutralization.

  Supplementally, for the static eliminator 1 of the first embodiment, the same test as in Example 1 was performed with the distance between the sealed radiation source holding member 3 and the charging plate 34 being 50 mm. The decay time of the potential of the charging plate 34 at this time was 10.3 (sec) from + 100V to + 5V, and 17.8 (sec) from -100V to -5V. Therefore, it can be seen that as the distance between the sealed radiation source holding member 3 and the charging plate 34 becomes longer, the time required for neutralizing the charged body becomes abruptly longer. Therefore, the static eliminator 1 of the first embodiment and the static eliminator 11 of the second embodiment are particularly effective when the sealed radiation source holding member 3 and the charged body X can be disposed relatively close to each other.

  The offset voltage is substantially 0 V in any of Examples 1 to 4 and Comparative Examples 1 and 2. This is considered to be because positive and negative air ions are uniformly generated by generating air ions by radiation.

  Next, for the static eliminator 11 of the second embodiment, four types having different wire diameters and mesh widths (openings) of the mesh-shaped covering member 12 are prepared, and for each of the above Examples 1 to 4 Similarly, the decay time of the potential of the charging plate 34 and the offset voltage were measured. In this case, the distance between the sealed radiation source holding member 3 of the static eliminator 11 and the charging plate 34 was 20 mm, and the distance between the covering member 12 and the radiation emitting surface 2a of the sealed radiation source 2 was 2 mm. The material of the covering member 12 is stainless steel.

  The test results of Example 5 are shown in Table 3.

表３を参照して、被覆部材１２の線径および開き目が最も小さいもの（被覆部材の種類Ａのもの）では、帯電プレート３４の電位の減衰時間が、他のもの（被覆部材の種類Ｂ，Ｃ，Ｄのもの）よりも多少長くなるもものの、線径が０．４７ｍｍ以上で、開き目２．０７ｍｍ以上のもの（被覆部材の種類Ｂ，Ｃ，Ｄのもの）では、ほぼ同じように良好な除電効果が得られている。このことから、第２実施形態の除電装置１１は、被覆部材１２の線径や開き目が極端に小さくない限り、良好な除電効果（除電を迅速に行なうこと）が得られることが判る。

Referring to Table 3, in the covering member 12 having the smallest wire diameter and opening (covering member type A), the potential decay time of the charging plate 34 is different (covering member type B). , C, D) is slightly longer than that of a wire diameter of 0.47 mm or more and an opening of 2.07 mm or more (coating member types B, C, D) is almost the same. In addition, a good static elimination effect is obtained. From this, it can be seen that the static eliminator 11 of the second embodiment can provide a good static elimination effect (quickly eliminate the static electricity) unless the wire diameter and the opening of the covering member 12 are extremely small.

  Next, the sealed radiation source holding member 3 of the static eliminator 21 of the third embodiment is arranged at a distance of 50 mm from the charging plate 34, and the potential decay time of the charging plate 34 is measured as in the first embodiment. did. However, in this case, when the charging plate 34 is charged to + 100V, the DC voltage applied to the ion accelerating electrode member 22 of the static eliminator 21 is maintained at a constant value of + 24V, and the charging plate 34 is charged to −100V. When it was, it was kept at a constant value of -24V. The distance between the ion accelerating electrode member 22 and the sealed radiation source 2 (distance in the axial direction of the ion accelerating electrode member 22) was set to four types of 5 mm, 10 mm, 20 mm, and 30 mm. The ion accelerating electrode member 22 is an annular member having a diameter of 20 mm. The decay time measured in Example 6 is the decay time from +100 V (or -100 V) to +10 V (or -10 V).

[Comparative Example 3]
For comparison with Example 6, a sealed radiation source holding member obtained by removing the ion accelerating electrode member 22 from the static eliminator 21 of the third embodiment (having the same structure as the static eliminator 1 of the first embodiment) is used. The attenuation time of the charging plate 34 was measured in the same manner as in Example 1 with a distance of 50 mm from the charging plate. The decay time measured in Comparative Example 3 is the decay time from +100 V (or −100 V) to +10 V (or −10 V), as in Example 6.

  The measurement results of Example 6 and Comparative Example 3 are shown in Table 4.

表４に見られるように、密封線源２からイオン加速用電極部材２２までの距離が５〜２０ｍｍの範囲では、実施例６のものは、イオン加速用電極部材を備えない比較例３のものに比べて、帯電プレート部材３４の電位の減衰時間を短縮できることが判る。特に、密封線源２からイオン加速用電極部材２２までの距離が１０ｍｍの場合に、帯電プレート３４の電位の減衰時間を比較例３のものよりも大幅に短くできる。このことから、帯電体と密封線源保持部材３の距離をあまり短くできないような場合に、第３実施形態の除電装置２１の如く、イオン加速用電極部材２２を備えて、このイオン加速用電極部材２２に帯電体の電位と同極性の直流電圧を付与することで、帯電体の除電に要する時間を短縮できることが判る。

As seen in Table 4, when the distance from the sealed radiation source 2 to the ion accelerating electrode member 22 is in the range of 5 to 20 mm, the example 6 is that of the comparative example 3 not including the ion accelerating electrode member. It can be seen that the decay time of the potential of the charging plate member 34 can be shortened as compared with FIG. In particular, when the distance from the sealed radiation source 2 to the ion accelerating electrode member 22 is 10 mm, the decay time of the potential of the charging plate 34 can be significantly shorter than that of the comparative example 3. Therefore, when the distance between the charged body and the sealed radiation source holding member 3 cannot be made too short, the ion accelerating electrode member 22 is provided as in the static eliminator 21 of the third embodiment, and the ion accelerating electrode is provided. It can be seen that applying a DC voltage having the same polarity as the potential of the charged body to the member 22 can shorten the time required for neutralizing the charged body.

  However, when the distance from the sealed radiation source 2 to the ion accelerating electrode member 22 is 30 mm and the ion accelerating electrode member 22 is disposed closer to the charging plate 34 than the sealed radiation source 2, The potential decay time is worse than that of Comparative Example 3. In the sixth embodiment, the voltage of the ion acceleration electrode member 22 is kept constant at + 24V or −24V. Therefore, particularly when the ion acceleration electrode member 22 is close to the charging plate 34, When the magnitude (absolute value) of the potential is smaller than the voltage magnitude of the ion accelerating electrode member 22, charging of air ions having a polarity opposite to that of the charging plate 34 is performed between the charging plate 34 and the ion accelerating electrode member 22. This is because the intensity of the electric field acting on the air ions so as to prevent the movement to the plate 34 is increased.

  Therefore, in the third embodiment, as described above, the DC voltage is applied to the ion acceleration electrode member 22 so that the absolute value of the detected potential of the charged body X and the absolute value of the potential of the ion acceleration electrode member 22 are substantially equal. Was added. In this case, even if the ion accelerating electrode member 22 is disposed at a position closer to the charging plate 34 than the sealed radiation source 2, the potential decay time of the charged body can be sufficiently shortened.

1 is an external perspective view of a static eliminator according to a first embodiment as a reference example related to the present invention. Sectional drawing of a static elimination apparatus and a charging body shown by the II-II line cross section of FIG. The external appearance perspective view of the static elimination apparatus of 2nd Embodiment as a reference example relevant to this invention. Sectional drawing of a static elimination apparatus and a charging body shown in the IV-IV line cross section of FIG. The external appearance perspective view of the principal part of the static elimination apparatus of 3rd Embodiment which is one Embodiment of this invention. Sectional drawing of the static elimination apparatus and charged body which are shown in the VI-VI line cross section of FIG. The figure which shows schematically the structure of the apparatus for testing the static elimination effect of a static elimination apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11,21 ... Static elimination apparatus, 2 ... Sealed radiation source, 2a ... Radiation emission surface, 3 ... Sealed radiation source holding member, 4b, 5a ... Annular conductor part, 12 ... Cover member, 22 ... Ion acceleration electrode member , X: Charged body.

Claims (5)

In a static eliminator that includes a sealed radiation source that emits radiation and generates air ions for neutralizing a charged body by the radiation.
A sealed radiation source holding member made of a conductor for holding the sealed radiation source so as to expose a radiation emitting surface of the sealed radiation source ; a potential detecting means for detecting a potential of the charged body; and at least discharging of the charged body. An ion accelerating electrode member made of a conductor provided so as to be positioned between the charged body and the radiation emitting surface of the sealed radiation source, and a positive or negative DC voltage applied to the ion accelerating electrode member. A DC voltage power source for selectively applying the charge source, and at least when removing the charged body, the sealed radiation source holding member is electrically connected with the radiation emitting surface of the sealed radiation source facing the charged body. In addition to being grounded, a voltage having the same polarity as the potential of the charged body detected by the potential detecting means is applied to the ion accelerating electrode member from the direct current voltage power source, thereby releasing the radiation from the radiation emitting surface of the sealed radiation source. An electric field for moving air ions having a polarity opposite to the electric potential of the charged body among the air ions generated by the applied radiation between the ion accelerating electrode member and the sealed radiation source holding member. A static eliminator characterized by being formed .   2. The static eliminator according to claim 1, wherein the sealed radiation source holding member has an annular conductor portion around a radiation emission surface of the sealed radiation source. In a static eliminator that includes a sealed radiation source that emits radiation and generates air ions for neutralizing a charged body by the radiation.
A covering member made of a conductor provided facing the radiation emitting surface so as to cover the radiation emitting surface of the sealed radiation source and having a plurality of holes through which the radiation emitted from the radiation emitting surface is transmitted ; And a potential detecting means for detecting the potential of the charged body, and at least a conductor provided so as to be positioned between the charged body and the radiation emitting surface of the sealed radiation source when discharging the charged body. An ion accelerating electrode member; and a DC voltage power source that selectively applies a positive or negative DC voltage to the ion accelerating electrode member, and at least when discharging the charged body, radiation emission of the sealed radiation source The covering member positioned between the sealed radiation source and the charged body is electrically grounded with the surface facing the charged body, and the potential detecting means detects the ion acceleration electrode member. By applying a voltage having the same polarity as the potential of the charged body from the DC voltage power source, the polarity of the charged body is opposite to that of air ions generated by the radiation emitted from the radiation emitting surface of the sealed radiation source. The static eliminator is characterized in that an electric field for moving the air ions toward the charged body is formed between the ion accelerating electrode member and the covering member .   4. The static eliminator according to claim 3, wherein the covering member is a net-like member. It claims 1-4 magnitude of the voltage applied to the ion accelerating electrode member from the DC voltage power supply, which is a size substantially equal to the voltage potential of the charged body that is detected by the potential detection means The static elimination apparatus of any one of these .

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