JPH05107177A - Method and device for charging fine particle - Google Patents

Abstract

PURPOSE:To electrically charge fine particles by using ultraviolet light which does not generate particle by irradiation. CONSTITUTION:By applying ultraviolet light 22 to a photoelectron discharge material 21 for inducing photoelectron discharge, the fine particles included in a space are charged by the photoelectron in this charging method. For the ultraviolet light used in this method, the wave length 200nm and below is cut with an ultraviolet light cutting filter 26 and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for charging fine particles by photoelectric effect, and more particularly to a method and apparatus for charging fine particles by photoelectrons generated by irradiating a photoelectron emitting material with ultraviolet rays. Then, as the field of using the charged fine particles, a) the field of measuring the fine particles in a gas such as air or exhaust gas or in a space by the charged fine particles. b) A field for collecting and removing charged fine particles to obtain a cleaning liquid such as a cleaning gas, a cleaning space or chemicals, and pure water. c) Fields for separation / classification of fine particles, surface modification, and control,
Etc.

[0002]

2. Description of the Related Art A conventional technique will be described by taking indoor air cleaning as an example. The conventional indoor air cleaning methods or the apparatus therefor are roughly classified into (1) a mechanical filtration method (for example, a HEPA filter) (2) a high-voltage charged and conductive filter that electrostatically collects fine particles. There are methods (for example, MESA filter), but each of these methods has the following drawbacks. That is, in the mechanical filtration method, it is necessary to use a fine filter to increase the cleanliness (class) of air, but in this case, the pressure loss is high, and the increase in pressure loss due to clogging is also remarkable. In addition, the life of the filter is short, and maintenance, management or replacement of the filter is not only troublesome, but when replacing the filter, it is necessary to stop the work during that time, and it takes a long time to restore. However, there was a drawback that production efficiency was poor.

Further, the number of ventilations (the number of air circulations by a fan) is also increased in order to improve the cleanliness of air, but in this case, there is a drawback that the power cost becomes high. Also, the conventional filter method can be used as an industrial clean room because it is only intended to remove fine particles, but the filter has pinholes, and some of the contaminated air leaks. Therefore, its use in the biological clean room was limited. Further, in the method of electrostatically collecting fine particles, a high voltage of, for example, 15 to 70 kV is required in the pre-charging section, so that the apparatus becomes large and there is a problem in safety and maintenance. It was

In order to solve these problems, the present inventor has proposed an air cleaning method by ultraviolet irradiation or irradiation. Also, various proposals have been made in fields of use other than air cleaning. Among the things that the present inventor has proposed in the gas cleaning relationship, the following are particularly relevant to the present invention. (1) JP-A-61-178050, (US Patent.
4,750,917) (2) JP-A-62-244459 (3) JP-A-63-77557 (4) JP-A-63-100955 (5) JP-A-1-262954 (1) JP-A-62-242838, (2) JP-A-2-
47536 (3) There is Japanese Patent Application No. 1-134781. Further proposed in the separation / classification relationship is Japanese Patent Application No. 1-177198. In addition, regarding the charging conditions, there are (1) Japanese Patent Application No. 1-12056
3 and (2) Japanese Patent Application No. 1-120564.

While these schemes are effective in some fields of application, there is room for improvement in particular applications in particular fields. For example, in the cleaning of air containing semiconductor exhaust gas, the exhaust gas component coexisting with the airborne particles may be converted into a particulate matter (gaseous substance) by irradiation with ultraviolet rays having a short wavelength, particularly 220 nm or less. In such a case, the load of the charged particulate matter collecting material is increased, which is a problem. That is, the burden on the collection unit for collecting the charged fine particles becomes large, and there is a need for improvement. As another example, in the measurement of ultrafine particles (eg, <0.1 μm) in air pollution, air pollutants coexisting with the particles may be irradiated with ultraviolet rays having a short wavelength, particularly 220 nm or less depending on the kind of the pollutant ( In some cases (gaseous substances) may be converted to fine particles, and in such a case (because fine particles are generated only by UV irradiation and the blank value becomes high), the measurement accuracy decreases, so no fine particles are generated (fine particles). There is a need for a method and apparatus for charging fine particles. Depending on the field of application, it is necessary to make improvements so that the practicality is further improved and the method becomes more practically advantageous.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a method and apparatus for charging fine particles that do not generate fine particles even when irradiated with ultraviolet rays.

[0007]

In order to achieve the above object, in the present invention, a photoelectron emitting material is irradiated with ultraviolet rays to emit photoelectrons, and the photoelectrons are charged to charge microparticles existing in space. In the method, ultraviolet rays from which a wavelength of 200 nm or less, preferably 220 nm or less is removed are used as ultraviolet rays, which is a method for charging fine particles. Further, in order to achieve the above-mentioned other object, in the present invention, in a charging device for fine particles present in a space consisting of an ultraviolet ray source for irradiating ultraviolet rays and a photoelectron emitting material for emitting photoelectrons, an ultraviolet ray source is used. 200 nm
The charging device for fine particles is characterized in that means for removing wavelengths of 220 nm or less is provided. In the above apparatus, the means for removing the wavelength of 200 nm or less, preferably 220 nm or less is selected from an ultraviolet ray removing filter, a short wavelength ultraviolet absorbing glass material or a short wavelength ultraviolet absorbing Teflon material.

Next, the respective constitutions of the present invention will be explained in detail. The photoelectron emitting material may be any material as long as it emits photoelectrons upon irradiation with ultraviolet rays, and a material having a smaller photoelectric work function is more preferable.
r, Ca, Y, Gd, La, Ce, Nd, Th, Pr,
Be, Zr, Fe, Ni, Zn, Cu, Ag, Pt, C
d, Pb, Al, C, Mg, Au, In, Bi, Nb,
Any one of Si, Ti, Ta, U, B, Eu, Sn, P, W, or a compound or alloy or mixture thereof is preferable, and these are used alone or in combination of two or more kinds. As the composite material, a physical composite material such as amalgam can also be used. For example, compounds include oxides, borides, and carbides, and oxides include BaO, SrO, and Ca.
O, Y ₂ O ₅ , Gd ₂ O ₃ , Nd ₂ O ₃ , ThO ₂ , Z
rO ₂ , Fe ₂ O ₃ , ZnO, CuO, Ag ₂ O, La
₂ O ₃ , PtO, PbO, Al ₂ O ₃ , MgO, In _{2
O 3, BiO, NbO, YB} 6 is to include BeO, also _{borides, GdB 6, LaB 5, NdB} 6, CeB
₆ , BuB ₆ , PrB ₆ , ZrB _{2 and the} like, and as carbides, UC, ZrC, TaC, TiC, Nb.
C, WC, etc.

As the alloy, brass, bronze, phosphor bronze, an alloy of Ag and Mg (Mg is 2 to 20 wt%), Cu
With Be and alloys (Be is 1 to 10 wt%) and Ba and Al
And an alloy of Ag and Mg, an alloy of Cu and Be, and an alloy of BaAl are preferable. The oxide can also be obtained by heating only the metal surface in air, or by oxidizing with a chemical. As another method, it is also possible to heat before use to form an oxide layer on the surface to obtain a stable oxide layer for a long period of time. An example of this is an alloy of Mg and Ag in steam
An oxide film can be formed on the surface thereof under the condition of a temperature of 00 to 400 ° C., and the oxide thin film is stable for a long time. Further, the one having a multilayer structure of the photoelectron emitting material as already proposed by the present inventor can be preferably used (Japanese Patent Laid-Open No. 1-155857). Further, a substance capable of emitting photoelectrons in a thin film form may be added to an appropriate base material and used. As an example of this, there is a thin film of Au added as a substance capable of emitting photoelectrons on a quartz glass as a UV-transparent substance (base material) (Japanese Patent Application No. Hei.
-295423).

The shape of these materials used may be any of a plate shape, a pleat shape, a curved surface shape, a net shape and the like, but a shape having a large irradiation area of ultraviolet rays and a large contact area with the processing space is preferable. The emission of photoelectrons from the photoelectron emitting material can be effectively carried out by appropriately using a reflecting surface, a curved reflecting surface, or the like, as already proposed by the present inventor (JP-A-63-100955). Bulletin). The shapes of the photoelectron emitting material and the reflecting surface differ depending on the shape and structure of the device or the desired efficiency, and can be appropriately determined. Any kind of ultraviolet light may be used as long as the photoelectron emitting material can emit photoelectrons without generating particulate matter from the substance coexisting in the fine particles upon irradiation (in this example, air and airborne fine particle components). In some fields, those having a sterilizing action are also preferable. The types of UV rays are applicable fields,
It can be appropriately determined depending on the work content, application, economic efficiency, and the like.

The ultraviolet ray is 200 nm or less, preferably 220
Ultraviolet rays from which wavelengths below nm are removed can be preferably used. The wavelength of ultraviolet rays to be removed depends on the coexisting substance (cause of the generated particulate matter) and can be determined by conducting a preliminary test, but it is usually as described above. As the ultraviolet source, any source can be used as long as it emits ultraviolet rays.
It can be appropriately selected and used depending on the application field, the shape of the device, the structure, the effect, the economical efficiency and the like. For example, a mercury lamp, a hydrogen discharge tube, a xenon discharge tube, a Lyman discharge tube, or the like can be used as appropriate. In the biological field, sterilization wavelength 2
It is preferable to use an ultraviolet ray having a wavelength of 54 nm because the sterilizing effect can be used together. When the ultraviolet rays from the ultraviolet source include ultraviolet rays having a wavelength of 200 nm or less, the wavelength is removed by an appropriate method. Any method can be used for removing the ultraviolet rays as long as the ultraviolet rays can be removed. Usually, a UV cut filter, a short wavelength UV absorbing glass material, and a short wavelength UV absorbing Teflon material are preferably used. The particles in the air (in the space) are efficiently charged by irradiating the photoelectron emitting material with ultraviolet rays in an electric field.

The present inventors have already proposed charging in an electric field (eg, JP-A-61-178050).
No. 6, JP-A-62-244459, Japanese Patent Application No. 1-1
20653). The electric field voltage is 0.1 V / cm to 2 kV / cm
Is. The suitable strength of the electric field can be determined by conducting preliminary tests and examinations depending on the field of use, conditions, device shape, scale, effect, economical efficiency and the like. Collection material for charged fine particles (dust collection material)
Can be used as long as it can collect charged fine particles. Generally, dust collecting plates, dust collecting electrodes, various electrode materials, and electrostatic filter systems in ordinary charging devices are used.
A wool-like structure such as a steel wool electrode or a tungsten wool electrode in which the collecting portion itself constitutes an electrode is also effective. Electret materials can also be preferably used. Also,
The method of collecting using an ion exchange filter (or fiber), which has been already proposed by the present inventor, is also effective (Japanese Patent Laid-Open No. Sho 63-63).
-54959, 63-77557, 63-84.
No. 656). For collection, these collection methods may be used alone, or two or more kinds of these methods may be used in combination as appropriate.

As the electrode material for the electric field, those used in ordinary charging devices can be preferably used. That is, a known one can be used. The electrode material for an electric field can be used also as a charged particle collecting material (dust collecting material) or in an integrated manner. For example, among the above-mentioned charged particulate matter collecting materials, various electrode materials such as a dust collecting plate, a dust collecting electrode, or a wool-like electrode material such as a steel wool electrode and a tungsten wool electrode are used as an electric field electrode and a collection of charged particulate matter. It is preferable because it can be combined with the above. Further, a material other than the electrode material such as an electret material or an ion exchange filter (a material characterized by collecting fine particles) can be integrally used with the above-mentioned appropriate electric field electrode material. As a method of charging particles in the air (in the space), we explained the method of charging by forming an electric field in the charging part. However, by irradiating the photoelectron emitting material with ultraviolet rays without forming an electric field, photoelectrons can be emitted. It is also possible to charge fine particles in a gas.

The present invention can be mainly applied to the charging of fine particles in the air, but can be similarly carried out in other gases such as nitrogen and argon, in air, or in vacuum, in addition to air.
It can be appropriately used depending on the type of device, scale, and the like. In this example, by removing ultraviolet rays having a wavelength of 200 nm or less, preferably 220 nm or less, generation of particulate matter from a substance coexisting with the fine particles is prevented. On the other hand, as previously proposed by the present inventor, when it is desired to remove the trace component, conversely, the trace component is converted into a particulate substance by using ultraviolet rays having a wavelength of 220 nm or less, and the particulate substance is charged. Then, the minute particles can be removed by collecting the charged fine particles.

That is, when the substance coexisting with the fine particles is harmful and may damage or affect the human body, it can be removed by the method already proposed by the present inventor. When the above can be ignored, the operation can be practically and effectively performed by performing as in the invention of this example. Further, depending on the kind of the substance such as the harmful gas that coexists in the fine particles, it may be easier to collect the substance without converting it into the particulate substance. In such a case, only the fine particles are charged by this method to collect them, and the coexisting substances are practically and effectively collected by collecting them using an appropriate collecting material such as an ion exchange filter. can do.

[0016]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples. Example 1 The present invention will be described with an example of air cleaning in a clean room. Based on FIG. 1, an air cleaning method of a combined use of a clean bench in a clean room using an ultraviolet irradiation method, that is, a method of keeping only a part of a work area at high cleanliness will be described. In the clean room 1, after the coarse particles of the outside air introduced from the pipe 2 are filtered by the pre-filter 3, the temperature in the air conditioner 6 is passed through the fan 5 together with the air taken out from the air outlet 4 of the clean room 1. The air whose humidity has been adjusted and whose fine particles have been removed by the HEPA filter 7 is circulated and supplied, and the cleanliness (class 10,000
0).

On the other hand, the fan section 8 in the clean room 1,
High cleanliness (class 10) is placed on the workbench 13 in the clean bench 11 provided with the ultraviolet irradiation unit 9 and the filter 10.
Is supplied with sterile air. That is, clean bench 1
1, cleanliness in clean room 1 (class 1
The air of about 10,000) is sucked by the fan of the fan unit 8, and the ultraviolet irradiation unit 9 irradiates the particles with ultraviolet rays to charge the fine particles in the air and sterilize microorganisms such as viruses, bacteria, yeasts and molds. After being sterilized,
By removing the charged fine particles with the filter 10, the work table 13 is maintained at high cleanliness (presence of fine particles is class 10 cleanliness). On the other hand, the work on the workbench 13 may generate a very small amount of gas. The gas concentration is so low that it does not cause a health hazard in terms of occupational health, and there is no problem.

The movable shutter 12 provided in the clean bench 11 is used to take in and out instruments, products and the like from and to the workbench 13 in the clean bench 11. As shown in FIG. 2, the ultraviolet irradiation unit 9 for charging the particles in the air stream, which is a feature of the present invention, is shown in FIG.
The outline is shown in. That is, the air 24 containing the fine particles sucked by the fan of the fan unit 8 is filtered by the pre-filter 20 and then the fine particles in the air are charged by the ultraviolet irradiation unit 9 mainly including the photoelectron emitting material 21 and the ultraviolet lamp 22. After that, the charged fine particles are collected by the charged fine particle collecting filter 23 to obtain clean air 25. In the ultraviolet irradiation unit 9, the emission of photoelectrons is accelerated by irradiating the photoelectron emitting material 21 with ultraviolet rays from the ultraviolet lamp 22 under an electric field, and the photoelectrons efficiently charge the fine particles in the air 24 containing the fine particles ( Fine particle charging section). The ultraviolet cut filter 26 is an ultraviolet transmitting window having a function of removing ultraviolet rays of 220 nm or less. That is, 220
It is composed of an ultraviolet ray cut filter that removes ultraviolet rays having a wavelength of nm or less. In the ultraviolet irradiation unit 9, microorganisms such as viruses, bacteria, yeasts and molds are sterilized (sterilized) by the energy of ultraviolet rays.

Example 2 The measurement of airborne particles in a semiconductor factory according to the present invention will be specifically described with reference to the drawings. FIG. 3 is a schematic view in which a classifying plate is used for the classification unit of charged fine particles and an electrometer is used for the detection unit. Air 31 containing suspended fine particles from which large particles of 10 μ or more have been removed in advance by an impactor (not shown) or the like is introduced from the air introduction port, and the fine particles contained in the air are irradiated with ultraviolet rays at the charging section A ₁ . It is charged by the photoelectrons emitted from the photoelectron emission surface 23 which has been irradiated with the ultraviolet rays from the source (lamp) 32.
The charging section A ₁ is mainly composed of an ultraviolet lamp 32, a photoelectron emitting material 33, and an electrode 34. In the charging portion A ₁ , an electric field is formed between the photoelectron emitting material 33 and the electrode 34, and photoelectrons are effectively generated from the photoelectron emitting material 33 irradiated with the ultraviolet lamp 32. The fine particles in the air 31 introduced from the air inlet are charged by the action of the photoelectrons. The fine particles charged in the charging section A ₁ are classified in the charged fine particle classifying section B ₁ .

The charged fine particle classification section B ₁ is a portion for classifying charged fine particles with a compact and simple structure, and has a function of classifying the charged fine particles by changing the applied voltage of the classifying material. The operation when using the classifying plate having the pores 35 and 36 will be described below. Classification plate 37,
An electric field is formed between 38 by a power source. All charged fine particles in the classification section B ₁ are designated as b ₁ . Classification plate 37,
When a weak electric field of a ₁ is first formed between 38, fine charged fine particles b ₂ affected by the electric field are collected by the classifying plate. As a result, the remaining charged fine particles (b ₁
In −b ₂ ), the charge amount d ₁ is measured by the detector C _{1 including} the electrometer 39 in the downstream, and the particle concentration is measured.

Next, when an electric field a ₂ stronger than a ₁ is formed between the classifying plates 37 and 38, it is affected by the electric field (b ₂
The charged fine particles b _{3 (} having a larger particle diameter than that) are collected by the classification plate. As a result, the remaining charged fine particles (b ₁ -b ₃ ) having a large particle diameter are similarly detected in the wake electrometer 39.
Is measured at. Thereafter, the electric field of the classifying plate is sequentially changed appropriately, and the same operation is performed. In this way, the particle size (distribution) and the concentration of the fine particles in the air 31 at the air inlet can be known by performing the classification and the measurement of the fine particle concentration. C ₁ is a charged fine particle detection unit, and the electrometer 39 detects the charged fine particles classified by the classification unit B ₁ as described above. The electrometer 39 measures the charge amount of the charged fine particles,
It is sufficient that the concentration of fine particles classified can be understood from this. 40 is an air outlet.

The photoelectron emitting material 33 of this example has a function of emitting photoelectrons and removing ultraviolet rays of 220 nm or shorter.
That is, an ultraviolet cut filter for removing ultraviolet rays of 220 nm or less and a material for emitting photoelectrons in which a substance (50Å, Au) capable of emitting thin film photoelectrons is added on synthetic quartz are integrated and combined. .. The electric field voltage is 50 V / cm. In Examples 1 and 2, the material that emits photoelectrons and the ultraviolet cut filter are used individually or in combination and apparently integrated. However, an ultraviolet cut filter that appropriately removes ultraviolet rays having a wavelength of 220 nm or less or the cut material ( It goes without saying that a substance capable of emitting photoelectrons can be added to the base material) to be used as a photoelectron emitting material having a function of removing ultraviolet rays of 220 nm or less. As an example of this, there is a method in which a thin film Au is used as a photoelectron emitting material on an ultraviolet cut filter of 220 nm or less. The fields of application in which this example is particularly effective are shown below. a) Field of measuring fine particles in a gas such as air or exhaust gas or in a space by using charged fine particles. b) A field for collecting and removing charged fine particles to obtain a cleaning gas, a cleaning space, or a cleaning liquid such as chemicals and pure water. c) Field of separation / classification of fine particles, surface modification, and control.

Example 3 Using the fine particle charging section having the structure shown in FIG. 2, dust particles in the laboratory were irradiated with a deuterium lamp with and without an ultraviolet cut filter to examine the concentration and particle size of the fine particles. Charged part size: 1 liter (volume) Flow rate: 0.5 liter / min, electric field: 50V
/ Cm Deuterium lamp; 50W photoelectron emission material; Cu-Zn base material with 50 Å of Au added. UV transmission window; synthetic quartz UV cut filter; UV cut filter (220 nm)
50% of the following UV rays, 80% of 200 nm or less
Filter to cut above Fine particle measurement method Fine particle concentration: Condensation nucleus measuring instrument (CN
C). Particle size: Particles are first classified by an electrostatic aerosol classifier, and then the concentration is measured by CNC. Result 1. Without particle concentration filter: 3,500 to 5,0
With 00 filter / cm ³ filter: 0 to 0.5 filter / cm ³ 2. Particle size The particle size of the generated particles without the above filter was 0.005 to 0.04 μm.

[0024]

According to the present invention, the following effects can be obtained. 1. In the charging of fine particles using ultraviolet irradiation, ultraviolet rays having a wavelength of 200 nm or less, preferably 220 nm or less are removed, so that (1) no particulate matter is generated from the charged space. 2. The above-mentioned 1 brings about the following effects particularly in each application field. (1) In the field of measuring the concentration and particle size of fine particles such as air or exhaust gas, the measurement accuracy is improved and stable for a long time. (2) In the field of obtaining a clean gas or a clean space, the performance is stable and continuous operation can be performed for a long time, so that the apparatus can be downsized and the processing capacity can be increased. (3) In the fields of fine particle separation, classification, surface modification, and charge control, stable performance, long-term continuous operation, downsizing of equipment, and increase in processing amount are possible. The treatment of fine particles was effective in improving the treatment performance.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a clean room using the present invention.

FIG. 2 is an enlarged cross-sectional view of the charging / collecting unit of FIG.

FIG. 3 is a cross-sectional view of a fine particle measuring apparatus using the present invention.

[Explanation of symbols]

1: clean room, 2: outside air, 3: prefilter,
4: air outlet, 5: fan, 6: air conditioner, 7:
HEPA filter, 8: fan part, 9: ultraviolet irradiation part,
Reference numeral 10: filter, 11: clean bench, 13: workbench, 20: pre-filter, 21, 33: photoelectron emitting material, 22, 32: ultraviolet lamp, 23: charged particle collecting filter, 25: clean air, 26: ultraviolet ray Cut filter, 34: electrode, 35, 36: pores, 37, 38: classifying plate, 39: electrometer, A ₁ : charged part, B ₁ :
Charged fine particle classification unit, C ₁ : detection unit

Claims (12)

[Claims] 1. A method of charging fine particles in which a photoelectron emitting material is irradiated with ultraviolet rays to emit photoelectrons, and the fine particles existing in space are charged by the photoelectrons, wherein ultraviolet rays from which a wavelength of 200 nm or less is removed are used. And a method for charging fine particles. 2. The method for charging fine particles according to claim 1, wherein the photoelectrons are emitted in an electric field. 3. The method for charging fine particles according to claim 1, wherein the photoelectron emitting material is made of a substance having a small photoelectric work function. 4. The photoelectron emission material is Ba, Sr, C
a, Y, Gd, La, Ce, Nd, Th, Pr, Be,
Zr, Fe, Ni, Zn, Cu, Ag, Pt, Cd, P
b, Al, C, Mg, Au, In, Bi, Nb, Si,
4. The method of charging fine particles according to claim 3, which is made of one kind of material selected from Ta, Ti, U, B, Eu, Sn, P, W and compounds thereof. 5. The photoelectron emitting material is Ba, Sr, C
a, Y, Gd, La, Ce, Nd, Th, Pr, Be,
Zr, Fe, Ni, Zn, Cu, Ag, Pt, Cd, P
b, Al, C, Mg, Au, In, Bi, Nb, Si,
The method for charging fine particles according to claim 3, which comprises an alloy, a mixture, or a composite material of two or more kinds selected from Ta, Ti, U, B, Eu, Sn, P, W and compounds thereof. 6. The electric field has a voltage of 0.1 V / cm to 2 kV
The method for charging fine particles according to claim 2, wherein the charging method is / cm. 7. A charging device for fine particles existing in a space consisting of an ultraviolet ray source for irradiating ultraviolet rays and a photoelectron emitting material for emitting photoelectrons, wherein the ultraviolet ray source is provided with means for removing wavelengths of 200 nm or less. A fine particle charging device characterized by the above. 8. A means for removing a wavelength of 200 nm or less,
The particulate charging device according to claim 7, which is one or more selected from an ultraviolet ray removing filter, a short wavelength ultraviolet absorbing glass material or a short wavelength ultraviolet absorbing Teflon material. 9. A method for cleaning a space, which comprises charging the particles in a space by the method for charging the particles according to claim 1, 2 or 3 and collecting and removing the charged particles. 10. The method of charging fine particles according to claim 1, 2 or 3, wherein the fine particles in the space are charged, and the concentration and particle size of the charged fine particles are measured. Measuring method. 11. A method of separating / classifying fine particles, which comprises charging the fine particles by the method of charging fine particles according to claim 1, 2 or 3 and separating / classifying the charged fine particles. 12. A method of modifying a fine particle, comprising: charging the fine particle by the method for charging a fine particle according to claim 1, 2 or 3, and modifying the surface of the fine particle by controlling the charge amount of the fine particle. Method.