JPH07318129A - Clean room - Google Patents

Abstract

PURPOSE:To provide a clean room in which operating expenses is low, clean air can be effectively generated and ultraclean state can be easily obtained without increasing an installation area. CONSTITUTION:A clean room comprises an illumination lamp 4 provided at a ceiling 11 in a room 1, a photoelectron emitting material 5 for emitting photoelectron by irradiating with the ultraviolet rays of the lamp, and a charged fine particle collecting material 6, wherein the lamp 4 may be covered at least partly with the photoelectron emitting material 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clean room, and more particularly to a clean room having an air cleaning section on a ceiling. INDUSTRIAL APPLICABILITY The clean room of the present invention is used for a high-tech clean room such as semiconductors, liquid crystals, chemicals, foods, agricultural materials, pharmaceuticals, and precision machinery industries.

[0002]

2. Description of the Related Art Conventionally, air purification by removing fine particles in a clean room is carried out by installing a HEPA or ULPA filter on the ceiling of the clean room and forcibly ventilating air through the filter with a fan. In this method, for ultra-cleaning, since the particulate removal rate per aeration by the filter is constant, the air in the entire clean room can be removed by a large number of circulations (for example, air in the room 300 times / hour). I had to cycle through the filters. Therefore, the power cost is high, the generation of particles from the contact area of air due to forced ventilation, and the presence of a stagnation space (for example,
There was a problem that there was a limit to the degree of cleanliness (creating a super-clean space) that can be reached from the vicinity of the lamp for lighting.

On the other hand, the present inventors have previously proposed charge collection of fine particles (UV / photoelectron method) by photoelectrons generated by irradiating a photoelectron emitting material with ultraviolet rays, and it is effective in some fields of application. That is.
(Japanese Patent Publication No. 3-5859, Japanese Patent Laid-Open No. 63-77557,
(See Japanese Patent Laid-Open No. 63-100955) In the above cleaning method, a photoelectron emitting material is used in the clean room.
It is an apparatus in which ultraviolet rays, electrodes, a fan, etc. are combined and installed as an individual apparatus, and cleaning is performed as the individual apparatus, which is effective depending on the application field. However, depending on the field of application, there is also a field in which, in terms of the space of the work space, it is desirable to perform the cleaning without installing the individual device (device in which all parts are integrated).

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned problems, does not require an integrated device, has a low operating cost, and effectively and efficiently purifies air. The object is to provide a clean room that can be easily made ultra-clean.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a lamp for illumination provided on the ceiling of a room and irradiation of ultraviolet rays from the lamp installed near the lamp are provided. The clean room is characterized by having a photoelectron emitting material for emitting photoelectrons and a charged fine particle collecting material. In the clean room, the photoelectron emitting material may be coated on at least a part of the illumination lamp, or may be coated on the coating base material having an uneven shape.

As described above, according to the present invention, a clean room for charging and collecting photoelectrons on the ceiling is used. Depending on the type and application field of the clean room, the lighting lamp is coated with the photoelectron emitting material, and the photoelectron emitting material is used to remove the photoelectron emitting material. Is generated, the fine particles are charged, and the fine particles are collected by a charged fine particle collecting material installed at an appropriate position to effectively make the clean room ultra-clean. That is, the present invention installs a photoelectron emitting material and an electrode material on the ceiling of a clean room by a filter method, utilizes ultraviolet rays and thermal convection from an illumination lamp to effectively emit photoelectrons, and the photoelectrons generate fine particles. It efficiently charges and collects.

Next, the respective constitutions of the present invention will be explained in detail. The photoelectron emitting material used in the present invention may be any one as long as it emits photoelectrons upon irradiation with ultraviolet rays, and the smaller the photoelectric work function is, the more preferable. From the viewpoint of effect and economy, Ba, Sr, Ca, Y , Gd, La, Ce,
Nd, Th, Pr, Be, Zr, Fe, Ni, Zn, C
u, Ag, Pt, Cd, Pb, Al, C, Mg, Au,
In, Bi, Nb, Si, Ti, Ta, U, B, Eu,
Any one of Sn, P, W or a compound, 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, the compounds include oxides, borides, and carbides, and the 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, there is such as BeO, also in borides _{is, YB 6, GdB 6, LaB} 5, NdB 6, Ce
_{B 6, EuB 6, PrB 6} , ZrB 2 include, as a further carbide 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%), C
An alloy of u and Be (1 to 10 wt% of Be) and an alloy of Ba and Al can be used, and the alloy of Ag and Mg, the alloy of Cu and Be, and the alloy of Ba and Al are preferable. . Oxide heats only the metal surface in air,
Alternatively, it can be obtained 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. As an example of this, an alloy of Mg and Ag can form an oxide film on its surface in water vapor at a temperature of 300 to 400 ° C., and this oxide thin film is stable for a long period of time.

The photoelectron emitting material used can be appropriately selected depending on the type of lamp used, required performance and the like. For example, in the case of a lamp having low irradiation energy, a photoelectron emitting material having Zn or a Zn compound in a part where photoelectrons are emitted by relatively long wavelength ultraviolet rays (Japanese Patent Application No. 5-347163).
Can be preferably used. The shape of the photoelectron emitting material may be any as long as the photoelectron emitting material is installed on the ceiling of a clean room and emits photoelectrons, and may be appropriately selected depending on the type and shape of the lamp described later and the installation situation of the photoelectron emitting material. You can choose. For example, a flat plate shape, a curved surface shape, a net shape, a grid shape, a linear shape, which is installed on the ceiling of a clean room or in the vicinity of a mounting portion of a lighting lamp, emits photoelectrons, or covers the surface of an irradiation lamp, There are things that emit. Further, depending on the clean room, the shape of the coating base material of these photoelectron emitting materials can be uneven.

As the photoelectron emitting material, a substance capable of emitting photoelectrons in a thin film is added to a base material having an appropriate shape,
It can be used (JP-A-4-152296). As an example of this, as a substance capable of emitting photoelectrons on quartz glass as an ultraviolet-transparent substance (base material), Au is used.
Has been added in the form of a thin film (JP-A-4-17106).
No. 2). When the photoelectron emitting material is used by adding it to the base material, a conductive material can be added and used as proposed by the present inventor (JP-A-5-6).
8875).

The emission of photoelectrons from the photoelectron emission material becomes effective by irradiating the photoelectron emission material with ultraviolet rays under an electric field. In the present invention, the emission of photoelectrons is performed in the ceiling of the clean room, and the moving speed of the treated air is relatively slow, so the electric field strength is 0.1 V / cm to 2 kv / cm. The strength of the electric field depends on the shape of the photoelectron emitting material, the type of electrode,
Preliminary tests can be used to make a decision, depending on how the electric field is applied, how it is installed on the ceiling, and the required performance.

As the ultraviolet ray source, any lighting lamp that emits ultraviolet rays can be used, and it can be appropriately selected depending on the required performance of the clean room, type, size, kind of work, etc.
Can be used. In the present invention, an illumination lamp that emits ultraviolet rays can be coated with a photoelectron emitting material and used for both emission of photoelectrons and illumination. For example, the photoelectron emitting material may be coated only in the upper direction (ceiling side) of the lamp to emit photoelectrons, and the lower direction (floor surface side) may be used only for illumination. In addition, depending on the type of lamp (in the case of a lamp that strongly emits ultraviolet rays), depending on the type and thickness of the coating of the photoelectron emitting material, only the ultraviolet rays are absorbed by the photoelectron emitting material, photoelectrons are generated by the energy, and visible light is transmitted. It can also be used for lighting. Further, depending on the type of lamp, there is also a method of coating the surface of the lamp with a phosphor and irradiating the phosphor with ultraviolet rays to emit visible light for illumination.

Such lamps include fluorescent chemical lamps, black lights, UV-B ultraviolet lamps, and germicidal lamps. For example, germicidal lamp (main wavelength: 254 nm)
Using, to coat the phosphor in the downward direction of the lamp (floor side),
Further, when the photoelectron emitting material is coated in the upper direction (ceiling side) of the lamp, the phosphor absorbs 254 nm ultraviolet light and emits visible light for illumination. On the other hand, the photoelectron emitting material emits photoelectrons when it is irradiated with ultraviolet rays of 254 nm. That is, when the germicidal lamp is coated with a phosphor, the ultraviolet rays of the germicidal ray are effectively absorbed by the phosphor, and visible light is emitted.

The photoelectron emitting material can appropriately absorb the germicidal rays depending on the coating thickness thereof, so that leakage to the outside can be controlled. The fluorescent substance can emit visible light in a suitable wavelength region by appropriately selecting the type. In addition, since a fluorescent lamp for illumination usually emits ultraviolet rays of about 320 nm or more, it can be used for emission of photoelectrons and for illumination by coating a photoelectron emitting material in a thin film form. Further, the emission of photoelectrons by coating the lamp with a photoelectron emitting material is effective by making the surface shape of the lamp uneven, and thus can be appropriately used. The uneven shape is effective when the ultraviolet rays from the lamp are weak. FIG. 2 shows an example in which a photoelectron emitting material and an electrode are arranged on the uneven portion. In FIG. 2, 14 is a photoelectron emission material (-), 15 is an electrode (+), and 13 is a lamp central part.

Further, a collection material (dust collection material) for charged fine particles
Can be used as long as it can collect charged fine particles. Various electrode materials such as a dust collecting plate and a dust collecting electrode in an ordinary charging device and an electrostatic filter method are generally used, but a wool-like structure in which the collecting portion itself such as a steel wool electrode or a tungsten wool electrode constitutes an electrode. Are also valid. Ecretette material can also be used suitably. These trapping materials can be installed at an appropriate position depending on the required performance of clean room, type, size, air flow direction, thermal convection direction, work mode, etc. to effectively collect charged fine particles. You can Usually, it is mounted near the lamp mounting portion or the photoelectron emitting material, and has the two functions of the electric field electrode and the charge / fine particle collection.

A higher class clean room aims for a complete laminar flow (laminar flow), but turbulent flow occurs in the vicinity of a lighting device (for example, a fluorescent lamp) which is indispensable for work, and dust is accumulated on the upper part of the lamp or the like. Although the cleanliness was hindered by making it huge and falling, the present invention keeps the vicinity of the illumination part clean, so that a high-class clean room can be easily achieved. In other words, this method effectively utilizes the area of the lighting equipment that occupies about several percent of the ceiling area of the clean room by this method, and creates an ultra-clean space.

[0018]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. Example 1 FIG. 1 shows a schematic configuration diagram of an example of a clean room of the present invention. In FIG. 1, the air 2 in the clean room 1 is HE
Dust removal by the PA filter 3, photoelectron emission material 5 coated only in the upper direction of the illumination lamp 4 (upper surface of the lamp), and a flat plate-shaped electrode 6 placed at a distance of several cm above the lamp 4 0.1 the class 10 (1 ft ³ of the dust in the charged-collecting portion a of the particles by more composed photoelectrons
The clean air of (the number of fine particles of μm or more) is held. The dust removal by the HEPA filter 3 is performed by circulating the air in the clean room by the fan 4.

On the other hand, dust removal by photoelectrons is performed under an electric field (50
(V / cm), the fine particles are charged by the photoelectrons emitted by irradiating the photoelectron emitting material 5 with ultraviolet rays from the lamp 4 at V / cm), and then the charged fine particles are collected by the electrode 6. The electric field is formed between the photoelectron emitting material 5 and the electrode 6. The present inventors have already proposed a mechanism for charging and collecting fine particles by the photoelectrons (eg, Japanese Patent Laid-Open No. Hei 4
-171061). As described above, the air 2 in the clean room 1 is effectively removed by the dust removal by the HEPA filter 3 and the charge / collection of fine particles by photoelectrons.

The photoelectron dust removing section (A) can clean the stagnation portion of the clean room 1, so that an extremely clean clean room with a high degree of cleanliness can be obtained. It is considered that the dust removal part (A) by the photoelectrons in the stagnation part effectively occurs because the convection action due to the heat dissipation of the lamp is also added. In FIG. 1, 7 is an air conditioner (control of temperature and humidity), 8 is outside air, 9 is a dust filter, and 10 is a dust filter.
Is a grating floor, 11 is a ceiling wall surface, and 12 is a flow of air.

Example 2 FIG. 3 shows another type of the particle charging / collecting section A for photoelectrons in the ceiling in Example 1. Reference numeral 4 is an illumination lamp, 5 is a photoelectron emitting material, 6 is an electrode, and 11 is a ceiling wall surface.

Example 3 FIG. 4 shows another type of the particle charging / collecting section A for photoelectrons in the ceiling in Example 1. Reference numeral 4 is an illumination lamp, 5 is a net-like photoelectron emitting material, 6 is an electrode, 1
1 is a ceiling wall surface.

Example 4 Air cleaning in the clean room shown in FIG. 1 was carried out for the presence or absence of charge / collection of fine particles by photoelectrons, and the fine particle concentration in the air was measured using a fine particle measuring device (particle counter). Clean room size: 50m ³ , wind speed: 0.3m /
s, Dust filter type: HEPA filter, Lamp: Fluorescent lamp 110W

Photoemissive material; Z on the upper half surface of the fluorescent lamp
n-Pb-Sn is coated in a thin film (thickness: 50Å) Electrode material: Flat Cu-Zn plate Charge / fine particle collecting material; also used as electrode material Electric field voltage; 50 V / cm Fine particle measuring instrument; Light scattering type (0.1 μm or more)

Results The clean room was operated for 16 hours or more, and after the steady state was reached, the measurement was performed. The results are shown in Table 1.

[Table 1]

[0026]

According to the present invention, the following effects can be obtained. (1) In a clean room, by charging and collecting fine particles by photoelectrons in the ceiling part, (a) fine particles in the stagnation part in the ceiling part were effectively collected and removed. (B) Since the dust removal by photoelectrons is added to the dust removal by the normal filter system, an ultra-clean clean room was created. (C) Since ultra-clean air can be obtained at the ceiling, a separate cleaning device is not needed in the clean room. This made the work space wider. (D) Since the dust removal is all performed on the ceiling, the work space becomes wider.

(2) In the above (1), by installing the photoelectron emitting material in the ceiling of the clean room or in the vicinity of the lamp mounting portion for illumination, energy in the ceiling direction of the illumination lamp can be effectively used. (3) In the above (1), the illumination lamp is coated with the photoelectron emitting material, so that (a) the illumination lamp becomes a lamp having two functions of dust emission photoelectron emission and illumination. (B) Energy from the lighting lamp was effectively used.
That is, although the wavelength of the light for illumination is different from the wavelength for the photoelectron emission, both wavelengths of light can be effectively used. (4) In the above (1), by making the shape of the coating base material of the photoelectron emitting material uneven, the ultraviolet irradiation area is increased, so that the amount of emitted photoelectrons is increased and the charging / collecting efficiency of fine particles is effective. Became.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a clean room of the present invention.

FIG. 2 is an enlarged view of an uneven base material portion.

FIG. 3 is a partially enlarged view showing an example of a charging / collecting unit for fine particles.

FIG. 4 is a partially enlarged view showing another example of the charge collecting unit of fine particles.

[Explanation of symbols]

1: Clean room, 2: Air, 3: HEPA filter, 4: Lighting lamp, 5: Photoelectron emitting material, 6: Electrode,
7: Air conditioner, 8: Outside air, 9: Dust filter, 10:
Grating floor, 11: Ceiling wall surface, 12: Air flow, 13: Lamp center part, 14: Photoelectron emitting material, 15:
Electrode, A: Charging / collecting unit (dust removing unit)

Claims (3)

[Claims] 1. A lighting lamp provided on a ceiling of a room, a photoelectron emitting material which is installed in the vicinity of the lamp and which emits photoelectrons by irradiation of ultraviolet rays of the lamp, and a charged fine particle collecting material. A clean room characterized by that. 2. The clean room according to claim 1, wherein at least a part of the lighting lamp is covered with the photoelectron emitting material. 3. The clean room according to claim 1, wherein the photoelectron emitting material is coated on a coating base material having an uneven shape.