JP2001149450A - Air cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air cleaning device with sufficient deodorizing effect by allowing the device to exhibit photocatalytic effect sufficiently. SOLUTION: A fan 2 as a blowing means is provided in a prescribed position on a casing of a main body 1. An ozone generating part 3, a dust collecting filter 4, a photocatalytic part 5 and a light source 6 for irradiation of light of 300 nm of more wavelength are arranged in this order from the upstream to the down stream of an sir flow formed by the fan 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air purifier, and more particularly to an air purifier having a photocatalyst for purifying (mainly deodorizing) intake air.

[0002]

2. Description of the Related Art Conventionally, an air purifying apparatus having a photocatalyst for purifying indoor air has been proposed (see JP-A-8-309229).

[0003] The air purifying apparatus described in Japanese Patent Application Laid-Open No. 8-309229 has a cylindrical case in which a dust collecting electrode and a dust collecting paper are attached to a peripheral surface of the cylindrical case, and an ionizing electrode is arranged outside a lower portion of the cylindrical case. A deodorizing section having an ultraviolet lamp, a photocatalyst, and an ozone catalyst is provided inside the case.

[0004] When the air purifying apparatus of this configuration is employed, dust particles in the air can be collected by the dust collecting electrode and the dust collecting paper, and the photocatalyst of the photocatalyst is irradiated with ultraviolet rays from an ultraviolet lamp. It is described that the deodorizing function can be achieved by action and ozone generated by a UV lamp.

[0005]

Problems to be Solved by the Invention Japanese Patent Application Laid-Open No. 8-30922
In the case where the air purifying device described in Japanese Patent Application Laid-Open No. 9-222 is adopted, the following inconvenience occurs because the photocatalyst functions by simply irradiating the photocatalyst with ultraviolet rays from an ultraviolet lamp. That is, since the ultraviolet lamp not only emits ultraviolet light but also generates ozone, it emits light having a wavelength of at least 300 nm or less.

[0006] Since light having a wavelength of 300 nm or less is harmful to the human body, it is necessary to almost completely prevent the light from leaking out of the apparatus, and the design of the air purifying apparatus becomes more difficult.

Since the life of a light source that emits light of 300 nm or less is shorter than the life of a light source that emits only light of 300 nm or more, it is necessary to replace the light source in order to extend the life of the air cleaning device. In addition, since the frequency of replacing the light source increases, the cost associated with the replacement of the light source increases, and the replacement work increases.

Light having a wavelength of 300 nm or less has lower energy efficiency in the photocatalytic reaction than light having a wavelength of 300 nm or more, so that the energy required to achieve the required deodorizing performance increases.

[0009] Even when the ability is sufficient only by light deodorization (for example, when the load of odor is small), extra ozone is released, so that energy is wasted. Is shortened by unnecessarily generated ozone.

Further, it is known that most hydrocarbon-based gases such as toluene and acetaldehyde are difficult to directly decompose with ozone.
These odors cannot be removed by the ozone deodorizing method shown in the air purifying apparatus described in JP-309229A. As a result, the deodorizing ability is insufficient.

When the odor is decomposed only by a photocatalyst in order to prevent the above-mentioned inconvenience caused by the use of ozone, the amount of light is increased in order to increase the decomposing ability, and / or titanium oxide or the like is used. It is conceivable to increase the amount of the photocatalyst material described above, but a new disadvantage arises in that the cost increases in proportion to the increase and increase in the amount.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an air purifying apparatus having a sufficient deodorizing effect.

[0013]

According to the first aspect of the present invention, there is provided an air cleaning apparatus comprising: a photocatalyst for purifying air by a photocatalytic action; a light source for irradiating the photocatalyst with light having a wavelength of about 300 nm or more; And ozone generating means for generating ozone.

According to a second aspect of the present invention, the air purifying apparatus employs, as the ozone generating means, a means for generating ozone and supplying it to a reaction field of the photocatalytic means.

According to a third aspect of the present invention, there is provided the air purifying apparatus, wherein the ozone generating means generates ozone having a concentration of 0.05 ppm to 10 ppm.

According to a fourth aspect of the present invention, there is provided the air purifying apparatus, wherein the ozone generating means generates ozone having a concentration of 0.1 ppm to 1 ppm.

According to a fifth aspect of the present invention, there is provided the air purifying apparatus, wherein the light source irradiates the photocatalyst unit with light from at least the side to which ozone is supplied.

According to a sixth aspect of the present invention, there is provided an air purifying apparatus which employs a photocatalyst disposed inside an ozone generator.

The air purifying apparatus according to claim 7 further includes an ozone removing means.

The air purifying apparatus according to claim 8 employs an ozone generating means which generates ozone by electric discharge.

According to a ninth aspect of the present invention, there is provided the air purifying apparatus wherein the photocatalyst is provided on a discharge electrode.

According to a tenth aspect of the present invention, the air purifying device employs at least a part of an electric dust collecting device as the ozone generating means.

[0023]

According to the air purifying apparatus of the present invention, the photocatalytic means can be irradiated with light having a wavelength of about 300 nm or more by the light source to perform the photocatalytic action. At the same time, ozone can be generated by the ozone generating means. As a result, a synergistic effect of the treatment with ozone and the treatment with the photocatalyst, that is, a high air purification effect due to suppression of electron-hole recombination due to ozone electron acceptance, mutual decomposition of intermediate products, and an increase in radical production, etc. Can be achieved, and the light from the light source does not adversely affect the human body.

According to the second aspect of the present invention, since the ozone generating means employs a means for generating ozone and supplying it to the reaction field of the photocatalytic means, the deodorizing performance can be efficiently improved even in a small space. Besides, the same operation as the first aspect can be achieved.

In the air purifying apparatus according to the third aspect, the ozone generating means has a concentration of 0.05 ppm to 10 pp.
m ozone is used.
Claims 1 and 2 can improve the performance by the synergistic effect and suppress the ozone emission concentration to a reference value or less.
Alternatively, the same operation as the second aspect can be achieved.

In the air purifying apparatus according to the fourth aspect, since the ozone generating means which generates ozone having a concentration of 0.1 ppm to 1 ppm is employed, the performance is sufficiently improved by the synergistic effect and the ozone generation is improved. In addition to achieving suppression of the emission concentration below the reference value, it is possible to achieve the same effect as in claim 1 or claim 2.

In the air purifying apparatus according to the fifth aspect, since the light source irradiates the photocatalyst means with light from at least the side to which ozone is supplied, the light source is provided in the reaction field of the photocatalyst means. In addition to being able to irradiate light, the amount of generated ozone decomposed by the photocatalytic means is small, and it is possible to irradiate light with high ozone concentration to a sufficient effect of ozone and photocatalyst,
The same operation as any one of claims 2 to 4 can be achieved.

According to the air purifying apparatus of the present invention, since the photocatalyst disposed inside the ozone generating means is employed, the air purifying apparatus can be reduced in size as a whole, and the photocatalytic means can be used. The ozone supply efficiency can be improved, and the same operation as any one of claims 1 to 5 can be achieved.

In the air purifying apparatus according to the seventh aspect, since the ozone removing means is further provided, it is possible to prevent the inconvenience that ozone is discharged to the outside and to prevent the occurrence of the inconvenience. The same operation as any one of the sixth aspect can be achieved.

According to the air purifying apparatus of the present invention, since the ozone generating means which generates ozone by electric discharge is adopted, the structure of the ozone generating means can be simplified. Accordingly, the same function as any one of claims 7 can be achieved.

In the air purifying apparatus according to the ninth aspect, since the photocatalytic means is provided on the discharge electrode, the ozone generating means and the photocatalytic means can be miniaturized. The same operation as that of the item 8 can be achieved.

In the air purifying apparatus according to the tenth aspect, since the ozone generating means which also serves as at least a part of the electric precipitator is adopted, the deodorizing and deodorizing can be performed without increasing the size of the air purifying apparatus as a whole. Dust removal can be achieved, and the same operation as that of claim 8 or claim 9 can be achieved.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an air purifying apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view showing a main part of an embodiment of the air purifying apparatus of the present invention.

In this air purifying apparatus, a fan 2 is provided at a predetermined position of a main body casing 1 as a blowing means.
Ozone generation unit 3, dust collection filter 4, photocatalyst unit 5, light source 6
Are arranged in this order.

The main body casing 1 has, for example, a cylindrical shape and constitutes a ventilation path for allowing the intake air to flow in a predetermined direction. However, the fan 2 may supply air from the upstream side as shown in FIG. 1, or may be provided on the downstream side to attract air.

The ozone generator 3 is of a discharge type in which, for example, a plate-like negative electrode 3b and a linear positive electrode 3a are alternately arranged. The ozone is generated by causing the discharge in the above. Then, for example, the amount of ozone generated can be controlled by controlling the discharge current.

The dust collecting filter 4 is for collecting dust particles and the like in the air, and may be a conventionally known one.

In the photocatalyst section 5, a large number of fine photocatalysts made of a semiconductor of a metal compound such as titanium oxide, zinc oxide, cadmium sulfide, or a mixture thereof are arranged on the surface of a corrugated base to ensure air permeability. It is made.

The light source 6 emits only light having a wavelength of, for example, 300 nm or more (in other words, light that does not adversely affect the human body and includes light having an energy larger than the band gap of the photocatalyst). Thus, generation of ozone can be prevented beforehand. Then, the light intensity may be freely controlled. Specifically, a cold cathode tube, a black light and the like can be exemplified.
Then, depending on the type of the photocatalyst, a visible light source can be employed.

The operation of the air purifying apparatus having the above configuration is as follows.

When the light from the light source 6 is applied to the photocatalyst unit 5 and the ozone generation unit 3 is operated to generate ozone, the generated ozone is reacted by the flow of air from the fan 2 into the reaction field of the photocatalyst unit 5. Supplied to Then, in this reaction field, the photocatalytic reaction is enhanced by the presence of ozone, and thus the air cleaning effect (deodorizing effect) can be enhanced. Of course, dust particles and the like can be collected by the dust collection filter 4.

Further description will be given.

When the photocatalyst is irradiated with light, electrons are generated in the conduction band of the photocatalyst and holes are generated in the valence band. Normally, holes greatly contribute to the decomposition of odors, but many of them recombine with electrons before reacting with odors and disappear (recombination of electrons and holes). Here, if ozone is present in the vicinity of the photocatalyst, the ozone accepts and combines electrons on the surface of the photocatalyst. Therefore, recombination of holes and electrons can be suppressed, and the activity of the photocatalyst is kept high. On the other hand, ozone recombined with electrons produces OH radicals in a series of subsequent reactions. Since this OH radical has a strong oxidizing action, it also contributes to deodorization.

Furthermore, odors such as toluene can hardly be decomposed by ozone, but can be easily decomposed by contact with ozone after toluene is converted to another intermediate substance by a photocatalyst. The reverse is also true depending on the type of odor.

As described above, the deodorizing effect can be greatly enhanced by utilizing the synergistic effect of the two.

The ozone concentration (= the amount of ozone generated / the amount of ventilation air) generated by the ozone generator 3 is 0.05 p.
The ozone generator 3 is controlled so as to be pm to 10 ppm. However, the above-mentioned ozone concentration may be satisfied only in a part of the operation state of the air cleaning device (such as when the odor load is high). Here, the reason why the ozone concentration is set to 0.05 ppm or more is to achieve deodorization by a synergistic effect,
The reason why the concentration is set to 10 ppm or less is that the concentration of ozone remaining and discharged irrespective of the reduction of ozone is 0.01 pp.
m or less so that there is almost no effect on the human body. However, it is preferable to control the ozone generator 3 so that the ozone concentration is 0.1 ppm to 1 ppm.
Here, if the ozone concentration is set to 0.1 ppm or more,
Sufficient deodorization can be achieved by a synergistic effect,
When the pressure is set to pm or less, the concentration of ozone remaining and discharged irrespective of the reduction of ozone is sufficiently reduced to less than 0.01 ppm, so that the influence on the human body can be further reduced. Further, 1 ppm is an upper limit concentration at which a drastic improvement in the synergistic effect by the supply of ozone can be expected.

Table 1 is a table showing the relationship between the decomposition rate of toluene, carbon dioxide generation rate and ozone concentration, FIG. 2 is a view showing the relationship between the improvement of the decomposition rate of toluene and ozone concentration, and FIG. It is a figure which shows the relationship between the improvement of a carbon production rate, and ozone concentration. Here, the reason why the carbon dioxide generation rate is shown is that carbon dioxide is generated when a substance containing carbon such as toluene is completely oxidized and decomposed. The ozone concentration was 0.02 ppm, 0.05 ppm,
0.10 ppm, 0.20 ppm, 0.50 ppm,
0.80 ppm and 1.00 ppm are selected. 2 and 3, white squares represent measured values, and black squares represent average values.

[0049]

[Table 1] As can be seen from Table 1, FIG. 2 and FIG.
When set to 05 ppm, the rate of decomposition of toluene can be increased by about 8.6%, and the rate of carbon dioxide generation can be increased by about 5.2%. Furthermore, by setting the ozone concentration to 0.1 ppm, the toluene decomposition rate can be increased about 1.5 times,
The rate of carbon dioxide production can be increased about 1.4 times.

Therefore, the ozone concentration is set to 0.05 ppm
With the above setting, an increase in the toluene decomposition rate can be achieved, and by setting the ozone concentration to 0.1 ppm or more, a sufficient increase in the toluene decomposition rate can be achieved.

As can be seen from the above, the toluene decomposition rate (in other words, the deodorizing performance) can be greatly improved only by using a very small amount of ozone in combination with the photocatalyst. Further, since the amount of ozone required to produce such an effect is very small, there is almost no increase in cost. Further, since ozone at such a concentration has almost no ozone deodorizing effect, it can be seen that the ozone deodorization is caused by a synergistic effect of the photocatalyst and a very small amount of ozone.

Here, the photolysis rate coefficient (see Table 1) can be obtained as follows.

First, the odor is adsorbed without irradiating light to the photocatalyst provided in the box, and after the adsorption is saturated, the irradiation of light to the photocatalyst is stopped and the irradiation of light is repeated to repeat the odor in the box. The concentration is measured (see FIG. 4, where the vertical axis is logarithmic). Then, a formula α · e ^−k0t representing a change in the odor concentration during the light irradiation stop period is calculated, and a formula β · e ^−k1t representing the change in the odor concentration during the light irradiation period is calculated. Also, since k0 corresponds to the light irradiation stop period, it can be said that it is a natural decay (attenuation due to leakage from the box, adsorption, etc.) rate coefficient, and the photodegradation coefficient k is given by k1-k0. Can be.

In the embodiment shown in FIG. 1, the light source 6 is disposed downstream of the air flow with respect to the photocatalyst unit 5.
The light source 6 is preferably arranged on the upstream side of the flow of air with respect to the photocatalyst unit 5, and light can be emitted to the photocatalyst unit 5 from the ozone supply side. The reason why it is preferable to adopt this configuration is as follows.

Titanium oxide has a function of decomposing ozone by contact with ozone even when it is not irradiated with light, and when the photocatalyst section 5 has a certain thickness, the titanium oxide is not oxidized while passing through the photocatalyst section 5. And the ozone concentration decreases at the outlet side. However, in this configuration, since the light is irradiated from the upstream side of the photocatalyst section 5, the light having the highest ozone concentration is irradiated with the strongest light, and the generated ozone is utilized to the maximum to improve the energy efficiency. Can be done.

FIG. 5 is a longitudinal sectional view schematically showing a main part of another embodiment of the air cleaning apparatus of the present invention, and FIG. 6 is a perspective view of the same.

In this air cleaning device, the light source 6, the needle electrode 3c and the flat plate electrode 3d constituting the ozone generating section 3 are arranged in this order from the upstream side to the downstream side of the air flow. The photocatalyst layer 5a is formed on the surface on the upstream side of the plate electrode 3d.

The method for forming the photocatalyst layer 5a is as follows.
For example, a plate electrode 3d
Immersion, slowly pulling it up (while keeping the solution attached to the surface of the plate electrode 3d), removing water at a high temperature to fix titanium oxide or the like to the surface of the plate electrode 3d (dip coating method), A method in which a solution in which titanium or the like is dissolved is sprayed and sprayed on the flat electrode 3d to remove water in the same manner as described above (spray method) can be exemplified.

In the case of adopting this embodiment, since the photocatalyst layer 5a is provided inside the ozone generating section 3, the overall size can be reduced and the structure can be simplified. The supply of ozone to the photocatalyst layer 5a can be made more reliable than in the above embodiment.

In addition, the same operation as the above embodiment can be achieved.

FIG. 7 is a longitudinal sectional view schematically showing a main part of still another embodiment of the air purifying apparatus of the present invention.

In this air purifying apparatus, the first mesh electrode 3e constituting the ozone generating section 3 from the upstream side to the downstream side of the air flow, a photocatalyst section having the same configuration as the embodiment of FIG. 5, the second mesh-shaped electrode 3f constituting the ozone generating section 3, and the light source 6 are arranged in this order. Note that an AC high voltage power supply 3j is connected between the first mesh electrode 3e and the second mesh electrode 3f.

In the case of adopting this embodiment, since the photocatalyst layer 5a is provided inside the ozone generating section 3, it is possible to realize the miniaturization as a whole and the simplification of the configuration. The supply of ozone to the photocatalyst unit 5 can be made more reliable than in the embodiment of FIG.
In addition, the same operation as the embodiment of FIG. 1 can be achieved.

FIG. 8 is a longitudinal sectional view schematically showing a main part of still another embodiment of the air purifying apparatus of the present invention.

In this air cleaning device, the first metal flat plate 3g and the second metal flat plate 3h are arranged in a direction orthogonal to the flow of air.
Are alternately arranged, and the dielectric layer 3i is provided on the surface of the second metal flat plate 3h to constitute the ozone generating unit 3.
The photocatalyst unit 5 and the light source 6 are located downstream of the ozone generation unit 3.
And are arranged in this order.

When this embodiment is adopted, the mechanical strength of the ozone generating section 3 can be improved as compared with the embodiment shown in FIG. 1, and the dielectric layer 3i is provided. Creepage discharge can be performed to increase the amount of ozone generated, and the same operation as the embodiment of FIG. 1 can be achieved.

FIG. 9 is a longitudinal sectional view schematically showing a main part of still another embodiment of the air cleaning apparatus of the present invention.

In this air cleaning device, a flat plate-
On the downstream side of the discharge type ozone generator 3 in which the poles 3b and the linear + poles 3a are alternately arranged, a dust collector 4, a photocatalyst 5,
The light source 6 is arranged. Then, the light source 6 is arranged in the internal space of the photocatalyst section 5 to increase the light use efficiency.

In this embodiment, the shape of the photocatalyst unit 5 is schematically shown as a rectangular tube, but any shape may be used as long as the light source 6 can be arranged inside. For example, a cylindrical one or a thin sheet-like photocatalyst wound around a light source is also included. The photocatalyst unit 5
Preferably has sufficient air permeability.

When this embodiment is adopted, the light source 6
Since all of the light emitted from the light source is irradiated to the photocatalyst unit 5, the light use efficiency can be increased, and the light emission amount of the light source 6 does not need to be increased, so that energy saving can be achieved. 1, the same operation as the embodiment of FIG. 1 can be achieved.

In each of the embodiments shown in FIGS. 5 to 8, a dust collection unit such as HEPA may be provided upstream of the ozone generation unit 3. The dust collecting part for collecting may be provided on the downstream side of the ozone generating part 3. And it is preferable that the ozone generation part 3 also serves as at least one part of an electric dust collection part. Further, the photocatalyst unit can be provided outside the ozone generation unit in the embodiments of FIGS. 5, 6, and 7, and the photocatalyst unit is provided inside the ozone generation unit in the embodiments of FIGS. Is possible.

As can be seen from the above description, the concentration of ozone discharged from the air purifier is 0.01 ppm or less and has little effect on the human body, but samples of activated carbon, soda lime, etc., NiO, NiO-CuO , Nio-F
It is preferable to provide an ozone removing unit containing a catalyst such as e ₃ O _4, so that the concentration of discharged ozone can be significantly reduced.

[0073]

According to the first aspect of the present invention, the synergistic effect of the treatment with ozone and the treatment with a photocatalyst, such as suppression of electron-hole recombination by electron acceptance of ozone, mutual decomposition of intermediate products, and increased production of radicals. Thus, a high air purifying effect can be achieved, and a unique effect that the light from the light source does not adversely affect the human body is exhibited.

According to the second aspect of the invention, the photocatalytic action can be efficiently enhanced in a small space, and the same effect as that of the first aspect can be obtained.

According to the third aspect of the present invention, the performance can be improved by the synergistic effect and the ozone emission concentration can be suppressed to the reference value or less, and the same effect as the first or second aspect can be obtained.

According to the fourth aspect of the present invention, it is possible to achieve a sufficient improvement in performance due to a synergistic effect and to suppress the emission concentration of ozone to a reference value or less.
It has the same effect as.

According to the fifth aspect of the present invention, it is possible to irradiate the reaction field of the photocatalyst means with light, and furthermore, irradiate light to a portion where the generated ozone is decomposed by the photocatalyst means is small and the ozone concentration is high. Thus, the synergistic effect of ozone and the photocatalyst can be sufficiently exhibited, and the same effect as any one of claims 2 to 4 can be obtained.

According to the sixth aspect of the present invention, the air purifying apparatus can be reduced in size as a whole, the efficiency of supplying ozone to the photocatalyst means can be increased, and the same effect as any of the first to fifth aspects can be obtained. Play.

The invention of claim 7 can prevent the occurrence of the disadvantage that ozone is discharged to the outside,
The same effect as any one of claims 1 to 6 is achieved.

According to the eighth aspect of the present invention, the configuration of the ozone generating means can be simplified, and the first to seventh aspects of the present invention can be applied.
The same effect as any of the above is achieved.

According to the ninth aspect of the present invention, the size of the ozone generating means and the photocatalytic means can be reduced, and the same effect as that of the eighth aspect can be obtained.

According to the tenth aspect of the present invention, deodorization and dust removal can be achieved without increasing the size of the air purifying apparatus as a whole, and the same effects as in any of the first to ninth aspects can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a main part of an embodiment of an air cleaning device of the present invention.

FIG. 2 is a graph showing a relationship between an improvement in the decomposition rate of toluene and an ozone concentration.

FIG. 3 is a diagram showing the relationship between the improvement of the carbon dioxide generation rate and the ozone concentration.

FIG. 4 is a diagram illustrating a process of calculating a photolysis rate coefficient.

FIG. 5 is a longitudinal sectional view schematically showing a main part of another embodiment of the air cleaning device of the present invention.

FIG. 6 is a perspective view of the same.

FIG. 7 is a longitudinal sectional view schematically showing a main part of still another embodiment of the air cleaning device of the present invention.

FIG. 8 is a longitudinal sectional view schematically showing a main part of still another embodiment of the air cleaning device of the present invention.

FIG. 9 is a longitudinal sectional view schematically showing a main part of still another embodiment of the air cleaning device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body casing 2 Fan 3 Ozone generation part 5 Photocatalyst part 6 Light source

Continuation of the front page F term (reference) 4C080 AA07 AA10 BB02 CC02 CC12 HH05 JJ09 KK02 KK08 MM02 MM08 QQ11 QQ17 QQ20

Claims (10)

[Claims] 1. Photocatalytic means (5) for purifying air by photocatalytic action, and approximately 300
An air purifier comprising: a light source (6) for irradiating light having a wavelength of at least nm; and ozone generating means (3) for generating ozone. 2. The air purifying apparatus according to claim 1, wherein the ozone generating means (3) generates ozone and supplies the ozone to a reaction field of the photocatalytic means (5). 3. The air cleaning apparatus according to claim 1, wherein the ozone generating means (3) generates ozone having a concentration of 0.05 ppm to 10 ppm. 4. The air purifying apparatus according to claim 1, wherein said ozone generating means (3) generates ozone having a concentration of 0.1 ppm to 1 ppm. 5. The air according to claim 2, wherein the light source (6) irradiates the photocatalyst means (5) with light from at least a side to which ozone is supplied. Purifier. 6. The air purifying apparatus according to claim 1, wherein the photocatalyst means is disposed inside the ozone generating means. 7. The air purifying apparatus according to claim 1, further comprising an ozone removing unit. 8. The air cleaning device according to claim 1, wherein the ozone generating means (3) generates ozone by discharging. 9. The air cleaning device according to claim 8, wherein the photocatalyst means (5) is provided on a discharge electrode. 10. The air cleaning device according to claim 8, wherein the ozone generation means (3) also serves as at least a part of an electric dust collector.