JPH09100104A - Electric discharger for generating ozone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric discharger for generating ozone capable of reducing the change of the amount of ozone generation for a long period even if it generates heat on use and enabling a long life by forming a dielectric layer and/or a protecting layer with a mullite-based ceramic. SOLUTION: The electric discharger for generating ozone is provided by forming a planer induction electrode 3 on an unburnt ceramic plate 1 and a linear discharging electrode 4 on the another unburnt ceramic plate 2 with applying a paste of tungsten, molybdenum, etc., to each of them, laminating these ceramic plates 1, 2, then forming a protecting layer 5 consisting of a ceramic for covering the discharging electrode 4 with printing, spraying, CVD method, PVD method, etc., and making the whole part as one unit by burning. This discharging body for generating ozone can generate ozone by generating the discharge along to surfaces since the ceramic plate 2 becomes a dielectric layer on applying an electric voltage between the dielectric electrode 3 and the discharging electrode 4. Also, by covering the dielectric electrode with a ceramic coating layer to form the dielectric layer, the discharging characteristics are improved and the efficiency of ozone generation is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electric discharge body for generating ozone.

[0002]

2. Description of the Related Art Ozone is obtained by discharging in dry air, has a strong oxidizing power, deodorizes, sterilizes,
It is used for bleaching.

As such an ozone generator, there has been used, for example, a device in which a dielectric made of alumina ceramics is used for discharging as shown in Japanese Patent Publication No. 55-37483. Also, Japanese Unexamined Patent Publication No.
-44797, etc., a planar induction electrode and a linear discharge electrode are formed on the inside of a dielectric made of ceramics, and a high frequency voltage is applied between these electrodes. A device that generates a creeping discharge has also been used.

Further, in the ozone-generating discharge body formed by forming the induction electrode and the discharge electrode, the discharge electrode is easily worn during discharge. Therefore, a protective layer made of glass may be formed so as to cover the discharge electrode. It was known (JP-A-63-6)
6880).

[0005]

However, such an ozone generating discharge body generates heat during use, and heat generation and cooling are repeated during long-term use. Therefore, when the dielectric or protective layer is made of alumina ceramics or glass, there is a problem that the characteristics deteriorate during long-term use and the amount of ozone generated decreases.

Further, in order to increase the ozone generation efficiency, it is necessary to shorten the distance between the induction electrode and the discharge electrode, but in the conventional ozone generation discharge body, the induction electrode is sandwiched between the substrates such as ceramics. Since the discharge electrodes are formed, it is difficult to reduce the thickness of the substrate and shorten the distance between the electrodes.

[0007]

In view of the above, the present invention provides an ozone generating discharge body comprising an induction electrode and a discharge electrode sandwiching a dielectric layer, and forming a protective layer so as to cover the discharge electrode. The dielectric layer and / or the protective layer are made of mullite ceramics.

Further, according to the present invention, an induction electrode is formed on a ceramic plate, the induction electrode is covered with a ceramic coating layer to form a dielectric layer, and a discharge electrode and a ceramic covering the discharge electrode are protected on the dielectric layer. A layer was provided to form an ozone generating discharge body.

[0009]

According to the present invention, since the dielectric layer and / or the protective layer constituting the ozone generating discharge body are made of mullite ceramics having high heat resistance, the amount of ozone generated changes over a long period of time even if heat is generated during use. Can be reduced and the life can be extended.

Further, according to the present invention, since the dielectric layer between the induction electrode and the discharge electrode is composed of the ceramic coating layer, it can be easily formed thin, and the distance between both electrodes can be shortened to reduce ozone. The generation efficiency can be improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

In the ozone generating discharge body shown in FIGS. 1 (a) and 1 (b), a planar induction electrode 3 is provided on an unfired ceramic plate 1.
Another unfired ceramic plate 2 and a linear discharge electrode 4
Are formed by applying pastes such as tungsten and molybdenum, and these ceramic plates 1 and 2 are laminated, and then a protective layer 5 made of ceramics is printed and sprayed by the CVD method so as to cover the discharge electrodes 4. It is formed by a PVD method or the like and is integrally fired and integrated.

In this ozone generating discharge body, the ceramic plate 2 serves as a dielectric layer, and when a voltage is applied between the induction electrode 3 and the discharge electrode 4, a creeping discharge occurs and ozone can be generated.

Further, as another embodiment, FIG.
The ozone generating discharge body shown in (b) and (c) of FIG.
As shown in (a), a planar induction electrode 1 made of tungsten, molybdenum, or the like is formed on the surface of an unfired ceramic plate 11.
3 is formed, and a ceramic layer 12 as a dielectric layer is formed by printing, spraying, CVD method, PVD method or the like so as to cover the same, and then a linear wire made of tungsten, molybdenum or the like is formed on the ceramic layer 12. The discharge electrode 14 is formed, and a ceramic protective layer 15 is formed so as to cover the discharge electrode 14 by the same means as described above.

In this ozone generating discharge body, since the ceramic layer 12 formed by coating is used as a dielectric layer, the dielectric layer can be thinned to improve discharge characteristics and increase ozone generating efficiency.

Various ceramics such as alumina, mullite, forsterite, steatite, zircon, titania can be used as the ceramics forming the dielectric layer and the protective layer. Among them, mullite ceramics are particularly preferable. preferable. That is, the ceramic substrate 2 forming the dielectric layer, the ceramic layer 12, and the protective layers 5 and 15
Is preferably formed of mullite ceramics,
In this case, in order to match the firing temperature and the coefficient of thermal expansion, it is preferable that the ceramic plates 1 and 11 forming the base body are also made of the same mullite ceramics.

Here, mullite is 3Al ₂ O ₃ .2Si.
It is represented by the molecular formula of O ₂ and has a molar ratio of 3: 2: Al ₂ O ₃ and S
It is a compound obtained by reacting iO ₂ . The mullite ceramics are ceramics containing mullite as a main component.

The mullite ceramics can be used to form the dielectric layer and the protective layer by a known manufacturing method. For example, Al ₂ O ₃ and SiO ₂ powder are mixed and reacted by means such as calcination to form mullite, and mullite powder obtained by crushing this is molded and fired, or the above mullite powder is formed into a paste. The dielectric layer and the protective layer can be formed by coating or the like.

Since this mullite ceramic is particularly excellent in heat resistance among various ceramics, its characteristics are not deteriorated even when heat is generated when it is used as a discharge body for ozone generation, and the ozone generation efficiency is lowered for a long period of time. Can be prevented.

[0020]

EXAMPLE A trial production of the ozone generating discharge body shown in FIG. 2 in which the material and thickness T ₁ of the ceramic layer 12 as the dielectric layer and the material and thickness T ₂ of the protective layer 15 were variously changed was produced. , The capacitance C _{1 of} the dielectric layer and the protective layer respectively,
After measuring C ₂ , the actual amount of ozone generated was examined.

The capacitance C ₁ of the dielectric layer is the capacitance between the induction electrode 13 and the discharge electrode 14, and the capacitance C ₂ of the protective layer is the capacitance of the induction electrode on the upper surface of the protection layer 15. This electrode and discharge electrode 1 when an electrode of the same size as 13 is placed
It is the capacitance between the four.

The induction electrode 13 has a size of 5 mm × 20 m.
m, the discharge electrode 14 is formed of tungsten with a size of 1 mm × 17.5 mm, and the condition for ozone generation is 5
The ozone generation amount was examined when a primary voltage of 3.5 V was applied for 60 seconds at 30 ° C. and humidity.

As the material of the dielectric layer 12 and the protective layer 15,
Mullite ceramics and alumina ceramics were used. Mullite ceramics has a dielectric constant of 6.8, and alumina ceramics contains 92% Al ₂ O ₃ and the balance S.
A material having a dielectric constant of 9.5 and made of iO ₂ , MgO, CaO or the like was used.

The results are shown in Tables 1 to 3. Further, FIG. 3 shows the relationship between the capacitance ratio C ₁ / C ₂ and the ozone generation amount in Table 3.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

From these results, as shown in Tables 1 and 2, when mullite ceramics were used as the protective layer, the heat resistance was excellent. Thickness T ₂ is 11.4
Even if it is as thin as μm, it can be suitably used.

Further, in these examples, since the dielectric layer is formed by ceramic coating as shown in FIG. 2,
It can be formed thin and the ozone generation efficiency can be increased.

Further, from these results, it is clear that when the capacitance ratio C ₁ / C ₂ is larger than 0.4, the ozone generation amount is extremely lowered, and particularly C ₁ / C ₂ is larger than 0.5. It can be seen that the ozone generation amount becomes almost zero.

Further, for example, No. 1 in Table 3 is used. 3 and N in Table 2
o. Comparing the two, the dielectric layers and the protective layer have almost the same thickness, but the materials of the protective layer are different, so that the capacitance ratio C ₁ / C ₂ is also different and the ozone generation amount is also different. . That is, it was confirmed that the ozone generation amount is determined not by the thickness ratio of the dielectric layer and the protective layer but by the capacitance ratio.

Therefore, in order to increase the ozone generation amount in the ozone generating discharge body in which the ceramic protective layer is formed on the discharge electrode, the capacitance C ₁ of the dielectric layer and Capacitance C of protective layer
₂ of the ratio C ₁ / C ₂ may be 0.5 or less, in particular C ₁
It was found that the best value was obtained when / C ₂ was 0.4 or less.

However, this is from the viewpoint of the amount of ozone generated, and from the viewpoint of protecting the discharge electrode, the thicker the protective layer, the better. Therefore, in practice, the capacitance ratio C ₁
The thickness of the protective layer may be maximized when / C ₂ is in the range of 0.5 or less.

Further, the capacitance C ₂ of the capacitance C ₁ and the protective layer of the dielectric layer is respectively determined by theoretically the following formula.

C ₁ = ε ₀ · ε ₁ · S / T ₁ C ₂ = ε ₀ · ε ₂ · S / T ₂ where ε ₀ : dielectric constant in vacuum ε ₁ : relative dielectric constant of the dielectric layer ε ₂ : Relative permittivity of protective layer S: Area of electrode (discharge electrode) T ₁ : Distance between electrodes (thickness of dielectric layer) T ₂ : Distance between electrodes (thickness of protective layer) From these two equations, It can be expressed as C ₁ / C ₂ = ε ₁ · T ₂ / ε ₂ · T ₁ .

Therefore, in order to reduce C ₁ / C ₂ , the dielectric constant ε ₂ of the protective layer is increased or the thickness T ₂ is decreased, or the dielectric constant ε ₁ of the dielectric layer is decreased or the thickness T is decreased. You can see that you can increase ₁ by _one .

Since the mullite ceramics has a low dielectric constant of 6.8, the capacitance ratio C ₁ /
It is possible to reduce C ₂ and improve ozone generation efficiency.

[0038]

As described above, according to the present invention, in the ozone generating discharge body having the induction electrode and the discharge electrode sandwiching the dielectric layer, the protective layer is formed so as to cover the discharge electrode. In addition, since the dielectric layer and / or the protective layer are formed of mullite ceramics, the mullite ceramics have excellent heat resistance, and thus can be used for a long period of time without lowering the ozone generation amount.

According to the present invention, an induction electrode is formed on a ceramic plate, the induction electrode is covered with a ceramic coating layer to form a dielectric layer, and a discharge electrode and a ceramic covering the discharge electrode are formed on the dielectric layer. Since the ozone-generating discharge body is provided with the protective layer, the dielectric layer can be formed thin and the ozone-generating efficiency can be improved.

[Brief description of the drawings]

FIG. 1A is an exploded perspective view showing a discharge body for ozone generation of the present invention, and FIG. 1B is a sectional view taken along line XX in FIG.

2 (a) and 2 (b) are perspective views showing a manufacturing process of an ozone generating discharge body according to another embodiment of the present invention, and FIG. 2 (c) is (b).
It is YY line sectional drawing in a middle.

FIG. 3 is a graph showing a relationship between a ratio C ₁ / C ₂ of electrostatic capacities of a dielectric layer and a protective layer and an ozone generation amount in the ozone generating discharge body of the present invention.

[Explanation of symbols]

 1, 11: Ceramic plate 2, 12: Dielectric layer 3, 13: Induction electrode 4, 14: Discharge electrode 5, 15: Protective layer

Claims (2)

[Claims] 1. In an ozone-generating discharge body comprising an induction electrode and a discharge electrode sandwiching a dielectric layer, a protective layer is formed so as to cover the discharge electrode, and the dielectric layer and / or the protection layer are formed. A discharge body for ozone generation, wherein the layer is formed of mullite ceramics. 2. An induction electrode is formed on a ceramic plate, the induction electrode is covered with a ceramic coating layer to form a dielectric layer, and a discharge electrode and a ceramic protective layer covering the discharge electrode are provided on the dielectric layer. A discharge body for ozone generation.