JP2017010659A - Plasma generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma generator capable of suppressing generation of ozone and obtaining stable discharge.SOLUTION: A plasma generator 1 comprises: a low dielectric layer 4; a first electrode 2a and a second electrode 2b which are provided to interpose the low dielectric layer 4 therebetween; a first high dielectric layer 3a which is provided between the first electrode 2a and the low dielectric layer 4; and a second high dielectric layer 3b which is provided between the second electrode 2b and the low dielectric layer 4. The plasma generator 1 generates plasma between the first high dielectric layer 3a and the second high dielectric layer 3b. In the plasma generator 1, the first high dielectric layer 3a and the second high dielectric layer 3b include side faces extending in one direction. Electric field concentration parts 5 are formed on the side faces and in the vicinity of the low dielectric layer 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a plasma generator.

  As a plasma generator for generating plasma for generating ions or radicals (hereinafter also referred to as active species) used for air purification, sterilization, sterilization, deodorization, and the like, there is one disclosed in Patent Document 1, for example. In the plasma generator disclosed in Patent Document 1, two electrodes having a plurality of through holes are arranged in parallel so that the positions of the through holes coincide with each other, and a porous dielectric film is exposed on one of the electrodes. Is formed.

  By the way, in the plasma generator of patent document 1, the air which stagnates in the area | region which an electrode opposes ozonized with plasma, and there existed a subject that the generation amount of ozone increased.

  Therefore, for example, there is a device described in Patent Document 2 as a plasma generator that suppresses the amount of ozone generated. In the plasma generator described in Patent Document 2, a low dielectric layer is disposed in a region where the electrodes face each other so that air cannot stay.

JP 2009-081134 A JP 2012-264271 A

  However, in the plasma generator described in Patent Document 2, since the low dielectric layer is disposed between the electrodes, the discharge voltage for generating plasma increases, and abnormal discharge such as spark discharge is likely to occur between the opposing electrodes. There is a problem that stable discharge cannot be obtained.

  The present invention has been made in view of the above problems, and its main object is to provide a plasma generator capable of suppressing ozone generation and obtaining stable discharge.

  The plasma generator of the present invention is provided between a low dielectric layer, a first electrode and a second electrode provided so as to sandwich the low dielectric layer, and the first electrode and the low dielectric layer. A first high dielectric layer and a second high dielectric layer provided between the second electrode and the low dielectric layer, the first high dielectric layer and the second high dielectric layer. A plasma generating apparatus for generating plasma between the first high dielectric layer and the second high dielectric layer having side surfaces extending in one direction, the side surfaces of the low dielectric layer. An electric field concentration portion is formed in the vicinity of.

  With this configuration, plasma is generated between the first high dielectric layer and the second high dielectric layer provided with the low dielectric layer interposed therebetween, so that the portion that comes into contact with the circulating air It is possible to generate plasma only in this case and to suppress generation of ozone. In addition, since plasma is not generated in unnecessary portions, power efficiency can be improved. In addition, by providing the electric field concentration portion to facilitate discharge, the discharge voltage can be lowered compared to the case where there is no electric field concentration portion, and abnormal discharge such as spark discharge can be prevented.

  The electric field concentration portion is preferably provided with minute unevenness, and the electric field is concentrated by the minute unevenness, so that discharge can be further easily caused. The height of the projections of the minute irregularities is configured to be 1 μm or more and 100 μm or less. Further, the minute irregularities may be configured by roughening the surfaces of the first high dielectric layer and the second high dielectric layer. In this case, the surface roughness is configured such that the average roughness (Rm) is 1 μm or more and 100 μm or less, and the average interval (Sm) is 1 μm or more and 100 μm or less.

  As another configuration for facilitating the discharge, the electric field concentration portion may include a portion having a relative dielectric constant different from that of the first high dielectric layer and the second high dielectric layer. .

  The low dielectric layer has a side surface extending in one direction, and further includes a side surface of the first high dielectric layer and the second high dielectric layer, and a blower mechanism for flowing air to the side surface of the low dielectric layer. If provided, active species such as ions can be generated by bringing the plasma generated in the electric field concentration region into contact with air, and the active species can be discharged to an arbitrary space on the wind sent from the blower mechanism.

  According to the present invention, generation of ozone can be suppressed and stable discharge can be obtained.

A sectional view of a plasma generator concerning a 1st embodiment of the present invention. Sectional drawing of the plasma generator concerning 2nd Embodiment of this invention. The graph which shows the relationship between the voltage applied to a low dielectric material layer and an electrode.

  A plasma generator 1 according to a first embodiment of the present invention will be described below.

  As shown in FIG. 1, the plasma generator 1 in the first embodiment includes a low dielectric layer 4, a first electrode 2 a and a second electrode 2 b provided so as to sandwich the low dielectric layer 4, A first high dielectric layer 3a provided between the electrode 2a and the low dielectric layer 4; a second high dielectric layer 3b provided between the second electrode 2b and the low dielectric layer 4; A blower mechanism (not shown) for flowing air to the side surfaces of the high dielectric layer 3 a and the second high dielectric layer 3 b and the side surfaces of the low dielectric layer 4 is provided.

  The low dielectric layer 4 has a flat plate shape having side surfaces extending in one direction, and is made of a material having a relative dielectric constant of 30 or less, preferably 10 or less, and a thickness of 10 μm or more and 100 μm. It is comprised so that it may become the following.

  The first electrode 2a and the second electrode 2b have a flat plate shape, and the width thereof is configured to be smaller than the width of the first high dielectric layer 3a and the second high dielectric layer 3b. . The distance between the side surfaces of the first electrode 2a and the second electrode 2b and the side surfaces of the high dielectric layer 3a and the second high dielectric layer 3b is configured to be 25 μm or more and 100 μm or less.

  The first high dielectric layer 3a and the second high dielectric layer 3b have a flat plate shape having side surfaces extending in one direction, and are made of a material having a relative dielectric constant of 100 or more, preferably 1000 or more. The An electric field concentration portion 5 is formed in the vicinity of the low dielectric layer 4 on the side surface.

  The electric field concentration portion 5 is provided integrally with the first high dielectric layer 3a and the second high dielectric layer 3b, and protrudes from the side surface of the low dielectric layer 4 in the sectional view. It is configured as follows. In the present embodiment, a semicircular shape in cross section is formed, and minute irregularities are provided on the surface. The height from the surface of the minute uneven first high dielectric layer 3a or second high dielectric layer 3b to the convex tip surface is configured to be 1 μm or more and 100 μm or less.

  Further, the minute unevenness may be configured by roughening the surface of the first high dielectric layer 3a or the second high dielectric layer 3b. In this case, the surface roughness is configured such that the average roughness (Rm) is 1 μm or more and 100 μm or less, and the average interval (Sm) is 1 μm or more and 100 μm or less.

  When a voltage is applied to the first electrode 2a and the second electrode 2b, the electric field is concentrated by the electric field concentrating portion 5, and discharge is generated by using this portion as a trigger. Then, plasma is generated between the first high dielectric layer 3a and the second high dielectric layer 3b by this discharge, and this plasma and air react to generate ions and radicals (hereinafter also referred to as active species). Will occur. Then, the generated active species are released into an arbitrary space by the blower mechanism.

  Here, the voltages applied to the first electrode 2a and the second electrode 2b are the relative dielectric constant and thickness of the first high dielectric layer 3a and the second high dielectric layer 3b, and the ratio of the low dielectric layer 4 to each other. It is determined by the dielectric constant and thickness. This correlation is described below.

The voltage V applied to the first electrode 2a and the second electrode 2b and the voltage V _εL appearing on the surface of the low dielectric layer 4 are relative dielectric constants of the first high dielectric layer 3a and the second high dielectric layer 3b. epsilon _H, and the high dielectric layer of thickness d _.epsilon.h, using the thickness d _.epsilon.L low dielectric layer 4 of dielectric constant epsilon _L and a low dielectric layer is expressed by the following.
_{V εL = {ε H × d} εL / (ε H d εL + 2ε L d εH)} × V ··· (1)

Further, the discharge gap d _plasma and the discharge start voltage V _start with respect to air can be obtained as follows from Pashen's law.
V _start = P ₀ Ad _plasma / ln (P ₀ Bd _plasma / ln (1+ (1 / γ)))
... (2)
A and B are constants, P ₀ is atmospheric pressure, and γ is a secondary electron emission coefficient.

When V _εL = V _start and d _εL = d _plasma are substituted into the above equations (1) and (2), they are applied to cause discharge to the first electrode 2a and the second electrode 2b under ideal conditions. The necessary voltage V is expressed by the following equation.
_{V = (ε H d εL +} 2ε L d εH) P 0 A / ε H (ln (P 0 Bd plasma / ln (1+ (1 / γ)))) ··· (3)

In the above formula (3), d _εH = 230 μm, ε _H = 2000, ε _L = 10, and the relationship between the voltage and the thickness of the low dielectric layer 4 is shown in the graph shown in FIG.
Since the actual electrode is different from the ideal condition, considering that a higher voltage than the graph shown in FIG. 3 is required, when the voltage applied to the first electrode 2a and the second electrode 2b is 1000 V, the voltage is low. It can be seen that the thickness of the dielectric layer 4 may be 10 μm to 100 μm. Also, considering that it is better to set the voltage applied between the electrodes to 700 V or less from the viewpoint of safety, it is understood that the thickness of the low dielectric layer 4 is preferably set between 10 μm and 50 μm.

  In this way, the first electrode 2a can be set by appropriately setting the relative dielectric constant and thickness of the first high dielectric layer 3a and the second high dielectric layer 3b and the relative dielectric constant and thickness of the low dielectric layer 4. The voltage applied to the second electrode 2b can be determined.

  In the plasma generator 1 of the first embodiment configured as described above, plasma is generated between the first high dielectric layer 3a and the second high dielectric layer 3b provided with the low dielectric layer 4 interposed therebetween. Since it is set as the structure, plasma can be generated only in a portion in contact with the circulating air, and generation of ozone can be suppressed. In addition, since plasma is not generated in unnecessary portions, power efficiency can be improved.

  In addition, by providing the electric field concentration portion 5 to easily cause discharge, the discharge voltage can be reduced compared to the case where there is no electric field concentration portion 5, and abnormal discharge such as spark discharge can be prevented. .

  Furthermore, since the electric field concentration portion 5 is provided with minute irregularities, the electric field is concentrated by the minute irregularities, so that discharge can be more easily caused.

  In addition, since the width of the first electrode 2a and the second electrode 2b is configured to be smaller than the width of the first high dielectric layer 3a and the second high dielectric layer 3b, The side surfaces of the first electrode 2a and the second electrode 2b are disposed inside the side surfaces of the first high dielectric layer 3a and the second high dielectric layer 3b. Therefore, it is possible to reliably prevent an intermetallic discharge from occurring directly between the first electrode 2a and the second electrode 2b.

Next, a second embodiment of the plasma generator 1 according to the present invention will be described.
In addition, the same code | symbol is attached | subjected to the part similar to 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 2, the plasma generating apparatus 1 according to the second embodiment of the present invention has a portion having a relative dielectric constant different from that of the first high dielectric layer 3a and the second high dielectric layer 3b in the electric field concentration portion 10. Is different from the first embodiment.

  A portion having a relative dielectric constant different from that of the first high dielectric layer 3a and the second high dielectric layer 3b is formed in a hole provided in the electric field concentration portion 10 in the first high dielectric layer 3a and the second high dielectric layer 3b. It is configured by fitting a high dielectric material having a relative dielectric constant higher than that of the body layer 3b. At this time, the high dielectric material is fitted so that a part thereof protrudes from the side surface of the low dielectric layer 4. In the present embodiment, the electric field concentration portion 10 has a rectangular shape in a sectional view.

  Also in the plasma generator 1 of the second embodiment configured as described above, electrons are likely to accumulate in portions having different relative dielectric constants provided in the electric field concentration portion, and discharge is likely to occur, so that the discharge voltage can be lowered. .

  The present invention is not limited to the above embodiment.

  In the above embodiment, the electric field concentration portion protrudes from the side surface of the low dielectric layer in the sectional view shape, but may be configured to be flush with the low dielectric layer. In that case, the electric field concentration portion may be provided with minute irregularities, or a portion having a relative dielectric constant different from that of the first high dielectric layer and the second high dielectric layer may be used.

  The present invention can be variously modified without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Plasma generator 2a ... First electrode 2b ... Second electrode 3a ... First high dielectric layer 3b ... Second high dielectric layer 4 ... Low dielectric layer 5 ... Electric field Concentration part

Claims (11)

A low dielectric layer;
A first electrode and a second electrode provided so as to sandwich the low dielectric layer;
A first high dielectric layer provided between the first electrode and the low dielectric layer;
A second high dielectric layer provided between the second electrode and the low dielectric layer;
A plasma generator for generating plasma between the first high dielectric layer and the second high dielectric layer,
The first high dielectric layer and the second high dielectric layer have side surfaces extending in one direction, and an electric field concentration portion is formed on the side surfaces in the vicinity of the low dielectric layer. A plasma generator.   2. The plasma generator according to claim 1, wherein minute unevenness is provided in the electric field concentration portion.   3. The plasma generator according to claim 2, wherein the height of the projections of the minute irregularities is 1 μm or more and 100 μm or less.   3. The plasma generating apparatus according to claim 2, wherein the minute irregularities are formed by roughening the surfaces of the first high dielectric layer and the second high dielectric layer.   5. The plasma generating apparatus according to claim 4, wherein the surface has an average roughness of 1 to 100 [mu] m and an average interval of 1 to 100 [mu] m.   6. The electric field concentration portion is provided with a portion having a relative dielectric constant different from that of the first high dielectric layer and the second high dielectric layer. Plasma generator. The low dielectric layer has side surfaces extending in one direction;
The air blow mechanism for flowing air to the side surface of the said 1st high dielectric material layer and the 2nd high dielectric material layer, and the side surface of the said low dielectric material layer is further provided. Plasma generator.   The relative dielectric constant of the first high dielectric layer and the second high dielectric layer is 100 or more, preferably 1000 or more, 8. 1, 2, 3, 4, 5, 6 or 7 Plasma generator.   The plasma generator according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the low dielectric layer has a relative dielectric constant of 30 or less, preferably 10 or less.   The plasma generator according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, wherein the low dielectric layer has a thickness of 10 µm or more and 100 µm or less. The distance from the side surfaces of the first high dielectric layer and the second high dielectric layer to the side surfaces of the first electrode and the second electrode is 25 μm or more and 100 μm or less. The plasma generator according to 2, 3, 4, 5, 6, 7, 8, 9 or 10.