JP2008277175A - Dbd plasma type static eliminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DBD plasma type static eliminator capable of carrying charged particles generated by plasma to a distant place in a windless manner without using an external force such as a fan or compressed air. <P>SOLUTION: The static eliminator includes at least two electrodes to which an AC voltage is applied and a dielectric covering these electrodes and also includes a plasma discharging electrode body for generating plasma to constitute an ion source. An inner grid electrode and an outer grid electrode are disposed around the plasma discharging electrode body. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a static eliminator using plasma as an ion source, and more particularly, to a DBD (Dielectric Barrier Discharge) plasma type static eliminator.

   As a background art, there is a DBD plasma type static eliminator using a plasma as a charged particle source (ion source) described in Japanese Patent Application No. 2006-055714 of a prior application which has not been published at the present time when the present applicant applied for a patent.

  In the invention described in this patent application, charged particles exist in the vicinity of the plasma, and it was possible to neutralize the object to be removed from the nearby area. The particles had to be removed from the plasma and transported to the object to be neutralized.

However, if FAN or compressed air is used, even if static electricity can be removed, wind will be generated around the surroundings, causing a problem that dust rises and promotes a dust defect. For this purpose, a new method of flying charged particles without wind has been required.
Accordingly, an object of the present invention is to provide a DBD plasma type static eliminator (hereinafter referred to as a static eliminator) that can carry charged particles created by plasma without using an external force such as FAN or compressed air. There is to do.

  In order to solve the above-mentioned problems, the static eliminator of the present invention comprises a plasma discharge electrode body comprising at least two electrodes to which an alternating current is applied and a dielectric covering the electrodes, and creating a plasma to constitute an ion source. And an inner grid electrode arranged around the plasma discharge electrode body and an outer grid electrode arranged outside the inner electrode.

  According to the present invention, unlike the conventional case, the discharge electrode is not exposed and is covered with a dielectric, so that there is no scattering of the metal oxide of the conductor constituting the electrode, and a clean removal that does not pollute the environment. An electric appliance is obtained.

  Further, since the charged particles can be released far away without wind even without using an external force such as FAN or compressed air as in the past, the static electricity of the static elimination object can be removed without polluting the clean environment. For this reason, the static eliminator which can be used also in a clean room is obtained. Furthermore, a static eliminator that does not generate ozone is obtained.

  In the static eliminator of the present invention, there is provided a plasma discharge electrode main body which is composed of at least two electrodes to which an alternating current is applied and a dielectric covering the electrodes, and creates a plasma to constitute an ion source. And an inner side grid electrode and an outer side grid electrode are arrange | positioned around this plasma discharge electrode main body.

Next, embodiments of the present invention will be described with reference to the drawings.
Example 1
1 shows a static eliminator of Embodiment 1 of the present invention, FIG. 1a is a plan view, FIG. 1b is a front view, FIG. 1c is a sectional view taken along line AA in FIG. 1a, and FIG. FIG. 1e is a schematic view showing the system, and FIG. 1e is a side view showing only the plasma discharge electrode body of the static eliminator.

  First, a plasma discharge electrode body that generates plasma (generates charged particles 120) will be described. As shown in FIG. 1 a, a plasma discharge electrode body 100 is disposed at the center of the static eliminator 10. As shown in FIG. 1e, as an example, the plasma discharge electrode main body 100 includes electrodes 102 and 104 made of two juxtaposed conductors and a dielectric 106 covering these conductors. A depression (recess) 108 for forming a thin portion where plasma is likely to be generated is formed. This recess is not always necessary.

Another example of the plasma discharge electrode main body 100 is described in detail in Japanese Patent Application No. 2006-055714 of the prior application. For example, the electrodes 102 and 104 are arranged in a straight line so that the tips face each other instead of being juxtaposed. The recess may take various shapes. For details, refer to the description of Japanese Patent Application No. 2006-055714.
As shown in FIGS. 1 a to 1 c, a double grid electrode (mesh electrode) is disposed outside the plasma discharge electrode body 100, that is, first, outside the plasma discharge electrode body 100, An inner grid electrode (hereinafter referred to as an inner grid) Gi formed in a cylindrical mesh shape is disposed, and an outer grid electrode (hereinafter referred to as an outer grid) Go formed in a cylindrical mesh shape on the outside thereof. Is arranged. Further, a reflective electrode Gr made of a conductor mesh or a plate whose cross section is formed in a parabolic shape, for example, is disposed on a part of the outside thereof. The plasma (charged particles 120) is created, for example, in the vicinity of the depression of the dielectric 106 of the plasma discharge electrode main body 100, and the created charged particles 120 diffuse and pass through the inner grid Gi. Thereafter, the charged particles that are accelerated by the electric field between the inner grid Gi and the outer grid Go and directed toward the reflective electrode Gr are reflected by the reflective electrode Gr and emitted to the outside. The polarity of the radiated electric charge becomes + or − depending on the polarity of the voltage applied to the inner grid Gi, the outer grid Go, and the reflective electrode Gr.

As shown in FIGS. 1b-d, AC voltages S, T from an AC power source are applied to the electrodes 102, 104 of the plasma discharge electrode body 100, and voltages U, V, W from other power sources are respectively applied to the inner grid Gi, It is applied to the outer grid Go and the reflective electrode Gr. The types (polarity, etc.) of the voltages U, V, and W to be applied will be described in the examples described later.
(Example 2)
FIG. 2 shows a static eliminator according to Embodiment 2 of the present invention, FIG. 2a is a schematic plan view showing the entire static eliminator, and FIG. 2b shows the polarity of a voltage applied to the inner and outer grids, It is a table | surface which shows the relationship between the direction of the electric field between outer side grids, and the polarity of discharge | released charged particle.

  As shown in FIG. 2a, double mesh electrodes (grid electrodes) Gi and Go are provided around a charged particle (ion) source of plasma generated in the plasma discharge electrode body 100, and a voltage is applied to these to apply an electric field. Is generated. At this time, as shown in FIG. 2b, when the outer grid Go is grounded and a + voltage is applied to the inner grid Gi, the electric lines of force go outward from the inner grid Gi to the outer grid Go. Conversely, when a voltage is applied to the inner grid Gi, the lines of electric force are directed inward from the outer grid Go to the inner grid Gi.

  Reference is now made to FIG. FIG. 3 shows the relationship between the electric field and the force applied to the charged particles, FIG. 3a shows the case of + charged particles, and FIG. 3b shows the case of -charged particles. The + charged particles are subjected to a force in the direction of the electric field (of the lines of electric force), as shown in FIG. 3a. On the other hand, -charged particles are subjected to a force in the opposite direction of the electric field (the lines of electric force) as shown in FIG. 3b.

This operation will be described with reference to FIG. As shown in case a of FIG. 2b, if the outer grid Go is grounded and the control voltage of the inner grid Gi is set to +, the electric field is directed outward, and the charged particles emitted are +. On the other hand, as shown in case b of FIG. 2b, if the outer grid Go is grounded and the control voltage of the inner grid Gi is-, the electric field is inward and the charged particles emitted are-. That is, charged particles having the same polarity as the control voltage applied to the inner grid Gi are emitted.
(Example 3)
FIG. 4 shows the static eliminator of Embodiment 1 of the present invention. A reflective electrode Gr is provided outside the inner grid Gi and the outer grid Go. In the example, −voltage (−V) is applied to the outer grid Go or grounded, and + voltage (+ V1) is applied to the inner grid Gi. On the left side of the drawing, a reflective electrode Gr to which a + voltage (+ V2) is applied is further provided outside. In this case, + charged particles are emitted from the right half of the drawing, and + charged particles that have advanced to the left half are also reflected by the reflective electrode Gr and emitted to the right.
Example 4
FIG. 5 shows a static eliminator of Embodiment 4 of the present invention. When the outer grid Go is grounded and + and − voltages are alternately applied to the inner grid Gi, + and − charged particles are alternately emitted on the time axis. With a corona discharge type static eliminator that uses a conventional discharge needle, the high-voltage power supply is switched between + and-, so it takes time to neutralize the charged charge when switching, and high-speed switching cannot be performed at most. 33HZ was the limit. That is, since only low-speed operation is possible, + and − ions (charged particles) are not sufficiently mixed, causing pulsation of ion balance, which is a problem. This method of switching the grid voltage has a low voltage, can be easily increased in speed without charge accumulation, can be increased in orders of magnitude, and can solve the pulsation problem of ion balance.
(Example 5)
6 shows a static eliminator of Embodiment 5 of the present invention, FIG. 6a is a schematic plan view of the static eliminator, and FIG. 6b is a table showing polarities of voltages applied to two inner grids and outer grids. . This static eliminator shows an example of a windless static eliminator without a reflection electrode, and two charged particle emission portions on the upper side and the lower side (that is, a combination of two sets of plasma discharge electrode bodies, an inner grid and an outer grid). It has something. In case a of FIG. 6b, the outer grid Go (Go1 and Go2) is grounded, the polarities of the inner grid Gi (Gi1 and Gi2) are reversed from each other, and when + charged particles are emitted from one side, −charge from the other side Release particles.

On the other hand, in case b, the outer grid Go (Go1 and Go2) is grounded, the applied voltage to the inner grid electrode Gi (Gi1 and Gi2) is changed in a pulsed manner, and the upper and lower polarities are reversed to emit. The charged particles to be changed can be alternately changed to + and-, and the mixing of charged particles (ions) can be easily improved. In addition, the area | region enclosed with the dashed-dotted line becomes a static elimination effective area | region.
(Example 6)
FIG. 7 shows a static eliminator according to Embodiment 6 of the present invention, FIG. 7a is a schematic plan view, and FIG. 7b is a diagram showing polarities of voltages applied to the inner grid, the outer grid, and the reflective electrode. This static eliminator shows another example of a windless static eliminator with a reflection electrode, and includes two upper and lower charged particle emitting portions (that is, two sets of plasma discharge electrode bodies, an inner grid, and an outer grid). , A combination of reflective electrodes). In case a of FIG. 6b, the outer grid Go (Go1 and Go2) is grounded, the polarities of the inner grid Gi (Gi1 and Gi2) are reversed from each other, and when + charged particles are emitted from one side, −charge from the other side Release particles.

Further, if a reflective electrode (plate) Gr (Gr1 and Gr2) is provided behind the plasma ion source (charged particle source) on the opposite side to the discharge direction of the charged particles and a voltage having the same polarity as that of the inner grid Gi is applied, charging is performed. It is also possible to direct the radiation direction of the particles to one side. In the case b of FIG. 7b, if the applied voltage to the inner grid is changed in a pulse manner, the charged particles to be emitted can be changed alternately between + and −, and the mixing of charged particles (ions) can be easily improved. Can be. In addition, the area | region enclosed with the dashed-dotted line becomes a static elimination effective area | region.
(Example 7)
FIG. 8 is a schematic plan view showing a static eliminator of Embodiment 7 of the present invention. When the outer grid Go is grounded and the control voltage V is applied to the inner grid Gi, charged particles corresponding thereto are emitted.
In this case, since the outer grid Go is grounded, leakage of the electric field created by the voltage applied to the inner grid Gi to the outside can be prevented. Therefore, when the static elimination object is a semiconductor, electrostatic breakdown of the static elimination object weak against an electrostatic field can be prevented.
(Example 8)
FIG. 9 shows a static eliminator of Embodiment 8 of the present invention, FIG. 9a is a schematic plan view, FIG. 9b is a sectional view taken along line AA in FIG. 9a, and FIG. 9c is a diagram showing a heater drive circuit. . A heater 12 is provided outside the plasma discharge electrode body 100 and inside the inner grid Gi. In order to decompose and detoxify the ozone generated when the plasma is generated, the heater 12 heats the plasma to 80 ° C. or higher. Since ozone is an unstable substance, it is decomposed into oxygen when heated to 80 ° C or higher. At this time, if the heater 12 has a potential, it will affect the plasma, so the secondary side of the transformer 14, that is, the midpoint of the heater side may be grounded.
Example 9
10 shows a static eliminator of Embodiment 9 of the present invention, FIG. 10a is a schematic plan view, FIG. 10b is a sectional view taken along line AA in FIG. 10a, and FIG. 10c is a diagram showing a heater drive circuit. . In this embodiment, the action of decomposing ozone is the same as in the previous embodiment. In this embodiment, unlike the previous embodiment, an inner grid / heater GiH that uses the inner grid also as a heater is used. Therefore, the inner grid / heater GiH serves as a heating element. This grid inner grid / heater GiH applies a voltage of + Vgi, but it is preferable to apply it to the secondary side of the transformer 14, that is, the midpoint of the heater side.

FIG. 1A is a plan view, FIG. 1B is a front view, FIG. 1C is a cross-sectional view taken along line AA of FIG. 1A, and FIG. 1D shows a power supply system. FIG. 1e is a side view showing only the plasma discharge electrode body of the static eliminator. FIG. 2A is a schematic plan view illustrating the entire static eliminator, and FIG. 2B illustrates the polarity of a voltage applied to the inner grid and the outer grid, and the inner grid and the outer grid. It is a table | surface which shows the relationship between the direction of an electric field, and the polarity of discharge | released charged particle. The relationship between the electric field and the force applied to the charged particles is shown, FIG. 3a shows the case of + charged particles, and FIG. 3b shows the case of -charged particles. The static eliminator of Example 1 of this invention is shown. 8 shows a static eliminator of Embodiment 4 of the present invention. FIG. 6A is a schematic plan view of a static eliminator, and FIG. 6B is a table showing polarities of voltages applied to two inner grids and an outer grid. FIG. 7A is a schematic plan view, and FIG. 7B is a table showing polarities of voltages applied to an inner grid, an outer grid, and a reflective electrode. It is a schematic plan view which shows the static eliminator of Example 7 of this invention. FIG. 9A is a schematic plan view, FIG. 9B is a sectional view taken along line AA in FIG. 9A, and FIG. 9C is a diagram showing a heater driving circuit. FIG. 10A is a schematic plan view, FIG. 10B is a sectional view taken along line AA in FIG. 10A, and FIG. 10C is a diagram showing a heater driving circuit.

Explanation of symbols

10 DBD plasma type static eliminator (static eliminator)
12 Heater 14 Transformer 100 Plasma discharge electrode body 102 Electrode 104 Electrode 106 Dielectric 108 Recess 120 Plasma Gi Inner grid electrode (inner grid)
Go Outer grid electrode (outer grid)
Gr Reflective electrode GiH Inner grid and heater

Claims (11)

  A plasma discharge electrode main body comprising at least two electrodes to which an alternating voltage is applied and a dielectric covering the electrode and creating a plasma to constitute an ion source, and an inner grid electrode disposed around the plasma discharge electrode main body And an outer grid electrode disposed outside the inner electrode.   2. The static eliminator according to claim 1, wherein a voltage adjustable to control the strength of the electric field is applied between the inner grid electrode and the outer grid electrode.   3. The static eliminator according to claim 2, wherein an electric field that is outward or inward is generated between the inner grid electrode and the outer grid electrode.   3. The static eliminator according to claim 2, wherein an outward or inward electric field is alternately generated between the inner grid electrode and the outer grid electrode.   The static eliminator according to any one of claims 1 to 4, further comprising a reflection electrode disposed outside the outer grid electrode.   6. The static eliminator according to claim 5, wherein a voltage having the same polarity is applied to the reflective electrode and the inner grid electrode.   The static eliminator according to claim 5 or 6, wherein the reflective electrode is disposed on the opposite side of the plasma discharge electrode main body from the direction of ions emitted from the static eliminator.   The static eliminator according to claim 1, wherein a plasma discharge electrode main body serving as an ion source that emits + ions and a plasma discharge electrode main body serving as an ion source that emits − ions are juxtaposed. A static eliminator characterized by comprising:   The static eliminator according to any one of claims 1 to 8, wherein the outer grid electrode is grounded.   10. The static eliminator according to claim 1, wherein a heater is provided outside the plasma discharge electrode body.   The static eliminator according to claim 1, wherein the inner grid electrode is also used as a heater.