JP4873461B2 - Tube ion supply mechanism - Google Patents

Description

  The present invention relates to an ion supply mechanism and a static eliminator using the ion supply mechanism, and more specifically, positive ions and negative ions generated at an electrode are efficiently mixed and conveyed by the action of an air current, and ions are locally irradiated on an object surface. The present invention relates to a tube-type ion supply mechanism and a static eliminator using the same.

  For example, in the case of a conventional static eliminator, a general conventional ion generator / static eliminator applies a high voltage to a sharp needle-shaped ion generating electrode by a high voltage power source to locally maximize the tip. Corona discharge is generated by the action of the electric field strength, and ions are generated by ionizing the air (see Patent Documents 1 to 6).

  In the needle-shaped ion generating electrodes described in Patent Documents 1 to 3, in order to reduce variations in discharge due to pressure fluctuations and the action of fluid, the needles should not be disturbed at locations away from the airflow. The method of installing the tip part of is used (see FIG. 1).

  Since the ion concentration is maximized at the tip of the needle, it is difficult for this method to efficiently carry out the generated ions with an air stream. In addition, there is a problem that a flow path not including ions and a flow path including ions are mixed, and the concentration distribution is biased. Therefore, a reduction in static elimination performance is inevitable.

  In Patent Document 4, a tapered insulating member is provided on the downstream side of the electrode in order to generate a stable discharge. In Document 5, a nozzle having a variable flow rate is provided downstream of the electrode in order to suppress atmospheric pressure fluctuation. On the side. However, even in these methods, since a local high ion concentration field is formed before the ions and the air current are mixed, loss of ions due to electrostatic repulsion and diffusion is large, and efficient mixing is difficult.

  On the other hand, in a static eliminator using a needle electrode, a method of increasing an ion concentration by passing an air flow through an electrode portion or its vicinity has also been devised (see FIG. 2, Patent Documents 6 to 9).

  In Patent Document 6, a laminar flow is formed so that an air current is wound around the electrode, and in Patent Document 7, a needle electrode protrudes from the central axis of the contracted portion. Furthermore, in patent document 8, in order to promote mixing with an airflow, the gas ejection mechanism is provided in the electrode center. In Patent Document 9, a contracted portion is provided on the downstream side of the needle electrode in order to obtain a stable corona discharge even when an airflow is jetted onto the needle.

  Among the above-mentioned patent documents, in particular, the configurations described in Patent Documents 6 and 7 have a problem that corona discharge tends to become unstable due to gas flow velocity and pressure fluctuation. In addition, since the airflow passes through a very narrow hole similar to the needle, the adhesion of impurities to the electrodes and the flow path due to dust and moisture has been a problem.

  Further, the needle-shaped ion generating electrode has a configuration as in Patent Document 8 because ions of the same polarity generated by the voltage applied to the electrode tend to repel instantaneously and scatter as a directional ion flow. However, it is difficult to obtain a uniform ion concentration, and the configuration in Patent Document 9 has a problem that the disappearance due to the adhesion of ions to the inside of the pipe line becomes remarkable.

  Also, since the tip of a needle-type static eliminator that is normally used is sharp, it is extremely dangerous if the electrode scatters and gets stuck in an object or human body. It was not realistic to install the electrodes (see FIG. 2).

  On the other hand, a dielectric with a discharge electrode and induction electrode on its surface is used as an ion generating element, and a method of generating and transporting ions with a plate-like or tubular ion generating element instead of a needle shape and a static eliminator have been developed. (See Patent Documents 10 to 15).

JP 2005-196977 A Japanese Patent Laid-Open No. 2005-78990 JP 11-347505 A JP 2004-319358 A Japanese Patent Laid-Open No. 2004-213988 JP-A-5-47490 JP 11-176557 A JP-A-8-131980 JP 2004-95271 A Japanese Patent Publication No. 22-22998 Japanese Patent Publication No. 3-49198 JP 2004-225983 A JP 2004-251497 A JP 2004-362855 A Japanese Patent No. 2794117

  In the techniques shown in Patent Documents 10 to 15, since a high voltage is applied between a discharge electrode and an induction electrode via a dielectric to locally discharge and generate ions, a flat structure having no physical sharp structure is provided. It has a shape. In addition, since local discharge is used, it is possible to generate an equivalent amount of ions at a lower voltage and lower power consumption than a needle-shaped ion generation electrode, and a coating layer is formed on the discharge electrode. By forming the insulating protective layer, it becomes possible to stably generate both positive and negative ions due to electric field concentration, so that the problems of the needle-shaped ion generating electrode are reduced. In addition, stable ions can be supplied regardless of the change in atmosphere.

However, since the element-type electrode does not have the feature that the generated ions of the needle-type element are accelerated with directivity in the self-electric field, the problem is that the generated ions stay in the vicinity of the electrode.
In particular, as shown in a part of Patent Documents 10 and 11, an ion generating element is installed on the outer wall of the tube, or as shown in Patent Documents 12 and 13, a thin film element is placed in a gentle laminar flow. Even if it is installed, the ions and the fluid are not sufficiently mixed, and the desired static elimination performance cannot be obtained (see FIG. 3). Further, when the element-like electrode is installed in the pipeline as shown in FIG. 7A of Patent Document 11, not only the structure of the contact point with the power source is complicated, but also a sufficient amount to block most of the pipeline. It becomes difficult to convey the airflow. In Patent Document 14, an enlarged tube structure is installed on the upstream side of the element to cause the air current to collide with the element. However, in this case as well, the air flow gently passes through the element surface. It is difficult to mix. Further, for example, in order to mix ions and airflow, there is a problem that a complicated form such as an element embedded in a propeller is required as shown in Patent Document 15.

In particular, when an AC type power supply is applied to generate positive and negative ions alternately from one ion generating element, the generated ions are localized in the vicinity of the electrode and the ion concentration is spatially nonuniform. Has the disadvantage of becoming.
In addition, when a high voltage power source (pulse wave or the like) having a direct current component including a high frequency component that can easily adjust the ion concentration is applied, a positive ion generator and a negative ion generator are required, respectively. Ensuring ion balance becomes difficult. Further, no merit in terms of cost and space can be expected.

  Therefore, an object of the present invention is to use a device-type electrode that is difficult to scatter even when installed in an air stream and can ensure a stable discharge even when the air stream fluctuates, and is space-saving, simply and sufficiently mixed with the air stream. Another object of the present invention is to provide a tubular ion supply mechanism that locally supplies high-concentration ions and a static eliminator using the same.

  The present invention for solving the above-described problems has the following configuration.

  That is, the present invention provides an ion generating element comprising a dielectric, a discharge electrode having fine protrusions disposed on the dielectric surface, and an induction electrode disposed on the back surface of the dielectric. In a static eliminator that neutralizes static electricity on the surface of an object by transporting positive and negative ions generated by the ion generating element by an air stream and irradiating the surface of the object, the pressure is applied to the air stream. A tube-type ion supply mechanism in which the ion generating element is installed within a range that receives an action of a jet generated by providing a gradient, and an air flow and ions are mixed by the action of the jet.

  Further, in the present invention, a nozzle that is sufficiently smaller than the diameter of the tubular conveyance path in the method of forming the pressure gradient of the airflow can be installed on the upstream side of the ion generating element.

  Furthermore, in this invention, the formation method of the pressure gradient of an airflow can have the function of removing the dust contained in an airflow.

In the present invention, the method of forming the pressure gradient of the airflow can also have a buffer function for reducing the pulsation of the airflow.
Furthermore, the present invention is a static eliminator in which such a tube-type ion supply mechanism is mounted in a static eliminator casing.

According to the first aspect of the present invention, by installing the ion generating element under the pressure gradient of the air flow, the fluid and ions can be efficiently mixed by the action of the jet, and high concentration ions can be supplied. Static neutralization is possible.
According to the second aspect of the present invention, a small static eliminator that is simple and space-saving can be provided by disposing the nozzle upstream of the element without having a particularly complicated function.

  According to the third aspect of the present invention, it is possible to supply high-concentration ions and at the same time have a dust removing function.

According to the fourth aspect of the present invention, in addition to the above effects, the pulsation of the airflow that causes a reduction in the charge removal performance can be reduced.
The invention according to claim 5 can provide a static eliminator having a good static elimination effect.

Hereinafter, details of the ion generating element of the present invention will be described with reference to the accompanying drawings.
1 and 2 are tubular ion supply mechanisms each using a conventional needle electrode, FIG. 3 is a comparative example in which fine electrode elements are installed in a laminar flow, and FIG. 4 is a configuration of an ion supply mechanism according to an example of the present invention. FIG. 5 is a block diagram of an ion supply mechanism as an example of the present invention, FIG. 6 is an explanatory diagram showing the positional relationship between nozzles and elements, and the arrangements (1) to (4) in FIG. Table 1 shows the static elimination time.

図７は図５の配置における上流側ノズルと電極中心部の距離に対する除電特性の変化を示す説明図、図８はノズルの有無による除電性能の比較のグラフ、図９はイオン照射対象物の表面電位の時間変動を示すグラフである。

FIG. 7 is an explanatory view showing a change in the charge removal characteristics with respect to the distance between the upstream nozzle and the electrode center in the arrangement of FIG. 5, FIG. 8 is a graph comparing the charge removal performance with and without the nozzle, and FIG. 9 is the surface of the ion irradiation object It is a graph which shows the time fluctuation of an electric potential.

  An ion generating element according to the present invention includes an ion having a dielectric, a discharge electrode having fine protrusions disposed on the surface of the dielectric, and an induction electrode disposed on the back surface of the dielectric. In the static eliminator that neutralizes static electricity on the surface of the object by installing the generating element in a tube-shaped transport path, transporting positive and negative ions generated by the ion generating element by an air current, and irradiating the object surface, A tube-type ion supply mechanism and a static eliminator, characterized in that the ion generating element is installed within a range that receives the action of a jet generated by providing a pressure gradient in the fluid, and fluid and ions are mixed by the action of the jet It is.

  One of the embodiments of the invention described above, that is, as shown in FIG. 4, the ion generating element comprises a dielectric 6, an induction electrode 5, and a discharge electrode 7 having fine protrusions. A ring-shaped structure is provided so that it can be installed in the center of the air flow, and the airflow is introduced from 1 and stirred by the effect of the jet generated by the action of the pressure gradient formed when passing through the nozzle structure 2 and the slits 3 and 9 And efficiently mixed with ions. Desirably, it is most effective to generate bipolar ions by applying a high frequency AC high voltage of 60 to 100 kHz (voltage is 1 kV or more) generated by a high frequency, for example, a piezoelectric transformer, to the discharge electrode. The positive and negative discharge electrodes may be arranged on the same element and pulse voltages of the respective polarities may be applied. However, each power source and wiring are necessary, and the device structure becomes complicated. Even if the flow rate of the airflow is about several liters / minute, sufficient static elimination performance can be obtained, but it is desirably 20 L to 100 L / minute. At a flow rate of 100 L / min or more, since ion generation is periodically performed positively and negatively, it is more effective to use a high-voltage power supply having a sufficient frequency in order to reduce the influence on the object. In order to obtain a jet, it is effective to adjust the distance between the pressure gradient forming mechanism (for example, nozzle) and the element to an effective position so that ions are efficiently transported by the jet.

  FIG. 5 shows another embodiment of the present invention, in which an ion generating element is provided with a discharge electrode 6, a plate-like dielectric 5 and an induction electrode 7 in parallel with the air flow. By the action of the jet 4 formed by 3, the airflow passes near the discharge electrode 6, which is an ion generation region, and the airflow is efficiently mixed with the ions. As the power source, a high-frequency AC high-voltage power source is most suitable as in the above-described form (FIG. 4). However, in the form of FIG. 5, positive and negative discharge electrodes are separately provided on the upper surface and the lower surface, and pulses of the respective polarities are provided. A voltage may be applied.

  FIG. 6 is an example in which the arrangement of the airflow and the nozzle is changed in order to verify the form in which the best static elimination efficiency is obtained in the form shown in FIG. (1) to (3) in FIG. 6 are cases where the element is placed under a jet formed by a pressure gradient by a nozzle, and (4) is a comparative example placed outside the jet, which is a form of the present invention. It is.

  Table 1 shows the static elimination time corresponding to (1) to (4) in FIG. 6, that is, the time required for the voltage on the charging plate to drop from 1000V or -1000V to 100V or -100. The distance from the element to the charging plate was 50 mm. As a comparison, the result using the needle-type electrode shown in FIG. 1 was 1.1 seconds.

  From the results in Table 1, the arrangements of the present inventions (1) and (2) gave better static elimination performance than the comparative example, but (3) showed good performance but the ion balance was lost. Moreover, since the comparative example (4) could not be mixed well with the airflow, the static elimination performance decreased. That is, in the present invention, the best result was obtained when the element was placed in the jet stream downstream of the nozzle and further ions were generated toward the downstream side or side of the air stream. As the method for forming the jet, the nozzle structure based on the combination of the contracted flow and the expanded flow as shown in the present embodiment is the simplest, but other pressure gradient forming methods such as a coarse filter, a porous body, a baffle, etc. A plate, a swirl flow, or the like can also be used.

  In the form of (1) in FIG. 6, inertia collection of coarse particles by an impactor can be expected as a secondary effect. That is, when the jet formed by the nozzle collides with the element surface, the coarse particles deviate from the streamline and collide with the element surface and are trapped, so that the element has an effect of collecting dust in the gas. It is also possible to prevent the dust from adhering to the static elimination object. For this purpose, the material of the element and the holding plate is preferably a material that does not vibrate or peel off even when an air current collides. For example, the dielectric is ceramic, mica, etc., and the holding material is a metal such as stainless steel or plastic. And ceramics are suitable. In addition, the discharge electrode and the induction electrode provided in the element are suitable for thin films formed by microfabrication such as sputtering and etching, and the dielectric and the dielectric are sufficient to prevent separation by airflow collision or jet flow. It is necessary to have adhesive strength. For this purpose, metallization under high temperature, coating on electrodes, etc. are effective.

  FIG. 7 is a graph showing the change of the static elimination characteristics with respect to the distance between the nozzle and the electrode center position in the embodiment of FIG. In the test, a nozzle of about 4 mm was used, and a high frequency high voltage of 67 kHz was used as a power source. According to FIG. 7, if the nozzle is too close to the element, it approaches a laminar flow or turbulent flow development region, and ions and fluid cannot be mixed well, resulting in a decrease in static elimination performance. On the other hand, if it was too far away, the flow velocity distribution developed and the performance deteriorated again. Therefore, when the element is at the position of the jet where the pressure gradient occurs, the best condition is obtained in the vicinity of 40 to 50 mm in FIG. This corresponds to a length of about 10 times the nozzle diameter.

  FIG. 8 shows the change in static elimination time obtained by changing the distance from the tube outlet to the charging plate. In this case, the distance between the nozzle and the element was fixed at 40 mm, and the flow rate was 28 L / min. When the nozzle was installed upstream of the element according to the present invention, the static elimination performance was improved by 30 to 50% compared to the comparative example without the nozzle.

  In Embodiment 2 of the present invention, the static elimination characteristics are 28 L / min. However, since a high-frequency and high-voltage power supply is used, the amount of ions generated is sufficiently large. If the flow rate is further increased, further static elimination performance can be obtained. We can expect improvement. However, the development area of the jet is a function of the flow rate, and the optimum distance between the nozzle and the element that provides the highest static elimination performance varies depending on the flow rate, and thus is not limited to 40 mm as in the above example.

In the present invention, a secondary effect that the pulsation of the airflow can be reduced by installing the nozzle upstream of the element was observed. FIG. 9 is a graph in which the temporal voltage change around 0 V during the ion irradiation to the charged plate is verified. As shown in the figure, in the case of no nozzle, which is a comparison, voltage fluctuation is noticeable due to the pulsation of the pump, in this case, the diaphragm pump. On the other hand, in the present invention, the pulsation of the air flow is reduced by the buffer effect at the nozzle, and as a result, the voltage fluctuation can be reduced. As a method of forming a jet to obtain a buffer effect, the nozzle structure is the simplest, but other pressure gradient forming methods for efficiently mixing ions and air flow, such as a coarse filter, a porous body, A baffle plate, a swirl flow, or the like can also be used.

Tubular ion supply Organization using a needle-type electrode of the traditional Tubular ion supply mechanism using conventional needle electrode Comparative example with microelectrode elements installed in laminar flow Configuration diagram of ion supply mechanism of embodiment 1 of the present invention Configuration diagram of ion supply mechanism of embodiment 2 of the present invention Explanatory drawing showing the positional relationship between nozzles and elements Explanatory drawing which shows the change of the static elimination characteristic with respect to the distance of an upstream nozzle and electrode center part in arrangement | positioning of FIG. Graph of comparison of static elimination performance with and without nozzle Time fluctuation of surface potential of ion irradiation target

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airflow 2 Nozzle structure 3 Slit 4 Combined airflow 5 Discharge electrode 6 Dielectric 7 Induction electrode 8 Pipe-shaped conveyance path 9 Slit 10 Induction power supply 11 High-voltage power supply for discharge

Claims (2)

An ion generating element comprising a dielectric, a discharge electrode having fine protrusions disposed on the dielectric surface, and an induction electrode disposed on the back surface of the dielectric is formed into a tube-shaped transport path. In a static eliminator that neutralizes static electricity on the surface of an object by transporting positive and negative ions generated by the ion generating element by an air current and irradiating the object surface ,
A tube type ion supply mechanism in which the ion generating element is installed within a range that receives the action of a jet generated by providing a pressure gradient in the air flow, and the air flow and ions are mixed by the action of the jet ,
When the jet formed by the nozzle collides with the surface of the ion generating element, the dust in the airflow is deviated from the streamline and captured by inertial collision with the surface. you characterized by having both function of removing dust tubular ion supply mechanism included in the. An ion generating element comprising a dielectric, a discharge electrode having fine protrusions disposed on the dielectric surface, and an induction electrode disposed on the back surface of the dielectric is formed into a tube-shaped transport path. In a static eliminator that neutralizes static electricity on the surface of an object by transporting positive and negative ions generated by the ion generating element by an air current and irradiating the object surface ,
A tube type ion supply mechanism in which the ion generating element is installed within a range that receives the action of a jet generated by providing a pressure gradient in the air flow, and the air flow and ions are mixed by the action of the jet ,
The formation of the pressure gradient of the airflow is by installing a nozzle that is sufficiently smaller than the diameter of the tube-shaped conveyance path in the tube-shaped conveyance path on the upstream side of the ion generating element, ion generating element, you characterized in that toward the downstream side of the airflow is installed so as to generate ions tubular ion supply mechanism.

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