JP2005222869A - Ion generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep a generation amount of ions at a high value even if a method for driving a piezoelectric transformer by using a battery as a power source is used. <P>SOLUTION: This ion generating device is provided with: an ion generation electrode for generating ions by an applied high voltage; the piezoelectric transformer for applying the high voltage to the ion generation electrode; a driving circuit for driving the piezoelectric transformer; an oscillation circuit for oscillating a driving frequency for driving the piezoelectric transformer; a frequency sweep part for continuously changing the frequency oscillated by the oscillation circuit; and a battery for supplying power for driving the piezoelectric transformer. The piezoelectric transformer is driven based on the continuously changed frequency. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery-driven ion generator.

  2. Description of the Related Art Conventionally, ion generators for removing pollen or house dust floating in the air or for eliminating static electricity are known.

  For example, Japanese Patent Application Laid-Open No. 2002-324651 discloses a negative ion generator intended to generate stable ions without requiring a blowing means for eliminating ions gathering around the electrodes that generate ions. It is disclosed. This negative ion generator is provided with means for grounding an insulating cover surrounding the high voltage electrode or a grill through which negative ions pass.

  Also, for example, Japanese Patent Application Laid-Open No. 2001-85189 discloses an ion generator that is small and lightweight, and that aims to reliably generate corona discharge with little troublesome maintenance. . This ion generator has a needle-shaped corona discharge electrode to which a high voltage is supplied from a high-voltage power supply. The high-voltage power supply inputs a piezoelectric transformer and a drive signal having a frequency matched to the resonance frequency of the piezoelectric transformer. Input means for driving, and drive control means for intermittently driving corona discharge of the corona discharge electrode.

Further, for example, Japanese Patent Application Laid-Open No. 11-191478 discloses an ion generator that can stably supply ions and does not affect the human body even when a person touches the ion outlet. It is disclosed. This ion generator is configured by installing an electrode for generating ions and a negative ion generator composed of a high-voltage power source inside an ABS main body case and connecting an AC power source. Only the blowout port of the negative ion blowout portion is formed of a semiconductor, and this semiconductor is grounded by ground. In addition, a conductive ABS material in which an antistatic agent is kneaded is used as a semiconductor.
JP 2002-324651 A JP 2001-085189 A JP 11-191478 A

  In the ion generator as described above, there are three types of methods for generating ions: a corona discharge method, a water crushing method, and a direct radiation method. Hereinafter, a case where negative ions are generated will be described.

  In the corona discharge method, corona discharge is generated by a DC voltage applied between the electrodes, and electrons are emitted from the negative pole toward the positive pole. The emitted electrons react with oxygen molecules and water molecules in the air to form negative ions.

  In the water crushing method, a Leonard effect is used in which water is ejected vigorously and large water droplets are positively charged and small water droplets are negatively charged when the water flies off.

  In the direct emission method, a high voltage is applied to an electrode that is bent like a needle, and a high electric field region is formed around the electrode. This high electric field ionizes oxygen molecules and water molecules to form negative ions.

  Thus, each type of ion generator is known, but in order to reduce the size and weight of the device, it is preferable to adopt a direct radiation method that can simplify the device configuration. Furthermore, in order to be portable, it is necessary to use a battery as a power source.

  FIG. 8 is a diagram showing a schematic configuration of a general ion generator that is portable and can be carried by a direct radiation method using a battery as a power source. In this ion generator 70, a control circuit 72 that receives power from a battery 71 applies a high voltage to the ion emission electrode 73. The ion generating electrode 73 to which a high voltage is applied forms a high electric field region around it. Then, oxygen molecules and water molecules are ionized by this high electric field, and negative ions are generated as shown in FIG.

  The battery 71, the control circuit 72, and the ion generating electrode 73 are accommodated in a case 74 formed of an insulating material, for example, resin. Since a high voltage is applied to the ion generating electrode 73, the case 74 is indispensable for ensuring safety. The case 74 is provided with an ion emission port 74 a in the vicinity of the end of the ion generation electrode 73. As described above, when the ion generation electrode 73 generates negative ions under the control of the control circuit 72, the negative ions are released into the air from the ion emission port 74a.

  On the other hand, for example, fine particles such as pollen, house dust, and cigarette smoke are present in the air in a building. Most of these particles are positive ions with a positive charge.Furthermore, since the floors and human bodies in buildings have a positive charge, they are suspended in the air due to the electric repulsive force. continuing. When the negative ions generated as described above adhere to the fine particles, the fine particles are electrically neutralized, and the repulsive force that causes floating is removed. As a result, the fine particles can be dropped on the floor or the ground.

However, in the case of a portable ion generator, the case 74 is floated without being grounded with respect to the ground. Therefore, the case 74 is so-called capacitor coupled with the ground. That is, releasing negative ions into the atmosphere corresponds to discharging current into the atmosphere, and thus circuit elements are configured including environmental elements such as the atmosphere and the ground. This is shown in FIG. In FIG. 10, C1 is a capacitance between the control circuit 72 and the ground, and C2 is a capacitance between the case 74 and the ground. When a voltage of −V is applied to the ion generating electrode 73 in this state, the potential −V1 of the ion generating electrode 73 is
−V1 = −V−V _C1 (where −V _C1 is a voltage generated across C1)
It becomes.

On the other hand, when a negative charge −Q is accumulated on the inner surface of the case 74, the surface potential of the case 74 is
−V2 = −V _C2 = −Q / C2 (where −V _C2 is a voltage generated at both ends of C2)
It becomes.

  As described above, in the portable ion generating apparatus, even if the potential of the ion generating electrode 73 with respect to the control circuit 72 is constant, the environment of the potential of the ion generating electrode 73 with respect to the ground and the potential of the case 74 with respect to the ground changes. Then, it becomes unstable that changes accordingly.

  In this case, since the capacitances C1 and C2 are very small, if the case 74 is charged even a little, the case has a high potential (−V2) with respect to the ground. As a result, the potential difference between the ion generating electrode 73 and the case 73 is reduced, and negative ions are not generated. This is a problem caused by difficulty in grounding when the ion generator is portable.

  As described with reference to FIG. 10, in the portable ion generator, the potential of the ion generating electrode with respect to the ground is very unstable, and the amount of ions generated changes accordingly. On the other hand, it is known that a piezoelectric transformer is preferably used to reduce the size and weight of the device. This piezoelectric transformer has a characteristic that the frequency characteristic changes when the load changes, and the output voltage changes. Therefore, when the potential of the ion generating electrode with respect to the ground changes, the output voltage of the piezoelectric transformer also changes. Accordingly, in order to maintain the ion generation amount at a high value, a method of detecting a change in the potential of the ion generation electrode and changing the driving frequency of the piezoelectric transformer based on the detection result can be considered.

  FIG. 11 is a diagram showing a schematic configuration of a conventional ion generator. In this ion generator, AC power is supplied from a commercial power source 80 and converted into DC by a DC power source 81. In response to the supply of a direct current from the DC power supply 81, the oscillation circuit 82 oscillates the drive frequency of the drive circuit 83, and the drive circuit 83 drives the piezoelectric transformer 84 based on the drive frequency oscillated by the oscillation circuit 82. The piezoelectric transformer 84 applies a high voltage to the ion generation electrode 85. Usually, the potential difference between the ion generating electrode 85 and the ground is several kV. The detection circuit 86 detects the output voltage of the piezoelectric transformer 84 and outputs the detected data to the frequency control circuit 87. The frequency control circuit 87 controls the oscillation circuit 82 so as to oscillate a frequency for driving the piezoelectric transformer 84 most efficiently based on the detection data input from the detection circuit 86. As a result, an optimum driving frequency is oscillated.

  However, in the portable ion generator, it is not easy to detect the output voltage of the piezoelectric transformer under the above situation. In an ion generator driven by a battery, even if the detection circuit as described above is provided to detect the output voltage of the piezoelectric transformer, the detected voltage is an output voltage in the circuit system, and is output to the ground. It is not a voltage.

  Here, it is assumed that a battery-driven ion generator is configured as shown in FIG. In this ion generator, a DC current is supplied from the battery 90, and the oscillation circuit 91 oscillates the drive frequency of the drive circuit 92. The drive circuit 92 generates a piezoelectric transformer based on the drive frequency oscillated by the oscillation circuit 91. 93 is driven. The piezoelectric transformer 93 applies a high voltage to the ion generation electrode 94. The detection circuit 95 detects the output voltage of the piezoelectric transformer 94 and outputs the detected data to the frequency control circuit 96. The frequency control circuit 96 controls the oscillation circuit 91 so as to oscillate a frequency for driving the piezoelectric transformer 93 most efficiently based on the detection data input from the detection circuit 95.

  However, since the circuit in the ion generator is not grounded, there is no correlation between the voltage detected by the detection circuit 95 and the amount of ions generated. That is, as described above, since the potential of the ion generating electrode 94 changes with respect to the ground, even if the output voltage of the piezoelectric transformer 93 is detected, it is not known whether or not ions are sufficiently generated. Become. Therefore, the method of detecting the output voltage of the piezoelectric transformer 93 and applying feedback as in the case of an ion generator as shown in FIG. 12 is meaningless.

  For this reason, it is only necessary to directly measure the amount of generated ions and provide feedback, but this is not possible with a portable type that requires downsizing. In addition, since the ion generator shown in FIG. 11 uses a commercial power supply, grounding (ground) is stable, and thus the problem that the potential of the ion generating electrode changes with respect to the ground does not occur in the first place.

  The present invention has been made in view of such circumstances, and provides an ion generator that can maintain the amount of ions generated at a high value even when a piezoelectric transformer is driven using a battery as a power source. For the purpose.

  (1) An ion generator of the present invention includes an ion generating electrode that generates ions by an applied high voltage, a piezoelectric transformer that applies a high voltage to the ion generating electrode, a drive circuit that drives the piezoelectric transformer, An oscillation circuit that oscillates a driving frequency for driving the piezoelectric transformer, a frequency sweep unit that continuously changes a frequency that the oscillation circuit oscillates, and a battery that supplies electric power for driving the piezoelectric transformer. The piezoelectric transformer is driven based on a continuously changing frequency.

  The piezoelectric transformer has a characteristic that when the load changes, the frequency characteristic changes and the output voltage changes. Therefore, when the potential of the ion generating electrode with respect to the ground changes, the output voltage of the piezoelectric transformer also changes. In the present invention, since the piezoelectric transformer is driven based on a continuously changing frequency, at least one frequency at which the output of the piezoelectric transformer is sufficiently generated regardless of any load change is It exists within the change range. Thereby, it becomes possible to maintain the generation amount of ions at a high value. Furthermore, since it is not necessary to detect the output voltage of the piezoelectric transformer and apply feedback, the circuit configuration can be simplified and the manufacturing cost can be reduced. Note that the high voltage applied to the ion generating electrode means a voltage that is large enough to generate a sufficiently high electric field for generating ions with respect to the reference potential (circuit or ground).

  (2) Further, in the ion generator of the present invention, the frequency sweep unit continuously changes the frequency at which the oscillation circuit oscillates within a certain frequency range including the resonance frequency of the piezoelectric transformer. It is said.

  By continuously changing the frequency in this manner, at least one frequency at which the output of the piezoelectric transformer is sufficiently generated exists within the frequency change range regardless of any load change. . Thereby, it becomes possible to maintain the generation amount of ions at a high value.

  According to the ion generator of the present invention, since the piezoelectric transformer is driven based on a continuously changing frequency, at least one of the outputs of the piezoelectric transformer is sufficiently generated regardless of any load change. One frequency exists within the frequency change range. Thereby, it becomes possible to maintain the generation amount of ions at a high value. Furthermore, since it is not necessary to detect the output voltage of the piezoelectric transformer and apply feedback, the circuit configuration can be simplified and the manufacturing cost can be reduced.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an ion generator according to the present embodiment. This ion generator 1 is a direct radiation system, is reduced in size and weight, and is configured to be carried by a person. That is, the ion generator 1 is supplied with power by the battery 2. The oscillation circuit 3 oscillates the drive frequency of the drive circuit 4, and the drive circuit 4 drives the piezoelectric transformer 5 based on the drive frequency oscillated by the oscillation circuit 3. The piezoelectric transformer 5 applies a high voltage to the ion generating electrode 6. The high voltage means a voltage that is large enough to generate a sufficiently high electric field for generating ions with respect to a reference potential (circuit or ground). The ion generating electrode 6 forms a high electric field region around it by the applied high voltage. This high electric field ionizes oxygen molecules and water molecules, generating negative ions.

  The frequency sweep circuit 7 is a circuit for sweeping the drive frequency oscillated by the oscillation circuit 3 within a certain frequency range, and constitutes a frequency sweep unit. In the ion generator 1 according to the present embodiment, the driving frequency of the piezoelectric transformer 5 is continuously changed in accordance with the change in the potential of the ion generating electrode 6, that is, the load of the piezoelectric transformer 5 with the change of the environment. By changing it, the amount of ions generated is set to a certain level or more. That is, the frequency sweep circuit 7 continuously changes (sweeps or sweeps) the driving frequency of the piezoelectric transformer 5 within a certain range.

  When the drive frequency changes continuously, at least one frequency at which the output of the piezoelectric transformer 5 is sufficiently generated exists within the frequency change range regardless of any load change. Therefore, it is only necessary to set a width (sweep width) that is continuously changed so as to include a frequency having a magnitude that allows a sufficient output to be output even at one location in the frequency range. Thereby, although it is intermittent, it becomes possible to generate ions.

  These components are accommodated in the case 8. The case 8 is formed of a material obtained by adding a surfactant to a resin as an insulating material. The case 8 is provided with an ion emission port 8a in the vicinity of the end of the ion generation electrode 6, and the generated negative ions are released from the ion emission port 8a into the air.

  For example, fine particles such as pollen, house dust, and cigarette smoke are present in the air in a building. Most of these particles are positive ions with a positive charge.Furthermore, since the floors and human bodies in buildings have a positive charge, they are suspended in the air due to the electric repulsive force. continuing. When the negative ions generated as described above adhere to the fine particles, the fine particles are electrically neutralized, and the repulsive force that causes floating is removed. As a result, since the fine particles can be dropped on the floor or the ground, it is possible to prevent a person from inhaling these fine particles.

  FIG. 2 is a diagram showing the relationship between the drive frequency and the output voltage of the piezoelectric transformer. As shown in FIG. 2, the driving frequency of the piezoelectric transformer is continuously changed within a certain range by the frequency sweep circuit. Then, in the environmental condition A, a voltage sufficient to generate ions in a relatively high frequency region is output. Further, under the environmental condition B, a sufficiently large voltage is output in a slightly lower frequency range from the middle of the frequency changing range. In the environmental condition C, a voltage sufficient to generate ions in a relatively low frequency region is output.

  This makes it possible to generate a sufficient amount of ions even when the environment of the portable ion generator changes.

  It has been found that when the surface resistivity of the case of the ion generator is high, the generated ions adhere to the inner surface of the case and hinder the generation of ions. For example, when the surface specific resistance value of the case 74 of the ion generator 70 shown in FIG. 8 is high, the amount of negative ions generated decreases after a predetermined time has elapsed since the generation of ions. That is, as shown in FIG. 9A, immediately after starting to generate negative ions, if the potential of the ion generating electrode 73 is −V1 (V), the surface potential of the case 74 is 0 (V), The potential difference between them is −V1 (V). In this state, many negative ions can be generated. However, when a predetermined time elapses, as shown in FIG. 9B, negative charges accumulate on the inner surface of the case 74, and the surface potential of the case 47 becomes −V2 (V). In this state, the potential difference between the two becomes − (V1−V2) (V), which is smaller than the initial −V1 (V). Since the amount of negative ions generated from the ion generating electrode 73 depends on the potential difference between the ion generating electrode 73 and the case 74, the amount of negative ions generated decreases as the potential difference decreases. For this reason, it is preferable to form the case 74 using what added surfactant to resin. In addition, a surfactant may be applied to the surface of the case 74 on the ion generating electrode 73 side.

In FIG. 1, the frequency sweep circuit 7 continuously changes the frequency within a range of 105 kHz to 115 kHz, for example. The change is repeated by changing the frequency from a low frequency to a high frequency or from a high frequency to a low frequency. Sufficient ions are generated at at least one frequency within this range. Thereby, although the generation of ions is intermittent, it is possible to maintain a high ion generation amount within a predetermined time. The range in which the frequency is changed is not limited to this. Moreover, when forming case 8, what added the commercially available antistatic agent (surfactant) to resin is used. For example, a polymer type antistatic agent “Pelestat (registered trademark) NC6321” added to ABS resin by 20 percent by mass is used. Thereby, the surface specific resistance value of the case 8 can be set to about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω.

FIG. 3 is a diagram showing the relationship between the amount of generated ions and time when the surface specific resistance value of the case 8 is about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω. FIG. 4 is a diagram showing the relationship between the amount of generated ions and time when the case 8 is formed of an insulator having a surface resistivity of 1 × 10 ¹⁶ Ω. FIG. 3 and FIG. 4 both represent the state until about 30 minutes have elapsed from the start of measurement. As shown in FIG. 4, when the case is formed of an insulator, the amount of ions generated decreases rapidly immediately after the start of measurement, whereas as shown in FIG. When the specific resistance value is about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω, many ions are generated after the start of measurement, and immediately decreases. However, the specific resistance value increases again, and then decreases gradually. I understand that. Here, the amount of ions generated decreases immediately after the start of measurement and then increases again. The charge stays on the inner surface of the case, preventing the generation of ions for a while, but the remaining ions decrease through the case. As a result, the absolute value of the potential of the case did not increase, and it is considered that the amount of ions generated has recovered.

FIG. 5 shows an ion generator (upper side) in which the surface specific resistance value of the case is 1 × 10 ¹⁶ Ω under conditions of an air temperature of 20 ° C. and a humidity of 30%, and the surface specific resistance value of the case from 5 × 10 ¹⁰ Ω to It is a figure showing the comparison of the amount of ion generation with the ion generator (lower side) which is about 1 * 10 < ¹¹ > (omega | ohm). As shown in the upper side of FIG. 5, in the case of an ion generator whose case has a surface resistivity of 1 × 10 ¹⁶ Ω, the amount of ions generated fluctuates with time, and the amount of generation itself is large. Absent. On the other hand, as shown in the lower side of FIG. 5, in the case of an ion generator whose case has a surface resistivity of about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω, the amount of ions generated increases with time. Nevertheless, it is stable and shows a value 1.5 to 2 times higher than the upper side.

FIG. 6 shows an ion generator (upper side) having a surface specific resistance value of 1 × 10 ¹⁶ Ω at an air temperature of 20 ° C. and a humidity of 30%, and a case specific surface resistance value of 5 × 10 ¹⁰ Ω to 1 ×. It is the figure showing the comparison at the time of changing a use condition in the ion generator (lower side) which is about 10 < ¹¹ > (omega | ohm), respectively. From the start of measurement to 5 minutes, the amount of ions generated was measured while being lowered on a person's neck using a strap or the like. In addition, from 5 minutes to 10 minutes, the amount of ions generated was measured with a person directly holding it in his hand. 6 shows the case of an ion generator having a case surface resistivity of 1 × 10 ¹⁶ Ω, and the case surface has a case surface resistivity of 5 × 10 ¹⁰ Ω to 1 ×. The case of an ion generator that is about 10 ¹¹ Ω is shown. As can be seen from FIG. 6, in the ion generator with the case surface resistivity of 1 × 10 ¹⁶ Ω, the amount of ions generated is slightly higher when held with bare hands than when lowered from the neck. Yes. On the other hand, in the ion generator whose case surface resistivity is about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω, the amount of ions generated is higher than that of the upper ion generator in any state. Many. In addition, the amount of ions generated in the state of holding with bare hands is much larger than the state of being lowered from the neck. This is because an ion generator having a case surface resistivity of about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω moves to the outside through a human hand when the ions are in contact with the case. As a result, it is considered that the potential difference between the ion generating electrode and the case is not reduced.

FIG. 7 shows the relationship between ion generation amount and time when a commercially available antistatic agent (surfactant) is sprayed on the surface of the case and the surface specific resistance of the case is about 1 × 10 ⁸ Ω. FIG. As shown in FIG. 7, the ion generation amount does not decrease rapidly but gradually decreases. As shown in FIG. 3, the amount of ions generated is larger than that in the case where the case is formed of an insulator having a surface resistivity of 1 × 10 ¹⁶ Ω. Yes.

  Note that if the surface resistivity of the case body becomes too small, the case body functions as the counter electrode of the ion generating electrode and corona discharge may occur. Therefore, the surface resistivity of the case body generates corona discharge. It should not be so large.

It is a figure which shows schematic structure of the ion generator which concerns on this Embodiment. It is a figure which shows the relationship between a drive frequency and the output voltage of a piezoelectric transformer. It is a figure which shows the relationship between the amount of ion generation, and time when the surface specific resistance value of a case is set to about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω. It is a figure which shows the relationship between the amount of ion generation, and time when the surface specific resistance value of a case is 1 * 10 < ¹⁶ > (omega | ohm). An ion generator (upper side) having a surface specific resistance value of 1 × 10 ¹⁶ Ω and a case specific surface resistance value of 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ under conditions of an air temperature of 20 ° C. and a humidity of 30%. It is a figure showing the comparison of the amount of ion generation with the ion generator (lower side) which is about Ω. An ion generator (upper side) having a surface resistivity of 1 × 10 ¹⁶ Ω at an air temperature of 20 ° C. and a humidity of 30%, and a surface resistivity of the case of about 5 × 10 ¹⁰ Ω to 1 × 10 ¹¹ Ω It is a figure showing the comparison at the time of changing a usage condition in the ion generator (lower side) which is. It is a figure which shows the relationship between ion generation amount and time at the time of spraying surfactant on the surface of a case and making the surface specific resistance value of a case into about 1 * 10 < ⁸ > (omega | ohm). It is a figure which shows schematic structure of the general ion generator which made the battery portable as a power supply by a direct radiation system. (A) It is the figure showing the electric potential difference of the ion generating electrode immediately after ion generation, and a case. (B) It is a figure showing the electric potential difference of the ion generating electrode and case after a fixed time passes since ion generation. It is a figure which shows the electrical constitution of the portable ion generator which considered the environmental element. It is a figure which shows schematic structure of the conventional ion generator. It is a figure showing the model of the portable ion generator which feeds back the output voltage of a piezoelectric transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ion generator 2 Battery 3 Oscillation circuit 4 Drive circuit 5 Piezoelectric transformer 6 Ion generation electrode 7 Frequency sweep circuit 8 Case 8a Ion discharge port

Claims (2)

An ion generating electrode for generating ions by an applied high voltage;
A piezoelectric transformer for applying a high voltage to the ion generating electrode;
A drive circuit for driving the piezoelectric transformer;
An oscillation circuit for oscillating a driving frequency for driving the piezoelectric transformer;
A frequency sweep unit that continuously changes the frequency at which the oscillation circuit oscillates;
A battery for supplying electric power for driving the piezoelectric transformer,
The piezoelectric transformer is driven based on a continuously changing frequency. The ion generator according to claim 1, wherein the frequency sweep unit continuously changes a frequency at which the oscillation circuit oscillates within a certain frequency range including a resonance frequency of the piezoelectric transformer.

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