Abstract:
In an ion generation apparatus, induction electrodes are formed on a surface of a substrate, holes are provided inside the induction electrodes, respectively, needle electrodes are disposed in a substrate, and tip end portions of the needle electrodes are inserted into the holes, respectively. Furthermore, a part of each of the induction electrodes is removed, thereby reducing the size of the substrate for entire size reduction. By such a configuration, it becomes possible to provide an ion generation apparatus that can stably generate ions even in a high humidity environment and that can be mounted also in small-sized electrical equipment.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an ion generation apparatus and electrical equipment made using the same, and particularly to an ion generation apparatus including an induction electrode and a needle electrode, and generating ions, and electrical equipment made using the ion generation apparatus. 
       BACKGROUND ART 
       [0002]    The ion generation apparatus includes a substrate, an induction electrode, and a needle electrode. The induction electrode is formed in an annular shape and mounted on the substrate. The needle electrode has a base end portion disposed in the substrate and a tip end portion arranged in the center portion of the induction electrode. When a high voltage is applied between the needle electrode and the induction electrode, corona discharge occurs at the tip end portion of the needle electrode, so that ions are generated. The generated ions are delivered by an air blower into a room, and then, surround fungi, bacteria and viruses floating in the air and degrade them (for example, see Japanese Patent Laying-Open No. 2010-044917 (PTD 1)). 
       CITATION LIST 
     Patent Document 
       [0003]    PTD 1: Japanese Patent Laying-Open No. 2010-044917 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    In the conventional ion generation apparatus, however, the needle electrode and the induction electrode are mounted on the surface of one substrate. Accordingly, when the ion generation apparatus is placed in a high humidity environment in the state where dust accumulates on the surface of the substrate, a current leaks between the needle electrode and the induction electrode through the dust absorbing moisture, so that the amount of ions to be generated may decrease. 
         [0005]    Furthermore, since the induction electrode is formed of a plate-shaped metal, size reduction of this induction electrode becomes difficult, so that the entire ion generation apparatus cannot be reduced in size. Accordingly, it is difficult to mount an ion generation apparatus in portable small-sized electrical equipment. 
         [0006]    Therefore, a main object of the present invention is to provide: an ion generation apparatus that can generate ions stably even in a high humidity environment, and can be mounted also in small-sized electrical equipment; and electrical equipment made using the ion generation apparatus. 
       Solution to Problem 
       [0007]    An ion generation apparatus according to the present invention includes an induction electrode and a needle electrode, and generates ions. The ion generation apparatus includes: a first substrate provided with a hole; and a second substrate provided so as to face a surface of the first substrate on one side. The induction electrode is provided around the hole of the first substrate. The needle electrode has a base end portion disposed in the second substrate and a tip end portion inserted into the hole. Thus, the induction electrode and the needle electrode are separately provided in the first substrate and the second substrate, respectively. Accordingly, even when the ion generation apparatus is placed in a high humidity environment in the state where dust accumulates on each of these first and second substrates, a current can be prevented from leaking between the needle electrode and the induction electrode, so that ions can be stably generated. 
         [0008]    Furthermore, a part of the induction electrode is removed in order to further allow size reduction of the entire ion generation apparatus, thereby reducing the size of the first substrate as small as possible, so that the entire ion generation apparatus is reduced in size. 
         [0009]    Furthermore, since the first substrate and the second substrate are covered by insulating resin, dust can be prevented from accumulating on the first substrate and the second substrate. Furthermore, a current can be more effectively prevented from leaking between the needle electrode and the induction electrode. 
         [0010]    Furthermore, the tip end portion of the needle electrode protrudes from the insulating resin. In this case, even when dust accumulates around the needle electrode, discharge of the needle electrode can be prevented from being blocked by the tip end portion of the needle electrode becoming buried in dust. Furthermore, even in the case where dust adheres to the tip end portion of the needle electrode, dust can be blown away from the needle electrode by applying a high voltage to the needle electrode while sending air to the tip end portion of the needle electrode. 
         [0011]    Further preferably, based on a basic shape annularly formed around the hole of the first substrate, the induction electrode is formed such that a part of the basic shape is removed. 
         [0012]    Further preferably, the first substrate is a printed circuit board, and the induction electrode is formed by a wiring layer of the printed circuit board. In this case, the induction electrode can be formed at low cost, so that the ion generation apparatus can be implemented at low cost. 
         [0013]    Furthermore, electrical equipment according to the present invention includes: the above-described ion generation apparatus; and an air blowing unit for sending out ions generated in the ion generation apparatus. 
       Advantageous Effects of Invention 
       [0014]    In the ion generation apparatus according to the present invention, the induction electrode and the needle electrode are separately provided in the first substrate and the second substrate, respectively. Accordingly, even when the ion generation apparatus is placed in a high humidity environment in the state where dust accumulates on each of the first and second substrates, a current can be prevented from leaking between the needle electrode and the induction electrode, so that ions can be stably generated. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a perspective view showing an external appearance of an ion generation apparatus according to one embodiment of the present invention. 
           [0016]      FIG. 2  is a plan view showing the external appearance of the ion generation apparatus shown in  FIG. 1 . 
           [0017]      FIG. 3  is a side view showing the external appearance of the ion generation apparatus shown in  FIG. 1 . 
           [0018]      FIG. 4  is a bottom view showing the external appearance of the ion generation apparatus shown in  FIG. 1 . 
           [0019]      FIG. 5  is an internal structure diagram showing the state where insulating resin is removed from the ion generation apparatus shown in  FIG. 2 . 
           [0020]      FIG. 6  is a cross-sectional view showing the internal structure of the ion generation apparatus shown in  FIG. 3 . 
           [0021]      FIG. 7  is a circuit diagram showing the configuration of the ion generation apparatus in the embodiment of the present invention. 
           [0022]      FIG. 8  is a diagram showing a method of forming an induction electrode of the ion generation apparatus in the embodiment of the present invention. 
           [0023]      FIG. 9  is a diagram showing the relation between the shape of the induction electrode and the generated amount of ions regarding the ion generation apparatus in the embodiment of the present invention. 
           [0024]      FIG. 10A  is a diagram showing a prototype shape of the induction electrode of the ion generation apparatus in the embodiment of the present invention. 
           [0025]      FIG. 10B  is another diagram showing the prototype shape of the induction electrode of the ion generation apparatus in the embodiment of the present invention. 
           [0026]      FIG. 10C  is still another diagram showing the prototype shape of the induction electrode of the ion generation apparatus in the embodiment of the present invention. 
           [0027]      FIG. 10D  is still another diagram showing the prototype shape of the induction electrode of the ion generation apparatus in the embodiment of the present invention. 
           [0028]      FIG. 11  is a cross-sectional view showing the configuration of an air cleaner made using the ion generation apparatus shown in  FIG. 1 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0029]    An ion generation apparatus according to one embodiment of the present invention includes: a needle electrode  1  for generating positive ions; a needle electrode  2  for generating negative ions; an annular induction electrode  3  for forming an electric field between this induction electrode  3  and needle electrode  1 ; an annular induction electrode  4  for forming an electric field between this induction electrode  4  and needle electrode  2 ; and two substrates  5  and  6  each formed in a rectangular shape, as shown in  FIGS. 1 to 6 . 
         [0030]    Substrates  5  and  6  are arranged at a prescribed distance in parallel with each other on the upper and lower sides as seen in  FIG. 1 . Induction electrode  3  is formed on the surface at one end of substrate  5  in the longitudinal direction using a wiring layer of substrate  5 . Induction electrode  3  is provided inside with a hole  5   a  passing through substrate  5 . Furthermore, induction electrode  4  is formed on the surface at the other end of substrate  5  in the longitudinal direction using a wiring layer of substrate  5 . Induction electrode  4  is provided inside with a hole  5   b  passing through substrate  5 . A part of each of induction electrodes  3  and  4  located on both outer sides, respectively, of substrate  5  is removed. 
         [0031]    Each of needle electrodes  1  and  2  is arranged at a right angle to substrates  5  and  6 . In other words, needle electrode  1  has: a base end portion that is inserted and fitted into the hole of substrate  6 ; and a tip end portion that passes through the center of hole  5   a  in substrate  5 . Furthermore, needle electrode  2  has: a base end portion that is inserted and fitted into the hole of substrate  6 ; and a tip end portion that passes through the center of hole  5   b  in substrate  5 . The base end portion of each of needle electrodes  1  and  2  is fixed to substrate  5  with solder. The tip end portion of each of needle electrodes  1  and  2  is keenly sharpened. 
         [0032]    Furthermore, this ion generation apparatus includes: a housing  10  formed in a rectangular parallelepiped shape and having a rectangular opening slightly larger than substrates  5  and  6 ; insulating resin  11  for closing the opening in housing  10 ; a circuit substrate  12 ; a circuit component  13 ; and a transformer  14 . 
         [0033]    Housing  10  is formed by insulating resin. The lower portion of housing  10  is formed slightly smaller than the upper portion thereof and shaped like a bottom of a ship. Transformer  14  is housed inside housing  10  on one side of both substrate  5  and substrate  6 . Circuit substrate  12  is provided across transformer  14  from substrate  5  and substrate  6 . Circuit component  13  is mounted on circuit substrate  12 . 
         [0034]    Substrates  5  and  6  are housed on one end side of housing  10 . On the other end side of housing  10 , a connector  15  for feeding electric power is provided so as to protrude to the outside. Connector  15 , circuit substrate  12 , transformer  14 , and substrates  5  and  6  are electrically connected by wiring. A high voltage portion within housing  10  is filled with insulating resin  11 . Substrate  6  is filled to its lower surface with insulating resin  11 . In the present embodiment, although circuit component  13  connected to the primary side of transformer  14  does not have to be insulated by insulating resin  11 , the space within the housing is filled up with insulating resin  11  for reasons of operation. 
         [0035]    While insulating resin  11  is applied so as to cover the outer surface of substrate  5 , the tip end portions of needle electrodes  1  and  2  protrude above insulating resin  11  by 5 mm. Although the length of each of needle electrodes  1  and  2  protruding from insulating resin  11  is not particularly limited, an appropriate length is determined based on the voltage of high voltage electricity applied to the needle electrode and the amount of generated ions. 
         [0036]      FIG. 7  is a circuit diagram showing the configuration of the ion generation apparatus. In  FIG. 7 , in addition to needle electrodes  1 ,  2  and induction electrodes  3 ,  4 , the ion generation apparatus includes a power supply terminal T 1 , a grounding terminal T 2 , diodes  20 ,  24 ,  28 ,  32 , and  33 , resistance elements  21  to  23  and  25 , an NPN bipolar transistor  26 , boost transformers  27  and  31 , a capacitor  29 , and a 2-terminal thyristor  30 . A portion of the circuit shown in  FIG. 7  other than needle electrodes  1  and  2  and induction electrodes  3  and  4  is formed of circuit substrate  12 , circuit component  13 , transformer  14 , and the like in  FIG. 3 . 
         [0037]    The positive electrode and the negative electrode of a direct-current (DC) power supply are connected to power supply terminal T 1  and grounding terminal T 2 , respectively. Power supply terminal T 1  is applied with a DC power supply voltage (for example, +12V or +15V) while grounding terminal T 2  is grounded. Diode  20  and resistance elements  21  to  23  are connected in series between power supply terminal T 1  and the base of transistor  26 . Transistor  26  has an emitter connected to grounding terminal T 2 . Diode  24  is connected between grounding terminal T 2  and the base of transistor  26 . 
         [0038]    Diode  20  serves as an element for protecting a DC power supply by interrupting a current in the case where the positive electrode and the negative electrode of the DC power supply are inversely connected to terminals T 1  and T 2 , respectively. Resistance elements  21  and  22  each serve as an element for limiting a voltage boosting operation. Resistance element  23  is a starting resistance element. Diode  24  operates as a reverse withstand voltage protection element for transistor  26 . 
         [0039]    Boost transformer  27  includes a primary winding  27   a,  a base winding  27   b,  and a secondary winding  27   c.  Primary winding  27   a  has one terminal connected to a node N 22  between resistance elements  22  and  23 , and the other terminal connected to the collector of transistor  26 . Base winding  27   b  has one terminal connected to the base of transistor  26  through resistance element  25 , and the other terminal connected to grounding terminal T 2 . Secondary winding  27   c  has one terminal connected to the base of transistor  26 , and the other terminal connected to grounding terminal T 2  through diode  28  and capacitor  29 . 
         [0040]    Boost transformer  31  includes a primary winding  31   a  and a secondary winding  31   b.  The 2-terminal thyristor  30  is connected between the cathode of diode  28  and one terminal of primary winding  31   a.  Primary winding  31   a  has the other terminal connected to grounding terminal T 2 . Secondary winding  31   b  has one terminal connected to induction electrodes  3  and  4 , and the other terminal connected to the anode of diode  32  and the cathode of diode  33 . The cathode of diode  32  is connected to the base end portion of needle electrode  1 , and the anode of diode  33  is connected to the base end portion of needle electrode  2 . 
         [0041]    Resistance element  25  serves as an element for limiting a base current. The 2-terminal thyristor  30  serves as an element that is brought into a conductive state when the voltage between the terminals reaches a breakover voltage, and brought into a non-conductive state when the current is equal to or less than the minimum holding current. 
         [0042]    Then, the operation of this ion generation apparatus will be hereinafter described. Capacitor  29  is charged by the RCC-type switching power supply operation. In other words, when a DC power supply voltage is applied between power supply terminal T 1  and grounding terminal T 2 , a current flows from power supply terminal T 1  through diode  20  and resistance elements  21  to  23  into the base of transistor  26 , thereby bringing transistor  26  into a conductive state. Thereby, a current flows through primary winding  27   a  of boost transformer  27 , and a voltage is generated between the terminals of base winding  27   b.    
         [0043]    The winding direction of base winding  27   b  is set so as to further raise the base voltage of transistor  26  when transistor  26  is brought into a conductive state. Accordingly, the voltage generated between the terminals of base winding  27   b  is in the positive feedback state, thereby lowering the conductive resistance value of transistor  26 . At this time, the winding direction of secondary winding  27   c  is set such that current conduction is prevented by diode  28 , so that a current is prevented from flowing through secondary winding  27   c.    
         [0044]    As the current flowing through primary winding  27   a  and transistor  26  continues to increase in this way, the collector voltage on transistor  26  rises beyond the saturation region. Thereby, the voltage between the terminals of primary winding  27   a  lowers and the voltage between the terminals of base winding  27   b  also lowers, while the collector voltage on transistor  26  further rises. Accordingly, the operation is carried out in the positive feedback state, to quickly bring transistor  26  into a non-conductive state. At this time, secondary winding  27   c  generates a voltage in the conductive direction of diode  28 . Thereby, capacitor  29  is charged. 
         [0045]    When the voltage between the terminals of capacitor  29  rises to reach the breakover voltage of 2-terminal thyristor  30 , this 2-terminal thyristor  30  operates like a Zener diode to cause a current to further flow. When the current flowing through 2-terminal thyristor  30  reaches the breakover current, 2-terminal thyristor  30  is brought into an approximately short-circuited state. Then, the electric charge charged into capacitor  29  is discharged through 2-terminal thyristor  30  and primary winding  31   a  of boost transformer  31 , so that an impulse voltage is generated in primary winding  31   a.    
         [0046]    When an impulse voltage is generated in primary winding  31   a , a positive high voltage pulse and a negative high voltage pulse are alternately generated in secondary winding  31   b  while attenuating. The positive high voltage pulse is applied to needle electrode  1  through diode  32  while the negative high voltage pulse is applied to needle electrode  2  through diode  33 . Thereby, a corona discharge occurs at the tip end of each of needle electrodes  1  and  2 , thereby generating positive ions and negative ions, respectively. 
         [0047]    On the other hand, when a current flows through secondary winding  27   c  of boost transformer  27 , the voltage between the terminals of primary winding  27   a  rises to bring transistor  26  into a conductive state again. Then, the above-described operation is repeated. The rate of repeating this operation is increased as the current flowing through the base of transistor  26  is larger. Therefore, by adjusting the resistance value of resistance element  21 , the current flowing through the base of transistor  26  is adjusted, so that the number of times of discharging needle electrodes  1  and  2  can be adjusted. 
         [0048]    In the present embodiment, a positive high voltage electricity is caused to be applied to needle electrode  1  and a negative high voltage electricity is caused to be applied to needle electrode  2 , so that positive ions are generated from needle electrode  1  and negative ions are generated from needle electrode  2 . 
         [0049]    In the present embodiment, a high voltage applied to each of needle electrodes  1  and  2  is adjusted, so that specific ions are generated. In this case, a positive ion is a cluster ion formed by a plurality of water molecules attached around a hydrogen ion (H + ) and represented by H + (H 2 O)m (where m is an optional natural number). Furthermore, a negative ion is a cluster ion formed by a plurality of water molecules attached around an oxygen ion (O 2 —) and represented by O 2 —(H 2 O)n (where n is an optional natural number). 
         [0050]    When positive ions and negative ions are emitted into a room, both ions surround fungi, bacteria and viruses floating in the air, and are attached and coupled to their surfaces, to cause a chemical reaction. Floating fungi, bacteria and the like are killed by sterilization due to actions of hydroxyl radicals (·OH) and hydrogen peroxide H 2 O 2  that are active species and generated in this case. 
         [0051]    In the present embodiment, a part of induction electrode  3  and a part of induction electrode  4  are removed. A part of substrate  5  is also removed. Consequently, the size of substrate  5  in the longitudinal direction is reduced.  FIG. 8  shows a definition of the shape of the induction electrode. The induction electrode is formed in a circular shape centering on the needle electrode, and a part of the induction electrode is removed so as to be formed in a sector shape centering on the needle electrode.  FIG. 8  illustrates a shape represented based on the opening angle that is formed centering on the needle electrode between both ends of the remaining portion obtained by removing a part of the induction electrode. If the opening angle is 0° (degree), the entire induction electrode is removed. If the opening angle is 360° (degree), a complete ring is to be formed. In addition, it is preferable that the opening angle is horizontally symmetrical with respect to the needle electrode, but can be changed in a range in which the balance is not significantly changed. 
         [0052]      FIG. 9  shows the relation between the opening angle of the induction electrode formed in a sector shape and the amount of generated ions. In the case where the opening angle is 20°, the amount of generated ions is about 65% of the amount of ions generated at the time when the opening angle is 360°. In the case where the opening angle is 90°, the amount of generated ions is about 80%. Also, in the case where the opening angle is 180°, the amount of generated ions is about 90%. Based on these results, the opening angle can be set at 20° or more and 360° or less, further more preferably 90° or more and 360° or less, and most preferably 180° or more and 360° or less. 
         [0053]      FIG. 10  shows a prototype of an induction electrode.  FIG. 10A  shows a prototype shape of the induction electrode at the time when the opening angle is 360°.  FIG. 10B  shows a prototype shape of the induction electrode at the time when the opening angle is 180°.  FIG. 10C  shows a prototype shape of the induction electrode at the time when the opening angle is 90°.  FIG. 10D  shows a prototype shape of the induction electrode at the time when the opening angle is 20°. 
         [0054]      FIG. 11  is a cross-sectional view showing the configuration of an air cleaner made using the ion generation apparatus shown in  FIG. 1 . In  FIG. 11 , in this air cleaner, an inlet port  40   a  is provided in the rear surface at the lower portion of main body  40 , and outlet ports  40   b  and  40   c  are provided in the rear surface and front surface, respectively, in the upper portion of main body  40 . Furthermore, duct  41  is provided inside main body  40 . The opening at the lower end of duct  41  is provided so as to face inlet port  40   a.  The upper end of duct  41  is connected to outlet ports  40   b  and  40   c.    
         [0055]    A cross flow fan  42  is provided in the opening at the lower end of duct  41 , and an ion generation apparatus  43  is provided in the center portion of duct  41 . Ion generation apparatus  43  is the same as that shown in  FIG. 1 . The main body of ion generation apparatus  43  is fixed to the outer wall surface of duct  41 , and needle electrodes  1  and  2  thereof penetrates through the wall of duct  41  and protrude into duct  41 . Two needle electrodes  1  and  2  are arranged in the direction that is orthogonal to the direction in which the air flows through duct  41 . 
         [0056]    Furthermore, inlet port  40   a  is provided with a lattice-shaped grill  44  made of resin, and a mesh-like thin filter  45  is affixed to the inside of grill  44 . A fan guard  46  is provided on the inner side of filter  45  so as to prevent foreign substances and user&#39;s fingers from coming into cross flow fan  42 . 
         [0057]    When cross flow fan  42  is driven to rotate, the air inside the room is suctioned through inlet port  40   a  into duct  41 . Fungi, bacteria the like contained in the suctioned air are killed by sterilization by the ions generated by ion generation apparatus  43 . The clean air having passed through ion generation apparatus  43  is emitted through outlet ports  40   b  and  40   c  into the room. 
         [0058]    In the present embodiment, induction electrodes  3  and  4  are mounted on substrate  5 , and needle electrodes  1  and  2  are mounted on substrate  6 . Accordingly, even when the ion generation apparatus is placed in a high humidity environment, a current can be prevented from leaking between needle electrodes  1 ,  2  and induction electrodes  3 ,  4 , so that ions can be stably generated. 
         [0059]    Furthermore, since substrates  5  and  6  are covered by insulating resin  11 , dust can be prevented from accumulating on substrates  5  and  6 . 
         [0060]    Furthermore, the tip end portions of needle electrodes  1  and  2  protrude above insulating resin  11 . Accordingly, even in the case where dust accumulates in the vicinity of the opening, discharge of needle electrodes  1  and  2  can be prevented from being blocked by the tip end portions of needle electrodes  1  and  2  becoming buried in dust. Furthermore, even in the case where dust adheres to the tip end portions of needle electrodes  1  and  2 , dust can be blown away from needle electrodes  1  and  2  by applying a high voltage to needle electrodes  1  and  2  while sending air to the tip end portions of needle electrodes  1  and  2 . 
         [0061]    Furthermore, since induction electrodes  3  and  4  each are formed using a wiring layer of substrate  5 , induction electrodes  3  and  4  can be formed at low cost, so that the ion generation apparatus can be implemented at low cost. 
       Second Embodiment 
       [0062]    In the first embodiment, based on the basic shape formed in a circular shape, the induction electrode is formed by removing a part of the basic shape, but this basic shape can be treated functionally equally to a circular shape as long as this basic shape is polygonal equal to or greater than hexagonal. Also, even if the basic shape is triangular or rectangular, the basic shape can be implemented in a shape similar to that in the present embodiment depending on the arrangement manner. As an example of the arrangement manner, the induction electrodes may be arranged horizontally symmetrical with respect to the position of the needle electrode as an object axis, which is considered as being applicable to practical use in the same way. 
       Third Embodiment 
       [0063]    In the first embodiment, the tip ends of needle electrodes  1  and  2  protrude above insulating resin  11 , but the tip ends of needle electrodes  1  and  2  may be located lower than the upper surface of insulating resin  11 . 
       Fourth Embodiment 
       [0064]    In the first embodiment, each of induction electrodes  3  and  4  is formed using a wiring layer of substrate  5 , but each of induction electrodes  3  and  4  may be formed of a metal plate. Furthermore, each of induction electrodes  3  and  4  may not be formed in an annular shape. 
         [0065]    It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims. 
       REFERENCE SIGNS LIST 
       [0066]      1 ,  2  needle electrode,  3 ,  4  induction electrode,  5 ,  6  substrate,  5   a,    5   b  hole,  10  housing,  11  insulating resin,  12  circuit substrate,  13  circuit component,  14  transformer,  15  connector, T 1  power supply terminal, T 2  grounding terminal,  20 ,  24 ,  28 ,  32 ,  33  diode,  21  to  23 ,  25  resistance element,  26  NPN bipolar transistor,  27 ,  31  boost transformer,  27   a,    31   a  primary winding,  27   b  base winding,  27   c,    31   b  secondary winding,  29  capacitor,  30  2-terminal thyristor,  40  main body,  40   a  inlet port,  40   b,    40   c  outlet port,  41  duct,  42  cross flow fan,  43  ion generation apparatus,  44  grill,  45  filter,  46  fan guard.