Abstract:
An ion generation unit ( 1 ) provided with an ion generation element ( 20 ) for generating ions through application of voltage, and a casing ( 10 ) housing the ion generation element. The casing is constituted by a casing body ( 11 ) and a rear cover ( 12 ). To the inside face of the casing are attached suppressing members ( 30, 31, 32, 33 ) for suppressing the radiation noise associated with ion generation. Openings ( 13, 14 ) through which the ions generated by the ion generation element are emitted to the outside are formed in the casing body, and the suppressing members are attached at locations other than the openings.

Description:
TECHNICAL FIELD 
     The present invention relates to an ion generation unit. 
     BACKGROUND ART 
     In recent years, there are many electric apparatuses that generate one or both of positive ions and negative ions to obtain effects of germ eradication, deodorization, refreshing and the like. An air conditioner, an air cleaner, a dehumidifier and the like are typical electric apparatuses with which an ion generation apparatus is combined. Some are put in the market as stand-alone ion generation apparatuses. 
     A traditional method to generate ions is corona discharge. In this method, a high voltage is applied to a discharge body in the atmosphere to produce corona discharge, thereby generating ions electrically. Patent document 1 discloses an example of an ion generation apparatus that uses the corona discharge. 
     The ion generation apparatus disclosed in the patent document 1 steps up an input voltage from a commercial power supply by means of a voltage step-up apparatus, further transforms it into a drive voltage that has a predetermined drive waveform, then applies it to the ion generation device to generate positive ions and negative ions. 
     CITATION LIST 
     Patent Literature 
     
         
         PLT1: JP-A-2006-127855 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     According to its operation principle, an ion generation apparatus requires switching at a high voltage and cannot evade occurrence of a radiant noise caused by the switching. As anti-radiant-noise measures, the following measures are employed:
         (a) Lowering the peak value of an ion generation voltage of the ion generation apparatus.   (b) Enclosing a voltage step-up transformer with a shield case.   (c) Attaching an adhesive tape (hereinafter “metal-foil tape” in the present specification) containing a metal (usually aluminum) foil as a component, to an outer surface of the ion generation device.       

     In the ion generation apparatus disclosed in the patent document 1, a measure mainly following the lead of above measure (b) is adopted. Namely, a copper tape, a kind of metal-foil tape, is wound around a voltage step-up coil, and a shield case formed of a tin plate is disposed around the voltage step-up coil to curb occurrence of a radiant noise. 
     According to the above measure (a), a voltage applied to a discharge body declines and it becomes hard to generate intended amount of ions. Also the measure (b) has the same problem as the measure (a) that the voltage applied to the discharge body declines. This is because a discharge occurs between a secondary terminal of the voltage step-up transformer and the shield case. 
     In a case of taking the above measure (c), a degree of radiant noise curbing changes depending on the manner how the metal-foil tape is attached. It is possible to look for, through trial and error, a way of metal-foil tape attachment that curbs the radiant noise and does not reduce the amount of generated ions so much. However, this method requires preparation of ion generation devices, to which the metal-foil tape has been attached, as service parts. Besides, an acceptable level of radiant noise depends on the type of electric apparatuses into which the ion generation device is incorporated, and it is necessary to provide, as service parts, many kinds of ion generation devices having the metal-foil tape attached in different ways. 
     The present invention has been made in light of the above points, and it is an object to provide an ion generation unit that reduces a radiant noise to improve the reliability of a product without reducing an amount of generated ions, and further does not require many kinds of ion generation devices as service parts. 
     Solution to Problem 
     An ion generation unit according to the present invention includes: an ion generation device that generates ions by voltage application; and a casing that houses the ion generation device; wherein an inner surface of the casing is provided with a curbing member that curbs a radiant noise caused by ion generation. 
     In the ion generation unit having the above structure, it is preferable that the casing is provided with an opening portion that discharges the ions generated from the ion generation device to outside, and a portion other than the opening portion is provided with the curbing member. 
     In the ion generation unit having the above structure, it is preferable that the curbing member is composed of a metal plate. 
     In the ion generation unit having the above structure, it is preferable that the curbing member is composed of an adhesive sheet that contains a metal foil as a component. 
     Advantageous Effects of Invention 
     According to the present invention, the inner surface of the casing that houses the ion generation device is provided with the curbing member that curbs the radiant noise: accordingly, it is possible to reduce the radiant noise without reducing an amount of generated ions. Besides, the ion generation device is not modified: accordingly, it is unnecessary to prepare many kinds of the ion generation devices as service parts. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view of an ion generation unit according to an embodiment of the present invention. 
         FIG. 2  is an exploded perspective view of components. 
         FIG. 3  is a perspective view of an ion generation unit in an assembled state to which a rear lid is ready to be fitted. 
         FIG. 4  is a sectional view of an ion generation unit. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An ion generation unit  1  as an embodiment of the present invention is designed as a unit to be incorporated in other apparatuses such as, for example, an indoor unit of an air conditioner, an air cleaner, a car and the like. The ion generation unit  1  includes a synthetic resin casing  10  that has a shape of a small-sized indoor unit of an air conditioner and is laterally long. The casing  10  includes a casing main body  11  and a rear lid  12  (see  FIG. 3 ). The rear lid  12  is visible from a rear side only, and when viewed from a front side, the casing main body  11  makes up an entire appearance. In the meantime, an upper side and a lower side of  FIG. 1  correspond to an upper side and a lower side of the ion generation unit  1 , respectively, and a left side and a right side of  FIG. 1  correspond to a left side and a right side of the ion generation unit  1 , respectively. This orientation also applies to other components. 
     An ion generation device  20  is housed in the casing  10 . The ion generation device  20  has a rectangular parallelepiped shape. When applied a predetermined voltage to the ion generation device  20 , the ion generation device  20  generates ions by corona discharge. The ion generation device  20  is able to generate positive ions H + (H 2 O) m  (m is an arbitrary natural number) and negative ions O 2   −  (H 2 O) n  (n is an arbitrary natural number) concurrently. 
     The casing main body  11  is provided with opening portions at a position near the left end and at a position near the right end, through both of which ions generated by the ion generation device  20  are discharged. The positions of the opening portions correspond to positions of ion generation portions (not shown) of the ion generation device  20 . Both the left opening portion and the right opening portion are formed by arranging an opening portion  13  that extends from the front surface to an upper surface of the casing main body  11  and an opening portion  14  that extends from the upper surface to a lower surface of the casing main body  11  vertically. The opening portions  13 ,  14  are provided with sets of a plurality of vertical crosspieces at predetermined intervals that prevent foreign matter from entering the casing  10 . Crosspieces  13   a  are arranged at relatively narrow intervals in the opening portion  13  while crosspieces  14   a  are arranged at relatively wide intervals in the opening portion  14 . 
     As shown in  FIG. 2 , the casing main body  11  is placed on an assembly table or the like with the front surface thereof down and the rear opening thereof, into which the rear lid  12  is fitted, up. The ion generation device  20  is inserted into the casing main body  11  through the rear opening. A power supply cable  21  is connected to the ion generation device  20 . The power supply cable  21  has connectors  22 ,  23  at both ends. The connector  22  is to be connected to the ion generation device  20 , while the connector  23  is to be connected to an external power supply cable (not shown). The connector  23  is fixed to the casing main body  11  by means of a screw  24 . 
     As shown in  FIG. 3 , when the rear lid  12  is fitted with the ion generation device  20  and the power supply cable  21  set in the casing main body  11 , the ion generation unit  11  reaches completion. As to the rear lid  12 , a surface facing an inside of the casing  10  is provided with two stripes of protrusions  15 ,  16  that go into an internal space of the casing main body  11 . Both protrusions  15  and  16  extend in a horizontal direction. The protrusion  15  is formed at a position that is lower than an upper edge of the rear lid  12  by a thickness of an outer shell of the casing main body  11 , while the protrusion  16  is formed at a position that is higher than a lower edge of the rear lid  12  by the thickness of the outer shell of the casing main body  11 . 
     An upper surface of the protrusion  15  and a lower surface of the protrusion  16  are each provided with a plurality of engagement protrusions  17 . In the embodiment, the protrusion  15  is provided with four engagement protrusions  17 , and also the protrusion  16  is provided with four engagement protrusions  17  at an equal interval. In the meantime, the number “four” defining protrusion quantity is a mere example and does not limit the invention. The casing main body  11  is provided with a plurality of engagement holes  18  at positions corresponding to the engagement protrusions  17 . 
     When the rear lid  12  is placed on the casing main body  11  in the state of  FIG. 3  and a downward force is exerted on the rear lid  12 , the engagement protrusion  17  engages with the engagement hole  18  to go to a state shown in  FIG. 4 . In this state, protrusions  19  formed at some positions of an inner surface of the rear lid  12  push down the ion generation device  20 , whereby the ion generation device  20  is firmly fixed. 
     An inner surface of the casing  10  is provided with a curbing member that curbs a radiant noise caused by the ion generation. The curbing member can be composed of a metal plate. The metal plate can be fixed to the casing  10  by means of an adhesive, a double-faced adhesive tape, a screw or the like. 
     The curbing member can be composed of an adhesive sheet that contains a metal foil, an aluminum foil for example, as a component. Such a curbing member is easy to mount. If the adhesive sheet is formed into a roll of adhesive tape, it becomes easy to handle. 
     It is preferable to mount the curbing member on both the casing main body  11  and the rear lid  12 .  FIG. 2  shows a state where the curbing member is mounted on an inner surface of the casing main body  11 . The curbing member  30  is mounted on a flat inner surface between the left and right opening portions  13 ,  14 , the curbing member  31  is mounted on a lower inner surface, and the curbing member  32  is mounted on a left inner surface. A curbing member, which pairs with the curbing member  31 , is mounted on an upper inner surface that is hidden in  FIG. 2 . Likewise, a curbing member, which pairs with the curbing member  32 , is mounted on a right inner surface that is hidden in  FIG. 2 . 
       FIG. 3  shows a state where a curbing member is mounted on the inner surface of the rear lid  12 . The curbing member  33  covers a flat portion between the protrusions  15 ,  16 . 
     As described above, the curbing members  30 ,  31 ,  32 , and  33  are mounted on the inner surface of the casing main body  11 : accordingly, it is possible to reduce the radiant noise without mounting a curbing member on the ion generation device  20 . The curbing members  30 ,  31 ,  32 , and  33  are mounted on places other than the opening portions  13 ,  14 : accordingly, discharge of the ions through the opening portions  13 ,  14  is not discouraged, i.e. an amount of discharged ion is not reduced. 
     The ion generation device  20  is not modified: accordingly, it is unnecessary to prepare many kinds of the ion generation devices  20  as service parts. In other words, the ion generation device  20  is standardizable. 
     In various apparatuses that incorporate the ion generation unit  1 , the structure of a holder that holds the ion generation unit  1  is unique to each apparatus. However, even if an apparatus is modified, as long as the holder structure is the same, the same ion generation unit  1  is incorporable. In other words, the same ion generation device  20  as a standard service part is usable. 
     Hereinbefore, the embodiment of the present invention is described. However, the scope of the present invention is not limited to the embodiment, and various modifications can be made if the modifications do not depart from the spirit of the invention. 
     INDUSTRIAL APPLICABILITY 
     The present invention is widely applicable to ion generation units. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  ion generation unit 
               2  casing 
               11  casing main body 
               12  rear lid 
               13 ,  14  opening portions 
               20  ion generation device 
               30 ,  31 ,  32 ,  33  curbing members