Abstract:
Provided is a portable wireless device capable of preventing deterioration in performance of an antenna caused by reverse phase current. The portable wireless device ( 100 ) comprises at least two box-shaped housings each of which is formed by fitting respective annular fitting surfaces of two cases. Further, in the portable wireless device ( 100 ), a first circuit board ( 110 ) is provided in a first housing ( 101 ). A second circuit board ( 115 ) is provided in a second housing ( 102 ). A signal line ( 119 ) electrically connects the first circuit board ( 110 ) and the second circuit board ( 115 ). A waterproofing packing ( 116 ) has an annular shape, and is provided between the fitting surfaces of the two cases and held by the two cases which constitute the second housing ( 102 ). A conductive element ( 118 ) is integrally formed with the waterproofing packing ( 116 ), electrically connected to an end of the second circuit board ( 115 ), and electrically connected to the signal line ( 119 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a portable radio device. More particularly, the present invention relates to a portable radio device that is equipped with a plurality of casings and has a waterproof structure. 
       BACKGROUND ART 
       [0002]    Conventionally, a portable radio device equipped with two or more casings and a signal line for electrically connecting circuit boards to each other in each casing, has been known. In such a portable radio device, since a signal line has a strong antenna current distribution, the antenna current flowing through the signal line significantly influences antenna performance. 
         [0003]    In addition, conventionally, a position for connecting the above signal line to the circuit board is not the end of the circuit board but the inner side of the circuit board in terms of manufacturing or packaging. In this case, there is a problem that, since the signal line and the circuit board overlap in vertical direction, a reverse-phase current may flow in the signal line and the circuit board and the antenna performance may be deteriorated. In addition, since the phase of the antenna current flowing through the signal line vary depending on the length of the signal line, the influence on the antenna performance is also different, so that it is difficult to ensure desired antenna performance. 
         [0004]    Therefore, in the portable radio device described above, it is possible to improve the antenna performance by minimizing generation of the reverse-phase current and controlling the antenna current flowing through the signal line. 
         [0005]    In addition, conventionally, the portable radio device disclosed in Patent Literature 1 has been known as the portable radio device for controlling the antenna current. The portable radio device disclosed in Patent Literature 1 has a casing dipole configuration and controls the antenna current flowing through a hinge metal section, by providing a sheet metal combined with the hinge metal section serving as an antenna element. 
       CITATION LIST 
     Patent Literature 
     PTL 1 
     Japanese Patent Application Laid-open No. 2005-236396  
     SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    However, in Patent Literature 1, there has been a problem that, since it is not possible to control the antenna current flowing through the signal line connecting the upper and lower casings, the reverse-phase current may flow in the signal line and the circuit board, and the antenna performance may be deteriorated. 
         [0007]    It is therefore an object of the present invention to provides a portable radio device capable of preventing deterioration of the antenna performance due to the reverse-phase current. 
       Solution to Problem 
       [0008]    The portable radio device of the present invention that includes two or more box-shaped casings formed by fitting two cases at a mating surface that is annular, employs a configuration having: a first circuit board provided in the first casing, a second circuit board provided in the second casing, a signal line that electrically connects the first circuit board and the second circuit board, a first packing that is annular and is interposed between the first case and the second case on the mating surface between the first case and the second case forming the second casing, and a first conductive element integrated with the first packing, electrically connected to an end of the second circuit board, and electrically connected to the signal line on the mating surface. 
       ADVANTAGEOUS EFFECTS OF INVENTION 
       [0009]    According to the present invention, it is possible to prevent deterioration of the antenna performance due to the reverse-phase current, 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a plan view illustrating a portable radio device in an opened state according to Embodiment 1 of the present invention; 
           [0011]      FIG. 2  is a perspective view illustrating the main part of the portable radio device describing the flow of the antenna current when the conductive element according to Embodiment 1 of the present invention is not provided; 
           [0012]      FIG. 3  is a side view illustrating the main part of the portable radio device describing the flow of the antenna current when the conductive element according to Embodiment 1 of the present invention is not provided; 
           [0013]      FIG. 4  is a perspective view illustrating the main part of the portable radio device for describing the flow of the antenna current when the conductive element according to Embodiment 1 of the present invention is provided; 
           [0014]      FIG. 5  is a plan view illustrating the portable radio device in an opened state according to Embodiment 2 of the present invention; 
           [0015]      FIG. 6  is a perspective view illustrating the main part of the portable radio device describing the flow of the antenna current when the conductive element according to Embodiment 2 of the present invention is not provided; 
           [0016]      FIG. 7  is a side view illustrating the main part of the portable radio device describing the flow of the antenna current when the conductive element according to Embodiment 2 of the present invention is not provided; 
           [0017]      FIG. 8  is a perspective view illustrating the main part of the portable radio device describing the flow of the antenna current when the conductive element according to Embodiment 2 of the present invention is provided; 
           [0018]      FIG. 9  is a plan view illustrating the portable radio device in an opened state according to Embodiment 3 of the present invention; and 
           [0019]      FIG. 10  is a plan view illustrating the portable radio device in an opened state according to Embodiment 4 of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0020]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 1 
       [0021]      FIG. 1  is a plan view illustrating portable radio device  100  in an opened state according to Embodiment 1 of the present invention. 
         [0022]    Portable radio device  100  is mainly formed by first casing  101 , second casing  102 , hinge section  103 , and signal line  119 . 
         [0023]    First casing  101  includes first circuit board  110 , power feeding section  111 , connector  112 , and waterproof packing  113 . Second casing  102  includes second circuit board  115 , waterproof packing  116 , connector  117 , and conductive element  118 . In addition, hinge section  103  includes hinge metal section  114 . Hereinafter, each configuration will be described in detail. 
         [0024]    First casing  101  has a substantially box shape formed by fitting two cases at an annular mating surface and foldably connected to second casing  102  through hinge section  103 . Specifically, the state of first casing  101  changes from a closed state (not illustrated) in which first and second casings  101  and  102  are vertically overlapped to an opened state of  FIG. 1  or from the opened state of  FIG. 1  to the closed state. First casing  101  has first circuit board  110  therein. First casing  101  includes waterproof packing  113  provided in the mating surface where two cases are fitted, and interposed by two cases. 
         [0025]    Second casing  102  has a substantially box shape formed by fitting two cases at an annular mating surface and foldably connected to first casing  101  through hinge section  103 . Specifically, the state of second casing  102  changes from a closed state (not illustrated) in which first and second casings  101  and  102  are vertically overlapped to an opened state of  FIG. 1  or from the opened state of  FIG. 1  to the closed state. Second casing  102  has second circuit board  115  therein. Second casing  102  is provided in the mating surface where two cases are fitted and includes waterproof packing  116  interposed by two cases. Second casing  102  includes conductive element  118  integrated with waterproof packing  116  in hinge section  103  side. 
         [0026]    Hinge section  103  connects first and second casings  101  and  102  in a rotatable manner. Hinge section  103  has hinge metal section  114  therein. 
         [0027]    First circuit board  110  is provided across substantially the entire surface of the inner side of first casing  101 . In addition, first circuit board  110  includes power feeding section  111 . Connector  112  is mounted on first circuit board  110 , and first circuit board  110  is electrically connected to second circuit board  115  through connector  117 , signal line  119 , and connector  112 . 
         [0028]    Power feeding section  111  is provided in first circuit board  110  and feeds electricity to hinge metal section  114  to excite hinge metal section  114 . 
         [0029]    Connector  112  is mounted on first circuit board  110  to electrically connect signal line  119  and first circuit board  110 . Connector  112  is located in an inner side than waterproof packing  113  of first casing  101  and is mounted on first circuit board  110 . 
         [0030]    Waterproof packing  113  has an annular shape and is provided in the mating surface where two cases of first casing  101  are fitted. Waterproof packing  113  hermitically seals the gap between the two case formed when the two cases are fitted. Waterproof packing  113  is formed of a material having an elastic force that can reliably and hermetically seal the gap between two fitted cases. 
         [0031]    Hinge metal section  114  serves as an antenna by providing in the inner side of hinge section  103  and electricity being fed from power feeding section  111 . 
         [0032]    Second circuit board  115  is provided across substantially the entire surface of the inner side of second casing  102 . Connector  117  is mounted on second circuit board  115 , and second circuit board  115  is electrically connected to first circuit board  110  through connector  112 , signal line  119 , and connector . 117 . Second circuit board  115  is electrically connected to conductive element  118  in the end of hinge section  103  side. 
         [0033]    Waterproof packing  116  has an annular shape and is provided in the mating surface where two cases of second casing  102  are fitted. In addition, waterproof packing  116  hermitically seals the gap between the two cases formed when two cases are fitted. Waterproof packing  116  is formed of a material having an elastic force that can reliably and hermetically seal the gap between two fitted cases. Moreover, waterproof packing  116  is provided integrally with conductive element  118 , and conductive element  118  is firmly connected to signal line  119  by pressedly bonding conductive element  118  and signal line  119  using the elastic force. 
         [0034]    Connector  117  is mounted on second circuit board  115 , and is electrically connected to signal line  119  and second circuit board  115 . Connector  117  is located in the inner side than waterproof packing  116  of second casing  102  and is mounted on second circuit board  115 . 
         [0035]    Conductive element  118  is formed, for example, using a printed pattern of a flexible printed circuit (hereinafter, referred to as “FPC”), and is provided integrally with waterproof packing  116  in second casing  102 . Conductive element  118  is electrically connected to signal line  119  on the mating surface of the case where two cases of second casing  102  are fitted. Conductive element  118  is electrically connected to the end of second circuit board  115 . Conductive element  118  includes wide-width section  118   a  formed to have a wide width and electrically connected to signal line  119  and connection ends  118   b  and  118   c  that horizontally extend from wide width section  118   a  and are electrically connected to the end of second circuit board  115 . 
         [0036]    Signal line  119  made of, for example, FPC is electrically connected to first circuit board  110  through connector  112  and is electrically connected to second circuit board  115  through connector  117 . Specifically, signal line  119  is electrically connected to first circuit boards  110  and second circuit boards  115 . Signal line  119  is electrically connected to conductive element  118 . In this case, conductive element  118  may be electrically connected to signal line  119  directly or equivalently by capacitively coupling them through a capacitor. 
         [0037]    Hereinbefore, the configuration of portable radio device  100  has been described. 
         [0038]    Next, the flow of the current in portable radio device  100  will be described with reference to  FIGS. 2 to 4 .  FIG. 2  is a perspective view illustrating the main part of portable radio device  100  for describing the flow of the antenna current when conductive element  118  is not provided.  FIG. 3  is a side view illustrating the main part of portable radio device  100  describing the flow of the antenna current when conductive element  118  is not provided. FIG  4  is a perspective view illustrating the main part of portable radio device  100  describing the flow of the antenna current when conductive element  118  is provided. In  FIGS. 2 to 4 , the same components as  FIG. 1  will be assigned the same reference numerals. 
         [0039]    In  FIGS. 2 and 3 , an antenna current e 1  in signal line  119  flows to second circuit board  115  from first circuit board  110 . 
         [0040]    Meanwhile, connector  117  is electrically connected to second circuit board  115 , so that reverse-phase current e 2  having a phase reverse to that of antenna current e 1  flows in a part of second circuit board  115  vertically overlapped with signal line  119 . Therefore, antenna current e 1  is canceled out by reverse-phase current e 2  so that the antenna performance is deteriorated. 
         [0041]    In contrast, as illustrated in  FIG. 4 , a part of antenna current e 1  may be distributed to conductive element  118  by providing conductive element  118 . If connection ends  118   b  and  118   c  are connected to the end of second circuit board  115 , antenna currents e 3  and e 4  distributed to conductive element  118  may flow upwardly to be the same phase as that of antenna current e 1  in second circuit board  115 . Antenna current e 1  in a portion of signal line  119  overlapped with second circuit board  115  may be reduced by distributing the current to conductive element  118  in comparison with the related art. As a result, it is possible to suppress reverse-phase current e 2  flowing through second circuit board  115  and antenna current e 1  canceled out by reverse-phase current e 2 . 
         [0042]    Thus, according to the present embodiment, it is possible to prevent deterioration of the antenna performance due to the reverse-phase current by providing the conductive element to distribute the antenna current flowing through the signal line. According to the present embodiment, since the conductive element is provided integrally with the waterproof packing, it is possible to firmly connect the conductive element to the signal line using the elastic force of the waterproof packing and improve electrical connection between the conductive element and the signal line. In addition, according to the present embodiment, since the connection portion between the conductive element and the signal line is formed wider than other portions, it is possible to improve the electrical connection between the conductive element and the signal line. In addition, according to the present embodiment, since the conductive element is formed of a printed pattern of FPC, it is possible to improve adhesion between the conductive element made of a flexible material and the signal line and electrical connection between the conductive element and the signal line. In addition, according to the present embodiment, since the waterproof packing and the conductive element are integrally formed, it is possible to simplify installation of the conductive element to the second casing and reduce the manufacturing cost. 
       Embodiment 2 
       [0043]      FIG. 5  is a plan view illustrating portable radio device  500  in an opened state according to Embodiment 2 of the present invention. 
         [0044]    Portable radio device  500  of  FIG. 5  includes further conductive element  501  in addition to portable radio device  100  according to Embodiment 1 of  FIG. 1 . In  FIG. 5 , the same components in  FIG. 1  will be assigned the same reference numerals and overlapping explanation will be omitted. 
         [0045]    Portable radio device  500  is mainly formed by first casing  101 , second casing  102 , hinge section  103 , and signal line  119 . 
         [0046]    First casing  101  includes first circuit board  110 , power feeding section  111 , connector  112 , waterproof packing  113 , and conductive element  501 . Hereinafter, the present embodiment will describe components different from the above Embodiment 1 in detail. 
         [0047]    First circuit board  110  is provided across substantially the entire surface of the inner side of first casing  101 . Connector  112  is mounted on first circuit board  110  to electrically connect first circuit board  110  to second circuit board  115  through connector  112 , signal line  119 , and connector  117 . First circuit board  110  is electrically connected to conductive element  501  in the end of hinge section  103  side. 
         [0048]    Conductive element  501  is made of, for example, a printed pattern of FPC, and is provided integrally with waterproof packing  113  in first casing  101 . Furthermore, conductive element  501  is electrically connected to signal line  119  on the mating surface used to fit two cases of first casing  101 . Conductive element  501  is electrically connected to the end of first circuit board  110 . Conductive element  501  includes wide-width section  501   a  that is formed to have a wide width and electrically connected to signal line  119 , and connection ends  501   b  and  501   c  that horizontally extended from wide-width section  501   a  and are electrically connected to the end of first circuit board  110 . 
         [0049]    Waterproof packing  113  has an annular shape and is provided in the mating surface used to fit two cases of first casing  101 . Waterproof packing  113  hermitically seals the gap between the two cases formed when the two cases are fitted. Waterproof packing  113  is formed of a material having an elastic force that can reliably and hermetically seal the gap between two fitted cases. Waterproof packing  113  is provided integrally with the conductive element  501 , and conductive element  501  is firmly connected to signal line  119  by pressedly bonding conductive element  501  and signal line  119 . 
         [0050]    Signal line  119  made of, for example, FPC is electrically connected to first circuit board  110  through connector  112 , and is electrically connected to second circuit board  115  through connector  117 . Specifically, signal line  119  is electrically connected to first and second circuit boards  110  and  115 . Signal line  119  is electrically connected to conductive elements  118  and  501 . In this case, conductive element  118  may be electrically connected to signal line  119  directly or equivalently using a capacitive coupling through a capacitor. Similarly, conductive element  501  may be electrically connected to signal line  119  directly or equivalently using a capacitive coupling through a capacitor. 
         [0051]    Hereinbefore, the configuration of portable radio device  500  has been described. 
         [0052]    Next, the flow of the current in portable radio device  500  will be described with reference to  FIGS. 6 to 8 .  FIG. 6  is a perspective view illustrating the main part of portable radio device  500  for describing the flow of the antenna current when conductive elements  118  and  501  are not provided.  FIG. 7  is a side view illustrating the main part of portable radio device  500  for describing the flow of the antenna current when the conductive elements  118  and  501  are not provided.  FIG. 8  is a perspective view illustrating the main part of portable radio device  500  for describing the flow of the antenna current when the conductive elements  118  and  501  are provided. In  FIGS. 6 to 8 , the same components as  FIG. 5  will be assigned the same reference numerals. 
         [0053]    In  FIGS. 6 and 7 , antenna current e 10  in signal line  119  flows in a direction from first circuit board  110  to second circuit board  115 . 
         [0054]    Meanwhile, connector  112  is electrically connected to first circuit board  110 , so that reverse-phase current e 11  having a phase reverse to that of antenna current e 10  flows in a part of first circuit board  110  vertically overlapped with signal line  119 . Similarly, connector  117  is electrically connected to second circuit board  115 , so that reverse-phase current e 12  having a phase reverse to that of antenna current e 10  flows in a part of second circuit board  115  vertically overlapped with signal line  119 . 
         [0055]    Therefore, antenna current e 10  is canceled out by reverse-phase currents e 11  and e 12 , so that the antenna performance is deteriorated. 
         [0056]    In contrast, as illustrated in  FIG. 8 , a part of antenna current e 10  may be distributed to conductive element  118  by providing conductive element  118 . If connection ends  118   b  and  118   c  are connected to end of second circuit board  115 , antenna currents e 13  and e 14  distributed to conductive element  118  may flow upwardly with the same phase as that of antenna current e 10  in second circuit board  115 . Antenna current e 10  in a portion of signal line  119  overlapped with second circuit board  115  may be reduced by distributing antenna current e 10  to conductive element  118  in comparison with the related art. As a result, it is possible to suppress reverse-phase current e 12  flowing through second circuit board  115 , so that antenna current e 10  is prevented from being canceled out by reverse-phase current e 12 . 
         [0057]    In the present embodiment of  FIG. 8 , conductive element  501  is provided, and connection ends  501   b  and  501   c  are connected to the end of first circuit board  110 . Therefore, reverse-phase current e 11  flowing to a portion vertically overlapped with signal line  119  of first circuit board  110  can flow to conductive element  501  (currents e 15  and e 16 ). As a result, currents e 15  and e 16  flowing to conductive element  501  can flow upwardly with the same phase as that of antenna current e 10  of signal line  119 , so that it is possible to prevent antenna current e 10  from being canceled out by reverse-phase current e 11 . 
         [0058]    In this manner, according to the present embodiment, in addition to the effects of Embodiment 1, the conductive element connecting the first circuit board of the first casing is provided, so that it is possible to further prevent the antenna current from being canceled out by the reverse-phase current in the portion where the signal line and the first circuit board are vertically overlapped and improve the antenna performance. 
       Embodiment 3 
       [0059]      FIG. 9  is a plan view illustrating portable radio device  900  in an opened state according to Embodiment 3 of the present invention. 
         [0060]    Portable radio device  900  illustrated in  FIG. 9  further includes reactance element  901  in addition to portable radio device  100  according to Embodiment 1 of  FIG. 1 . In  FIG. 9 , the same components in  FIG. 1  will be assigned the same reference numerals and overlapping explanation will be omitted. 
         [0061]    Portable radio device  900  is mainly formed by first casing  101 , second casing  102 , hinge section  103 , and signal line  119 . 
         [0062]    Second casing  102  includes circuit board  115 , waterproof packing  116 , connector  117 , conductive element  118 , and reactance element  901 . Hereinafter, the present embodiment will describe components different from the above Embodiment 1 in detail. 
         [0063]    Second circuit board  115  is provided substantially the entire inner side of second casing  102 . Connector  117  is mounted on second circuit board  115 , and second circuit board  115  is electrically connected to first circuit board  110  through connector  112 , signal line  119 , and connector  117 . Second circuit board  115  is electrically connected to conductive element  118  in the end of hinge section  103  side. Reactance element  901  is mounted on second circuit board  115 , and conductive element  118  is grounded through reactance element  901 . 
         [0064]    Conductive element  118  made of, for example, a printed pattern of FPC is provided integrally with waterproof packing  116  in second casing  102 . Furthermore, conductive element  118  is electrically connected to signal line  119  in the mating surface used to fit two cases of second casing  102 . Conductive element  118  is electrically connected to the end of second circuit board  115 , and is grounded to second circuit board  115  through reactance element  901 . Conductive element  118  includes: wide-width section  118   a  that is formed to have a wide width and is electrically connected to signal line  119 ; connection end  118   b  that horizontally extends from wide-width section  118   a  and is electrically connected to the end of second circuit board  115 ; and connection end  118   c  that horizontally extends in a direction opposite to the extending direction of connection end  118   b  from wide-width section  118   a,  is electrically connected to reactance element  901 , and is grounded to second circuit board  115  through reactance element  901 . 
         [0065]    Reactance element  901  is provided in second circuit board  115 . Reactance element  901  is connected in series between second circuit board  115  and conductive element  118 . 
         [0066]    In addition, the flow of the antenna current in portable radio device  900  is the same as Embodiment 1 described above and overlapping explanation will be omitted. 
         [0067]    Thus, according to the present embodiment, in addition to the effects of above Embodiment 1, the conductive element is grounded through the reactance, so that it is possible to control the antenna current depending on the use frequency or the length of the signal line and further improve the antenna performance. 
         [0068]    Although the conductive element is provided only in the second casing according to the present embodiment, the present invention is not limited thereto and the conductive element may be provided in the first casing in addition to the second casing, and the conductive element provided in the first casing may be grounded to the first circuit board through the reactance element. 
       Embodiment 4 
       [0069]      FIG. 10  is a plan view illustrating portable radio device  1000  in an opened state according to Embodiment 4 of the present invention. 
         [0070]    Portable radio device  1000  of  FIG. 10  includes antenna  1003  excluding waterproof packing  113  in comparison with portable radio device  100  according to Embodiment 1 of  FIG. 1 ; first casing  101 , is substituted with first casing  1001 ; and power feeding section  111  is substituted with power feeding section  1002 . In  FIG. 10 , the same components in  FIG. 1  will be assigned the same reference numerals and overlapping explanation will be omitted. 
         [0071]    Portable radio device  1000  is mainly formed by first casing  1001 , second casing  102 , hinge section  103 , and signal line  119 . 
         [0072]    First casing  1001  includes first circuit board  110 , connector  112 , power feeding section  1002 , and antenna  1003 . Hereinafter, the present embodiment will describe components different from the above Embodiment 1 in detail. 
         [0073]    First casing  1001  has a substantially box shape and a rectangular shape in plan view, and is foldably connected to second casing  102  through hinge section  103 . Specifically, the state of first casing  1001  changes from a closed state (not illustrated) in which first casing  1001  and second casing  102  are vertically overlapped to an opened state of  FIG. 10  or from the opened state of  FIG. 10  to the closed state. First casing  1001  has first circuit board  110  therein. First casing  1001  includes antenna  1003  in the downward end (bottom of FIG  10 ). 
         [0074]    Second casing  102  has a substantially box shape formed by fitting two cases at an annular mating surface and is foldably connected to first casing  1001  through hinge section  103 . Specifically, the state of second casing  102  changes from a closed state (not illustrated) in which first casing  1001  and second casing  102  are vertically overlapped to an opened state of  FIG. 1  or from the opened state of  FIG. 1  to the closed state. Second casing  102  has second circuit board  115  therein. Second casing  102  includes waterproof packing  116  provided in the mating surface used to fit two cases and interposed between two cases and conductive element  118  integrated with waterproof packing  116  in hinge section  103  side. 
         [0075]    Hinge section  103  connects first casing  1001  and second casing  102  in a rotatable manner. 
         [0076]    First circuit board  110  is provided across substantially the entire surface of the inner side of first casing  1001 . First circuit board  110  includes power feeding section  1002 . Connector  112  is mounted on first circuit board  110  to electrically connect first circuit board  110  to second circuit board  115  through connector  117 , signal line  119 , and connector  112 . 
         [0077]    Power feeding section  1002  is provided in first circuit board  110  and feeds electricity to antenna  1003  to excite antenna  1003 . 
         [0078]    Antenna  1003  receives electricity fed from power feeding section  1002  and resonates at a desired frequency. 
         [0079]    The flow of the antenna current in portable radio device  1000  is the same as Embodiment 1 described above and overlapping explanation will be omitted. 
         [0080]    In this manner, according to the present embodiment, it is possible to obtain the effects that is the same as Embodiment 1 using the portable radio device in which the antenna is arranged in the downward end of the first casing. 
         [0081]    Although the conductive element is directly connected to the end of the circuit board according to the present embodiment, the present invention is not limited thereto, and similarly to Embodiment 3 described above, the conductive element may be grounded to the second circuit board through the reactance element. Although the waterproof packing is not provided in the first casing according to the present embodiment, the present invention is not limited thereto, the waterproof packing may be provided in the first casing, and the conductive element electrically connected to the end of the first circuit board may be provided in the waterproof packing provided in the first casing. 
         [0082]    Although the waterproof packing is used in Embodiments 1 to 4 described above, the present invention is not limited thereto, and any purpose packing having an excellent sealing property such as a dustproof packing may be used instead of the waterproof packing. Although description has been made for a folder type portable radio device in Embodiments 1 to 4, the present invention is not limited thereto, and the present invention may be applied to any type of portable radio devices such as a slide type portable radio device. Although description has been made for the portable radio device using two casings in Embodiments 1 to 4, the present invention is not limited thereto, and the present invention may be applied to the portable radio device using casings with an arbitrary number equal to or more than three. 
         [0083]    The disclosures of Japanese Patent Application No 2009484693 filed on Aug. 7, 2009, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0084]    The present invention is suitable especially for the portable radio device that is equipped with a plurality of casings and has a waterproof structure.