Abstract:
Provided is a portable wireless device which has a waterproofing effect and, at the same time, can improve resistance to static electricity. The portable wireless device ( 100 ) comprises a box-shaped housing ( 101 ) formed by fitting two cases at respective annular fitting surfaces of the two cases. In the portable wireless device ( 100 ), a circuit board ( 102 ) is provided in the housing ( 101 ). A waterproofing packing ( 103 ) has an annular shape and is provided between the fitting surfaces of the two cases and held by the two cases which constitute the housing ( 101 ). A conductor pattern ( 105 ) is integrally formed with the waterproofing packing ( 103 ) and is electrically connected to the circuit board ( 102 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a portable radio device especially having a waterproofing structure. 
       BACKGROUND ART 
       [0002]    It is important to secure resistance to static electricity from the outer side for an EMC countermeasure of electronic equipment. In particular, it is significantly difficult to secure resistance to static electricity in a mobile telephone because it is held by the hand, a circuit becomes integrated, and a gap between a case and a circuit is narrow due to miniaturization. In addition, problems such as a display-stop error may occur if the EMC countermeasure is not sufficient. 
         [0003]    As EMC countermeasures of the related art, there are known three techniques as follows. As a first technique, the intrusion of static electricity from a gap is prevented by minimizing the gap caused at the time of fitting a casing. As a second technique, a countermeasure component for static electricity such as a varistor is used. As a third technique, a ground configuration of the circuit board is optimized in order to reliably dissipate the static electricity. 
         [0004]    Under such circumstances, a waterproofing structure is widely employed as an essential structure of a mobile telephone. As a waterproofing structure for a mobile telephone, it is common to insert a waterproofing rubber packing to a gap between the casings (for example, Patent Literatures 1 and 2). 
         [0005]    Specifically, in Patent Literature 1, the waterproofing structure is implemented by arranging a packing in the vicinity of the circuit board and interposing a cable for connecting an upper casing and a lower casing therebetween. In addition, an antenna is disposed in the inner side of the waterproof packing disclosed in Patent Literature 2. 
       CITATION LIST 
     Patent Literature 
     PTL 1 
       [0000]    
       
         Japanese Patent Application. Laid-open No. 2005-32752 
       
     
       PTL 2 
       [0000]    
       
         Japanese Patent Application Laid-open No. HEI 6-37876 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0008]    However, in Patent Literature 1, there is a problem that, although it has a waterproofing effect, a gap between casings is generated than before due to the addition of the packing, so that resistance to static electricity is reduced. In addition, in Patent Literature 2, although it has an effect for static electricity countermeasure when static electricity is intruded from the vicinity of antenna elements, it has no effect for the static electricity when the static electricity is intruded from portions except the vicinity of antenna elements. 
         [0009]    It is therefore an object of the present invention to provide a portable radio device having a waterproofing effect and capable of improving resistance to static electricity at the same time. 
       Solution to Problem 
       [0010]    The portable radio device of the present invention has a casing that is box-shaped and formed by fitting two cases at a mating surface that is annular, employs a configuration having: a circuit board that is provided in the casing, a packing that is annular and is interposed between the first case and the second case on a mating surface between the first case and the second case forming the casing, and a conductive element that is integrated with the packing and electrically connected to the circuit board. 
       Advantageous Effects of Invention 
       [0011]    According to the present invention, it is possible to provide a portable radio device having a waterproofing effect and capable of improving resistance to static electricity at the same time. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  is a plan view illustrating a portable radio device according to Embodiment 1 of the present invention; 
           [0013]      FIG. 2  is a plan view illustrating a portable radio device according to Embodiment 2 of the present invention; and 
           [0014]      FIG. 3  is a plan view illustrating a portable radio device according to Embodiment 3 of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0015]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 1 
       [0016]      FIG. 1  is a plan view illustrating portable radio device  100  according to Embodiment 1 of the present invention. 
         [0017]    Portable radio device  100  is mainly formed by casing  101 , circuit board  102 , waterproof packing  103 , flexible printed circuit  104  (hereinafter, referred to as “FPC”), and IC  108 . Hereinafter, each configuration will be described in detail. 
         [0018]    Casing  101  has a box shape formed by fitting two cases at an annular mating surface. Casing  101  includes waterproof packing  103  arranged in the mating surface where two cases are fitted, and interposed between two cases. Moreover, casing  101  includes circuit board  102  and EPC  104 . 
         [0019]    Circuit board  102  is provided in casing  101 . IC  108  is mounted on circuit board  102 . Circuit board  102  is electrically connected to contact sections  106  and  107 . 
         [0020]    Waterproof packing  103  has an annular shape and is provided in the mating surface where two cases forming casing  101  are fitted. Waterproof packing  103  hermitically seats the gap between two cases formed when two cases are fitted by being interposed between two cases, Waterproof packing  103  is formed of a material having an elastic force that can reliably and hermitically seal the gap between two fitted cases. Waterproof packing  103  is formed integrally with FPC  104 . In this case, waterproof packing  103  is formed integrally with FPC  104  by flowing and cooling a liquid rubber material into annular FPC  104 . 
         [0021]    Conductor pattern  105  is formed in FPC  104 . FPC  104  has an annular shape and is formed integrally with waterproof packing  103 . 
         [0022]    Conductor pattern  105  is formed in FPC  104  and is arranged along outer peripheral section  101   a  of casing  101  and waterproof packing  103 . Conductor pattern  105  is formed integrally with contact sections  106  and  107  and is electrically connected to ground section of circuit board  102  through contact sections  106  and  107 . 
         [0023]    Contact section  106  is formed integrally with conductor pattern  105  and is electrically connected to the ground section of circuit board  102  in the upper left corner of circuit board  102  in  FIG. 1 . Contact section  106  is electrically connected to the ground section of circuit board  102  at a location farthest from IC  108  of circuit board  102 . Contact section  106  is electrically connected to the ground section of circuit board  102  by an elastic force of a spring structure or pressing of a protrusion (not illustrated) provided in casing  101  and the like. 
         [0024]    Contact section  107  is formed integrally with conductor pattern  105  and is electrically connected to the ground section of circuit board  102  in the rower right corner of circuit board  102  in  FIG. 1 . Contact section  107  is electrically connected to the ground section of circuit board  102  at a location farthest from IC  108  of circuit board  102 . Furthermore, contact section  107  is electrically connected to the ground section of circuit board  102  by an elastic force of a spring structure or pressing of a protrusion (not illustrated) provided in casing  101  and the like. 
         [0025]    IC  108  constitutes the circuit section and is mounted on circuit board  102 . 
         [0026]    Hereinbefore, the configuration of portable radio device  100  has been described. 
         [0027]    In portable radio device  100  having the configuration described above, static electricity intruding into the inner side of casing  101  from the outer side may dissipate to the ground section of circuit board  102  through contact section  106  and conductor pattern  105  of FPC  104  (path r 1 ), and may dissipate to the ground section of circuit board  102  through contact section  107  and conductor pattern  105  of FPC  104  (path r 2 ). 
         [0028]    Thus, according to the present embodiment, it is possible to provide a waterproof effect and improve a static electricity resistance by electrically connecting the conductor pattern integrated with the waterproof packing to the ground section of the circuit board. According to the present embodiment, since the conductor pattern is electrically connected to the ground section of the circuit board using two contact sections, it is possible to reliably and electrically connect the conductor pattern and the ground section of the circuit board. According to the present embodiment, since the conductor pattern and the ground section of the circuit board are connected at a location farthest from the IC of the circuit board, it is possible to minimize negative influence on the IC when static electricity dissipates to the ground section of the circuit board. According to the present embodiment, since the waterproof packing and the FPC having the conductor pattern are formed integrally, it is possible to simplify a task for arranging the conductor pattern to the casing and reduce the manufacturing cost. 
       Embodiment 2 
       [0029]      FIG. 2  is a plan view illustrating portable radio device  200  according to Embodiment 2 of the present invention. 
         [0030]    In portable radio device  200  illustrated in  FIG. 2 , resistors  201  and  202  are added to portable radio device  100  according to Embodiment 1 illustrated in  FIG. 1 . In addition, in  FIG. 2 , the same components in  FIG. 1  will be assigned the same reference numerals and overlapping explanation will be omitted. 
         [0031]    Portable radio device  200  is mainly formed by casing  101 , circuit board  102 , waterproof packing  103 , FPC  104 , IC  108 , and resistors  201  and  202 . Hereinafter, the present embodiment will describe components different from the above Embodiment 1 in detail. 
         [0032]    Casing  101  has a box shape formed by fitting two cases at an annular mating surface. Casing  101  includes waterproof packing  103  arranged in the mating surface where two cases are fitted, and interposed between two cases. Casing  101  includes circuit board  102 , FPC  104 , and resistors  201  and  202 . 
         [0033]    Circuit board  102  is provided in casing  101 . IC  108  is mounted on circuit board  102 , Circuit board  102  is electrically connected to resistors  201  and  202 . 
         [0034]    Conductor pattern  105  is formed in FPC  104  and is arranged along outer peripheral section  101   a  of casing  101  and waterproof packing  103 . In addition, conductor pattern  105  is formed integrally with contact sections  106  and  107 , is electrically connected to the ground section of circuit board  102  through contact section  106  and resistor  201 , and is electrically connected to the ground section of circuit board  102  through contact section  107  and resistor  202 . 
         [0035]    Contact section  106  is formed integrally with conductor pattern  105  and is electrically connected to resistor  201  in the upper left corner of circuit board  102  of circuit board  102  in  FIG. 1 . Furthermore, contact section  106  is electrically connected to resistor  201  by an elastic force of a spring structure or pressing of a protrusion (not illustrated) provided in casing  101  and the like. 
         [0036]    Contact section  107  is formed integrally with conductor pattern  105  and is electrically connected to resistor  202  in the lower right corner of circuit board  102  of circuit board  102  in  FIG. 1 . Furthermore, contact section  107  is electrically connected to resistor  202  by an elastic force of a spring structure or pressing of a protrusion (not illustrated) provided in casing  101  and the like. 
         [0037]    Resistor  201  is connected in series between contact section  106  and circuit board  102  and electrically connects contact section  106  and the ground section of circuit board  102 . Moreover, resistor  201  is electrically connected to the ground section of circuit board  102  at a location farthest from IC  108  of circuit board  102 . 
         [0038]    Resistor  202  is connected in series between contact section  107  and circuit board  102  and electrically connects contact section  107  and the ground section of circuit board  102 . Resistor  202  is electrically connected to the ground section of circuit board  102  at a location farthest from IC  108  of circuit board  102 . 
         [0039]    Hereinbefore, the configuration of portable radio device  200  has been described. 
         [0040]    In the portable radio device  200  having the configuration described above, static electricity intruding to the inner side of casing  101  from the outer side may dissipate to the ground section of circuit board  102  through conductor pattern  105  of FPC  104 , contact section  106 , and resistor  201 , and may dissipate to the ground section of circuit board  102  through conductor pattern  105  of FPC  104 , contact section  107 , and resistor  202 . 
         [0041]    Thus, according to the present embodiment, in addition to the effect of the above Embodiment 1, it is possible to further improve resistance to static electricity by reducing energy of static electricity using a resistor. 
       Embodiment 3 
       [0042]      FIG. 3  is a plan view illustrating portable radio device  300  in an opened state according to Embodiment 3 of the present invention. 
         [0043]    Portable radio device  300  illustrated in  FIG. 3  includes casings  301  and  302  which have the same configuration as casing  101 , instead of casing  101 , and additionally includes hinge section  303  in comparison with portable radio device  100  illustrated in  FIG. 1 . In addition, in  FIG. 3 , the same components in  FIG. 1  will be assigned the same reference numerals and overlapping explanation will be omitted. 
         [0044]    Portable radio device  300  is mainly formed by first casing  301 , second casing  302 , and hinge section  303 . 
         [0045]    First casing  301  is foldably connected to second casing  302  through hinge section  303 . Specifically, the state of first casing  301  changes from a closed state (not illustrated) in which first and second casings  301  and  302  are overlapped vertically to an opened state of  FIG. 3  or from the opened state of  FIG. 3  to the closed state. 
         [0046]    Second casing  302  is foldably connected to first casing  301  through hinge section  303 . Specifically, the state of second casing  302  changes from a closed state (not illustrated) in which first and second casings  301  and  302  are overlapped vertically to an opened state of  FIG. 3  or from the opened state of  FIG. 3  to the closed state. 
         [0047]    Hinge section  303  connects first and second casings  301  and  302  in a rotatable manner. 
         [0048]    In this manner, according to the present embodiment, in the portable radio device connected with rotatably connecting two casings, it is possible to obtain effects similar to those of Embodiment 1 described above. 
         [0049]    In addition, according to the present embodiment, although the contact section of the conductor pattern and the ground section of the circuit board are connected directly, the present embodiment is not limited thereto and, similarly to Embodiment 2, the contact section of the conductor pattern and the ground section of the circuit board may be connected through a resistor. 
         [0050]    In Embodiments 1 to 3 described above, although description has been made for the case where the structure of the portable radio device having a single casing or a folder type portable radio device, the present invention is not limited thereto and the present invention may be applied to any structure of the portable radio device such as a slide type. Although the IC is mounted on the circuit board in Embodiments 1 to 3 described above, the present invention is not limited thereto and any electronic component such as an LSI circuit other than the IC or the like may be mounted. Although the conductive element is electrically connected to the ground section of the circuit board using two contact sections in Embodiments 1 to 3 described above, the present invention is not limited thereto and the conductive element may be electrically connected to the ground section of the circuit board through any number of contact sections such as one or three or above. Although the waterproof packing is used in Embodiments 1 to 3 described above, the present invention is not limited thereto and any purpose packing with an excellent scaling property such as a dustproof packing other than the waterproof packing may be used. 
         [0051]    The disclosures of Japanese Patent Application No 2009-183495 filed on Aug. 6, 2009, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0052]    The present invention is suitable especially for the portable radio device having a waterproofing structure.