PATENT ABSTRACT
Disclosed is mobile wireless equipment wherein degradation of antenna performance in a condition with the casing closed can be prevented. In this mobile wireless equipment, a first casing ( 101 ) is provided with a circuit board ( 111 ). A second casing ( 102 ) is provided with a circuit board ( 112 ). A first hinge ( 104 ) is conductive and freely rotatably links the first casing ( 101 ) and the second casing ( 102 ), and is electrically connected with a power supply unit ( 121 ) by way of an antenna element ( 701 ). A second hinge ( 105 ) is conductive and freely rotatably links the first casing ( 101 ) and the second casing ( 102 ). A wireless circuit ( 113 ) is provided on the circuit board ( 112 ). The power supply unit ( 121 ) is electrically connected with the wireless circuit ( 113 ) and supplies power to the antenna element ( 701 ).

PATENT DESCRIPTION
TECHNICAL FIELD 
       [0001]    The present invention particularly relates to a mobile radio device having cases that can be opened and closed. 
       BACKGROUND ART 
       [0002]    A mobile radio device in which a ground pattern on a circuit substrate that is provided in a metallic frame mounted in an upper case or in the upper case, a hinge section, and a ground pattern on a circuit substrate that is provided in a lower case function as a dipole antenna has been known heretofore (see, for example, patent literature 1). 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         PTL 1: Japanese Patent Application Laid-Open N. 2005-6096 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    However, with the mobile radio device of patent literature 1, in its closed state in which an upper case and a lower case overlap each other, the metallic frame of the upper case and the circuit substrate of the lower case are placed close to each other, and the current that flows in the metallic frame and the current that flows in the circuit substrate flow in directions to cancel each other, resulting in deteriorated dipole antenna performance. 
         [0005]    As a method of solving this problem, a study is underway to use a hinge section to connect an upper case and a lower case in a rotatable fashion as a monopole antenna element, and, by this means, use the above-mentioned dipole antenna in an open state and use a monopole antenna in a closed state. 
         [0006]    However, to use this hinge section as a monopole antenna element, the hinge section, having to have certain strength to function as a rotation axis to allow the upper case and the lower case to rotate, is difficult to miniaturize. As a result of this, the hinge section approaches a ground section in the lower case and a ground section in the upper case close, and, in a state where these cases are closed, deterioration of antenna performance becomes a problem. 
         [0007]    The present invention has been made in view of the above, and it is therefore an object of the present invention to provide a mobile radio device that can prevent antenna performance from deteriorating in a state in which cases are closed. 
       Solution to Problem 
       [0008]    A mobile radio device according to the present invention employs a configuration having: a first case having a first circuit substrate; a second case having a second circuit substrate; a hinge section that is electrically conductive and that connects the first case and the second case in a rotatable fashion; an antenna element; a radio circuit that is provided in the first circuit substrate or in the second circuit substrate; and a power feed section that is electrically connected with the radio circuit and that feeds power to the antenna element, and, in this mobile radio device, the hinge section is electrically connected with the power feed section via the antenna element. 
       Advantageous Effects of Invention 
       [0009]    With the present invention, it is possible to prevent antenna performance from deteriorating in a state in which cases are closed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is plan view showing a mobile radio device according to embodiment 1 of the present invention; 
           [0011]      FIG. 2  is plan view showing a mobile radio device according to embodiment 1 of the present invention; 
           [0012]      FIG. 3  is plan view showing a mobile radio device according to embodiment 1 of the present invention; 
           [0013]      FIG. 4  is a perspective view showing principal parts of a mobile radio device according to embodiment 1 of the present invention; 
           [0014]      FIG. 5  is plan view showing a mobile radio device according to embodiment 2 of the present invention; 
           [0015]      FIG. 6  is a perspective view showing principal parts of a mobile radio device according to embodiment 2 of the present invention; 
           [0016]      FIG. 7  is plan view showing a mobile radio device according to embodiment 3 of the present invention; 
           [0017]      FIG. 8  is a perspective view showing principal parts of a mobile radio device according to embodiment 3 of the present invention; 
           [0018]      FIG. 9  provides another view of principal parts of a mobile radio device according to embodiment 3 of the present invention; 
           [0019]      FIG. 10  is plan view showing a mobile radio device according to embodiment 4 of the present invention; and 
           [0020]      FIG. 11  is plan view showing a mobile radio device according to embodiment 5 of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0021]    Now, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 1 
       [0022]      FIG. 1  to  FIG. 3  shows plan views of mobile radio device  100  according to embodiment 1 of the present invention.  FIG. 1  and  FIG. 3  show mobile radio device  100  in an open state, and  FIG. 2  shows mobile radio device  100  in a closed state. 
         [0023]    Mobile radio device  100  has three cases: first case  101 , second case  102 , and third case  103 . Also, first case  101 , second case  102  and third case  103  are connected in a mutually rotatable fashion about first hinge section  104  as a rotation axis. Also, first case  101 , second case  102  and third case  103  are connected in a mutually rotatable fashion about second hinge section  105  as a rotation axis. 
         [0024]    Now, each component of mobile radio device  100  will be described in detail. 
         [0025]    First case  101  has a rectangular shape on a plan view, and is rotatably connected with second case  102 , via third case  103 , by means of first hinge section  104  or second hinge section  105 . Also, first case  101  has circuit substrate  111  inside. Also, first case  101  has a display surface (not shown) that is exposed to the outside and displays an image when mobile radio device  100  is open. 
         [0026]    Second case  102  has a rectangular shape on a plan view, and is rotatably connected with first case  101 , via third case  103 , by means of first hinge section  104  or second hinge section  105 . Also, first case  101  has an operation surface (not shown) that is exposed to the outside and is operated during a call and so on, when mobile radio device  100  is open. Second case  102  has circuit substrate  112  inside. 
         [0027]    Third case  103  accommodates first hinge section  104  and part of second hinge section  105  inside. Also, third case  103  accommodates antenna element  116  and matching circuit  117  inside. Also, third case  103  accommodates part of coaxial wire  115  inside. 
         [0028]    First hinge section  104  is formed of an electrically conductive material, and connects first case  101 , second case  102  and third case  103  in a rotatable fashion, so as to switch from the open state shown in  FIG. 1  to the closed state shown in  FIG. 2 , or from the closed state of  FIG. 2  to the open state of  FIG. 1 . That is to say, first hinge section  104  connects first case  101 , second case  102  and third case  103 , in a rotatable fashion, along the long direction of first case  101  or second case  102  (encompassing the upward or downward directions in  FIG. 1  to  FIG. 3 ). First hinge section  104  is furthermore electrically connected with antenna element  116  and is also electrically connected with terminating end section  114 . 
         [0029]    Second hinge section  105  is formed of an electrically conductive material, and connects first case  101 , second case  102  and third case  103  in a rotatable fashion, so as to switch from the open state shown in  FIG. 2  to the closed state shown in  FIG. 3 , or from the closed state of  FIG. 2  to the open state of  FIG. 3 . That is to say, second hinge section  105  connects first case  101 , second case  102  and third case  103 , in a rotatable fashion, along a direction perpendicular to the long direction (encompassing the left and right directions in  FIG. 1  to  FIG. 3 ). Also, second hinge section  105  is electrically connected with a ground section of matching circuit  117 , via connecting section  120 , and is also electrically connected with a ground section of circuit substrate  111 , via a terminating circuit (not shown in  FIG. 1  to  FIG. 3 ). Second hinge section  105  is designed to be able to rotate with first case  101  when rotating first case  101  about first hinge section  104  as a rotation axis. 
         [0030]    Circuit substrate  111  has an electrically conductive circuit pattern (not shown) on a flat surface part, and has a ground section nearly over the entire surface (now shown). Also, circuit substrate  111  is electrically connected with second hinge section  105 . The ground section is formed by, for example, printing a ground pattern on circuit substrate  111 . 
         [0031]    Circuit substrate  112  has an electrically conductive circuit pattern (not shown) on a flat surface part, and has a ground section nearly over the entire surface (now shown). Circuit substrate  112  has radio circuit  113  that is grounded to a ground section and terminating end section  114  that is grounded to a ground section. A ground section is formed by, for example, printing a ground pattern on circuit substrate  112 . 
         [0032]    Radio circuit  113  is electrically connected with coaxial wire  115 . Also, radio circuit  113  performs receiving processing for a signal received by an antenna and performs transmitting processing for a signal to be transmitted from an antenna. 
         [0033]    Terminating end section  114  is formed with a reactance element, and is electrically connected with a ground section of circuit substrate  112  and first hinge section  104 . 
         [0034]    Coaxial wire  115  is provided to supply power, and is electrically connected with radio circuit  113  and matching circuit  117 . The ground of coaxial wire  115  is connected to a ground of circuit substrate  112  and hinge section  105 . 
         [0035]    Antenna element  116  is electrically connected with matching circuit  117  via connecting section  118 . Also, antenna element  116  is electrically connected with first hinge section  104  by means of connecting section  119 . Antenna element  116  is formed by, foe example, printing an electrically conductive pattern on an insulating substrate. Also, antenna element  116  is designed, for example, as an antenna of an approximately ¼ wavelength to oscillate in the 800 MHz band. 
         [0036]    Matching circuit  117  is electrically connected with radio circuit  113  via coaxial wire  115 , is electrically connected with antenna element  116  via connecting section  118 , and matches impedance between antenna element  116  and radio circuit  113 . Also, a ground section of matching circuit  117  is electrically connected with second hinge section  105  by means of connecting section  120 . 
         [0037]    In mobile radio device  100  having the above configuration, antenna element  116 , first hinge section  104 , terminating end section  114 , and a ground section of circuit substrate  112  are mutually electrically connected, and antenna element  116  is fed power from power feed section  121 . By this means, in both an open state and a closed state of mobile radio device  100 , antenna element  116 , first hinge section  104 , terminating end section  114 , and a ground section of circuit substrate  112  function as an antenna of an approximately ¼ wavelength. This antenna of an approximately ¼ wavelength configured this way resonates, for example, in the 800 MHz band. 
         [0038]    Distance L 1  between antenna element  116  and a ground section of circuit substrate  112  is made greater than distance L 2  between first hinge section  104  and a ground section of circuit substrate  112  (L 1 &gt;L 2 ) (see  FIG. 2 ). Also, distance L 3  between antenna element  116  and a ground section of circuit substrate  111  is made greater than distance L 4  between first hinge section  104  and a ground section of circuit substrate  111  (L 3 &gt;L 4 ) (not shown). By this means, mobile radio device  100  is able to alleviate the influence of a ground section of circuit substrate  112  and a ground section of circuit substrate  111  upon antenna element  116 . 
         [0039]    Next, the configuration of mobile radio device  100  will be described in more detail with reference to  FIG. 4 .  FIG. 4  is a perspective view of mobile radio device  100 . Parts in  FIG. 4  that are the same as in  FIG. 1  to  FIG. 3  will be assigned the same reference numerals as in  FIG. 1  to  FIG. 3  and their explanations will be omitted. 
         [0040]    Connecting section  401  is formed of an electrically conductive material and electrically connects first hinge section  104  and terminating end section  114 . 
         [0041]    Connecting section  402  is formed of an electrically conductive material that allows elastic deformation, and electrically connects antenna element  116  and first hinge section  104 . 
         [0042]    Substrate  403  is formed of an insulating material, and, using an electrically conductive material, antenna element  116  and matching circuit  117  are printed on an upper surface section. Also, substrate  403  has a throughhole (not shown) that penetrates from the upper surface section to the back surface section, and has a conductive layer in the inner wall part of the throughhole. This throughhole electrically connects antenna element  116  and connecting section  402 . 
         [0043]    Connecting section  404  is formed of an electrically conductive material that allows elastic deformation, and electrically connects a ground section of matching circuit  117  and second hinge section  105 . Connecting section  404  is pressed against second hinge section  105 , so that connection section  404  maintains an electrical connection with second hinge section  105  when second hinge section  105  rotates following the rotation of first case  101 . 
         [0044]    Connecting section  405  is formed of an electrically conductive material and electrically connects second hinge section  105  and terminating end section  406 . 
         [0045]    Terminating end section  406  is grounded to a ground section of circuit substrate  111  and terminates second hinge section  105  in a ground section of circuit substrate  111  via connection section  405 . Also, terminating end section  406  is formed with a reactance element and electrically connects a ground section of circuit substrate  111  and second hinge section  105 . In  FIG. 1  and  FIG. 3 , terminating end section  406  is not shown for ease of explanation. 
         [0046]    For example, antenna element  116  is placed such that distance L 1  between antenna element  116  and a ground section of circuit substrate  112  is 12 mm and distance L 3  between antenna element  116  and a ground section of circuit substrate  111  is 11 mm. First hinge section  104  has to function as a rotation axis and therefore cannot be miniaturized and cannot be provided in a place of poor balance, and, as a result, distance L 2  between first hinge section  104  and a ground section of circuit substrate  112  has to be 5 mm, for example. Thus, with the present embodiment, antenna element  116  is placed such that L 1 &gt;L 2  and L 3 &gt;L 2 . Also, although not shown in  FIG. 4 , antenna element  116  is placed such that distance L 4  between first hinge section  104  and a ground section of circuit substrate  111  holds the relationship L 1 &gt;L 4  and L 3 &gt;L 4 . By this means, compared to first hinge section  104 , antenna element  116  is placed in a location substantially distant from both a ground section of circuit substrate  111  and a ground section of circuit substrate  112 , so that it is possible to reduce the influence of both the ground section of circuit substrate  111  and the ground section of circuit substrate  112  upon antenna element  116 . 
         [0047]    In this way, with the present embodiment, by feeding power to a hinge section via an antenna element, it is possible to allow a ground section of a circuit substrate provided in the first case, a hinge section, and a ground section of a circuit substrate provided in a second case, as a dipole antenna, and achieve high antenna performance in an open state. Also, in addition to this, by feeding power to an antenna element provided in a distant location from a ground section of a circuit substrate, it is possible to prevent antenna performance from deteriorating in a closed sate. Also, with the present embodiment, for example, the length of an antenna element can be changed easily, so that, by adjusting an antenna element, it is possible to provide an antenna of better sensitivity. 
       Embodiment 2 
       [0048]      FIG. 5  is a plan view of mobile radio device  500  according to embodiment 2 of the present invention.  FIG. 5  shows mobile radio device  500  in an open state. 
         [0049]    Mobile radio device  500  shown in  FIG. 5  adds filter  501 , connecting section  502 , and connecting section  503  to mobile radio device  100  of embodiment 1 shown in  FIG. 1 , except for connecting section  119 . Parts in  FIG. 5  that are the same as in  FIG. 1  will be assigned the same reference numerals as in  FIG. 1  and their explanations will be omitted. Also, with mobile radio device  500  according to the present embodiment, the closed state is the same as shown in  FIG. 2  and the state in which first case  101  rotates in a direction perpendicular to the rotation direction in  FIG. 5  and is open, is the same as in  FIG. 3 , and their explanations therefore will be omitted. 
         [0050]    Third case  103  accommodates first hinge section  104  and part of second hinge section  105  inside. Also, third case  103  accommodates part of coaxial wire  115  inside. 
         [0051]    Antenna element  116  is electrically connected with matching circuit  117  via connecting section  118 . Also, antenna element  116  is fed power from power feed section  121  and functions as an antenna. Also, antenna element  116  is electrically connected with filter  501  by means of connecting section  502 . Antenna element  116  is formed by, for example, printing an electrically conductive pattern on an insulating substrate. Antenna element  116  has, for example, an electrical length to resonate in the 2 GHz band. 
         [0052]    Filter  501  is formed with a reactance element and is connected between antenna element  116  and first hinge section  104 . Also, filter  501  is electrically connected with antenna element  116  by means of connecting section  502  and is also electrically connected with first hinge section  104  by means of connecting section  503 , thereby electrically connecting first hinge section  104  and antenna element  116 . Also, filter  501  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  116  resonates in the 2 GHz band, filter  501  prevents first hinge section  104  from functioning as an antenna. Also, filter  501 , by designing filter  501  to have high impedance in other radio frequency bands as well, it is possible to allow filter  501  to secure isolation from antennas of other radio circuits. For example, it is possible to allow filter  501  to function as a filter to block the frequency band for digital television broadcast by having high impedance also in the 400 MHz band. 
         [0053]    In mobile radio device  500  having the above configuration, antenna element  116 , filter  501 , first hinge section  104 , terminating end section  114 , and a ground section of circuit substrate  112  are electrically connected with each other, and antenna element  116  is fed power from power feed section  121 . By this means, in a state in which mobile radio device  500  is open, antenna element  116 , filter  501 , first hinge section  104 , terminating end section  114 , and a ground section of circuit substrate  112  function as an antenna of an approximately ¼ wavelength. An antenna of an approximately ¼ wavelength configured this way resonates at a lower frequency (for example, in the 800 MHz band) than the 2 GHz band, which is a resonant frequency of antenna element  116 . 
         [0054]    Antenna element  116  has an electrical length of an approximately ¼ wavelength in the 2 GHz band, and resonates in the 2 GHz band in both an open state and a closed state. Filter  501  then blocks the 2 GHz band, so that the electrical connection between antenna element  116  and first hinge section  104  is blocked. As a result of this, when antenna element  116  resonates in the 2 GHz band, antenna element  116  alone functions as an antenna. 
         [0055]    Next, the configuration of mobile radio device  500  will be described in more detail with reference to  FIG. 6 .  FIG. 6  is a perspective view of principal parts of mobile radio device  500 . 
         [0056]    Mobile radio device  500  shown in  FIG. 6  adds filter  501  and connecting section  602  to mobile radio device  100  of embodiment 1 shown in  FIG. 4 , and has connecting section  601  in place of connecting section  402 . Parts in  FIG. 6  that are the same as in  FIG. 4  and  FIG. 5  will be assigned the same reference numerals as in  FIG. 4  and  FIG. 5  and their explanations will be omitted. 
         [0057]    Substrate  403  is formed of an insulating material, and, using an electrically conductive material, antenna element  116 , matching circuit  117 , filter  501  and connection section  602  are printed on an upper surface section. Also, substrate  403  has a throughhole (not shown) that penetrates from the upper surface section to the back surface section, and has a conductive layer in the inner wall part of the throughhole. This throughhole electrically connects filter  501  and connecting section  601 . 
         [0058]    Connecting section  601  is formed of an electrically conductive material that allows elastic deformation, and electrically connects filter  501  and first hinge section  104 . 
         [0059]    Connecting section  602  is formed of an electrically conductive material and electrically connects antenna element  116  and filter  501 . 
         [0060]    Like  FIG. 4 , with the present embodiment, antenna element  116  is provided such that L 1 &gt;L 2  and L 3 &gt;L 2 . Also, although not shown in  FIG. 4 , antenna element  116  is placed such that distance L 4  between first hinge section  104  and a ground section of circuit substrate  111  holds the relationship L 1 &gt;L 4  and L 3 &gt;L 4 . By this means, compared to first hinge section  104 , antenna element  116  is placed in a location substantially distant from both a ground section of circuit substrate  111  and a ground section of circuit substrate  112 , so that it is possible to reduce the influence of both the ground section of circuit substrate  111  and the ground section of circuit substrate  112  upon antenna element  116 . 
         [0061]    Heretofore, to supply power to a hinge section directly and allow a hinge section to have a function to connect cases in a rotatable fashion, the shape has been limited, and, when forming a double-resonance antenna, it has been difficult to form an antenna to resonate at a desired frequency due to the hinge part. 
         [0062]    In this way, with the present embodiment, to prevent a hinge section from resonating in the 2 GHz band, the 2 GHz band is blocked by means of a filter, and an antenna element that resonates in the 2 GHz band is placed distant from a ground section of a circuit substrate, so that it is possible to achieve high antenna performance in the 2 GHz band in both an open state and a closed state. Also, in the 800 MHz band, by supplying power to a hinge section via an antenna element, it is possible to allow a ground section of a circuit substrate provided in the first case, a hinge section, and a ground section of a circuit substrate provided in a second case function as a dipole antenna to resonate in the 800 MHz band, and achieve high antenna performance in the 800 MHz band in an open state. Also, the present embodiment makes it easy to change the length of antenna element, so that, by changing the length of an antenna element, it is possible to adjust a resonant frequency flexibly. 
         [0063]    Although the present embodiment is configured to connect antenna element  116  and first hinge section  104  via filter  501 , the present invention is by no means limited to this, and it is equally possible to connect antenna element  116  and first hinge section  104  via an arbitrary reactance element. For example, instead of filter  501 , it is equally possible to use capacitance and coil circuit configurations that function as an arbitrary capacitor and an inductor in the 800 MHz band and in the 2 GHz band. 
       Embodiment 3 
       [0064]      FIG. 7  is a plan view of mobile radio device  700  according to embodiment 3 of the present invention.  FIG. 7  shows mobile radio device  700  in an open state. 
         [0065]    Mobile radio device  700  shown in  FIG. 7  adds filter  703 , filter  704 , connecting section  705  and connecting section  706 , to mobile radio device  100  according to embodiment 1 shown in  FIG. 1 , except for connecting section  119 , and has antenna element  701  and antenna element  702  instead of antenna element  116 . Parts in  FIG. 7  that are the same as in  FIG. 1  will be assigned the same reference numerals as in  FIG. 1  and their explanations will be omitted. Also, with mobile radio device  700  according to the present embodiment, the closed state is the same as shown in  FIG. 2  and the state in which first case  101  rotates in a direction perpendicular to the rotation direction in  FIG. 5  and is open, is the same as in  FIG. 3 , and their explanations therefore will be omitted. 
         [0066]    Third case  103  accommodates first hinge section  104  and part of second hinge section  105  inside. Also, third case  103  accommodates antenna element  701 , antenna element  702 , matching circuit  117 , filter  703  and filter  704  inside. Third case  103  also accommodates part of coaxial wire  115  inside. 
         [0067]    Antenna element  701  is electrically connected with matching circuit  117  via connecting section  118 . Antenna element  701  is fed power from power feed section  121  and functions as an antenna. Also, antenna element  701  is electrically connected with first hinge section  104  via filter  704 . Antenna element  701  is also electrically connected with antenna element  702  via filter  703 . Antenna element  701  is formed by, for example, printing an electrically conductive pattern on an insulating substrate. Antenna element  701  also has an electrical length to resonate, for example, in the 2 GHz band. 
         [0068]    Filter  703  is, for example, a bandpass filter, and is formed with a reactance element. Filter  703  is electrically connected between antenna element  701  and antenna element  702 , and, by this means, electrically connects antenna element  701  and antenna element  702 . Also, filter  703  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  701  resonates in the 2 GHz band, filter  703  prevents antenna element  702  from functioning as an antenna. 
         [0069]    Antenna element  702 , including antenna element  701  and filter  703 , has an electrical length to have an approximately ¼ wavelength in the 800 MHz. Antenna element  702  is also electrically connected with antenna element  701  via filter  703 . Antenna element  702  is formed by, for example, printing an electrically conductive pattern on an insulating substrate. 
         [0070]    Filter  704  is formed with a reactance element and is connected between antenna element  701  and first hinge section  104 . Also, filter  704  is electrically connected with antenna element  701  by means of connecting section  705  and is also electrically connected with first hinge section  104  by means of connecting section  706 , thereby electrically connecting first hinge section  104  and antenna element  701 . Also, filter  704  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  701  resonates in the 2 GHz band, filter  704  prevents first hinge section  104  from functioning as an antenna. 
         [0071]    In mobile radio device  700  having the above configuration, antenna element  701 , filter  704 , first hinge section  104 , terminating end section  114 , and a ground section of circuit substrate  112  are mutually electrically connected, and antenna element  701  is fed power from power feed section  121 . By this means, in a state in which mobile radio device  700  is open, antenna element  701 , filter  704 , first hinge section  104 , terminating end section  114 , and a ground section of circuit substrate  112  function as an antenna of an approximately ¼ wavelength in the 800 MHz band. Also, in mobile radio device  700  having the above configuration, antenna element  701 , filter  703 , antenna element  702  are mutually electrically connected, and antenna element  701  is fed power from power feed section  121 . By this means, in a state in which mobile radio device  700  is closed, antenna element  701 , filter  703 , and antenna element  702  function as an antenna of an approximately ¼ wavelength in the 800 MHz band. This antenna of an approximately ¼ wavelength configured this way resonates, for example, in the 800 MHz band. 
         [0072]    Meanwhile, antenna element  701  functions as an antenna to resonate in the 2 GHz band in both an open state and a closed state. Filter  703  and filter  704  block the 2 GHz band, so that the electrical connection between antenna element  701  and first hinge section  104  is blocked and the electrical connection between antenna element  701  and antenna element  702  is blocked. As a result of this, when antenna element  701  resonates in the 2 GHz band, antenna element  701  alone functions as an antenna. 
         [0073]    Next, the configuration of mobile radio device  700  will be described in more detail with reference to  FIG. 8 .  FIG. 8  is a perspective view of principal parts of mobile radio device  700 . 
         [0074]    Mobile radio device  700  shown in  FIG. 8  adds antenna element  701 , antenna element  702 , filter  703 , filter  704 , and connecting section  802 , to mobile radio device  100  of embodiment 1 shown in  FIG. 4 , and has connecting section  801  instead of connecting section  402 . Parts in  FIG. 8  that are the same as in  FIG. 4  and  FIG. 7  will be assigned the same reference numerals as in  FIG. 4  and  FIG. 7  and their explanations will be omitted. 
         [0075]    Substrate  403  is formed of an insulating material, and, using an electrically conductive material, antenna element  701 , antenna element  702 , matching circuit  117 , filter  703 , filter  704  and connection section  702 , are printed on an upper surface section. Also, substrate  403  has a throughhole (not shown) that penetrates from the upper surface section to the back surface section, and has a conductive layer in the inner wall part of the throughhole. This throughhole electrically connects filter  704  and connecting section  801 . 
         [0076]    Connecting section  801  is formed of an electrically conductive material that allows elastic deformation, and electrically connects filter  704  and first hinge section  104 . 
         [0077]    Connecting section  802  is formed of an electrically conductive material and electrically connects antenna element  701  and filter  704 . 
         [0078]    Like  FIG. 4 , with the present embodiment, antenna element  701  and antenna element  702  are provided such that L 1 &gt;L 2  and L 3 &gt;L 2 . Also, although not shown in  FIG. 8 , antenna element  701  and antenna element  702  are placed such that distance L 4  between first hinge section  104  and a ground section of circuit substrate  111  holds the relationship L 1 &gt;L 4  and L 3 &gt;L 4 . By this means, compared to first hinge section  104 , antenna element  701  and antenna element  702  are placed in locations substantially distant from both a ground section of circuit substrate  111  and a ground section of circuit substrate  112 , so that it is possible to reduce the influence of both the ground section of circuit substrate  111  and the ground section of circuit substrate  112  upon antenna element  701  and antenna element  702 . 
         [0079]      FIG. 9  provides another view of principal parts of mobile radio device  700 . Parts in  FIG. 9  that are the same as in  FIG. 7  will be assigned the same reference numerals as in  FIG. 7  and their explanations will be omitted. 
         [0080]      FIG. 9  shows connecting section  901  in place of filter  703 . 
         [0081]    Connecting section  901  has a meander shape and electrically connects matching circuit  117  and antenna element  702 . Also, connecting section  901  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  701  resonates in the 2 GHz band, connecting section  901  prevents antenna element  702  from functioning as an antenna. 
         [0082]    By this means, with the present embodiment, by providing a double-resonant antenna element apart from a ground section of a circuit substrate, it is possible to achieve high antenna performance in both the 800 MHz band and 2 GHz band in a closed state. Also, in the 800 MHz band, by supplying power to a hinge section via an antenna element, it is possible to allow a ground section of a circuit substrate provided in the upper first case, a hinge section, and a ground section of a circuit substrate provided in a lower second case function as a dipole antenna to resonate in the 800 MHz band, and achieve high antenna performance in the 800 MHz band in an open state. Furthermore, to prevent a hinge section from resonating in the 2 GHz band, the 2 GHz band is blocked by means of a filter, and an antenna element that resonates in the 2 GHz band is placed distant from a ground section of a circuit substrate, so that it is possible to prevent antenna performance from deteriorating in the 2 GHz band. Also, the present embodiment makes it easy to change the length of antenna element, so that, by changing the length of an antenna element, it is possible to adjust two resonant frequencies flexibly. 
         [0083]    Although the present embodiment is configured to connect antenna element  703  and first hinge section  104  via filter  704 , the present invention is by no means limited to this, and it is equally possible to connect antenna element  703  and first hinge section  104  via an arbitrary reactance element. For example, instead of filter  704 , it is equally possible to use capacitance and coil circuit configurations that function as an arbitrary capacitor and an inductor in the 800 MHz band and in the 2 GHz band. 
       Embodiment 4 
       [0084]      FIG. 10  is plan view showing mobile radio device  1000  according to embodiment 4 of the present invention. 
         [0000]      FIG. 10  shows mobile radio device  1000  in an open state. 
         [0085]    Mobile radio device  1000  has three cases: first case  1001 , second case  1002 , and third case  1003 . Also, first case  1001 , second case  1002  and third case  1003  are connected in a mutually rotatable fashion about hinge section  1004  as a rotation axis. 
         [0086]    First case  1001  has a rectangular shape on a plan view, and is rotatably connected with second case  1002 , via third case  1003 , by means of hinge section  1004 . Also, first case  1001  has circuit substrate  1011  inside. Also, first case  1001  has a display surface (not shown) that is exposed to the outside and displays an image when mobile radio device  1000  is open. 
         [0087]    Second case  1002  has a rectangular shape on a plan view, and is rotatably connected with first case  1001 , via third case  1003 , by means of hinge section  1004 . Also, second case  1002  has an operation surface (not shown) that is exposed to the outside and is operated during a call and so on, when mobile radio device  1000  is open. Second case  1002  furthermore has circuit substrate  1012  inside. 
         [0088]    Third case  1003  has hinge section  1004 . Also, third case  1003  has antenna element  1015 , antenna element  1016 , filter  1017 , and filter  1018 . 
         [0089]    Hinge section  1004  is formed of an electrically conductive material, and connects first case  1001  and second case  1002  in a rotatable fashion, along the long direction of first case  1001  or second case  1002  (encompassing the upward or downward directions in  FIG. 10 ), so as to switch from the open state shown in  FIG. 10  to a closed state in which first case  1001  and second case  1002  overlap (not shown) or from the closed state to the open state of  FIG. 10 . Hinge section  1004  is furthermore electrically connected with antenna element  1016  and is also electrically connected with a ground section of circuit substrate  1012  via terminating end section  1019 . 
         [0090]    Circuit substrate  1011  has an electrically conductive circuit pattern (not shown) formed on a flat surface section, and has a ground section (not shown) over nearly the entire surface. Circuit substrate  1011  has radio circuit  1013  that is grounded in a ground section and matching circuit  1014 . The ground section is formed by, for example, printing a ground pattern on circuit substrate  1011 . 
         [0091]    Circuit substrate  1012  has an electrically conductive circuit pattern (not shown) on a flat surface part, and has a ground section nearly over the entire surface (now shown). Circuit substrate  1012  also has terminating end section  1019 . The ground section is formed by, for example, printing a ground pattern on circuit substrate  1012 . 
         [0092]    Radio circuit  1013  is grounded to a ground section of circuit substrate  1011  and is also electrically connected with matching circuit  1014 . Also, radio circuit  113  performs receiving processing for a signal received by an antenna and performs transmitting processing for a signal to be transmitted from an antenna. 
         [0093]    Matching circuit  1014  is electrically connected between radio circuit  1013  and antenna element  1015  and matches impedance between radio circuit  1013  and antenna element  1015 . 
         [0094]    Antenna element  1015  is electrically connected with matching circuit  1014 . Antenna element  1015  is fed power from power feed section  1020  and functions as an antenna. Also, antenna element  1015  is electrically connected with antenna element  1016  via filter  1017 . Antenna element  1015  is also electrically connected with hinge section  1004  via filter  1018 . Antenna element  1015  also has an electrical length to resonate, for example, in the 2 GHz band. Antenna element  1015  is formed by, for example, printing an electrically conductive pattern on an insulating substrate. 
         [0095]    Antenna element  1016 , including antenna element  1015  and filter  1017 , has an electrical length to have an approximately ¼ wavelength in the 800 MHz. Antenna element  1016  is also electrically connected with antenna element  1015  via filter  1017 . Antenna element  1016  is formed by, for example, printing an electrically conductive pattern on an insulating substrate. 
         [0096]    Filter  1017  is, for example, a bandpass filter, and is formed with a reactance element. Filter  1017  is electrically connected between antenna element  1015  and antenna element  1016 , and, by this means, electrically connects antenna element  1015  and antenna element  1016 . Also, filter  1017  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  1015  resonates in the 2 GHz band, filter  1017  prevents antenna element  1016  from functioning as an antenna. 
         [0097]    Filter  1018  is formed with a reactance element, and is connected between antenna element  1015  and hinge section  1004 . Also, filter  1018  is electrically connected with antenna element  1015  and is also electrically connected with hinge section  1004 , thereby electrically connecting hinge section  1004  and antenna element  1015 . Also, filter  1018  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  1015  resonates in the 2 GHz band, filter  1018  prevents hinge section  1004  from functioning as an antenna. 
         [0098]    Terminating section  1019  is formed with a reactance element, and electrically connects a ground section of circuit substrate  1012  and hinge section  1004 . 
         [0099]    In mobile radio device  1000  having the above configuration, antenna element  1015 , hinge section  1004 , terminating end section  1019 , and a ground section of circuit substrate  1012  are mutually electrically connected, and antenna element  1015  is fed power from power feed section  1020 . By this means, in a state in which mobile radio device  1000  is open, antenna element  1015 , filter  1018 , hinge section  1004 , terminating end section  1019 , and a ground section of circuit substrate  1012  function as an antenna of an approximately ¼ wavelength in the 800 MHz band. Furthermore, in mobile radio device  1000 , antenna element  1015 , filter  1017 , and antenna element  1016  are mutually electrically connected, and antenna element  1015  is fed power from power feed section  1020 . By this means, in a state in which mobile radio device  1000  is closed, antenna element  1015 , filter  1017 , and antenna element  1016  function as an antenna of an approximately ¼ wavelength in the 800 MHz band. This antenna of an approximately ¼ wavelength configured this way resonates, for example, in the 800 MHz band. 
         [0100]    Meanwhile, antenna element  1015  functions as an antenna to resonate in the 2 GHz band in both an open state and a closed state. Filter  1017  and filter  1018  then block the 2 GHz band, so that the electrical connection between antenna element  1015  and hinge section  1004  is blocked, and the electrical connection between antenna element  1015  and antenna element  1016  is blocked. As a result of this, when antenna element  1015  resonates in the 2 GHz band, antenna element  1015  alone functions as an antenna. 
         [0101]    Distance L 10  between antenna element  1015  and antenna element  1016  and a ground section of circuit substrate  1012  is made greater than distance L 11  between hinge section  1004  and a ground section of circuit substrate  1012  (L 10 &gt;L 11 ) (see  FIG. 10 ). Also, distance L 12  between antenna element  1015  and antenna element  1016  and a ground section of circuit substrate  1011  is made greater than distance L 13  between hinge section  1004  and a ground section of circuit substrate  1012  (L 12 &gt;L 13 ) (not shown). By this means, mobile radio device  1000  is able to alleviate the influence of a ground section of circuit substrate  1011  and a ground section of circuit substrate  1012  upon antenna element  1015  and antenna element  1016 . 
         [0102]    By this means, with the present embodiment, by providing double resonant antenna elements apart from a ground section of a circuit substrate, it is possible to achieve high antenna performance in both the 800 MHz band and 2 GHz band in a closed state. Also, in the 800 MHz band, by supplying power to a hinge section via an antenna element, it is possible to allow a ground section of a circuit substrate provided in the first case, a hinge section, and a ground section of a circuit substrate provided in a second case function as a dipole antenna to resonate in the 800 MHz band, and achieve high antenna performance in the 800 MHz band in an open state. Furthermore, to prevent a hinge section from resonating in the 2 GHz band, the 2 GHz band is blocked by means of a filter, and an antenna element that resonates in the 2 GHz band is placed distant from a ground section of a circuit substrate, so that it is possible to prevent antenna performance from deteriorating in the 2 GHz band. Also, with the present embodiment, for example, the length of an antenna element can be changed easily, so that, by adjusting an antenna element, it is possible to provide an antenna of better sensitivity. 
         [0103]    Although a double-resonant antenna has been realized with the present embodiment, the present invention is by no means limited to this, and it is equally possible to present a single-resonant antenna. Also, although with the present embodiment an antenna element and a hinge section are electrically connected via a filter, the present invention is by no means limited to this, and it is equally possible to connect an antenna element and a hinge section electrically without involving a filter. 
       Embodiment 5 
       [0104]      FIG. 11  is a plan view of mobile radio device  1100  according to embodiment 5 of the present invention.  FIG. 11  shows mobile radio device  1100  in an open state. 
         [0105]    Mobile radio device  1100  has three cases: first case  1101 , second case  1102 , and third case  1103 . Also, first case  1101 , second case  1102  and third case  1103  are connected in a mutually rotatable fashion about first hinge section  1104  as a rotation axis. 
         [0106]    First case  1101  has a rectangular shape on a plan view, and is rotatably connected with second case  1102 , via third case  1103 , by means of hinge section  1104 . Also, first case  1101  has circuit substrate  1111  inside. Also, first case  1101  has a display surface (not shown) that is exposed to the outside and displays an image when mobile radio device  1100  is open. 
         [0107]    Second case  1102  has a rectangular shape on a plan view, and is rotatably connected with first case  1101 , via third case  1103 , by means of hinge section  1104 . Also, second case  1102  has an operation surface (not shown) that is exposed to the outside and is operated during a call and so on, when mobile radio device  1100  is open. Second case  1102  has circuit substrate  1112  inside. 
         [0108]    Third case  1103  accommodates hinge section  1104  inside. Third case  1103  accommodates antenna element  1115 , antenna element  1116 , filter  1117  and filter  1118  inside. 
         [0109]    Hinge section  1104  is formed of an electrically conductive material, and connects first case  1101  and second case  1102  via third case  1103 , in a rotatable fashion, along the long direction of first case  1101  or second case  1102  (encompassing the upward or downward directions in  FIG. 11 ), so as to switch from the open state shown in  FIG. 11  to a closed state in which first case  1101  and second case  1102  overlap (not shown) or from the closed state to the open state of  FIG. 11 . Hinge section  1104  is furthermore electrically connected with antenna element  1116  and is also electrically connected with a ground section of circuit substrate  1111  via terminating end section  1119 . 
         [0110]    Circuit substrate  1111  has an electrically conductive circuit pattern (not shown) on a flat surface part, and has a ground section nearly over the entire surface (now shown). Circuit substrate  1111  also has terminating end section  1119 . The ground section is formed by, for example, printing a ground pattern on circuit substrate  1111 . 
         [0111]    Circuit substrate  1112  has an electrically conductive circuit pattern (not shown) on a flat surface part, and has a ground section nearly over the entire surface (now shown). Circuit substrate  1112  has radio circuit  1113  that is grounded in a ground section and matching circuit  1114 . The ground section is formed by, for example, printing a ground pattern on circuit substrate  1112 . 
         [0112]    Radio circuit  1113  performs receiving processing for a signal received by an antenna and performs transmitting processing for a signal to be transmitted from an antenna. 
         [0113]    Matching circuit  1114  is connected between radio circuit  1113  and antenna element  1115 , and matches impedance between antenna element  1115  and radio circuit  1113 . 
         [0114]    Antenna element  1115  is electrically connected with matching circuit  1114 . Also, antenna element  1115  is fed power from power feed section  1120  and functions as an antenna. Antenna element  1115  is also electrically connected with antenna element  1116  via filter  1117 . Antenna element is also electrically connected with hinge section  1104  via filter  1118 . Antenna element  1115  furthermore has an electrical length to resonate, for example, in the 2 GHz band. 
         [0115]    Antenna element  1116 , including antenna element  1115  and filter  1117 , has an electrical length to have an approximately ¼ wavelength in the 800 MHz. Antenna element  1116  is also electrically connected with antenna element  1115  via filter  1117 . Antenna element  1116  is formed by, for example, printing an electrically conductive pattern on an insulating substrate. 
         [0116]    Filter  1117  is, for example, a bandpass filter, and is formed with a reactance element. Filter  1117  is electrically connected between antenna element  1115  and antenna element  1116 , and, by this means, electrically connects antenna element  1115  and antenna element  1116 . Also, filter  1117  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  1115  resonates in the 2 GHz band, filter  1117  prevents antenna element  1116  from functioning as an antenna. 
         [0117]    Filter  1118  is formed with a reactance element and is connected between antenna element  1115  and hinge section  1104 . Also, filter  1118  is electrically connected with antenna element  1115  and is also electrically connected with hinge section  1104 , thereby electrically connecting hinge section  1104  and antenna element  1115 . Also, filter  1118  has low impedance in the 800 MHz band and has high impedance in the 2 GHz band, thereby blocking the 2 GHz band. That is to say, when antenna element  1115  resonates in the 2 GHz band, filter  1118  prevents hinge section  1104  from functioning as an antenna. 
         [0118]    Terminating end section  1119  is formed with a reactance element and electrically connects a ground section of circuit substrate  1112  and hinge section  1104 . 
         [0119]    In mobile radio device  1100  having the above configuration, antenna element  1115 , filter section  1118 , hinge section  1104 , terminating end section  1119  and a ground section of circuit substrate  1111  are mutually electrically connected, and antenna element  1115  is fed power from power feed section  1120 . By this means, in a state in which mobile radio device  1100  is open, antenna element  1115 , filter  1118 , hinge section  1104 , terminating end section  1119 , and a ground section of circuit substrate  1111  function as an antenna of an approximately ¼ wavelength in the 800 MHz band. In mobile radio device  1100  having the above configuration, antenna element  1115 , filter  1117  and antenna element  1116  are mutually electrically connected, and antenna element  1115  is fed power from power feed section  1120 . By this means, in a state in which mobile radio device  1100  is closed, antenna element  1115 , filter  1117 , and antenna element  1116  function as an antenna of an approximately ¼ wavelength in the 800 MHz band. This antenna of an approximately ¼ wavelength configured this way resonates, for example, in the 800 MHz band. 
         [0120]    Meanwhile, antenna element  1115  functions as an antenna to resonate in the 2 GHz band in both an open state and a closed state. Filter  1117  and filter  1118  then block the 2 GHz band, so that the electrical connection between antenna element  1115  and hinge section  1104  is blocked and the electrical connection between antenna element  1115  and antenna element  1116  is blocked. As a result of this, when antenna element  1115  resonates in the 2 GHz band, antenna element  1115  alone functions as an antenna. 
         [0121]    Distance L 20  between antenna element  1115  and antenna element  1116  and a ground section of circuit substrate  1111  is made greater than distance L 21  between hinge section  1104  and a ground section of circuit substrate  1111  (L 20 &gt;L 21 ) (see  FIG. 11 ). Also, distance L 22  between antenna element  1115  and antenna element  1116  and a ground section of circuit substrate  1112  is made greater than distance L 23  between hinge section  1104  and a ground section of circuit substrate  1112  (L 22 &gt;L 23 ) (not shown). By this means, mobile radio device  1100  is able to alleviate the influence of a ground section of circuit substrate  1111  and a ground section of circuit substrate  1112  upon antenna element  1115  and antenna element  1116 . 
         [0122]    By this means, with the present embodiment, by providing double resonant antenna elements apart from a ground section of a circuit substrate, it is possible to achieve high antenna performance in both the 800 MHz band and 2 GHz band in a closed state. Also, in the 800 MHz band, by supplying power to a hinge section via an antenna element, it is possible to allow a ground section of a circuit substrate provided in the first case, a hinge section, and a ground section of a circuit substrate provided in a second case function as a dipole antenna to resonate in the 800 MHz band, and achieve high antenna performance in the 800 MHz band in an open state. Furthermore, to prevent a hinge section from resonating in the 2 GHz band, the 2 GHz band is blocked by means of a filter, and an antenna element that resonates in the 2 GHz band is placed distant from a ground section of a circuit substrate, so that it is possible to prevent antenna performance from deteriorating in the 2 GHz band. Also, with the present embodiment, for example, the length of an antenna element can be changed easily, so that, by adjusting an antenna element, it is possible to provide an antenna of better sensitivity. 
         [0123]    Although a double-resonant antenna has been realized with the present embodiment, the present invention is by no means limited to this, and it is equally possible to present a single-resonant antenna. Also, although with the present embodiment an antenna element and a hinge section are electrically connected via a filter, the present invention is by no means limited to this, and it is equally possible to connect an antenna element and a hinge section electrically without involving a filter. 
         [0124]    Although with above embodiment 1 to embodiment 5 an antenna element has been printed on a substrate, the present invention is by no means limited to this, and it is equally possible to process an electrically conductive material, without printing on a substrate. Also, although with above embodiment 1 to embodiment 5 an antenna has been configured to have an electrical length of an approximately ¼ wavelength, the present invention is by no means limited to this, and it is equally possible to form an antenna to have a different electrical length from ¼ wavelength. Furthermore, although with above embodiment 1 to embodiment 5 an antenna has been described to resonate at 800 MHz or 2 GHz, the present invention is by no means limited to this, and it is equally possible to set an arbitrary antenna resonant frequency by changing the electrical length of an antenna element. 
         [0125]    The disclosure of Japanese Patent Application No. 200-280332, filed on Oct. 30, 2008, including the specification, drawings and abstract, is incorporated herein by its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0126]    The present invention is particularly suitable for use with a radio device that has cases that can be opened and closed.