Patent Publication Number: US-2009221327-A1

Title: Audio Device

Description:
TECHNICAL FIELD 
     The present invention relates to an audio device including a magnetic sensor and a speaker. 
     BACKGROUND ART 
     A mobile phone provided with a magnetic sensor is known. For example, a mobile phone provided with a geomagnetic sensor as the magnetic sensor is disclosed (for example, Patent Document 1). In the mobile phone of Patent Document 1, a bearing specified based on a result of detection of the geomagnetic sensor is displayed on a display. Patent Document 1 also discloses that calibration of the geomagnetic sensor for eliminating the influence of a magnetic field formed by magnetized electronic parts on the geomagnetic sensor. 
     Other than this, a mobile phone provided with an opened and closed detecting sensor detecting an opened and closed state of an openable and closable mobile phone as the magnetic sensor is known. For example, a magnet is provided in one housing of the mobile phone, and an opened and closed detecting sensor is provided in the other housing. The magnet approaches or moves away from the opened and closed detecting sensor along with opening and closing of the mobile phone. The opened and closed detecting sensor detects a closed state when an intensity of the magnetic field becomes a predetermined value or more due to the approach of the magnet, while detects an opened state when the intensity of the magnetic field becomes less than the predetermined value due to the magnet moving. 
     Further, a technique of providing a speaker in a cradle for charging the mobile phone (charging stand, external speaker device) and converting an audio signal generated at the mobile phone to sound by the speaker of the cradle is known (Patent Document 2). Specifically, when the mobile phone is placed on the cradle to enable charging, audio signal terminals provided in the mobile phone and the cradle are connected to each other. Further, speech or music or another audio signal generated at the mobile phone is output via the terminals to the cradle, whereby the speech and music are emitted from the speaker of the cradle. 
     Patent Document 1: Japanese Patent Publication (A) No. 2005-291936 
     Patent Document 2: Japanese Patent Publication (A) No. 2003-32351 
     DISCLOSURE OF THE INVENTION 
     Problem to be Solved by the Invention 
     When a portable electronic device is placed on a cradle, the electronic parts of the portable electronic device are magnetized by a magnetic field formed by a speaker of the cradle. If the influence of the magnetization exerted upon the magnetic field at the position of arrangement of the geomagnetic sensor is large, the geomagnetic sensor must be calibrated. Further, there also exists the possibility that the opened and closed state will not be normally detected due to the detection by the opened and closed detecting sensor of the magnetic field formed by the speaker of the cradle. 
     However, the patent documents explained above do not disclose a combination of a portable electronic device provided with a magnetic sensor and a cradle provided with a speaker and do not suggests the influence of the magnetic field formed by the speaker of the cradle exerted upon the magnetic sensor of the portable electronic device when the portable electronic device is placed on a cradle. 
     It is desirable that an audio device able to reduce the influence of a magnetic field formed by an external speaker upon a magnetic sensor be provided. 
     Means for Solving the Problem 
     An audio device of the present invention has an external speaker converting an audio signal and outputting the result; a portable housing which can be arranged in a predetermined positional relationship with respect to the external speaker; an audio output unit arranged in the portable housing and configured to be outputable the audio signal to the external speaker when the portable housing is arranged in the predetermined positional relationship with respect to the external speaker; and a magnetic sensor arranged in the portable housing, wherein the magnetic sensor and the external speaker are arranged at positions not superposed (overlapped) on each other in a direction perpendicular to a predetermined surface of the portable housing facing the external speaker when the portable housing is arranged in the predetermined positional relationship with respect to the external speaker. 
     Preferably, the portable housing has a first housing and a second housing which are connected to be openable and closable, the predetermined positional relationship is a positional relationship where the first housing is arranged at a certain position with respect to the external speaker, and the magnetic sensor is arranged in the first housing. 
     Preferably, the portable housing has a first housing and a second housing which are connected to be openable and closable, and the magnetic sensor is a closing detecting magnetic sensor provided in either of the first housing and the second housing, and configured to detect the closed state of the portable housing based on a change of the magnetic field due to the magnet provided in the other of the first housing and the second housing approaching or moving away from the magnetic sensor along with the opening and the closing of the portable housing. 
     Preferably, the magnetic sensor is configured to detect the closed state of the portable housing based on whether or not an intensity of the magnetic field at the position of arrangement of the magnetic sensor is larger than a predetermined threshold value, and the external speaker and the magnetic sensor are arranged spaced apart from each other so that the intensity of the magnetic field formed by the external speaker at the position of arrangement of the magnetic sensor becomes smaller than the threshold value when the portable housing is arranged in the predetermined positional relationship with respect to the external speaker. 
     Preferably, the magnetic sensor is a geomagnetic sensor detecting geomagnetism, and the audio device has a report unit configured to report a bearing (azimuth, or compass direction) specified based on the geomagnetism detected by the geomagnetic sensor. 
     Preferably, the portable housing has a first housing and a second housing which are connected to be openable and closable, the predetermined positional relationship is a positional relationship where the first housing is arranged at a certain position with respect to the external speaker, the second housing can move in an opening and closing direction with respect to the first housing in a state where the first housing is arranged at the certain position, the report unit is a display unit provided in the second housing, and the magnetic sensor is provided in the first housing. 
     Preferably, the portable housing has a first housing and a second housing which are connected to be openable and closable, either of the first housing and the second housing is provided with, as the magnetic sensor, a closing detecting sensor configured to detect the closing of the portable housing based on a change of the magnetic field due to the magnet provided in the other of the first housing and the second housing approaching or moving away from the magnetic sensor along with the opening and closing of the portable housing, and a geomagnetic sensor detecting geomagnetism; and the external speaker, the closing detecting sensor and magnet, and the geomagnetic sensor are arranged at positions not superposed on each other in a direction perpendicular to the predetermined surface when the portable housing is arranged in the predetermined positional relationship with respect to the external speaker. 
     Preferably, the external speaker, the closing detecting sensor and magnet, and the geomagnetic sensor are arranged in an order of the external speaker, the closing detecting sensor and magnet, and the geomagnetic sensor on a surface parallel to the predetermined surface in the closed state when the portable housing is arranged in the predetermined positional relationship with respect to the external speaker. 
     EFFECTS OF THE INVENTION 
     According to the present invention, the influence of a magnetic field formed by an external speaker on a magnetic sensor can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  Front views partially including perspective views showing a mobile phone and a cradle of a portable electronic unit according to an embodiment of the present invention. 
         FIG. 2  Front views partially including perspective views showing the portable electronic unit of  FIG. 1A  to  FIG. 1C  in a state where the mobile phone is placed on the cradle. 
         FIG. 3  Side views partially including perspective views showing the portable electronic unit of  FIG. 1A  to  FIG. 1C  in a state where the mobile phone is placed on the cradle. 
         FIG. 4  A block diagram showing the configuration of a signal processing system of the portable electronic unit of  FIG. 1A  to  FIG. 1C . 
         FIG. 5  Diagrams showing measurement results of magnetic fields formed by a speaker of the cradle in the embodiment of the portable electronic unit of  FIG. 1A  to  FIG. 1C . 
     
    
    
     DESCRIPTION OF NOTATIONS 
       1  . . . mobile phone unit (portable electronic unit),  2  . . . mobile phone (portable electronic device),  3  . . . cradle (external speaker device),  5  . . . receiver housing (portable housing),  6  . . . transmitter housing (portable housing),  6   a  . . . back surface (predetermined surface),  18  . . . housing,  23  . . . speaker,  33  . . . audio processing unit (audio output unit),  42  . . . opened and closed detecting sensor (magnetic sensor), and  43  . . . geomagnetic sensor (magnetic sensor). 
     BEST MODE FOR CARRYING OUT THE INVENTION 
       FIG. 1A  to  FIG. 1C  are plan views partially including perspective views showing a mobile phone unit  1  configured by a mobile phone (portable electronic device)  2  and a cradle (external speaker device)  3  according to an embodiment of the present invention, in which  FIG. 1A  shows the cradle  3 ,  FIG. 1B  shows the mobile phone  2  in a closed state, and  FIG. 1C  shows the mobile phone  2  in an opened state. 
       FIG. 2A  and  FIG. 2B  are plan views partially including perspective views showing a state where the mobile phone  2  is placed on the cradle  3 , in which  FIG. 2A  shows a case where the mobile phone  2  is closed, and  FIG. 2B  shows a case where the mobile phone  2  is opened. 
       FIG. 3A  and  FIG. 3B  are side views partially including perspective views showing a state where the mobile phone  2  is placed on the cradle  3 , in which  FIG. 3A  shows the case where the mobile phone  2  is closed, and  FIG. 3B  shows the case where the mobile phone  2  is opened. 
     The mobile phone  2  is configured as a so-called flip-open type mobile phone and is provided with a receiver housing  5  and a transmitter housing  6 . Note that the combination of the receiver housing  5  and the transmitter housing  6  is an example of the portable housing, the receiver housing  5  is an example of the second housing, and the transmitter housing  6  is an example of the first housing. 
     The receiver housing  5  and the transmitter housing  6  are connected in their end portions by a connecting portion  7 , and the mobile phone  2  can be opened and closed with the connecting unit  7  as the center of pivot. The receiver housing  5  and the transmitter housing  6  are formed to schematically thin type parallelepiped bodies, and superposed on each other in the closed state so that their contours schematically coincide with each other when viewing the other housing side from one housing side. 
     The receiver housing  5  is formed to for example an approximately thin parallelepiped body by a plastic. The receiver housing  5  is provided with a display unit  9  displaying various information as images, a speech use speaker  39 , and a magnet  41  to be detected for an opened and closed detecting sensor  42  explained later. 
     The display unit  9  is configured by for example a liquid crystal display and can display an image on a counter surface facing the transmitter housing  6  in the closed state in the receiver housing  5 . Note that, a sub display unit displaying an image may be provided on a back surface side of the receiver housing  5  as well. 
     The speech use speaker  39  is provided at the center of an end portion  5   e  on the opposite side to the connecting portion  7  in the receiver housing  5 . The speaker  39  is configured by for example a dynamic speaker. Namely, it has a coil receiving as input an audio signal (electric signal) a magnet inserted through the coil, and a vibration plate fixed to the coil or magnet. 
     Note that the speaker  39  may be one converting an audio signal to sound by utilizing magnetism or one not utilizing magnetism such as a condenser speaker. Further, when the speaker is one converting an audio signal to sound by utilizing magnetism, it may be one other than a dynamic speaker for example a ribbon speaker as well. 
     The sound output by the speaker  39  is output from an emission hole  10 . The emission hole  10  is provided at the center of the end portion  5   e  on the opposite side to the connecting portion  7  in the receiver housing  5  corresponding to the position of the speaker  39  and is opened in the counter surface of the receiver housing  5 . 
     The transmitter housing  6  is formed to for example an approximately thin parallelepiped body by a plastic. The transmitter housing  6  is provided with an operation unit  12  accepting the operation of a user, a main antenna  13  and a sub antenna  14  performing transmission and reception of electric waves, a speaker  15  outputting report sounds etc., a speech use microphone  35 , an opened and closed detecting sensor  42 , and a geomagnetic sensor  43 . 
     The main antenna  13  is built in an end portion  6   e  on the opposite side to the connecting portion  7  in the transmitter housing  6 . The sub antenna  14  is built in the transmitter housing  6  on the side surface side of the transmitter housing  6  at a position between the center of the transmitter housing  6  and the main antenna  13 . The main antenna  13  and the sub antenna  14  are configured as diversity antennas. For example, the main antenna  13  is used for transmission and reception of speech, transmission and reception of e-mail, and so on and always utilized. The sub antenna  14  is utilized together with the main antenna  13  when data communication other than speech is carried out for example when music is downloaded. 
     Report use speakers  15  are provided in the end portion on the connecting portion  7  side of the transmitter housing  6 . Two speakers  15  are provided on sides of the transmitter housing  6 . The speaker  15  is configured by for example a dynamic speaker. Namely, it has a coil receiving as input an audio signal (electric signal), a magnet inserted through the coil, and a vibration plate fixed to the coil or magnet. 
     Note that the speaker  15  may be one converting an audio signal to sound by utilizing magnetism or one not utilizing magnetism such as a condenser speaker. Further, when the speaker is one converting an audio signal to sound by utilizing magnetism, it may be one other than a dynamic speaker, for example, a ribbon speaker as well. 
     The sound output from the speaker  15  is output from emission holes  17 . Two emission holes  17  are provided on sides of the end portion on the connecting portion  7  side of the transmitter housing  6  corresponding to the position of the speaker  15  and opened in the surface opposite to the surface facing the receiver housing  5  (surface facing the cradle). Note that, the sound emission holes  17  may be opened in side surfaces of the transmitter housing  6  as well. 
     The speech use microphone  35  is provided at the center of the end portion  6   e  on the opposite side to the connecting portion  7  in the transmitter housing  6 . The microphone  35  is configured by for example a dynamic microphone. Namely, it has a coil outputting an audio signal, a magnet inserted through the coil, and a vibration plate fixed to the coil or magnet. 
     Note that the microphone  35  may be one converting sound to an audio signal by utilizing magnetism or one not utilizing magnetism such as a condenser microphone. Further, only when the microphone is one converting sound to an audio signal by utilizing magnetism, it may be one other than a dynamic microphone, for example, a ribbon microphone as well. 
     To the microphone  35 , sound is input via a sound collecting hole  16 . The sound collecting hole  16  is provided at the center of the end portion  6   e  on the opposite side to the connecting portion  7  in the transmitter housing  6  corresponding to the position of the microphone  35  and opened in the counter surface facing the receiver housing  5 . 
     The opened and closed detecting sensor  42  is configured by a magnetic sensor. For example, the opened and closed detecting sensor  42  includes a Hall IC or magnetoresistance element and outputs a signal having a potential in accordance with the detected intensity of the magnetic field in the predetermined direction. The opened and closed detecting sensor  42  is provided near the center in a longitudinal direction (near the center between the connecting portion  7  and the end portion  6   e  on the opposite side to the connecting portion  7 ) and sideward in the transmitter housing  6 . 
     In the receiver housing  5 , the magnet  41  explained before is provided at a position facing the opened and closed detecting sensor  42  in the closed state. Accordingly, when the mobile phone  2  is closed, the magnet  41  and the opened and closed detecting sensor  42  become close, and the magnetic field at the position of arrangement of the opened and closed detecting sensor  42  becomes strong. When the mobile phone  2  is opened, the magnet  41  and the opened and closed detecting sensor  42  are spaced apart, and the magnetic field at the position of arrangement of the opened and closed detecting sensor  42  becomes weak. Accordingly, the detection of the opened and closed state (the detection of the closed state) can be performed according to whether or not the intensity of the magnetic field detected by the opened and closed detecting sensor  42  is larger than the predetermined threshold value. Note that, the opened and closed detecting sensor  42  may be configured to output an ON signal or OFF signal in accordance with whether or not the detected intensity of the magnetic field is larger than the predetermined threshold value as well. 
     The geomagnetic sensor  43  includes a Hall IC or a magnetoresistance element, detects the intensity of the magnetic field for each  2  axes or  3  axes, and outputs a signal in accordance with the detected intensity of the magnetic field. Then, the bearing is specified from a ratio of the intensity of the magnetic field for each axis output from the geomagnetic sensor  43 . Note that, the geomagnetic sensor  43  may be configured to perform computation for specifying the bearing and output a signal in accordance with the specified bearing. The geomagnetic sensor  43  is arranged in the transmitter housing  6  near the center in the longitudinal direction (near the center between the connecting portion  7  and the end portion  6   e  on the opposite side to the connecting portion  7 ) and sideward. In more detail, the geomagnetic sensor  43  is arranged closer to the end portion  6   e  side than the opened and closed detecting sensor  42 . 
     The cradle  3  is provided with a housing  18 , a cord  19  for supplying electric power to the cradle  3 , charge terminals  20  and  21  and an audio signal terminal  22  for electrically connecting the cradle  3  and the mobile phone  2 , and a speaker  23  outputting sound based on the audio signal input from the mobile phone  2 . Note that, the speaker  23  is an example of the external speaker. 
     The housing  18  has for example a lower cover  18   a  placed on a desk or the like and an upper cover  18   b  covered on the lower cover  18   a . The lower cover  18   a  and upper cover  18   b  are formed by for example plastic. The upper cover  18   b  is covered on the lower cover  18   a  to be inclined with respect to the surface on which the housing  18  is placed, and the housing  18  is formed as a whole to a trapezoidal shape having an inclined surface  18   c  inclined with respect to the placed surface (desk surface etc.). 
     In the top surface of the housing  18 , a recess (placing portion)  25  for placing the mobile phone  2  is formed. The recess  25  is provided on the lower side of the inclined surface  18   c . The recess  25  is formed to a shape so that the transmitter housing  6  of the mobile phone  2  is fit (although the illustration is omitted, formed to a shape with tabs formed at both ends of the recess  25  and engaged with recesses formed on the connecting portion  7  side and microphone  35  side of the transmitter housing  6 ) and formed so that a placing surface (bottom portion of the recess  25 )  18   d  against which the back surface  6   a  of the transmitter housing  6  abut is inclined with respect to on the surface (desk surface etc.) on which the cradle  3  is placed. The mobile phone  2  is placed on the cradle  3  by fitting and insertion of the transmitter housing  6  in the recess  25  while making the connecting portion  7  side face upward of the inclined surface  18   c.    
     Note that, the back surface  6   a  of the transmitter housing  6  is an example of the predetermined surface of the portable housing. The positional relationship of the transmitter housing  6  and the housing  18  of the cradle  3  when the transmitter housing  6  is fitted and inserted in the recess  25  of the cradle  3  is an example of the predetermined positional relationship. 
     As shown in  FIG. 3A  and  FIG. 3B , a depth of the recess  25  is approximately equal to or lower than the thickness of the transmitter housing  6 . Accordingly, even if the receiver housing  5  is moved in the opening and closing direction in the state where the transmitter housing  6  is fit in the recess  25 , a circumferential edge of the recess  25  of the inclined surface  18   c  does not abut against the receiver housing  5 . Namely, the mobile phone  2  can be opened and closed in the state where it is placed on the cradle  3 . 
     Accordingly, the mobile phone  2  can be brought to the open state or closed state in accordance with the state of use while it is placed on the cradle  3  as it is. For example, it can be opened in a case where an image is displayed in the display unit  9  such as movie playback and can be closed in a case where only charging is carried out or a case where music is played back. 
     The cord  19  is extended from the housing  18 . A not shown power plug is provided on its tip end. By insertion of the power plug into a power outlet for supplying electric power of commercial frequency, electric power is supplied to the cradle  3  via the cord  19 . 
     The charge terminals  20  and  21  are provided so as to protrude from the bottom portion of the recess  25 . When the mobile phone  2  is fit and inserted in the recess  25 , these terminals abut against the charge terminal  37  (see  FIG. 4 ) provided on the surface facing the recess  25  of the transmitter housing  6  of the mobile phone  2  and are connected. 
     The audio signal terminal  22  is provided so as to protrude from the bottom portion of the recess  25 . Further, this is provided adjacent to the charge terminals  20  and  21 . The audio signal terminal  22  is provided on the surface facing the recess  25  of the transmitter housing  6  of the mobile phone  2  when the mobile phone  2  is fit and inserted in the recess  25 , abutting against the audio signal terminal  36  (see  FIG. 4 ) exposed from the back surface  6   a  and connected. 
     The speaker  23  is provided on the upper side of the inclined surface  18   c  than the recess  25 . Accordingly, when the transmitter housing  6  of the mobile phone  2  fits in the recess  25 , the speaker  23  is located on the outer side than one end in the longitudinal direction of the transmitter housing  6 . Further, when the transmitter housing  6  is fit in the recess  25 , the speaker  23  is superposed on the receiver housing  5  when the mobile phone  2  is in the open state, but not superposed on the receiver housing  5  when the mobile phone  2  is in the closed state when seen in the direction perpendicular to the back surface  6   a  of the transmitter housing  6 . 
     The speaker  23  is configured by for example a dynamic speaker. Namely, it has a coil receiving as input an audio signal (electric signal), a magnet inserted through the coil, and a vibration plate fixed to the coil or magnet. 
     The speaker  23  is arranged so that the sound emission surface faces the inside surface of the inclined surface  18   c  (so that it faces upward). The sound output by the speaker  23  is emitted from sound emission holes  24 . The sound emission holes  24  are provided on the upper side of the housing  18  of the cradle  3  corresponding to the position of arrangement of the speaker  23  and opened in the inclined surface  18   c.    
     In the mobile phone unit  1 , the speaker  23 , the opened and closed detecting sensor  42 , and the geomagnetic sensor  43  are arranged at positions not superposed on each other when seen in the direction perpendicular to the back surface  6   a  of the transmitter housing  6  when the transmitter housing  6  of the mobile phone  2  fits in the recess  25  of the housing  18  of the cradle  3 . Namely, it can be said as well that the transmitter housing  6  and the speaker  23  are not superposed in an axial direction of the coil. 
     Specifically, the opened and closed detecting sensor  42  and the speaker  23  are arranged while being spaced apart from each other so that the intensity of the magnetic field in the predetermined direction at the position of arrangement of the opened and closed detecting sensor  42  formed by the speaker  23  becomes smaller than the threshold value for judging the opened and closed state based on the detection result of the magnetic field in the predetermined direction of the opened and closed detecting sensor  42  when the transmitter housing  6  of the mobile phone  2  fits in the recess  25  of the housing  18  of the cradle  3 . 
     The opened and closed detecting sensor  42  and magnet  41  and the geomagnetic sensor  43  are arranged at positions not superposed on each other when seen in the direction perpendicular to the back surface  6   a  of the transmitter housing  6  when the transmitter housing  6  of the mobile phone  2  fits in the recess  25  of the housing  18  of the cradle  3 . 
     The speaker  23 , the opened and closed detecting sensor  42  and magnet  41 , and the geomagnetic sensor  43  are arranged in the order of the speaker  23 , the opened and closed detecting sensor  42  and magnet  41 , and the geomagnetic sensor  43  in the longitudinal direction of the transmitter housing  6  when seen in the direction perpendicular to the back surface  6   a  of the transmitter housing  6  in the closed state when the transmitter housing  6  of the mobile phone  2  fits in the recess  25  of the housing  18  of the cradle  3 . 
       FIG. 4  is a block diagram showing the configuration of a signal processing system of the mobile phone unit  1 . 
     The mobile phone  2  has a control unit  31 , a communication processing unit  32 , an audio processing unit  33 , an image processing unit  45 , and a charge circuit  34 . Note that the audio processing unit  33  is an example of the audio output unit. The mobile phone  2  has, other than these, a GPS processing unit receiving and processing GPS signals transmitted from a plurality of GPS satellites, calculating the geographical position of the present spot, and making the display unit display map data around the present spot, and so on, but the illustration is omitted. 
     The control unit  31  is configured by an IC including for example a CPU, ROM, and RAM. The CPU runs a program stored in the ROM to control the operations of the communication processing unit  32 , audio processing unit  33 , image processing unit  45 , etc. based on signals etc. from the operation unit  12 , opened and closed detecting sensor  42 , geomagnetic sensor  43 , etc. 
     For example, when receiving as input a signal having a potential in accordance with the detected intensity of the magnetic field from the opened and closed detecting sensor  42 , based on this signal, the control unit  31  judges whether or not the detected intensity of the magnetic field is larger than the predetermined threshold value. It judges the closed state when the intensity is larger, while judges the opened state when the intensity is not larger. Then, the control unit  31  performs processing in accordance with the opened or closed state, for example, controls the operation of the image control unit  45  so that the display of the information by the display unit  9  is stopped when judging the closed state, while the display of the information is executed by the display unit  9  when judging the opened state. 
     Further, for example, the control unit  31  executes processing for reporting the bearing specified based on the detection result of the geomagnetic sensor  43 , for example, when receiving as input the detected value of the intensity of the magnetic field for each of a plurality of axes from the geomagnetic sensor  43 , the control unit  31  specifies the bearing based on the ratio of intensity of the magnetic field for each axis and controls the operation of the image processing unit  45  so as to make the display unit  9  display the specified bearing. The bearing is displayed by for example displaying a bearing symbol matched in orientation with the specified bearing or by matching the orientation of the map displayed by the GPS function with the specified bearing (heading up display). 
     The communication processing unit  32  includes a high frequency circuit and performs wireless communication utilizing radio waves. Specifically, the communication processing unit  32  modulates audio data, image data, and other various types of data processed at the control unit  31  etc. and transmits the same via the main antenna  13 . Further, the communication processing unit  32  demodulates signals received via the main antenna  13  and sub antenna  14  and outputs the same to the control unit  31  etc. 
     The audio processing unit  33  outputs an audio signal from the microphone  35  to the control unit  31 . The audio signal output to the control unit  31  is transmitted via the communication processing unit  32 . Further, the audio processing unit  33  mixes, amplifies, etc. an audio signal of speech received by the communication processing unit  32  and output from the control unit  31 , an audio signal based on music data stored in the external storage device, etc. and outputs the same to the speech use speaker  39 , the speaker  15  utilized for reports etc., and the audio terminal  36 . 
     The image processing unit  45  converts video data from the control unit  31  to a video signal and outputs the same to the display unit  9 . For example, the control unit  31  downloads the map data of the present spot specified based on the GPS signal from the server, performs coordinate conversion of map data in accordance with the orientation (bearing) of the mobile phone  2  at present specified based on the detection result of the geomagnetic sensor  43 , and outputs the map data after the coordinate conversion to the image processing unit  45  for display. Note that the coordinate conversion or other work may be shared by the image processing unit  45  as well. 
     The charge circuit  34  converts the electric power supplied to the charge terminal  37  to an electric power having an appropriate voltage and supplies this to the battery  38  serving as the power source of the mobile phone  2 . Further, it starts charging (supplies electric power) to the battery  38  or interrupts the charging in accordance with the charge state etc. of the battery  38 . 
     The cradle  3  has an amplifier  51  and a charger (AC converter)  52 . The amplifier  51  amplifies an audio signal input from the mobile phone  2  via the audio signal terminal  22  and outputs the result to the speaker  23 . The charger  52  converts an AC current having a commercial frequency supplied via the cord  19  to a DC current having an appropriate voltage and outputs the same to the charge terminals  20  and  21 . 
       FIG. 5A  to  FIG. 5D  are diagrams showing results of measurement of intensities of magnetic fields at the periphery for a speaker as an example of the speaker  23  of the cradle  3  in the example of the present embodiment.  FIG. 5A  shows the measurement result on the sound emission surface (front surface) side of the speaker,  FIG. 5B  is an enlarged diagram of  FIG. 5A ,  FIG. 5C  shows the measurement results on an opposite (back surface) side to the sound emission surface of the speaker, and  FIG. 5D  is an enlarged diagram of  FIG. 5C . The abscissas of the diagrams indicate distances in the direction along the sound emission surface of the speaker (see the x-axis direction in  FIG. 1A  to  FIG. 1C  and  FIG. 3A  to  FIG. 3B ), while the ordinates indicate the distances in the direction perpendicular to the sound emission surface of the speaker (see the z-axis direction in  FIG. 1A  to  FIG. 1C  and  FIG. 3A  to  FIG. 3B ). x=0 indicates the speaker center, and z=0 indicates the front surface or back surface of the speaker. 
     The speaker to be measured is the HDR9302-010010 made by HOSIDEN Corporation, that is, a woofer configured by a dynamic speaker. The intensity by which the influence by magnetization appears is 0.3 mT for a sensor as an example of the geomagnetic sensor  43 . The minimum detection magnetic flux density of a sensor as an example of the opened and closed detecting sensor  42  is 1.2 mT. 
     As shown in  FIG. 5A  to  FIG. 5D , near the front surface or back surface of the speaker, at the position 5 cm apart from the center portion of the speaker, the intensity of the magnetic field becomes less than 0.3 mT, so there is no problem even if the sensor as an example of the geomagnetic sensor  43  or opened and closed detecting sensor  42  is arranged there. Accordingly, if the sensor as an example of the geomagnetic sensor  43  or opened and closed detecting sensor  42  is arranged so as to be spaced apart from the center portion of the speaker by 5 cm or more, the position in the z-direction of the speaker of the cradle can be set at an optional position. 
     According to the above embodiment, the magnetic sensor such as opened and closed detecting sensor  42  and geomagnetic sensor  43  of the mobile phone  2  and the speaker  23  of the cradle  3  are arranged at positions not superposed on each other when seen in the direction perpendicular to the back surface  6   a  of the transmitter housing  6  when the transmitter housing  6  of the mobile phone  2  fits in the recess  25  of the cradle  3 , therefore the magnetic sensor will be arranged at a position where there is little influence of the magnetic field formed by the speaker  23  and malfunction of the magnetic sensor is prevented. If the magnetic sensor is sufficiently spaced apart from the speaker  23  of the cradle  3  in the direction along the back surface  6   a , the influence of the speaker  23  becomes sufficiently small even if the magnetic sensor is at the same surface of the speaker  23 . Therefore, as in this embodiment, the device may be designed so that the mobile phone  2  is located in substantially the same plane as that for the speaker  23  of the cradle  3  and reduction of thickness is achieved as a whole. The magnetic sensor and the speaker  23  are prevented from being superposed on each other when seen in the direction perpendicular to the surface having the largest area of the thin type housing (back surface  6   a  or counter surface). Therefore, even if the housing of the mobile phone  2  is not large in size, by appropriately selecting the position of arrangement of the magnetic sensor inside the mobile phone  2 , the magnetic sensor can be arranged at a position apart from the speaker  23 . The magnetic sensor is arranged at a position not superposed on the speaker  23  when seen in the direction perpendicular to the back surface  6   a  while the cradle  3  is supporting the wide surface (back surface  6   a ) of the mobile phone  2 , therefore the influence of the speaker upon the magnetic sensor can be reduced while stably placing the mobile phone  2  on the cradle  3 . Note that, in the present embodiment, the speaker  23  is arranged on one end side of the longitudinal direction of the transmitter housing  6 , and the magnetic sensor is provided at substantially the center of the longitudinal direction of the transmitter housing  6 , therefore the magnetic sensor is provided spaced apart from not only the speaker  23 , but also the speech use microphone  35 , the speech use speaker  39 , and the report use speaker  15 , and the influence of the magnetic field is small. 
     The mobile phone  2  is provided with the receiver housing  5  and transmitter housing  6  connected so that these can be opened and closed, the receiver housing  5  can move in the opening and closing direction with respect to the transmitter housing  6  in the state where the transmitter housing  6  fits in the recess  25  and is arranged at the certain position with respect to the housing  18  of the cradle  3 , and the magnetic sensor such as opened and closed detecting sensor  42  and geomagnetic sensor  43  is arranged in the transmitter housing  6 . Accordingly, the mobile phone  2  can be brought to the open state or closed state in accordance with the state of use while placing the mobile phone  2  on the cradle  3  as it is, the distance between the magnetic sensor and the speaker  23  of the cradle  3  does not change even if the opened state and the closed state are switched, and the performance of the magnetic sensor becomes stable. Further, as in the embodiment, when the speaker  23  of the cradle  3  is arranged at a position superposed with the receiver housing  5  in the open state and not superposed with the transmitter housing  6  in the closed state and the magnetic sensor is provided in the transmitter housing  6 , the magnetic sensor can be prevented from being superposed on the speaker  23  in the opened state, the speaker  23  is made very close to the recess  25  (transmitter housing  6 ), and a reduction of size is achieved. 
     The magnetic sensor arranged so as not to be superposed on the speaker  23  of the cradle  3  is the opened and closed detecting sensor  42 , therefore the opened and closed detection in the state where the mobile phone  2  is placed on the cradle  3  is correctly carried out. Accordingly, by opening and closing the mobile phone  2  while placing the mobile phone  2  on the cradle  3  as it is, various functions in accordance with the opened state or closed state can be appropriately utilized. Further, when seen from another viewpoint, the magnetic sensor which has been hard to utilize for the opened and closed detection of the mobile phone  2  due to the influence of the magnetic field from the cradle  3  can be utilized for the opened and closed detecting sensor. 
     The speaker  23  of the cradle  3  and the opened and closed detecting sensor  42  are arranged spaced apart from each other so that the intensity of the magnetic field formed by the speaker  23  at the position of arrangement of the opened and closed detecting sensor  42  becomes smaller than the threshold value of the opened and closed detection, therefore erroneous opened and closed detection is reliably prevented. 
     The magnetic sensor arranged so as not to be superposed on the speaker  23  of the cradle  3  is the geomagnetic sensor  43 , therefore the magnetization of electronic parts at the periphery of the geomagnetic sensor  43  due to the magnet of the speaker  23  is prevented. Accordingly, even after the mobile phone  2  is placed on the cradle  3 , the utilization of functions using the geomagnetic sensor  43  becomes possible without calibration. When the mobile phone  2  is detached from the cradle  3 , it is not necessary to force the user to perform troublesome work such as rotation of the mobile phone  2  for calibration. 
     The mobile phone  2  has the receiver housing  5  and transmitter housing  6  connected so that these can be opened and closed. The receiver housing  5  can move in the opening and closing direction with respect to the transmitter housing  6  in the state where the transmitter housing  6  is fit in the recess  25  and arranged at the certain position with respect to the housing  18  of the cradle  3 . The display unit  9  displaying the bearing based on the detection result of the geomagnetic sensor  43  is provided in the receiver housing  5 , and the geomagnetic sensor  43  is provided in the transmitter housing  6 . Therefore, the orientation of the display unit  9  can be appropriately changed by opening and closing the mobile phone  2  while placing the mobile phone  2  on the cradle  3  as it is. In addition, the distance between the geomagnetic sensor  43  and the speaker  23  of the cradle  3  does not change according to the opening and closing operation, therefore there is no apprehension that the geomagnetic sensor  43  will approach the speaker  23  by opening and closing and that the periphery of the geomagnetic sensor  43  will be magnetized. Further, if the geomagnetic sensor  43  is arranged so as to be sufficiently spaced apart from the speaker  23  of the cradle  3 , the orientation of the display unit  9  can be appropriately changed while utilizing the function of making the display unit  9  display the bearing based on the detection result of the geomagnetic sensor  43  while placing the mobile phone  2  on the cradle  3  as it is. 
     The speaker  23  of the cradle  3 , the opened and closed detecting sensor  42  and magnet  41 , and the geomagnetic sensor  43  are arranged at positions not superposed on each other when seen in the direction perpendicular to the back surface  6   a  of the transmitter housing  6  when the transmitter housing  6  is fit in the recess  25  of the housing  18  of the cradle  3 , therefore not only the influence of the magnetic field of the speaker  23  of the cradle  3  on the opened and closed detecting sensor  42  and the geomagnetic sensor  43 , but also the influence of the magnet  41  for the opened and closed detection on the geomagnetic sensor  43  can be reduced. When seen from another viewpoint, by strengthening the intensity of the magnetic field of the opened and closed detection use magnet  41  and increasing the threshold value for detecting the opened and closed state, the influence of the magnetic field of the speaker  23  of the cradle  3  on the opened and closed detecting sensor  42  is made relatively small and erroneous detection of the opened and closed state can be prevented. 
     The speaker  23  of the cradle  3 , the opened and closed detecting sensor  42  and magnet  41 , and the geomagnetic sensor  43  are arranged in the order of the speaker  23 , the opened and closed detecting sensor  42  and magnet  41 , and the geomagnetic sensor  43  when seen in a direction perpendicular to the back surface  6   a  of the transmitter housing  6  in the closed state when the transmitter housing  6  is fit in the recess  25  of the cradle  3 , therefore a reduction of size of the portable electronic unit  1  can be achieved. Namely, when these are arranged in the order of the speaker  23 , geomagnetic sensor  43 , and opened and closed detecting sensor  42  and magnet  41 , the geomagnetic sensor  43  at the center must be at a sufficient distance from the speaker  23  and must be at a sufficient distance from the magnet  41 , therefore the distance from the speaker  23  to the magnet  41  becomes long. However, when these are arranged as in the present embodiment, the speaker  23  and the magnet  41  can be made to approach each other, therefore the distance can be shortened as a whole. 
     The present invention is not limited to the above embodiments and may be executed in various ways. 
     The portable electronic device need only be a device able to output an audio signal to an external speaker and is not limited to a mobile phone. For example, it may be PDA or notebook personal computer as well. The external speaker device need only be provided with a speaker converting an audio signal from the portable electronic device to sound and outputting the same and is not limited to a charging cradle. For example, it may be a device dedicated to the speaker not provided with a charging function as well. 
     The predetermined positional relationship of the portable housing of the portable electronic device with respect to the speaker need only be a positional relationship where the audio output unit can output an audio signal to the speaker. Accordingly, the positional relationship is not limited to a positional relationship where the portable side audio terminal provided in the portable housing and the speaker side audio terminal provided in the speaker housing of the external speaker device are connected, but may be a positional relationship where the audio signal of the portable electronic device can be output to the external speaker by infrared ray communication or other communicating means as well. Further, the positional relationship is not limited to a positional relationship where the surface having the largest area in a thin type housing is supported, but may be for example a positional relationship where the portable housing is hung from the speaker housing or the speaker housing is placed on the portable housing. 
     The speaker of the external speaker device need only be one converting an audio signal from the portable electronic device to sound by utilizing magnetism and is not limited to the dynamic speaker. For example, it may be a ribbon speaker as well. 
     When the portable housing of the portable electronic device is one which can be opened and closed, the portable housing need only be one in which the relative positions of two or more housings change and is not limited to the flip-open type. For example, it may be a so-called turn type where the transmitter housing and the receiver housing are turned from each other in schematically a parallel state to be opened and closed or a slide type. Even in these types, if the magnetic sensor is provided in one housing, the magnetic field at the periphery of the magnetic sensor changes by the relative movement of the other housing with respect to the magnetic sensor, therefore the opened and closed state can be detected. 
     The opened and closed detecting sensor need only be one detecting an opened and closed state based on a change of the magnetic field along with opening and closing and is not limited to a sensor provided in one housing and detecting a magnetic field of the magnet provided in the other housing. For example, it may be one detecting a change of the magnetic field generated by the approach and moving apart of the magnetic body of the other housing along with opening and closing. Further, it is not limited to one provided in the housing fixed with respect to the external speaker and may be provided in a housing moveable with respect to the external speaker by the opening and closing operation. 
     When the geomagnetic sensor is provided in a housing which can be opened and closed, it may be arranged in the housing moveable with respect to the external speaker as well. In this case, the magnetization of parts at the periphery of the geomagnetic sensor can be prevented by connecting the portable electronic device to the external speaker in the state where the geomagnetic sensor is moved away from the external speaker. For example, in the embodiment, when the speaker  23  of the cradle  3  is provided on the end portion  6   e  side opposite to the connecting portion  7 , by arranging the mobile phone  2  in the cradle  3  in the opened state, the geomagnetic sensor  43  can be moved apart from the speaker  23  more than the case where the geomagnetic sensor is provided in the transmitter housing  6 , so the magnetization of parts at the periphery of the geomagnetic sensor  43  can be prevented. 
     The report unit reporting the bearing specified based on the geomagnetism detected by the geomagnetic sensor is not limited to the display unit displaying an image. For example, it may be one reporting the bearing by sound as well. 
     Note that the entire content of Japanese Patent Application No. 2006-040046 (filed on Feb. 16, 2006) is incorporated by reference in the description of the present application.