Abstract:
In a portable electronic device having two circuit boards having a heat generating electronic device, a frame arranged at a position pinched between the circuit boards, a first heat radiating plate brought into contact with the frame and having a higher thermal conductivity than the frame, and a second heat radiating member transferring a heat between the first heat radiating member and two circuit boards, each of two circuit boards is fixed to the frame and two circuit boards are directly connected by a connector. Accordingly, it is possible to provide the portable electronic device which can improve a heat radiating efficiency and achieve a further thin structure.

Description:
INCORPORATION BY REFERENCE 
   The present application claims priority from Japanese application JP2005-328247 filed on Nov. 14, 2005, the content of which is hereby incorporated by reference into this application. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to a technique of a portable electronic apparatus loading an electronic device thereon. 
   As a background art of the present technical field, for example, there is JP-A-2004-253752 (patent document 1). In the present publication, there is described “an object is to intend to make an electronic apparatus compact” as a problem. Further, there is described “an electronic apparatus having an electronic device generating heat and an electronic device in which a used environmental temperature is lower than a temperature generated from the electronic device, comprising a support means supporting a casing of the electronic apparatus, and a heat conducting means arranged between the support means and the heat generating electronic device for conducting the heat by the heat generating electronic device” as a solving means thereof. 
   In the portable electronic apparatus having a circuit board mounting the electronic device thereon, it is required to let the heat in an inner portion loose into an external portion as efficiently as possible, for preventing a performance of a circuit part such as an IC or the like corresponding to the electronic device from being adversely affected by the generated heat. In the conventional portable electronic apparatus, in order to get the heat in the inner portion out, the structure is made such that a copper plate is closely contacted with and fixed to a metal frame forming a frame of the portable electronic apparatus, and the heat is let loose into the casing in the external portion via the copper plate. A description will be given of one example of an electronic apparatus using the conventional art with reference to  FIG. 10 . 
     FIG. 10  shows a cross sectional view of a conventional video camera. A metal frame  1  forming an entire frame and made of a metal is arranged in a center portion of the camera, and a copper heat radiating plate  6  for letting a heat in an internal portion loose into an external portion is bonded to one side of the metal frame  1  in accordance with a caulking so as to be fixed. A main substrate  3  having a circuit controlling a function of an entire of the camera is fixed to the metal frame  1  by a screw  3   a.  A heat radiating rubber  7   b  is arranged between a circuit part  3   c  such as an IC or the like mounted on the main substrate  3  and the heat radiating plate  6 , and transfers the heat generated in the circuit part  3   c  to the heat radiating plate  6  via the heat radiating rubber  7   b.  A drive unit  4  reading and writing an information of an optical disc  9  is fixed to the metal frame  1  by a screw  5   a.  A drive substrate  2  on which a circuit part controlling the drive unit  4  is mounted is fixed to the drive unit  4  by a screw  2   a.  A heat radiating rubber  7   a  is arranged between a circuit part  2   c  such as an IC or the like mounted on the drive substrate  2  and the heat radiating plate  6 , and transmits the heat generated in the circuit part  2   c  to the heat radiating plate  6  via the heat radiating rubber  7   a.  The main substrate  3  and the drive substrate  2  are electrically connected by a flexible element  8 . The heat radiating plate  6  is brought into contact with an L case  10  corresponding to an outer shell part in a camera bottom surface portion X, and lets the heat in the circuit part  3   c  and the circuit part  2   c  loose into the external portion. A connector  2   b  mounted on the drive substrate  2  and a connector mounted on the flexible element  8  are connected, and the connector mounted on the flexible element  8  and a connector  3   b  mounted on the main substrate  3  are connected, whereby the drive substrate  2  and the main substrate  3  are electrically connected. 
   BRIEF SUMMARY OF THE INVENTION 
   In the conventional video camera using the optical disc, since the drive substrate  2  is fixed to the metal frame  1  via the drive unit  4  and a rubber damper  5  as shown in  FIG. 10 , an interval of a gap between the drive substrate  2  and the heat radiating plate  6  fixed to the metal frame  1  is not stabilized due to a deflection of the rubber damper  5 , an assembling dispersion or the like, and a dispersion is generated. Accordingly, even if the heat radiating rubber  7   a  is arranged between the circuit part  2   c  such as the IC or the like mounted on the drive substrate  2  and the heat radiating plate  6 , a contact pressure between the circuit part  2   c  and the heat radiating rubber  7   a  and between the heat radiating plate  6  and the heat radiating rubber  7   a  varies due to the dispersion of the interval of the gap. In the case that the interval of the gap is large, the contact pressure becomes low, so that there is a problem that it is impossible to securely transfer the heat of the drive substrate  2  to the heat radiating plate and an efficiency of the heat radiation is deteriorated. 
   Further, since two sets of connectors (the connector  2   b  and the connector  3   b ) are used for the connection between the drive substrate  2  and the main substrate  3  via the flexible element  8 , and the connector  3   b  in the main substrate  3  side can not be mounted on the metal frame  1  side in view of an workability at a time of assembling, it is necessary to arrange the connector  3   b  in the opposite outer shell part side. Accordingly, it is necessary to secure a space for the connector in the outer shell part side, and there is a problem that a thin structure is obstructed. 
   An object of the present invention is to provide a portable electronic apparatus which improves a heat radiating efficiency of a drive substrate and intends to achieve a further thin structure, thereby improving a usability of the portable electronic apparatus. 
   In order to achieve the object mentioned above, there is provided a portable electronic apparatus comprising: 
   two circuit boards having heat generating electronic devices; 
   a frame arranged at a position pinched by the circuit boards; and 
   a first heat radiating member brought into contact with the frame and having a higher heat conductivity than the frame, 
   wherein the two circuit boards are respectively fixed to the frame and the two circuit boards are directly connected by a connector. 
   Accordingly, it is possible to provide a portable electronic apparatus which improves a heat radiating efficiency and intends to achieve a further thin structure. 
   Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a rearward perspective view of a state in which a disc cover of a video camera in accordance with the present embodiment is open; 
       FIG. 2  is a frontward perspective view of the video camera in accordance with the present embodiment; 
       FIG. 3  is a cross sectional view of the video camera in accordance with the present embodiment; 
       FIG. 4  is an exploded view of the video camera in accordance with the present embodiment; 
       FIG. 5  is a schematic view of a connector portion between a drive substrate and a main substrate of the video camera in accordance with the present embodiment; 
       FIG. 6  is a perspective view in the case that a metal frame and a heat transfer member of the video camera in accordance with the present embodiment are integrally formed; 
       FIG. 7  is a cross sectional view around a rear case of the video camera in accordance with the present embodiment; 
       FIG. 8  is an internal perspective view of a video camera in accordance with a second embodiment of the present embodiment; 
       FIG. 9  is an internal perspective view of a video camera in accordance with a third embodiment of the present embodiment; and 
       FIG. 10  is a cross sectional view of a conventional video camera. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A description will be given below of an example of a video camera as a first embodiment in accordance with the present invention with reference to  FIGS. 1 to 7 . 
   A description will be first given of a summary of the video camera using an optical disc in accordance with the present embodiment with reference to  FIGS. 1 and 2 .  FIG. 1  is a rearward perspective view of a state in which a disc cover of the video camera in accordance with the present embodiment is open, and  FIG. 2  is a frontward perspective view of the video camera in accordance with the present embodiment. 
   The video camera in accordance with the present embodiment is sectioned into a front side constituted by a lens portion  18 , a microphone portion  23 , a lens cover  14 , a front case  24  and the like, a liquid crystal display side constituted by a liquid crystal display (LCD) panel portion  22 , an LCD supporting point portion  25 , a main body case  19  and the like, a grip side constituted by a disc cover  26 , an R case  17  and the like, and a rear side constituted by an electric view finder (EVF) portion  20  and a battery (not shown). 
   A screen image and a voice are photographed and collected through the lens portion  18  and the microphone portion  23 . The screen image and the like are displayed on the EVF portion  20  and the LCD portion  22  at a photographing time or a reproducing time. A mode switching knob  16  arranged in the rear side turns on and off a power source and switches a mode between a moving image mode and a static image mode. A picture recording button  13  corresponds to a button for starting and stopping the picture recording. The R case  17  in the grip side protects a drive unit (not shown) for recording a signal on an optical disc  15 . 
     FIG. 2  shows a state in which the LCD portion  22  is closed while setting a display surface to an inner side. The LCD portion  22  can be opened and closed, and rotated by the LCD supporting point portion  25 , and can adjust the display surface at an angle suitable for a used state. A reproducing operation button  21  mainly used at a reproducing time is arranged in a surface which is adjacent to the closed LCD portion  22 . 
   In this case, a description will be given of an internal fixing method and an internal structure of the video camera in accordance with the present embodiment with reference to  FIGS. 3 and 4 .  FIG. 3  is a cross sectional view of the video camera in accordance with the present embodiment, and  FIG. 4  is an exploded view of the video camera in accordance with the present embodiment. 
   First, a description will be given of the internal fixing method with reference to  FIG. 4 . A drive unit  35  is fixed to a metal frame  31  via a rubber damper  37  by a screw  37   a,  a main substrate  34  is further fixed to the metal frame  31  by a screw  34   b,  and a drive substrate  33  is fixed to the metal frame  31  by a screw  33   b.  The main substrate  34  and the drive substrate  33  are electrically connected through the metal frame  31  and an opening portion  31   a  of a heat radiating plate  32  by a connector  34   a  mounted on the main substrate  34  and a connector  33   a  mounted on the drive substrate  33 . A heat radiating rubber A  38   a  is arranged between an IC  33   c  mounted on the drive substrate  33  and the heat radiating plate  32 . A heat radiating rubber B  38   b  is arranged between an IC  34   c  mounted on the main substrate  34  and the heat radiating plate  32 . 
   Next, a description will be given of the internal structure with reference to  FIG. 3 . The metal frame  31  forming an entire frame and made of a metal is arranged in a center portion of the camera, and the copper heat radiating plate  32  for letting an internal heat loose into an external portion is bonded to one side of the metal frame  31  in accordance with a caulking so as to be fixed. The main substrate  34  having a circuit controlling an entire function of the present camera is fixed to the metal frame  31  by the screw  34   b,  and the heat radiating rubber B  38   b  is arranged between the IC  34   c  mounted on the main substrate  34  and the heat radiating plate  32 . Further, the drive substrate  33  on which a circuit part controlling the drive unit  35  is mounted is fixed to the metal frame  31  by the screw  33   b,  and the heat radiating rubber A  38   a  is arranged between the IC  33   c  mounted on the drive substrate  33  and the heat radiating plate  32 . The heat radiating plate  32  is brought into contact with an L case  41  corresponding to an outer shell part in a camera bottom surface portion, and lets the heat in the IC  33   c  and the IC  34   c  loose into the external portion. The drive unit  35  reading and writing the information of the optical disc  15  is fixed to the metal frame  31  via the rubber damper  37  by the screw  37   a.    
   As mentioned above, the dispersion of the gap between the IC  33   c  mounted on the drive substrate  33  and the heat radiating plate  32  becomes small by attaching the drive substrate  33  to the metal frame  31  by the screw  33   b,  and it is possible to improve a heat radiating efficiency by stabilizing the contact pressure between the IC  33   a  and the heat radiating rubber A  38   a  and between the heat radiating plate  32  and the heat radiating rubber A  38   a  high. Further, it is not necessary to secure the space for the connector in the outer shell part side by connecting by a set of connectors while utilizing the space between the drive substrate  33  and the main substrate  34 , and it is possible to contribute to the thin structure of the video camera. Further, since it is possible to reduce the number of the connectors connecting between the drive substrate  33  and the main substrate  34 , it is possible to reduce an electric loss. 
     FIG. 5  shows a schematic view of the connector portion between the drive substrate and the main substrate in accordance with the present embodiment. The main substrate  34  and the drive substrate  33  are electrically connected through the metal frame  31  and the opening portion  31   a  of the heat radiating plate  32  by the connector  34   a  mounted on the main substrate  34  and the connector  33   a  mounted on the drive substrate  33 . In accordance with the structure, since the connector is arranged in the overlapping portion between the drive substrate and the main substrate and the connector is arranged by utilizing the space pinched by two circuit boards, it is not necessary to enlarge two drive substrates and the main substrate, and the thin structure can be achieved without enlarging the outer shape such as the height of the portable electronic apparatus and the like. 
   A description will be further given of a path through which the heat of the IC  33   c  on the drive substrate  33  is radiated to the external portion via the heat radiating plate  32  with reference to  FIGS. 6 and 7 .  FIG. 6  is a perspective view in the case that the metal frame and the heat transfer member of the video camera in accordance with the present embodiment are integrally formed,  FIG. 7A  is a cross sectional view around the rear case of the video camera in accordance with the present embodiment, and  FIG. 7B  is an enlarged view of  FIG. 7A . 
   In order to let the heat generated from the drive substrate  33  loose into the external portion, the heat radiating rubber A  38   a  made of an elastic material is stuck to the portion between the circuit part of the IC  33   c  mounted on the drive substrate  33  and the heat radiating plate  32 , and the heat which the heat radiating rubber A  38   a  absorbs from the IC  33   c  is transferred to the outer shell part via the copper heat radiating plate  32  caulked in the metal frame  31 . On the other hand, the heat radiating rubber C  38   c  is stuck to the end portion of the heat radiating plate  32  in the rear direction of the video camera, and the heat radiating rubber C  38   c  is brought into contact with the rear case  40  so as to radiate the heat in a direction G via the rear case  40 . 
   In this case, a description of the heat transfer of the IC  34   c  mounted on the main substrate  34  will be omitted here. 
   Next, a description will be given of a second embodiment of a video camera corresponding to the other embodiment in accordance with the present invention. In the embodiment 2, a notch portion is provided in place of the opening portion  31   a  in the embodiment 1.  FIG. 8  shows an internal perspective view of the video camera in accordance with the present embodiment. 
   A main substrate (not shown) is connected to a metal frame  71  and a notch portion  71   a  of a heat radiating plate  72  through a connector  73   a  of a drive substrate  73 . In this case, since a working process is reduced in the metal frame  71  and the heat radiating plate  72  in comparison with the case that the opening portion is provided, it is possible to reduce a cost of the metal frame  71  and the heat radiating plate  72 . Further, if a position of the connector  73   a  is arranged near an end surface of the drive substrate  73 , the notch portion  71   a  becomes smaller, and it is possible to reduce a deterioration of a strength in the metal frame  71 . 
   Next, a description will be given of a third embodiment of a video camera corresponding to the other embodiment in accordance with the present invention. In the embodiment 3, the main substrate and the drive substrate are directly connected by the connector without forming the opening portion or the notch portion.  FIG. 9  shows an internal perspective view of the video camera in accordance with the present embodiment. 
   In  FIG. 9 , a main substrate (not shown) is connected to an outer side of a metal frame  81  and a heat radiating plate  82  through a connector  83   a  of a drive substrate  83 . In this case, it is not necessary to form the opening portion or the notch portion in the metal frame  81  and the heat radiating plate  82 , and it is possible to further improve a strength of the metal frame  81  and the heat radiating plate  82 . Further, a working process is reduced and it is possible to further reduce a cost of the metal frame  81  and the heat radiating plate  82 . 
   As mentioned above, in accordance with the present invention, it is possible to provide the portable electronic apparatus which can improve the heat radiating efficiency and achieve a further thin structure. 
   It should be further understood by those skilled in the art that although foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.