Abstract:
A power switch and connector that are conventionally included in a body are formed in spaces created at the outer ends of the shafts of hinges other than the body and a display, whereby the body is thinned. Electronic device comprises a body, a display, and a hinge that joins the body and display so that they can be freely opened or closed. A power switch is formed at an end of the shaft of the hinge. Furthermore, the electronic device comprises the body, the display, and another hinge that joins the body and display so that they can be freely opened or closed. A port of a connector opens at an end of the shaft of the hinge.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an electronic device having a hinge that joins a body and a display. More particularly, the present invention is concerned with the electronic device in which an outer space in the hinge is effectively utilized.  
         [0003]     2. Description of the Related Art  
         [0004]     Notebook computers have been known for some time as an electronic device with a body and a display which can freely be opened away from the body and closed onto the body.  
         [0005]     In the electronic device, for example, as disclosed in patent Document 1, a power switch is flush with a keyboard included in the body. Moreover, in the electronic device disclosed in patent Document 2, the power switch is juxtaposed with other operation switches on the lateral side of the body. Moreover, since a motherboard is incorporated in the body, connectors allowing linkage with external equipment or a communication line are disposed on the lateral side or rear side of the body. 
        [Patent Document 1] Japanese Unexamined Patent Publication No. 2002-108505     [Patent Document 2] Japanese Unexamined Patent Publication No. 2002-7048        
 
         [0008]     In recent years, the electronic device has become more and more compact. There is difficulty in preserving a space, in which components are disposed, in a body and a display alike. Moreover, for realization of thinner equipment, it proves effective to limit the number of components to be incorporated in the body. The present inventor et al. have given attention to a space created at an outer end of the shaft of a hinge other than the body and the display. A power switch or a connector that are conventionally included in the body is disposed in the space in efforts to thin the body.  
       SUMMARY OF THE INVENTION  
       [0009]     In one aspect, an electronic device in accordance with the present invention comprises a body, a display, and a hinge that joins the body and display so that they can freely be opened or closed. A power switch is formed at an edge of the shaft of the hinge.  
         [0010]     In another aspect, the electronic device in accordance with the present invention comprises a body, a display, and a hinge that joins the body and display so that they can be freely opened or closed. A port of a connector opens at an end of the shaft of the hinge.  
         [0011]     As mentioned above, since the power switch or connector is disposed in a space at an end of the shaft of a hinge which has been left unused as a so-called dead space in the past, the freedom in disposing components in the body or display is expanded accordingly. By devising the layout of the components, thinning of the body and display is facilitated.  
         [0012]     According to the electronic device in which the present invention is implemented, a power switch is disposed at an end of the shaft of a hinge. A space in the electronic device that has not been used at all in the past can be utilized effectively. The number of components to be incorporated in the body can be reduced, and the freedom in laying out components is expanded accordingly.  
         [0013]     Consequently, the body can be further thinned.  
         [0014]     Moreover, since the power switch is disposed away from a keyboard and other operation buttons, the power switch can be prevented from being pressed by mistake and accurately manipulated.  
         [0015]     Moreover, according to the electronic device in which the present invention is implemented, a port of a connector opens at an end of the shaft of a hinge. A space present in electronic device that is conventionally not used at all can be utilized effectively. The number of components to be incorporated in a body can be reduced. The freedom in laying out components is expanded accordingly.  
         [0016]     Consequently, the body can be further thinned. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a perspective view of an electronic device according to an embodiment of the invention in an opened state;  
         [0018]      FIG. 2  is a perspective view of the electronic device in a closed state;  
         [0019]      FIG. 3  is a plan view of the inside of a lower section  27  of a case  26  of the electronic device;  
         [0020]      FIG. 4  is a side view of the lower section  27  as seen along the arrows [ 4 ] and [ 4 ] of  FIG. 3 ;  
         [0021]      FIG. 5  is a plan view of the built-in components disposed in the case  26 ;  
         [0022]      FIG. 6  is a plan view of one surface of a motherboard to be fitted into the case  26 ;  
         [0023]      FIG. 7  shows the other surface of the motherboard shown in  FIG. 6 ;  
         [0024]      FIG. 8  is a plan view of connectors and a flexible wiring board provided in the case  26 ;  
         [0025]      FIG. 9  is a front view of the connectors and the flexible wiring board of  FIG. 8 ;  
         [0026]      FIG. 10  is an enlarged front view of the connectors shown in  FIGS. 8 and 9 ;  
         [0027]      FIG. 11  is a plan view of a keyboard fitted into the case  26 ;  
         [0028]      FIG. 12  is a front view of the keyboard;  
         [0029]      FIG. 13  is a rear view of the keyboard;  
         [0030]      FIG. 14  is a left-side view of the keyboard;  
         [0031]      FIG. 15  is a right-side view of the keyboard;  
         [0032]      FIG. 16  is a back side view of the keyboard;  
         [0033]      FIG. 17  is a plan view of the inside of the upper section  28  of the case  26 ;  
         [0034]      FIG. 18  is a schematic cross section of the inside of the case  26  where heat-generating components are placed;  
         [0035]      FIG. 19  is a plan view of the inside of a case  22 ;  
         [0036]      FIG. 20  is a side view of the case  22  as seen along the arrows [ 20 ] and [ 20 ] in  FIG. 19 ;  
         [0037]      FIG. 21  is a plan view of a liquid crystal panel and an inverter circuit board fitted in the inside of the case  22 ;  
         [0038]      FIG. 22  is an enlarged plan view of a principal part of the liquid crystal panel being housed in the case  22 ;  
         [0039]      FIG. 23  is an enlarged view of one of the two constituent parts of hinges formed at the back of the case  22 ;  
         [0040]      FIG. 24  is an enlarged view of the other constituent part of the hinges formed at the back of the case  22 ;  
         [0041]      FIG. 25  is a schematic diagram showing a construction of a power switch installed in the constituent part of the hinge shown in  FIG. 23 ;  
         [0042]      FIGS. 26A and 26B  are schematic cross sections of the laminated structure of the case  22  of the electronic device according to the present embodiment;  
         [0043]      FIGS. 27A and 27B  show the pieces of conductor foil being stuck onto the laminated layer of  FIGS. 26A and 26B ;  
         [0044]      FIG. 28  shows a resin material being stuck onto edge portions of the laminated layers shown in  FIG. 26 ;  
         [0045]      FIG. 29  is an enlarged view of the rear portion of the electronic device in an opened state according to the present embodiment; and  
         [0046]      FIG. 30  is an enlarged view of the front edge portion of the electronic device in a closed state according to the present embodiment. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0047]     Now, an embodiment of an electronic device in accordance with the present invention will be described below. The embodiment is a notebook computer.  
         [0048]      FIGS. 1 and 2  show the outer appearances of the electronic device  1  of the present embodiment. The electronic device  1  comprises a body  3 , a display  5 , and two hinges “h” which fasten the display  5  to the body  3 .  
         [0049]     The display  5  pivots on the hinges “h” to open away from the body  3  and close onto the body  3 . In  FIG. 1 , the display  5  is opened away from the body  3 . In  FIG. 2 , the display  5  is closed onto the body  3 .  
         [0050]     The body  3  has a case  26 . Disposed in the case  26  as shown in  FIG. 5  are a keyboard  11 , a motherboard  30 , a hard-disk drive  32 , a PC card slot  34 , and connectors  40   a - d.    
         [0051]     The keyboard  11  is an input unit of the electronic device  1 . The motherboard  30  is the substantially main functional component of the electronic device  1  and receives signals inputted through the keyboard  11  and makes various kinds of processing such as arithmetic processing, control processing, image processing, and processing to output signals to the display  5 .  
         [0052]     The motherboard  30  serves as a control circuit board to control individual components such as the keyboard  11  and the display  5 , too.  
         [0053]     The case  26  comprises an upper section  28  and a lower section  27 .  FIG. 3  is a plan view of the inside of the lower section  27 .  
         [0054]      FIG. 4  is a side view of the lower section  27  as seen along the arrows [4] and [4] of  FIG. 3 .  
         [0055]     The lower section  27  looks like a flat box and has an almost rectangular bottom plate  27   a , right and left side plates  27   b  and  27   d , and a back plate  27   c . As shown in  FIGS. 3 and 4 , the side and back plates  27   b - d  are erected on the three sides of the bottom plate  27   a.    
         [0056]     The back plate  27   c  is erected on the back side of the bottom plate  27   a  and has outward-protruding constituent parts  42   a  and  42   b  of the hinges “h” as shown in  FIGS. 3 and 4 .  
         [0057]     As shown in  FIGS. 3 and 4 , there are cuts  43   a - d  in the left side plate  27   b  for the connectors  40   a - d  and a cut  43   e  in the right side plate  27   d  for the PC card slot  34 .  
         [0058]     The inside of the bottom plate  27   a  is provided with a resin mold  45 , which is raised from the inside surface of the bottom plate  27   a  to reinforce the lower section  27  against bending and twisting.  
         [0059]     A heat-transmitting sheet  47  is stuck on the inside surface of the bottom plate  27   a . The heat-transmitting sheet  47  is positioned near to the center between the right and left sides of the bottom plate  27   a  and one-sided toward the back side of the bottom plate  27   a.    
         [0060]     The heat-transmitting sheet  47  is, for example, a graphite sheet 0.1 to 1.0 mm thick. Because the heat-transmitting sheet  47  is positioned in an area where the mold  45  does not exist, the heat-transmitting sheet  47  does not float, but is closely stuck onto the inside of the bottom plate  27   a ; accordingly, the heat from heat-generating components to be described later is diffused effectively through the lower section  27 .  
         [0061]     An elastic sheet  48  is laid between the heat-transmitting sheet  47  and the bottom plate  27   a . The elastic sheet  48  is rectangular and larger than the heat-generating components. The elastic sheet  48  is positioned substantially in the middle of the lateral width of the lower section  27  within about a half of the bottom  27   a  near the wall portion  27   c.    
         [0062]     To be specific, the elastic sheet  48  is 0.5-3.0 mm thick and made of Poron (of Rogers Inoac Corporation) which is high-density polyurethane foam whose cells are fine and uniform.  
         [0063]     An insulating sheet  49  is overlaid on the heat-transmitting sheet  47 ; accordingly, short circuits between the heat-transmitting sheet  47 , which is made of graphite and conductive, and the motherboard, which is put on the heat-transmitting sheet  47 , are prevented.  
         [0064]     The insulating sheet  49  is, for example, a transparent thin film of polyphenylene sulfide. It is as thin as, for example, 0.05-0.3 mm; therefore, it does not prevent heat transmission from the heat-generating components to the heat-transmitting sheet  47 .  
         [0065]     The lower section  27  is made of CFRP (carbon fiber reinforced plastics). To be specific, the CFRP consists of six layers  51   a ,  51   b ,  52   a ,  52   b ,  53   a , and  53   b  as shown in  FIG. 26 .  
         [0066]     As shown in  FIG. 26A , the six layers  51   a ,  51   b ,  52   a ,  52   b ,  53   a , and  53   b  are pressed together.  
         [0067]     Each layer is made of long carbon fibers solidified by epoxy resin. All the fibers of each layer are put side by side in one and the same direction.  
         [0068]     To be specific, the carbon fibers of the innermost layers  51   a  and  51   b  are laid in the longitudinal direction of the electronic device  1 . Accordingly, the carbon fibers of the layer  51   a  are parallel to those of the layer  51   b.    
         [0069]     The carbon fibers of the intermediate layers  52   a  and  52   b  are laid in the lateral direction of the electronic device  1 .  
         [0070]     The carbon fibers of the outermost layers  53   a  and  53   b  are laid in the direction at angles of 45° with the longitudinal and lateral directions of the electronic device  1 . Accordingly, the carbon fibers of the layer  53   a  are parallel to those of the layer  53   b.    
         [0071]     With the above laminated structure, the thin lower section  27  has sufficient strength. As the lower section  27  is thin, the electronic device  1  is also thin, which is an advantage for portable electronic devices in particular.  
         [0072]     As shown in  FIG. 28 , an insulating layer  56  is formed on the inside surface of the bottom plate  27   a . The insulating layer  56  is made of, for example, nylon (a trade name of Du Pont).  
         [0073]     The insulating layer  56  prevents short circuits between the lower section  27 , which is made of CFRP (carbon fiber reinforced plastics) containing conductive carbon fibers, and the motherboard  30  fitted in the lower section  27 .  
         [0074]     When the insulating layer  56  made of nylon is heated, it softens and becomes adhesive. By making use of the adhesiveness of the insulating layer  56 , the mold  45  is stuck and fixed to the insulating layer  56 . The mold  45  has bosses with threaded holes, etc.  
         [0075]     As shown in  FIG. 28 , the front edge of the lower section  27  is provided with a resin cover  45   a . By making use of the adhesiveness of the insulating layer  56 , the cover  45   a  is stuck onto the insulating layer  56  to cover the front edge of the lower section  27 . Thus, loose ends of carbon fibers, if any, at the, front edge of the lower section  27  are covered up.  
         [0076]     As shown in  FIG. 3 , because the resin cover  45   a  extends along the front edge of the lower section  27 , it serves as a beam, too, reinforcing the lower section  27  against bending and twisting.  
         [0077]     The resin cover  45   a  and the mold  45  are made of nylon as well as the insulating layer  56 ; accordingly, the cover  45   a  and the mold  45  are stuck on the insulating layer  56  sufficiently. As shown in  FIG. 28 , a groove  54  is made in the surface of the resin cover  45   a  which comes in contact with the insulating layer  56 . When the insulating layer  56  is heated and softened and the cover  45   a  is stuck on the insulating layer  56 , surplus softened, adhesive nylon enters into the groove  54 .  
         [0078]     Thus, the surplus softened, adhesive nylon is prevented from leaking out through the joint between the lower section  27  and the cover  45   a . If the surplus softened, adhesive nylon leaks out, the appearance of the electronic device  1  is spoiled.  
         [0079]     Because the right and left side plates  27   b  and  27   d  are erected on the right and left sides, respectively, and the back plate  27   c  is erected on the back side of the bottom plate  27   a , these plates  27   b ,  27   c , and  27   d  play the role of the cover  45   a.    
         [0080]     Now, the motherboard to be fitted in the lower section  27  will be described below by referring to  FIGS. 6 and 7 .  FIG. 6  shows the upper surface of the motherboard  30 ;  FIG. 7 , the lower surface. A central processor  58  is mounted on the upper surface. An image processor  60  and a plurality of semiconductor memories  62  are mounted on the lower surface. Although not shown in  FIGS. 6 and 7 , many other components are mounted on both the surfaces of the motherboard  30 .  
         [0081]     The central processor  58  and the image processor  60  are semiconductors and generate heat when they function. The central processor  58  and the image processor  60  are so positioned that they do not overlap with each other.  
         [0082]     The motherboard  30  comprises a multi-layer printed circuit board and the central processor  58 , the image processor  60 , the semiconductor memories  62 , and other components (not shown) mounted on both the surfaces of a multi-layer printed circuit board and is the substantial body of the electronic device  1  in terms of functions of the electronic device  1 .  
         [0083]     The multi-layer printed circuit board is made by the buildup method as follows. A two-layer printed circuit board (hereinafter “intermediate two-layer printed circuit board”) is laid on each of the upper and lower surfaces of an innermost two-layer printed circuit board. A single-layer printed circuit board is laid on the upper surface of the upper intermediate two-layer printed circuit board; a single-layer printed circuit board, on the lower surface of the lower intermediate two-layer printed circuit board. A single-layer printed circuit board is laid on the upper surface of the upper single-layer printed circuit board; a single-layer printed circuit board, on the lower surface of the lower single-layer printed circuit board. Thus, a ten-layer printed circuit board is made. The buildup method enables us to do wiring efficiently and high-density mounting of parts.  
         [0084]     The connectors  40   a - d  shown in  FIGS. 8-10  are also fitted in the lower section  27 . The connectors  40   a - d  are connected to the motherboard  30  through a flexible wiring board  67 . Namely, the connectors  40   a - d  are connected to wires at one end of the flexible wiring board  67 , and the other end  67   a  of the flexible wiring board  67  is inserted into a connector mounted on the motherboard  30 .  
         [0085]     As shown in  FIG. 10 , the connector  40   b  is provided two flanges  64  protruding from the right and left shorter sides of its socket. By fixing the flanges  64  to the left side plate  27   b  by using, for example, screws, the connector  40   b  can be fixed to the left side plate  27   b . The connector  40   c  has the same flanges  64  as the connector  40   b.    
         [0086]     The keyboard  11  shown in  FIGS. 11-16  is fitted to the lower section  27 .  FIG. 11  is a plan view of the keyboard  11 .  FIGS. 12 and 13  are front and rear views, respectively, of the keyboard  11 .  FIGS. 14 and 15  are left and right side views, respectively, of the keyboard  11 .  FIG. 16  is a bottom view of the keyboard  11 .  
         [0087]     The keyboard  11  comprises a case  37 , input keys  13 , a pointing device  14  called “track point,” and a cover  36 .  
         [0088]     The case  37  is made of, for example, magnesium and in the shape of a flat box, having a key-arrangement area and side plates erected around the key-arrangement area.  
         [0089]     The key-arrangement area is in the shape of an almost rectangular flat plate and the side plates are formed, as a single piece, at the right, left, top, and bottom sides of the key-arrangement area.  
         [0090]     As described above, the case  37  is not a flat plate, but in the shape of a flat box, having the side plates; accordingly, its rigidity is high. When a user presses keys  13 , the case  37  does not warp, giving good repulsion to the fingers of the user. Thus, the feeling of key operation is good.  
         [0091]     The four sides of each key of an ordinary keyboard are inclined, whereas the four sides of input keys  13  are not inclined. Accordingly, the occupancy area of each input key  13  is smaller than that of an ordinary key. Accordingly, the gaps between input keys  13  can be widened to prevent the user from pressing wrong input keys  13 .  
         [0092]     The cover  36  has cuts in it, and the input keys  13  and the pointing device  14  are exposed through the cuts. The key-arrangement area is covered with the cover  36 . Thus, the gaps between input keys  13  are covered and, hence, dust and water are prevented from entering through the gaps. The cover  36  and the input keys  13  are made of, for example, ABS resin.  
         [0093]     Now, the upper section  28  of the case  26  will be described below by referring to  FIG. 17 .  FIG. 17  is a plan view of the inside of the upper section  28  which faces the inside of the lower section  27  shown in  FIG. 3 .  
         [0094]     The upper section  28  is almost rectangular and has approximately the same area as the lower section  27 . The upper section  28  has a large cut  80  in its front area wherein the input keys  13  and the pointing device  14  are arranged.  
         [0095]     The reference numeral  81  in  FIG. 17  is a covered area. Outward-protruding constituent parts  74   a  and  74   b  of the hinges “h” are formed at the back side of the covered area  81 .  
         [0096]     A heat-transmitting sheet  72  is stuck to the inside of the covered area  81 . The heat-transmitting sheet  72  is positioned near to the center between the right and left sides of the covered area  81 .  
         [0097]     The heat-transmitting sheet  72  is made of, for example, graphite and 0.1-1.0 mm thick. The heat-transmitting sheet  72  is shaped and has cuts in it so as to avoid bosses and ribs erected inside the covered area  81 . Thus, the covered area  81  is not floated over the inside surface of the covered area  81 , but closely stuck onto the inside surface; accordingly, the heat from heat-generating components is effectively diffused through the upper section  28 .  
         [0098]     An elastic sheet  83  is laid between the heat-transmitting sheet  72  and the inside surface of the covered area  81 . The elastic sheet  83  is rectangular and larger than the heat-generating components in contact with the heat-transmitting sheet  72 . The elastic sheet  83  is positioned near to the center between the right and left sides of the covered area  81 .  
         [0099]     To be specific, the elastic sheet  83  is 0.5-3.0 mm thick and made of Poron (of Rogers Inoac Corporation) which is high-density polyurethane foam whose cells are fine and uniform.  
         [0100]     An insulating sheet (not shown) is overlaid on the heat-transmitting sheet  72 ; accordingly, short circuits between the heat-transmitting sheet  72 , which is made of graphite and conductive, and the motherboard  30 , which is put on the heat-transmitting sheet  72 , are prevented.  
         [0101]     The insulating sheet is, for example, a transparent film of polyphenylene sulfide. It is as thin as, for example, 0.05-0.3 mm; therefore, it does not prevent heat transmission from the heat-generating components to the heat-transmitting sheet  72 .  
         [0102]     The lower section  27  and the upper section  28  are coupled by, for example, screws. At this time, the keyboard  11 , motherboard  30 , hard-disk drive  32 , and PC card slot  34  are fitted in the inside of the lower section  27 .  
         [0103]     The cooling mechanism for the central processor  58  and the image processor  60 , which are mounted on the upper and lower surfaces, respectively, of the motherboard  30  and generate heat, will be described below by referring to  FIG. 18 .  
         [0104]     The lower surface, on which the image processor  60  is mounted, of the motherboard  30  faces the inside of the lower section  27 . The upper surface, on which the central processor  58  is mounted, faces the inside of the upper section  28 .  
         [0105]     The image processor  60  is in contact with the part of the heat-transmitting sheet  47  raised by the elastic sheet  48 . In this way, the image processor  60  is put in close contact with the heat-transmitting sheet  47  by the elasticity of the elastic sheet  48 . Thus, air is precluded from between the image processor  60  and the heat-transmitting sheet  47  and the heat from the image processor  60  is efficiently transmitted to the heat-transmitting sheet  47 .  
         [0106]     The heat transmitted to the heat-transmitting sheet  47  is diffused through the heat-transmitting sheet  47  and the lower section  27 . Thus, overheat of the image processor  60  is prevented.  
         [0107]     The central processor  58  is in contact with the part of the heat-transmitting sheet  72  lowered by the elastic sheet  83 . In this way, the central processor  58  is put in close contact with the heat-transmitting sheet  72  by the elasticity of the elastic sheet  83 . Thus, air is precluded from between the central processor  58  and the heat-transmitting sheet  72  and the heat from the central processor  58  is efficiently transmitted to the heat-transmitting sheet  72 .  
         [0108]     The heat transmitted to the heat-transmitting sheet  72  is diffused through the heat-transmitting sheet  72  and the upper section  28 . Thus, overheat of the central processor  58  is prevented.  
         [0109]     The central processor  58  and the image processor  60  are so positioned that they do not overlap with each other and, hence, the heat from the central processor  58  and the image processor  60  is not concentrated at a single spot. Beside, this arrangement of the central processor  58  and the image processor  60  enables the reduction of the distance between the lower section  27  and the upper section  28  and, hence, the reduction of the body  3 .  
         [0110]     The semiconductor memories  62  (see  FIG. 7 ) mounted on the lower surface of the motherboard  30  are also in contact with the heat-transmitting sheet  47  and their heat is diffused through the heat-transmitting sheet  47 .  
         [0111]     The hard-disk drive  32  as that is a storage device, which is positioned to the left of the motherboard  30  in  FIG. 5 , will be described below.  
         [0112]     As shown in  FIG. 3 , ribs  46  are formed in the four corners of a hard disk drive-mounting space  44  in the lower section  27 . In addition, as shown in  FIG. 17 , ribs  78  are formed in the four corners of a hard disk drive-mounting space  76  in the upper section  28 .  
         [0113]     Accordingly, the hard-disk drive  32  is supported by the ribs  46  and  78 , a gap of the height of ribs  78  kept between the top surface of the hard-disk drive  32  and the inside surface of the upper section  28 , a gap of the height of ribs  46  kept between the bottom surface of the hard-disk drive  32  and the inside surface of the lower section  27 .  
         [0114]     There are small gaps in spots, where the connectors  40   a - d  (see  FIG. 5 ) are mounted to expose their sockets, of the left side plates of the lower section  27  and the upper section  28 . The inside and the outside of the case  26  are connected by the small gaps. The space in which the motherboard  30  is fitted and the outside of the case  26  can be connected by the small gaps and the gaps on and under the hard-disk drive  32 .  
         [0115]     Accordingly, the discharge of heat from the central processor  58  and the image processor  60  can be accelerated. Besides, the hard-disk drive  32  can be air-cooled.  
         [0116]     The connectors  40   a - d  are connected to the motherboard  30  through the flexible wiring board  67  (see  FIG. 8 ). The flexible wiring board  67  is routed through the gap between the bottom surface of the hard-disk drive  32  and the inside surface of the lower section  27 .  
         [0117]     Because the connectors  40   a - d  are not mounted directly on the motherboard  30 , shock at the time of connection and disconnection of external cables to and from the connectors  40   a - d  is absorbed by the flexible wiring board  67 . Thus, the shock is not transmitted to the motherboard  30 , damage to and positional slippage of the motherboard  30  prevented.  
         [0118]     As shown in  FIGS. 8 and 9 , the connectors  40   b  and  40   c  are disposed so that the right flange  64  of the connector  40   b  and the left flange  64  of the connector  40   c  overlap with each other. The two flanges  64  overlapping with each other are fixed to the left side plate of the lower section  27  with, for example, a screw. Thus, the space to mount the connectors  40   a - d  is saved by the space of one flange  64 .  
         [0119]     As shown in  FIG. 5 , the PC card slot  34  is disposed at the right side of the case  26 . The PC card is the standards for card-type peripheral devices established jointly by PCMCIA (Personal Computer Memory Card International Association) and JEIDA (Japan Electronic Industry Development Association).  
         [0120]     The keyboard  11  is disposed in the space along the front of the case  26 . The input keys  13  and the pointing device  14  are exposed to the outside through the cut  80  in the upper section  28 .  
         [0121]     As described above, the motherboard  30 , hard-disk drive  32 , and PC card slot  34  are disposed in the space along the back of the case  26  and the keyboard  11  is disposed in the space along the front of the case  26 .  
         [0122]     Cuts are made in the right and left sides of the motherboard  30  to avoid the hard-disk drive  32  and the PC card slot  34 . The keyboard  11  does not overlap with the central processor  58  or the image processor  60  mounted on the motherboard  30  or the hard-disk drive  32  or the PC card slot  34 .  
         [0123]     As described above, because built-in components are arranged without their overlapping with one another, the body  3  can be made thin.  
         [0124]     Part of the motherboard  30  is placed under the keyboard  11 , but the central processor  58  and the image processor  60 , which account for a large part of the thickness of the motherboard  30 , do not overlap with the keyboard  11 . Accordingly, the body  3  is not prevented from being made thin. An insulating sheet made of, for example, polycarbonate is laid between the part of the motherboard  30  overlapping with the keyboard  11  and the keyboard  11  in order to prevent short circuits between the case  37  of conductive magnesium and the motherboard  30 . The motherboard  30  and the keyboard  11  may be arranged so that they do not overlap with each other at all.  
         [0125]     Because the heat-generating central processor  58  and image processor  60  do not overlap with the keyboard  11 , the heat of neither the central processor  58  nor the image processor  60  is transmitted to the keyboard  11  to annoy the user.  
         [0126]     Because the central processor  58  and the image processor  60  are disposed in the space along the back side of the case  26  and the keyboard  11  is disposed in the space along the front side of the case  26 , the user can operate the keyboard  11  without touching the upper section  28  covering the central processor  58  and the image processor  60 .  
         [0127]     The central processor  58  and the image processor  60  are positioned near to the center between the right and left sides of the case  26 ; accordingly, less heat is transmitted from the central processor  58  and the image processor  60  to the user&#39;s right and left hands which tend to be positioned toward the right and left sides of the keyboard  11 , respectively. When the user moves the electronic device  1  with the display  5  opened, the user holds the right and left sides of the part of the body  3  behind the keyboard  11 ; accordingly, less heat is transmitted from the central processor  58  and the image processor  60  to the hands of the user.  
         [0128]     Because the most heat-generating image processor  60  is mounted on the lower surface of the motherboard  30 , less heat is transmitted from the image processor  60  to the top, or keyboard, side of the body  3 , less annoying the user.  
         [0129]     Now, the display  5  will next be described. The display  5  comprises a case  22  (see  FIG. 19 ), a liquid crystal panel  7  (see  FIG. 21 ) housed in the case  22 , and an inverter circuit board  93  (see  FIG. 21 ).  
         [0130]      FIG. 19  is a plan view of the inside of the case  22 .  FIG. 20  is a side view of the case  22  as seen along the arrows [ 20 ] and [ 20 ] in  FIG. 19 . The case  22  is almost rectangular and side plates are erected at the right and left sides of the case  22 .  
         [0131]     Outward-protruding constituent parts  87   a  and  87   b  of the hinges “h” are formed at the right and left ends of the back side of the case  22 .  
         [0132]     Molds  85   a - d  are provided inside the case  22 . The molds  85   a - d  are disposed so that they enclose the four sides of the case  22  and reinforce the case  22  against bending and twisting.  
         [0133]     In the same way as the lower section  27 , the case  22  is made of CFRP (carbon fiber reinforced plastics). To be specific, the CFRP consists of six layers  51   a ,  51   b ,  52   a ,  52   b ,  53   a , and  53   b  as shown in  FIG. 26 .  
         [0134]     As shown in  FIG. 26A , the six layers  51   a ,  51   b ,  52   a ,  52   b ,  53   a , and  53   b  are pressed together.  
         [0135]     Each layer is made of long carbon fibers solidified by epoxy resin. All the fibers of each layer are put side by side in one and the same direction.  
         [0136]     To be concrete, the carbon fibers of the innermost layers  51   a  and  51   b  are laid in the longitudinal direction of the electronic device  1 . Accordingly, the carbon fibers of the layer  51   a  are parallel to those of the layer  51   b.    
         [0137]     The carbon fibers of the intermediate layers  52   a  and  52   b  are laid in the lateral direction of the electronic device  1 .  
         [0138]     The carbon fibers of the outermost layers  53   a  and  53   b  are laid in the direction at angles of 45° with the longitudinal and lateral directions of the electronic device  1 . Accordingly, the carbon fibers of the layer  53   a  are parallel to those of the layer  53   b.    
         [0139]     With the above laminated structure, the thin case  22  has sufficient strength. As the case  22  as well as the lower section  27  is thin, the electronic device  1  is also thin, which is an advantage for portable electronic devices in particular.  
         [0140]     As shown in  FIG. 28 , an insulating layer  56  is formed on the inside surface of the case  22 . The insulating layer  56  is made of, for example, nylon (a trade name of Du Pont).  
         [0141]     The insulating layer  56  prevents short circuits between the case  22  made of CFRP containing conductive carbon fibers and the liquid crystal panel  7 , the inverter circuit board  93 , etc. housed in the case  22 .  
         [0142]     When the insulating layer  56  made of nylon is heated, it softens and becomes adhesive. By making use of the adhesiveness of the insulating layer  56 , the molds  85   a - d  are stuck and fixed to the insulating layer  56 . Because the molds  85   a - d  are also made of nylon, they stick well to the insulating layer  56 .  
         [0143]     As shown in  FIG. 28 , the front and back edges of the case  22  are provided with the molds  85   a  and  85   b , respectively. By making use of the adhesiveness of the insulating layer  56 , the molds  85   a  and  85   b  are stuck onto the insulating layer  56  to cover the front and back edges of the case  22 . Thus, loose ends of carbon fibers, if any, at the front and back edges of the case  22  are covered up.  
         [0144]     Because the molds  85   a  and  85   b  extend along the front and back edges of the case  22 , they serve as beams, too, reinforcing the case  22  against bending and twisting.  
         [0145]     As shown in  FIG. 28 , grooves  54  are made in the surfaces of the molds  85   a  and  85   b  which come in contact with the insulating layer  56 . When the insulating layer  56  is heated and softened and the molds  85   a  and  85   b  are stuck on the insulating layer  56 , surplus softened, adhesive nylon enters into the grooves  54 .  
         [0146]     Thus, the surplus softened, adhesive nylon is prevented from leaking out through the joints between the case  22  and the molds  85   a  and  85   b . If the surplus softened, adhesive nylon leaks out, the appearance of the electronic device  1  is spoiled.  
         [0147]     Because the case  22  has the right and left side plates, these side plates play the role of the molds  85   a  and  85   b.    
         [0148]     The opposite of the inside surface of the case  22  in  FIG. 19  is a facing, which is the surface of one of the outmost layers  53   a  and  53   b . A layer of self-cure resin is formed on the facing.  
         [0149]     The layer of self-cure resin is formed by spraying, for example, acrylic or urethane resin with cross-linked structure and high capability of elastic recovery to the facing of the case  22 .  
         [0150]     If a flaw or dent is made in the self-cure resin layer on the facing of the case  22 , it exists as a flaw or dent temporarily and then it disappears gradually because of the high capability of elastic recovery of the self-cure resin layer.  
         [0151]     The self-cure resin used in the present embodiment is transparent and colorless. It gives luster to the facing of the case  22  made of dull black CFRP (carbon fiber reinforced plastics) to improve the appearance of the case  22 .  
         [0152]     The unit consisting of the liquid crystal panel  7  and the inverter circuit board  93  shown in  FIG. 21  is fitted in the inside of the case  22  of  FIG. 19 . Because the inverter circuit board  93  does not overlap with the liquid crystal panel  7  as shown in  FIG. 21 , the display  5  is thin. The thinness of the display  5  as well as the thinness of the body  3  contributes to the thinness of the electronic device  1 .  
         [0153]     The liquid crystal panel  7  has a back-light unit including a light source, light-guiding plates, etc. A fluorescent lamp, for example, is used as the light source, which may be built in the top of the liquid crystal panel  7 .  
         [0154]     As shown in  FIG. 19 , a piece of conductor foil  89  such as copper foil is stuck on the inside surface of the case  22  to earth the liquid crystal panel  7  to the case  22 .  
         [0155]     In general, there exists a thin resin film (for example, an epoxy-resin film) on the surface of a base plate made of CFRP; accordingly, the surface of the base plate does not have stable conductivity. As in  FIG. 27 , if a piece of copper foil  89  is pressed onto a resin film  127  on the surface of the outermost layer  53   a , the piece of copper foil  89  pushes aside the resin film  127  and sticks to the layer  53   a  to secure a stable electric connection between the piece of copper foil  89  and the conductive carbon fibers of the layer  53   a.    
         [0156]     As shown in  FIG. 22 , a leaf spring  95  is fitted between the piece of copper foil  89  on the inside of the case  22  and a metal bracket  91   a  mounted on a metal frame  91  of the liquid crystal panel  7  to electrically connect the liquid crystal panel  7  to the piece of copper foil  89 . The tip of the leaf spring  95  is in elastic contact with the piece of copper foil  89  and the base of the leaf spring  95  is fixed to the metal bracket  91   a  by, for example, a screw.  
         [0157]     Thus, the liquid crystal panel  7  is electrically stably connected to the case  22  with a large area to protect the liquid crystal panel  7  from external magnetic noises and prevent the magnetic noises generated by the liquid crystal panel  7  from affecting external components and devices.  
         [0158]     As shown in  FIG. 1 , a frame  24  is fitted to the case  22  housing the liquid crystal panel  7  to expose the screen  70  of the liquid crystal panel  7 .  
         [0159]     The hinges “h” to connect the body  3  and the display will next be described below.  
         [0160]     When the lower section  27  of  FIG. 3  and the upper section  28  of  FIG. 17  are combined, the part  42   a  of the lower section  27  and the part  74   a  of the upper section  28  are combined to become a cylinder of a hinge “h.” One hinge h (the left hinge h in  FIGS. 1 and 2 ) is constructed when the cylinder of the case  26  is rotatably connected with the constituent part  87   a  of the case  22  shown in  FIG. 19 .  
         [0161]     On the other hand, when the lower section  27  of  FIG. 3  and the upper section  28  of  FIG. 17  are combined, the part  42   b  of the lower section  27  and the part  74   b  of the upper section  28  are combined to become another cylinder. The other hinge h (the right hinge h in  FIGS. 1 and 2 ) is constructed when the cylinder of the case  26  is rotatably connected with the constituent part  87   b  of the case  22  shown in  FIG. 19 .  
         [0162]     As shown in  FIG. 23 , a hinge fitting  97  is provided on the other hinge h. One end of the hinge fitting  97  is fixed to the cylinder of the case  26  by, for example, a screw. The constituent part of the case  22  receives a cylindrical portion of the hinge fitting  97 , and the case  22 , or the display  5 , is relatively rotatable about the cylindrical portions of the hinge fittings  97 .  
         [0163]     Further, as shown in  FIG. 23 , a power switch  20  is provided on an edge of the hinge&#39;s shaft (a side portion which does not face the other hinge with respect to the longitudinal direction of the axis of the hinge, namely, a side portion on the right in  FIG. 23 ). (Also, see  FIG. 2 )  
         [0164]     The power switch  20  comprises, as shown in a schematic diagram of  FIG. 25 , a pressing operation part  101 , a light-emitting element  121 , a switch  125 , and a contact  123 .  
         [0165]     The pressing operation part  101  can be pressed along the longitudinal direction of the axis of the hinge (the direction shown by the arrow in  FIG. 25 ). The light-emitting element  121  is placed inside the pressing operation part  101 . The light-emitting element  121  is, for example, a light-emitting diode and is mounted on a surface, which faces the pressing operation part  101 , of the circuit board  103  joined with the pressing operation part  101 .  
         [0166]     The switch  125  is mounted on the other side of the circuit board  103 . The contact  123  provided facing the switch  125  is fixed to the constituent part of the case  22 .  
         [0167]     As shown in  FIG. 2 , the pressing operation part  101  is exposed to the outside. When the pressing operation part  101  is pressed in the direction of the arrow in  FIG. 25  by a user&#39;s finger and so on, it moves toward the contact  123  together with the circuit board  103 , and the light-emitting element  121  and the switch  125  mounted thereon.  
         [0168]     When the switch  125  is pressed touching the contact  123 , the power is turned off when the power of the electronic device  1  is on and the power is turned on when the power of the electronic device  1  is off.  
         [0169]     When the pressing operation part  101  is pressed sideways by the user&#39;s finger, the direction of the movement tends to be inclined compared to when it is pressed downward. To cope with such a problem, the surface of the switch  125  which meets the contact  123  is curved. Therefore, in spite of a little inclination, the contact  123  and the switch  125  can meet stably (for example, compared to when the surface is flat, the contact area can be larger) and the power can be turned on or off reliably.  
         [0170]     Incidentally, the pressing operation part  101  has substantially a round shape, and is disposed so that the rotation axis of the hinge will pierce substantially the center of the round pressing operation part  101 . Consequently, when the power switch is pressed in the direction of the rotation axis of the hinge, the power supply is turned on or off. Since the switch  125  is pressed in the direction of the rotation axis of the hinge, the pressing operation part  101  that is large for the thickness of the display  5  or the body  3  can be employed. Consequently, the power switch  20  is reliably manipulated.  
         [0171]     According to the present embodiment, the pressing operation part  101  that is large for the thickness of the display  5  or body  3  is adopted. As long as the pressing operation part  101  that is pressed in the direction of the rotation axis of the hinge is adopted, the pressing operation part  101  (switch or button) that is larger than a switch (button) to be formed in the lateral side of the case can be formed because of the thicknesses of the cases  22 ,  24 ,  27 , and  28  that determine the shapes of the display  5  and body  3  respectively.  
         [0172]     The usage of the space in the hinge is not limited to the power switch as it is in the present embodiment. Alternatively, a switch (button) for any purpose other than the purpose of power supply may be formed. For example, when electronic device includes an imaging means that has a CCD or the like, the space in the hinge may be used to form a shutter button required for producing still images or an imaging start/stop button required for producing a motion picture.  
         [0173]     Further, if all or a part (for example, a ring portion of the outer edge) of the portion of the pressing operation part  101  exposed to the outside is formed as a light-transmission part made of transparent resin material, the light from the light-emitting element  121  can be guided to the outside through such a light-transmission part. Accordingly, when the power is on, for example, a red light can be turned on to have a user confirm its state visually. Alternatively, when in a power-saving standby state, a green light can be turned on and off to have the user confirm its state visually.  
         [0174]     The light transmission part of the pressing operation part  101  is always exposed to the outside regardless of the electronic device  1  being opened or closed. Therefore, even if the display  5  is closed while the power is on, the state can be checked by the light visible through the light transmission part.  
         [0175]     Also, when carrying the electronic device  1  in a bag or so with the display  5  closed, the pressing operation part  101  may be pressed by an article in the bag. Accordingly, in the present embodiment, as in  FIG. 23 , a closed-state detecting switch  105  is provided on the constituent part of the case  22 , and a closed-state detecting contact  106  is provided on the hinge fitting  97  as a single piece.  
         [0176]     When the display  5  is closed onto the body  3  by the relative rotation of the constituent part of the case  22  and the hinge fitting  97 , the closed-state detecting switch  105  and the closed-state detecting contact  106  meet, turning on the closed-state detecting switch  105 . The closed-state detecting switch  105  is kept turned on while the display  5  is closed onto the body  3 .  
         [0177]     Accordingly, when the closed-state detecting switch  105  is on, that is, when the display is closed, the electronic device  1  can be prevented from being turned on even if the pressing operation part  10  is pressed. Alternatively, when it is closed while the power is on and the closed-state detecting switch  105  is turned on, it becomes possible to automatically turn the power off or to send the electronic device  1  into a power-saving standby state.  
         [0178]     Incidentally, a control mode is not limited to the mode of controlling the power supply according to whether the display is open or closed, but any other control mode may be adopted.  
         [0179]     For example, when electronic device has an imaging means that includes a CCD, the action of a shutter button required for producing still images or an imaging start/stop button required for producing a motion picture may be controlled based on whether the case is open or closed. For example, control is extended so that when the case is closed, even if the button is pressed, a still image or a motion picture will not be produced.  
         [0180]     Incidentally, the means for detecting whether the display  5  is open or closed is not limited to the one employed in the present embodiment, but any other means will do. For example, a magnetic body included in the display  5 , and a Hall sensor that is located in a region in the body  3  in which the Hall sensor is opposed to the magnetic body and that detects a magnetic field strength may be used to detect whether the display is open or closed.  
         [0181]     Further, as in  FIG. 24 , a connector  19  for an AC adapter is provided on the edge (side portion on the left in  FIG. 24 ) of the shaft of the hinge opposite the hinge in which the power switch  20  is provided (Also, see  FIG. 1 ). A socket for the connector  19  is always exposed to the outside regardless of the opened and closed state of the electronic device  1 .  
         [0182]     Moreover, the connector  19  is disposed so that the rotation axis of the hinge and the axis of the connector  19  will be aligned with each other.  
         [0183]     Since the port of the connector  19  opens in the direction of the rotation axis of the hinge, the connector  19  that is large for the thickness of the display  5  or body  3  can be employed.  
         [0184]     According to the present embodiment, the connector  19  that is large for the thickness of the display  5  or body  3  is employed. As long as the port of the connector opens in the direction of the rotation axis of the hinge, a connector larger than the one formed in the lateral side of any of the cases  22 ,  24 ,  27 , and  28 , which determine the shapes of the display  5  and body  3  respectively, can be formed because of the thicknesses of the cases.  
         [0185]     The usage of the space in the hinge is not limited to the connector for connection of an AC adaptor as it is in the present embodiment. A connector for any purpose other than the purpose of power supply may be formed. For example, a connector for connection of a headphone may be formed. Moreover, the shape of the port of the connector is not limited to a round but may be a rectangle. For example, a connector for plugging in of a universal serial bus (USB) 2.0 may be formed.  
         [0186]     As in  FIG. 24 , a cable  112  for connecting the connector  19  with the motherboard  30  of the body  3  is not directed straight from the connection with the connector  19  to the side of the body  3  (lower position in  FIG. 24 ). On the contrary, the cable  112  detours around the area near the connection with the connector  19  so that it forms a loop on the side of the display  5  and is drawn to the side of the body  3 .  
         [0187]     The detouring portion of the cable  112  forms a loop being guided by a boss  114  erected inside the case  22  and guide members  118 ,  119   a ,  119   b.    
         [0188]     Accordingly, even if opening and closing of the display  5  away from and onto the body  3  are repeated, the connection (soldered, for example) to the connector  19  of the cable  112  is prevented from receiving a concentrated excessive load such as twisting and pulling, thereby a break in the cable being prevented.  
         [0189]     Further, the guide members  119   a  and  119   b  restrict the rising of the detouring portion of the cable  112  from the inside surface of the case  22  so that the looped detouring portion can be held stably.  
         [0190]     Further, the previously described power switch  20  shown in  FIG. 23  is configured such that a cable (not shown) connected to the connector  110  via the flexible wiring board  108  formed on the inside surface of the case  22  is drawn to the side of the body  3 . Therefore, again, the cable is not drawn directly from the power switch  20  to the body  3 . This is because the previously described inverter circuit board  93  is not provided on the inside surface of the case  22  on this side and there is enough space for arranging the above flexible wiring board  108  and the connector  110 .  
         [0191]     As described above, the power switch  20  and the connector  19  are provided on the edge portion of the shaft of the hinge, which has not been used at all, namely, a dead space. Therefore, components of the body  3  and the display  5  can be positioned more freely. By suitably arranging those components, the body  3  and the display  5  can be made thinner as described above. Further, since the power switch  20  is positioned away from the keyboard  11  and other operation buttons  15   a - 15   c  (see  FIG. 1 ), it is prevented from being mistakenly pressed, ensuring reliable operation. Thus, mistakes such as turning the power off while the device is in use can be avoided.  
         [0192]     The embodiment has been described by taking for instance the electronic device including the display  5  and body  3  that can be freely turned on the hinges to be open or closed. The present invention can be adapted to any other type of electronic device as long as a first case and a second case can be freely turned on hinges to be open or closed. For example, electronic device including two displays that can be freely turned on hinges to be open or closed will do.  
         [0193]     Moreover, according to the aforesaid embodiment, the hinges are formed on the edge of the case of electronic device away from a user under the normal specifications. Alternatively, electronic device whose right and left cases are turned on hinges to be open or closed will do.  
         [0194]     Functions such as left-clicking, right-clicking, and scrolling are assigned to the three operation buttons  15   a - c  disposed on the front edge about the center between the right and left sides of the body  3 .  
         [0195]     Also, as shown in  FIGS. 1 and 2 , there is a battery  9  provided between the hinges h.  
         [0196]     Further, as shown in  FIGS. 1 and 2 , a bottom surface of the lower section  27  is not flat, and the rear end on the side of the hinges h is curved (so that it rises a little from the surface where the electronic device is placed). Compared to the bottom surface of the lower section  27  being flat, this structure reinforces the lower section  27  against bending and twisting.  
         [0197]     Also, as shown in  FIG. 29 , a stopper  130  is provided on a periphery of each hinge h facing backward of the electronic device  1 . when the display  5  is opened, the display  5  is prevented from opening further by the lower edge of the display  5  meeting the stopper  130 . For example, in the present embodiment, the angle of opening (an angle formed by the body  3  and the display  5 ) is restricted to 135°.  
         [0198]     Further, as shown in  FIGS. 2 and 30 , tapered portions  68  and  69  are formed respectively at the front edges of the case  26  and the case  22  facing with each other so that the front edges make a V-shape when the display  5  is closed onto the body  3 .  
         [0199]     The tapered portion  68  is inclined upward toward the front, and the tapered portion  69  is inclined downward toward the front. The distance between the tapered portions  68  and  69  in a closed state, namely, when the case  26  and the case  22  are closed, gradually increases toward the front.  
         [0200]     With such a structure, even if the body  3  and the display  5  are very thin like the ones in the present embodiment, the front edge of the display  5  can easily be lifted from the body  3  staying where it is by putting a finger in a V-shaped area between the tapered portions  68 ,  69  and hooking the tapered portion  68  of the case  22  with a fingertip.  
         [0201]     Further, as shown in  FIGS. 1 and 2 , various indicator lamps  17   a - 17   c  provided in the front edge of the body  3  extend to the downwardly inclined area of the front edge. Therefore, even when the display  5  is closed as in  FIG. 2 , the above various indicator lamps  17   a - 17   c  are visible to the user.  
         [0202]     Although the invention has been described in its preferred form, it is to be understood that the invention is not limited to the specific embodiments thereof and various changes and modifications may be made without departing from the sprit and the scope of the invention.  
         [0203]     In stead of the PC card slot of the body  3 , any other semiconductor-memory card slot may be provided.  
         [0204]     Further, the heat-transmitting sheets  72  and  47  may be stuck to the inside of the upper section  28  and an entire surface of the inside of the lower section  27 , respectively.