Abstract:
In a portable terminal device having a box casing including a pair of mutually opposed casing members and a board to be stored within the box casing, on one surface of the board, a first component group including a plurality of electronic components and a shield casing for covering these electronic components is provided. On the other surface of the board, a second component group including an electronic component and an electrical component is provided. In arranging the components selected from the first and/or second parts groups, when the key and/or one casing member is pressed, the pressing force thereof is supported by the other casing member through the selectively arranged components and the board.

Description:
[0001]     This application claims foreign priority based on Japanese Patent application No. 2005-048208, filed Feb. 24, 2005, the content of which is incorporated herein by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention The present invention relates to a portable terminal device including a board, an electronic component and the like in a box casing.  
         [0003]     2. Description of the Related Art  
         [0004]      FIG. 11  is a side sectional view of an internal structure of a box casing  4  of a related folding-type portable terminal device  2  as referred to JP-A-2004-274466, the box casing  4  including an operation section such as ten keys. As shown in  FIG. 11 , the box casing  4  of the folding-type portable terminal device  2  includes a rigid circuit board  6  and a key sheet  8  which is made of silicon rubber inside thereof. The rigid circuit board  6  is fixed to the box casing  4  at two end portions thereof in longitudinal direction or at two end portions thereof in width direction.  
         [0005]     On a first surface  6   a  of the rigid circuit board  6  on a side of the key sheet  8 , a plurality of key switches  10  are provided. On a second surface  6   b  thereof that is situated on the opposite side to the first surface  6   a , electronic components  12  and the like which are mounted thereon by soldering are disposed. On the key sheet  8 , key tops  14  respectively corresponding to the key switches  10  are provided, and the key tops  14  are respectively exposed externally from key holes  16  formed in the box casing  4 .  
         [0006]     In the box casing  4  of the folding-type portable terminal device  2  having the above structure, when any one of the key tops  14  is pressed down with a finger of a user&#39;s hand or the like, the key switch  10  corresponding to this key top  14  is pressed down and, at the same time, the rigid circuit board  6  bents due to a load of the press-down.  
         [0007]     Thus, since the rigid circuit board  6  is deformed repeatedly, the electronic component  12  may be broken and mounting portions thereof by soldering may be peeled off from the rigid circuit board  6 . In order to prevent these inconveniences, the positions of the soldered portions of the electronic components are adjusted and arranged in the longitudinal direction and the width direction of the rigid circuit board  6  so that the positions of the soldered portions do not overlap on the positions of the key switches  10  in a thickness direction of the rigid circuit board  6 .  
         [0008]     Also, as shown in  FIG. 12 , as another related folding-type portable terminal device which is different from the folding-type portable terminal device  2  as referred to JP-A-2004-274466, there is known a folding-type portable telephone  20  in which the electronic components  12  and the like are mounted on both of the first surface  6   a  and second surface  6   b  of the rigid circuit board  6 .  
         [0009]     This folding-type portable telephone  20  includes a shield casing  22  for covering the electronic components  12  and the like mounted on the first surface  6   a  of the rigid circuit board  6 , and a key FPC (Flexible Printed Circuit)  23  interposed between the shield casing  22  and key sheet  8 . The key switches  10  are respectively disposed on the key FPC  23 .  
         [0010]     The shield casing  22  includes a ceiling plate  24  extending parallel to the rigid circuit board  6  and having a certain space between the rigid circuit board  6  and itself, and a sidewall  26  formed along an outer periphery of the ceiling plate  24  on a plane-shaped side so as to be perpendicular to the rigid circuit board  6 . Also, the shield casing  22  includes ribs  28  respectively formed so as to be perpendicular to the rigid circuit board  6  in positions corresponding to intermediate positions of the rigid circuit board  6  in the longitudinal direction or in the width direction.  
         [0011]     In the folding-type portable telephone  20  having the above structure, when any one of the key tops  14  is pressed down with a finger of a user&#39;s hand, the key switch  10  corresponding to this key top  14  is pressed down and, at the same time, a load of the press-down is transmitted through the ribs  28  of the shield casing  22  to the rigid circuit board  6  to thereby bend the rigid circuit board  6 .  
         [0012]     However, in the above folding-type portable telephone  20 , although the electronic components  12  and the like can be disposed on both the first and second surfaces  6   a  and  6   b  of the rigid circuit board  6 , when the number of the electronic components  12  and the like to be disposed per unit area on the rigid circuit board  6  increases, they are densely disposed. Therefore, it is difficult to prevent the breakage of the electronic components  12  and the like and prevent the peeling-off of the soldered portions by the method of adjusting the positions of the electronic components  12  and the like as referred in JP-A-2004-274466.  
         [0013]     Also, in the folding-type portable telephone  20 , when the electronic components  12  and the like are disposed densely on the rigid circuit board  6 , a possible damage of the electronic components  12  and the like as well as the rigid circuit board  6  when impact loads or the like are applied from the outside due to a dropping down of the telephone  20  or the like needs to be prevented more positively than in the case of the related folding-type portable terminal device  2 .  
       SUMMARY OF THE INVENTION  
       [0014]     An object of the invention is to provide a portable terminal device which can sufficiently prevent breakage of a circuit board as well as electronic components and the like due to a load of press-down when a key is pressed down and due to an impact load or the like applied from the outside.  
         [0015]     In some implementations, a portable terminal device of the invention comprises: a first casing member; a second casing member facing the first casing member so as to form a box casing; a board being placed between the first casing member and the second casing member; a key component of which portions being exposed externally from key holes formed in the first casing member; a first electronic component mounted on one surface of the board, the one surface facing the first casing member; a shield member mounted on the one surface of the board so as to cover the first electronic component; and at least one of a second electronic component and an electrical component mounted on other surface of the board, the other surface facing the second casing member, wherein the shield member has at least one first supporting portion formed toward the one surface of the board at a position corresponding to an intermediate position of the one surface of the board, and the second casing member has at least one second supporting portion formed toward the other surface of the board at a position corresponding to an intermediate position of the other surface of the board. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a perspective view of a folding-type portable telephone  30 ,  100  according to a first embodiment and a second embodiment of the invention.  
         [0017]      FIG. 2  is an exploded side view of an upper casing  46  and a lower casing  48  of a second box casing  36  shown in  FIG. 1  as well as a rigid circuit board  54 , a shield casing  56  ( 102 ), a key FPC  57  and a key sheet  59  respectively to be stored within the second box casing  36 , showing a state before they are assembled together.  
         [0018]      FIG. 3  is a plan view of the rigid circuit board  54 , taken along the arrow lines A—A shown in  FIG. 2 .  
         [0019]      FIG. 4  is a plan view of the shield casing  56  according to a first embodiment of the invention, taken along the arrow line B—B shown in  FIG. 2 .  
         [0020]      FIG. 5  is a plan view of the lower casing  48 , taken along the arrow line C—C shown in  FIG. 2 .  
         [0021]      FIG. 6  is a sectional view of the second box casing  36 , taken along the arrow lines D—D shown in  FIG. 2 , showing a state in which the upper casing  46  and lower casing  48  of the second box casing  36  shown in  FIG. 2  as well as the rigid circuit board  54 , shield casing  56 , key FPC  57  and key sheet  59  respectively to be stored within the second box casing  36  are assembled together.  
         [0022]      FIG. 7  is a sectional view of the second box casing  36 , taken along the arrow lines E—E shown in  FIG. 2 , showing a state in which the upper casing  46  and lower casing  48  of the second box casing  36  shown in  FIG. 2  as well as the rigid circuit board  54 , shield casing  56 , key FPC  57  and key sheet  59  respectively to be stored within the second box casing  36  are assembled together.  
         [0023]      FIG. 8  is a plan view of the shield casing  102  of the folding-type portable telephone  100  according to a second embodiment of the invention, taken along the arrow line B—B shown in  FIG. 2 .  
         [0024]      FIG. 9  is a sectional view of the second box casing  36 , taken along the arrow lines D—D shown in  FIG. 2 , showing a state in which the upper casing  46  and lower casing  48  of the second box casing  36  of the folding-type portable telephone  100  according to a second embodiment as well as the rigid circuit board  54 , shield casing  102 , key FPC  57  and key sheet  59  respectively to be stored within the second box casing  36  are assembled together.  
         [0025]      FIG. 10  is a sectional view of the second box casing  36 , taken along the arrow lines E—E shown in  FIG. 2 , showing a state in which the upper casing  46  and lower casing  48  of the second box casing  36  of the folding-type portable telephone  100  according to the second embodiment as well as the rigid circuit board  54 , shield casing  102 , key FPC  57  and key sheet  59  respectively to be stored within the second box casing  36  are assembled together.  
         [0026]      FIG. 11  is a side sectional view of a box casing  4  of a related folding-type portable terminal device  2  as well as a rigid circuit board  6  and a key sheet  8  respectively to be stored in the box casing  4  of the terminal  2 .  
         [0027]      FIG. 12  is a side sectional view of a box casing  4  of another related folding-type portable telephone  20  as well as a rigid circuit board  6 , a key sheet  8 , a shield casing  22  and a key FPC  23  respectively to be stored in the box casing  4  of the telephone  20 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     Now, description will be certain below in detail of embodiments of a portable terminal device according to the invention with reference to the accompanying drawings.  
         [0029]     Here, FIGS.  1  to  7  are views which are used to explain a folding-type portable telephone  30  (a portable terminal device) according to a first embodiment of the invention.  
         [0030]     As shown in  FIG. 1 , the folding-type portable telephone  30  according to the present embodiment includes a first box casing  34  and a second box casing  36  which are rotatably connected together through a hinge  32 . The first box casing  34  includes a display  38  and a speaker  40 . Also, the second box casing  36  includes an operation section  42  and a microphone  44 , and the microphone  44  is disposed in a position near an end portion of the box casing  36  on an opposite side of the hinge  32  in the longitudinal direction of the second box casing  36 .  
         [0031]     The second box casing  36  includes an upper casing  46  (a first casing member) having the operation section  42  and a lower casing  48  (a second casing member) which is arranged on the back side of the upper casing  46 . As shown in  FIG. 2 , in an internal space formed between the upper and lower casings  46  and  48 , a rigid circuit board  54 , a shield casing  56 , a key FPC (Flexible Printed Circuit Board)  57 , and a key sheet  59  are sequentially placed from the lower casing  48  side.  
         [0032]     On a first surface  54   a  of the rigid circuit board  54  on the upper casing  46  side, as shown in  FIGS. 2 and 3 , a plurality of electronic components including semiconductor integrated circuits  62 ,  64  and  66  (IC chips) are disposed. Here, electronic components other than the semiconductor integrated circuits  62 ,  64  and  66  are not shown so as not to make the drawings complicated.  
         [0033]     On the first surface  54   a , as shown in  FIG. 3 , a reference potential pattern  68  which conducts a reference potential is formed. Actually, on the first surface  54   a , besides the reference potential pattern  68 , wiring patterns or the like which are used to supply electricity to a plurality of electronic components such as the electronic components  62 ,  64  and  66  are formed. However, wiring patterns other than the reference potential pattern  68  are not shown so as not to make the drawings complicated.  
         [0034]     Also, as shown in  FIG. 2 , on the second surface  54   b  of the rigid circuit board  54  which is on the opposite side of the first surface  54   a , a plurality of electronic components including a semiconductor integrated circuit  70  (IC chip), and a memory medium connector  72  (an electrical component) are arranged. The memory medium connector  72  is a device for, when a removable-type external memory medium such as an SD (Secure Digital) memory card (not shown) is inserted into its insertion opening  72   a , performing a circuit connection to this removable-type external memory medium.  
         [0035]     As shown in  FIG. 3 , the semiconductor integrated circuit  70  is arranged in a position which is the same in a longitudinal direction of the rigid circuit board  54  as the semiconductor integrated circuit  66  disposed on the first surface  54   a  side, and is arranged so as to overlap with the semiconductor integrated circuit  66  in a thickness direction of the rigid circuit board  54  in a certain length range in a width direction of the rigid circuit board  54 .  
         [0036]     Also, as shown in  FIG. 2 , the memory medium connector  72  is fixed so that a whole surface of a bottom plate  72   b  of the memory medium connector  72  contacts with the second surface  54   b  of the rigid circuit board  54 . The memory medium connector  72  is disposed such that an area thereof on the first surface  54   a  side corresponding to the contact area thereof on the second surface  54   b , as shown in  FIG. 31 , includes a contact area of the semiconductor integrated circuit  62  on the first surface  54   a.    
         [0037]     That is, the memory medium connector  72  is disposed in such position on the back side of the rigid circuit board  54  corresponding to the semiconductor integrated circuit  62 , and the contact area between the memory medium connector  72  and rigid circuit board  54  is larger than the contact area between the semiconductor integrated circuit  62  and rigid circuit board  54 .  
         [0038]     Next, as shown in  FIG. 2 , the shield casing  56  is placed on the first surface  54   a  of the rigid circuit board  54 . On the whole surface of the shield casing  56 , a thin metal layer (a conductive member) is formed by an evaporation method or the like.  
         [0039]     The shield casing  56  includes a ceiling plate  74  extending parallel to the rigid circuit board  54  and having a certain space between the rigid circuit board  54  and itself, and a side wall  76  formed along an outer periphery of the ceiling plate  74  on a plane-shaped side so as to be perpendicular to the rigid circuit board  54 .  
         [0040]     In the shield casing  56 , as shown in  FIG. 4 , a rib  78  of a certain thickness which partitions a space enclosed by the ceiling plate  74  and the side wall  76  vertically and horizontally in parallel to the ceiling plate  74  is formed. The rib  78  has the same height as the side wall  76  in a direction perpendicular to the ceiling plate  74 .  
         [0041]     The side wall  76  and the rib  78  of the shield casing  56  are respectively formed so that portions thereof extending parallel to the ceiling plate  74  are in part formed along the shape of the reference potential pattern  68  of the rigid circuit board  54  as shown in  FIG. 3 . Therefore, the portions of the rib  78  in part contact with the reference potential pattern  68 .  
         [0042]     Also, portions of the rib  78  of the shield casing  56  as shown in  FIG. 4 , which extend parallel to the ceiling plate  74 , other than the portions contacting with the reference potential pattern  68  of the rigid circuit board  54 , that is, the portions respectively designated by reference numerals  78   a ,  78   b  and  78   c  in  FIG. 4  are respectively formed so as to correspond to the edge portions on a plane-shaped side of the semiconductor integrated circuits  62 ,  64  and  66  as shown in  FIG. 3 .  
         [0043]     The heights of these ribs  78   a ,  78   b  and  78   c , as shown in  FIG. 2 , are respectively formed so as to correspond to the heights of the semiconductor integrated circuits  62 ,  64  and  66 , and so that the ribs  78   a ,  78   b  and  78   c  contact with the upper surfaces of the edge portions of these circuits.  
         [0044]     Next, the key FPC  57  is attached to the ceiling plate  74  of the shield casing  56 . On the surface of the key FPC  57  on the opposite side of the shield casing  56 , a plurality of key switches  58  are provided.  
         [0045]     Also, on the key sheet  59 , a plurality of key tops  60  which respectively correspond to the key switches  58  of the key FPC  57  are provided. Therefore, keys including the key switches  58  and the key tops  60  are disposed on the shield casing  56 . The key tops  60 , as shown in  FIG. 1 , are exposed to the outside from key holes  61  formed in the upper casing  46  of the second box casing  36 .  
         [0046]     Next, in the lower casing  48 , in one side wall  80  extending parallel to the lower casing  48  in the longitudinal direction thereof, a cut-out portion  82  is formed through which a removable-type external memory medium such as an SD memory card (not shown) can be inserted into the memory medium connector  72 . A position of the cut-out portion  82  in the longitudinal direction of the side wall  80  corresponds to a position of the memory medium connector  72  of the rigid circuit board  54  as shown in  FIG. 2 .  
         [0047]     In the lower casing  48 , as shown in  FIGS. 2 and 5 , a battery package storage section  86  is formed which is used to store a battery package  84  therein. The battery package storage section  86  is formed such that it includes, in a central portion on the plane-shaped side of the lower casing  48  as shown in  FIG. 5 , a storage bottom plate  87  having a certain depth in the thickness direction of the lower casing  48  from a bottom surface  88   a  of the bottom plate  88  which is on the opposite side of the upper casing  46  as shown in  FIG. 2 .  
         [0048]     Also, on the lower casing  48 , as shown in  FIG. 5 , a rib  90  (a supporting portion) of a certain thickness is formed which intersects a space existing in the interior of the lower casing  48  in a direction parallel to the bottom plate  88 , preferably, intersects the space at right angles to thereby partition the space vertically and horizontally. The rib  90  is formed so as to have a height in a direction perpendicular to the bottom plate  88 . In a state where the rigid circuit board  54  shown in  FIG. 2  is stored within the second box casing  36 , an end face of the rib  90  of the lower casing  48  in the height direction contacts with the second surface  54   b  of the rigid circuit board  54 .  
         [0049]     Portions of the rib  90  extending parallel to the bottom plate  88  are in part formed along the shapes of the side wall  76  and the rib  78  of the shield casing  56  shown in  FIG. 4 . That is, the portions of the rib  90  shown in  FIG. 5  extending parallel to the bottom plate  88 , as shown in  FIG. 2 , is in part formed to support portions of the second surface  54   b  of the rigid circuit board  54  that correspond to the side wall  76  and rib  78  of the shield casing  56 .  
         [0050]     Also, a portion of the rib  90  extending parallel to the bottom plate  88 , which is designated by reference numeral  90   a  in  FIG. 5 , is formed so as to correspond to the position of the semiconductor integrated circuit  64  of the rigid circuit board  54  shown in  FIG. 3 . Thus, the rib  90   a  of the lower casing  48  shown in  FIG. 5  faces a part of the rib  78   b  of the shield casing  56  shown in  FIG. 4  in the thickness direction of the second box casing  36 .  
         [0051]     Also, a portion of the rib  90  designated by reference numeral  90   b  in  FIG. 5  is formed so as to correspond to the position where the semiconductor integrated circuits  66  and  70  of the rigid circuit board  54  shown in  FIG. 3  overlap in the thickness direction of the rigid circuit board  54 . The rib portion  90   b  is lower in height by an amount corresponding to the thickness of the semiconductor integrated circuit  70 . Thus, the rib  90   b  of the lower casing  48  shown in  FIG. 5  faces a part of the rib  78   c  of the shield casing  56  shown in  FIG. 4  in the thickness direction of the second box casing  36 .  
         [0052]     In the lower casing  48 , as shown in  FIG. 5 , a rectangle hole  92  is formed which communicates with a space existing in the interior of the battery package storage section  86 . This rectangle hole  92  corresponds to a position of the memory medium connector  72  shown in  FIG. 3 , and is also formed smaller than the memory medium connector  72  on the plane-shaped side.  
         [0053]     Therefore, in a state where the rigid circuit board  54  is stored within the second box casing  36 , as for the ceiling plate  72   c  of the memory medium connector  72  shown in  FIG. 2 , only the peripheral edge portion on the substantially rectangular plane-shaped side (not shown) (refer to  FIG. 3 ) contacts with the storage bottom plate  87  of the battery package storage section  86  in the lower casing  48  shown in  FIG. 5 .  
         [0054]     Now,  FIG. 6  is a sectional view of the second box casing  36  along the arrow lines D—D shown in  FIG. 2 , showing an assembled state thereof. When any one of the key tops  60  shown in  FIG. 6  is pressed down with a finger of a user&#39;s hand or the like, a load of the press-down (pressure load) is transmitted, for example, as a first route, through the rib  78  positioned substantially in the central portion in the width direction of the shield casing  56 , the rigid circuit board  54  and the rib  90  of the lower casing  48  sequentially in this order.  
         [0055]     Also, the press-down load of the key top  60  is also transmitted, as a second route, through the rib  78   a  of the shield casing  56 , the semiconductor integrated circuit  62 , the rigid circuit board  54 , the memory medium connector  72 , and the storage bottom plate  87  of the lower casing  48  sequentially in this order. Further, the pressing-down load of the key top  60  is also transmitted, as a third route, through the rib  78   b  of the shield casing  56 , the semiconductor integrated circuit  64 , the rigid circuit board  54 , and the rib  90   a  of the lower casing  48  sequentially in this order.  
         [0056]     Next,  FIG. 7  is a sectional view of the second box casing  36  along the arrow lines E—E shown in  FIG. 2 , showing its assembled state. When any one of the key tops  60  shown in  FIG. 7  is pressed down with a finger of a user&#39;s hand or the like, the press-down load thereof is transmitted, similarly to the first route in  FIG. 6 , through the rib  78  of the shield casing  56 , the rigid circuit board  54  and the rib  90  of the lower casing  48  (which are respectively shown in  FIG. 7 ) sequentially in this order.  
         [0057]     Also, the press-down load of the key top  60  is also transmitted, as a fourth route, as shown in  FIG. 7 , through the rib  78   c  of the shield casing  56 , the semiconductor integrated circuit  66 , the rigid circuit board  54 , the semiconductor integrated circuit  70 , and the rib  90   b  of the lower casing  48  sequentially in this order.  
         [0058]     According to the folding-type portable telephone  30  of the present embodiment, the press-down load generated when the key is pressed down, the impact load applied from the outside or the like, which is transmitted to the intermediate position of the rigid circuit board  54  in the longitudinal direction or the width direction, is supported by the rib  90  formed in the lower casing  48 , the storage bottom plate  87  of the battery package storage section  86  and the like. Thus, the deformation of the rigid circuit board  54  due to the pressure load when the key is pressed down, due to the impact load from the outside or the like is prevented. Therefore, even when the electronic components such as the semiconductor integrated circuits  62 ,  64 ,  66  and  70  as well as the memory medium connector  72  and the like are arranged densely on the rigid circuit board  54  stored within the second box casing  36 , the circuit board, electronic components and the like can be sufficiently prevented from being broken due to the pressure load when the key is pressed down, the impact load applied from the outside or the like.  
         [0059]     Also, the portions of the rib  90  of the lower casing  48  extending parallel to the bottom plate  88  of the lower casing  48 , as shown in  FIG. 5 , are in part formed along the shapes of the side wall  76  and the rib  78  of the shield casing  56  shown in  FIG. 4 . Furthermore, the ribs  90   a  and  90   b  of the lower casing  48  shown in  FIG. 5  respectively face a part of the ribs  78   b  and  78   c  of the shield casing  56  shown in  FIG. 4  in the thickness direction of the second box casing  36 . Therefore, as shown in  FIGS. 6 and 7 , the transmission route of the pressure load, the impact load or the like is linear, and thus does not generate a shearing force or a bending moment in the rigid circuit board  54 , thereby being able to prevent the breakage of the circuit board, electronic components and the like.  
         [0060]     Also, as shown in  FIG. 2 , since the memory medium connector  72  has a space between the bottom plate  72   b  and ceiling plate  72   c , when a load P is applied to the center of the ceiling plate  72   c , the memory medium connector  72  may be bent and deformed. However, as shown in  FIGS. 5 and 6 , since the rectangle hole  92  is formed, and the storage bottom plate  87  contacts with the ceiling plate  72   c  of the memory medium connector  72  in only the peripheral edge portion thereof, the memory medium connector  72  can be prevented from being deformed when the load is applied to the center of the ceiling plate  72   c.    
         [0061]     Next, a folding-type portable telephone  100  (a portable terminal device) according to a second embodiment of the invention is described with reference to FIGS.  8  to  10 . In this embodiment, parts thereof same as those of the folding-type portable telephone  30  according to the above-mentioned first embodiment are given the same reference numerals in the following description, and thus the description of the similar structures is omitted.  
         [0062]     In the folding-type portable telephone  100  according to the present embodiment, the shape of the rib  78  of the shield casing  102  thereof is slightly different from that of the rib  78  of the shield casing  56  according to the first embodiment as shown in  FIG. 8 .  
         [0063]     That is, in a position inside the rib  78   a  and near to the central portion of the shield casing  102  in the width direction, an M-shaped rib  78   d  is formed. Also, instead of the ribs  78   b  and  78   c  of the shield casing  56  according to the first embodiment, ribs  78   e  and  78   f  are formed. These ribs  78   e  and  78   f  respectively correspond to parts of the rectangular-shaped ribs  78   b  and  78   c  of the shield casing  56  shown in  FIG. 4 . More particularly, the ribs  78   e  and  78   f  respectively correspond to the portions of one sides of the ribs  78   b  and  78   c  which extend parallel to the longitudinal direction of the shield casing  56  and are situated near the outside in the width direction of the shield casing  56 .  
         [0064]     Now,  FIG. 9  is a sectional view of the second box casing  36  along the arrow lines D—D shown in  FIG. 2 , showing its assembled state. When any one of the key tops  60  shown in  FIG. 9  is pressed down with a finger of a user&#39;s hand or the like, the press-down load thereof, similarly to the above-mentioned first embodiment, is transmitted, for example, as a first route, through the rib  78  situated substantially in the central position of the shield casing  102  in the width direction, the rigid circuit board  54  and the rib  90  of the lower casing  48  sequentially in this order.  
         [0065]     Also, the pressing-down load of the key top  60  is transmitted, as a second route, through the rib  78   d  of the shield casing  102 , the semiconductor integrated circuit  62 , the rigid circuit board  54 , the memory medium connector  72  and the storage bottom plate  87  of the lower casing  48  sequentially in this order. Alternatively, the load may be transmitted also through the rib  78   d  situated inside the rib  78   a  of the shield casing  102 .  
         [0066]     Therefore, referring to the press-down load transmitted to the memory medium connector  72  disposed on the side opposite to the ribs  78   a  and  78   d  with the rigid circuit board  54  in-between, more amount of the load is transmitted to the portion of the memory medium connector  72 , which is on the side opposite to the insertion opening  72   a  of the memory medium connector  72  in the width direction of the second box casing  36 , compared to the portion of the memory medium connector  72  near the insertion opening  72   a.    
         [0067]     Also, in the shield casing  102 , instead of the rib  78   b  formed in the shield casing  56  according to the first embodiment, the rib  78   e  is formed. Therefore, the press-down load of the key top  60  is transmitted, as a third route, through the rib  78   e  of the shield casing  102 , the semiconductor integrated circuit  64 , the rigid circuit board  54 , and the rib  90   a  of the lower casing  48  sequentially in this order.  
         [0068]     Next,  FIG. 10  is a sectional view of the second box casing  36  along the arrow lines E—E shown in  FIG. 2 , showing its assembled state. Since, in the shield casing  102 , the rib  78   f  is formed instead of the rib  78   c  of the shield casing  56  according to the first embodiment, the press-down load of the key top  60  is transmitted, as a fourth route, through the rib  78   f  of the shield casing  102 , the semiconductor integrated circuit  66 , the rigid circuit board  54 , the semiconductor integrated circuit  70 , and the rib  90   b  of the lower casing  48  sequentially in this order.  
         [0069]     Thus, according to the folding-type portable telephone  100  of the present embodiment, similarly to the above-mentioned first embodiment, the press-down load generated when the key is pressed down, the impact load applied from the outside or the like, which is transmitted to the intermediate position of the rigid circuit board  54  in the longitudinal direction or the width direction, is supported by the rib  90  formed in the lower casing  48 , the storage bottom plate  87  of the battery package storage section  86  and the like. Thus, the deformation of the rigid circuit board  54  due to the pressure load when the key is pressed down, due to the impact load from the outside or the like is prevented. Therefore, even when the electronic components such as the semiconductor integrated circuits  62 ,  64 ,  66  and  70  as well as the memory medium connector  72  and the like are arranged densely on the rigid circuit board  54  stored within the second box casing  36 , the circuit board, electronic components and the like can be sufficiently prevented from being broken due to the pressure load when the key is pressed down, the impact load applied from the outside or the like.  
         [0070]     Also, similarly to the first embodiment, the portions of the rib  90  of the lower casing  48  extending parallel to the bottom plate  88  of the lower casing  48 , as shown in  FIG. 5 , are in part formed along the shapes of the side wall  76  and the rib  78  of the shield casing  56  shown in  FIG. 4 . Furthermore, the ribs  90   a  and  90   b  of the lower casing  48  shown in  FIG. 5  respectively face a part of the ribs  78   e  and  78   f  of the shield casing  102  shown in  FIG. 8  in the thickness direction of the second box casing  36 . Therefore, as shown in  FIGS. 9 and 10 , the transmission route of the pressure load, the impact load or the like is linear, and thus does not generate a shearing force or a bending moment in the rigid circuit board  54 , thereby being able to prevent the breakage of the circuit board, electronic components and the like.  
         [0071]     Further, similarly to the first embodiment, as shown in  FIG. 2 , since the memory medium connector  72  has a space between the bottom plate  72   b  and ceiling plate  72   c , when a load P is applied to the center of the ceiling plate  72   c , the memory medium connector  72  may be bent and deformed. However, as shown in  FIGS. 8 and 9 , since the rectangle hole  92  is formed, and the storage bottom plate  87  contacts with the ceiling plate  72   c  of the memory medium connector  72  in only the peripheral edge portion thereof, the memory medium connector  72  can be prevented from being deformed when the load is applied to the center of-the ceiling plate  72   c.    
         [0072]     And, as shown in  FIG. 9 , since the rib  78   d  is formed in the shield casing  102 , the press-down load of the key top  60  to be transmitted to the memory medium connector  72  becomes larger in amount, in the width direction of the second body  36 , in the opposite portion of the memory medium connector  72  to the insertion opening  72   a  than in the portion of the memory connector  72  near to the insertion opening  72   a  which is weak in structure. Therefore, the memory medium connector  72  can be prevented more positively against deformation than in the first embodiment.  
         [0073]     Also, as shown in  FIGS. 9 and 10 , since, in the shield casing  102 , the ribs  78   e  and  78   f  are formed instead of the ribs  78   b  and  78   c  in the shield casing  56  according to the first embodiment, between the shield casing  102  and lower casing  48  with the rigid circuit board  54  interposed in-between, elements which cause impediments to the linear transmission of the press-down load or the impact load are eliminated, thereby being able to further suppress the occurrence of a shearing force and a bending moment in the rigid circuit board  54 . This makes it possible to prevent the breakage of the circuit board, electronic components and the like.  
         [0074]     By the way, in the above-mentioned first and second embodiments, the side wall  76  and the rib  78  of the shield casings  56  and  102  contact with the rigid circuit board  54  or semiconductor integrated circuits  62 ,  64 ,  66  and the like originally before the press-down load or impact load is applied. However, the side wall  76  and the rib  78  of the shield casings  56  and  102  may be formed such that they originally have a slight space with respect to the rigid circuit board  54  or semiconductor integrated circuits  62 ,  64 ,  66  and the like.  
         [0075]     In this case, the side wall  76  and the rib  78  of the shield casings  56  and  102  are slightly bent when the press-down load or impact load is applied, and thereby contact with the rigid circuit board  54  or semiconductor integrated circuits  62 ,  64 ,  66  and the like. Therefore, similarly to the first and second embodiments, the press-down load or impact load is transmitted therethrough, so that similar operation effects similar to the first and second embodiments are provided.  
         [0076]     Also, in the first and second embodiments, description is given of the cases in which the invention is applied to the folding-type portable telephones  30  and  100 . However, the present invention can also be applied to portable terminal devices other than the folding-type portable telephones  30  and  100 , such as a PHS (Personal Handy phone System), a PDA (Personal Digital Assistant), and a portable navigation device.  
         [0077]     It will be apparent to those skilled in the art that various modifications and variations can be made to the described preferred embodiments of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover all modifications and variations of this invention consistent with the scope of the appended claims and their equivalents.