Patent Publication Number: US-2009231786-A1

Title: Connection mechanism and mobile terminal

Description:
TECHNICAL FIELD 
     The present invention relates to a connection mechanism used in mobile telephones and mobile terminals such as PDA in which two casings are connected so as to be opened and spread out or closed, and a mobile terminal. 
     BACKGROUND ART 
     Conventionally, mobile telephones and various mobile terminals such as PDA and a laptop have been proposed. A so-called clam-shell type in which a lid with a display unit and a body with key operation unit are connected so as to be spread out and folded is proposed for such mobile terminals. 
     A connection part of such clam-shell type partially overlaps the lid and the body so that the lid and the body are superimposed in a folded state, and a uniaxial hinge is arranged at the overlapping site. 
     Various hinge structures have been proposed in recent years, and an open/close device of an equipment case with a biaxial hinge structure is also proposed (see Patent Document 1). 
     The open/close device enables the turning order of a first case and a second case connected to each axis of the hinge to always be constant. 
     However, the operation is awkward since the turning of the first case and the second case is performed separately and in order in the open/close device. In the relationship between a connection member and the first case (second case), two substantially rectangular solids merely turn with the axis as the center, and the structure is not as novel. 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-308710 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     In view of the above problems, the present invention aims to provide a connection mechanism that opens and closes with a novel structure, and a mobile terminal using the connection mechanism. 
     Means for Solving the Problems 
     The present invention relates to a connection mechanism which connects a first casing and a second casing so as to move between a closed state in which the casings are superimposed on each other and an open state in which the casings are open and spread out; the connection mechanism including opening parts formed on a connection side of the first casing and a connection side of the second casing; connection members of which both ends can be advanced into and retreated from the opening parts of the first casing and the opening parts of the second casing; and an advance/retreat ratio stabilization part for stabilizing a ratio of an advance/retreat amount of the connection member into/from the first casing to an advance/retreat amount of the connection member into/from the second casing to a predetermined value. 
     Therefore, a connection mechanism that opens and closes with a novel structure, and in which the ratio of the advance/retreat amount of the connection member into/from the first casing and the advance/retreat amount of the connection member into/from the second casing in opening/closing stabilizes is provided. 
     In one aspect of the present invention, the advance/retreat ratio stabilization part is formed by a first casing side arm connected to the first casing, a second casing side arm connected to the second casing, and a pivot attachment part for pivotally attaching the first casing side arm and the second casing side arm and connecting to the connection member; a first casing side connection for connecting the first casing side arm to the first casing, a second casing side connection for connecting the second casing side arm to the second casing, and a connection member side connection for connecting the pivot attachment part to the connection member are arranged; and in the connection methods, one of the casing side connection or the connection member side connection is a pivot attachment allowing pivotal movement, and the other is a movable support movable in a constant direction. 
     Thus, the operation in opening/closing of the first casing, the second casing, and the connection member is reliably regulated and stabilized. 
     In another aspect of the present invention, the movable support is a slidable support allowing slide movement; and the first casing side arm and the second casing side arm have surfaces on the side the first casing side arm and the second casing side arm face each other curved or bent formed to a concave form when the first casing and the second casing are in the closed state. Thus, a fully closed state in which the first casing and the second casing are folded and completely superimposed is realized without the first casing side arm and the second casing side arm inhibiting the transition of the first casing and the second casing towards the completely closed state. 
     In another further aspect of the present invention, first casing side arms, one of which being pivotally attached to the first casing; and second casing side arms, one of which being pivotally attached to the second casing are arranged; wherein a plurality of supporting parts for supporting the other first casing side arm and the other second casing side arm to be movable while drawing a circular arc are arranged on the connection member. 
     Thus, the operation in opening/closing of the first casing, the second casing, and the connection member is reliably regulated and stabilized. 
     Moreover, in the present invention, the supporting part is formed with a peripheral surface gear in which teeth are arranged on an inner side of the circular arc; a rolling gear which rolls on the peripheral surface gear is arranged on the other first casing side arm and the other second casing side arm; a center gear allowing rotation about a center axis of each peripheral surface gear while gearing with the rolling gear is arranged in correspondence to each peripheral surface gear; and the center gear gearing with the rolling gear of the first casing side arm and the center gear gearing with the rolling gear of the second casing side arm are connected to rotate in opposite directions to each other. 
     Thus, the operation in opening/closing of the first casing, the second casing, and the connection member is reliably regulated and stabilized. 
     The present invention also relates to a connection mechanism which connects a first casing and a second casing so as to move between a closed state in which the casings are superimposed on each other and an open state in which the casings are open and spread out; the connection mechanism including opening parts formed on a connection side of the first casing and a connection side of the second casing; and connection members of which both ends can be advanced into and retreated from the opening parts of the first casing and the opening parts of the second casing; wherein the connection member is axially supported by the first casing at a turning shaft on the first casing side and is axially supported by the second casing at a turning shaft on the second casing side. 
     Thus, the first casing, the second casing, and the connection member are connected by the turning shafts, and a stable opening/closing operation is realized with a novel structure. 
     The present invention also relates to a mobile terminal equipped with the connection mechanism. 
     The mobile terminal includes mobile electronic equipment such as a mobile telephone, PDA, a laptop, a digital camera, a digital video camera, mobile navigation equipment, a mobile DVD player, and a mobile music player. 
     A mobile terminal that opens and closes with a novel structure is thereby provided. 
     EFFECT OF THE INVENTION 
     According to the present invention, a connection mechanism that opens and closes with a novel structure, and a mobile terminal using the connection mechanism are provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a mobile telephone in a closed state. 
         FIG. 2  is a perspective view of the mobile telephone in an open state. 
         FIG. 3  is a perspective view of the mobile telephone with a cover partially detached. 
         FIG. 4  is an exploded perspective view of a connection unit seen from diagonally above. 
         FIG. 5  is an exploded perspective view of the connection unit seen from diagonally below. 
         FIGS. 6A to 6C  are partially enlarged explanatory views. 
         FIG. 7  is a perspective view of one part of the connection unit in the open state. 
         FIG. 8  is a perspective view of one part of the connection unit slightly changed towards the closing direction from the open state. 
         FIG. 9  is a perspective view of one part of the connection unit changed towards the closing direction. 
         FIG. 10  is a perspective view of one part of the connection unit in the closed state. 
         FIG. 11  is an enlarged cross sectional view of the connection unit portion in the open state. 
         FIG. 12  is an enlarged cross sectional view of the connection unit portion slightly changed towards the closing direction from the open state. 
         FIG. 13  is an enlarged cross sectional view of the connection unit portion further changed towards the closing direction. 
         FIG. 14  is an enlarged cross sectional view of the connection unit portion in the closed state. 
         FIGS. 15A to 15D  are explanatory views describing a mobile telephone in each state changing from the open state to the closed state in a perspective view. 
         FIG. 16  is a perspective view of a mobile telephone of Embodiment 2. 
         FIG. 17  is a partially exploded enlarged perspective view of the mobile telephone of Embodiment 2. 
         FIG. 18  is a plan view of a mobile telephone of Embodiment 3. 
         FIG. 19  is an exploded perspective view of a connection unit of Embodiment 3. 
         FIG. 20  is an exploded perspective view of the connection unit of Embodiment 3. 
         FIG. 21  is an explanatory view in which a link unit is partially enlarged of Embodiment 3. 
         FIG. 22  is a perspective view of a connection body of Embodiment 3. 
         FIG. 23  is a bottom view of one part of the connection unit of Embodiment 3. 
         FIG. 24  is a bottom view of one part of the connection unit of Embodiment 3. 
         FIG. 25  is a bottom view of one part of the connection unit of example 3. 
         FIG. 26  is an enlarged cross sectional view of the connection unit portion of Embodiment 3. 
         FIG. 27  is an enlarged cross sectional view of the connection unit portion of Embodiment 3. 
         FIG. 28  is an enlarged cross sectional view of the connection unit portion of Embodiment 3. 
         FIG. 29  is an enlarged perspective view of a locking guide body of Embodiment 3. 
         FIG. 30  is a plan view of a mobile telephone of Embodiment 4. 
         FIG. 31  is an explanatory view of the mobile telephone of Embodiment 4. 
         FIG. 32  is an exploded perspective view of a connection unit of Embodiment 4. 
         FIG. 33  is an exploded perspective view of the connection unit of Embodiment 4. 
         FIG. 34  is an exploded perspective view of the connection unit of Embodiment 4. 
         FIG. 35  is an exploded perspective view of the connection unit of Embodiment 4. 
         FIG. 36  is a perspective view of one part of the connection unit of Embodiment 4. 
         FIG. 37  is a perspective view of one part of the connection unit of Embodiment 4. 
         FIG. 38  is a perspective view of one part of the connection unit of Embodiment 4. 
         FIG. 39  is a perspective view of a link unit and a pushing unit of Embodiment 4. 
         FIG. 40  is a perspective view of the link unit and the pushing unit of Embodiment 4. 
         FIG. 41  is a perspective view of the link unit and the pushing unit of Embodiment 4. 
         FIG. 42  is a perspective view of the link unit and the pushing unit of Embodiment 4. 
         FIGS. 43C to 43E  are explanatory views of the connection unit portion of Embodiment 4 in an enlarged cross section. 
         FIGS. 44C to 44E  are explanatory views of the connection unit portion of Embodiment 4 in an enlarged cross section. 
         FIGS. 45C to 45E  are explanatory views of the connection unit portion of Embodiment 4 in an enlarged cross section. 
         FIGS. 46C to 46E  are explanatory views of the connection unit portion of Embodiment 4 in an enlarged cross section. 
         FIG. 47  is a plan view of a mobile telephone of Embodiment 5. 
         FIGS. 48A and 48B  are explanatory views of the mobile telephone of Embodiment 5. 
         FIG. 49  is an exploded perspective view of a connection unit of Embodiment 5. 
         FIG. 50  is an exploded perspective view of the connection unit of Embodiment 5. 
         FIG. 51  is a perspective view of a connection body of Embodiment 5. 
         FIG. 52  is a perspective view of one part of the connection unit of Embodiment 5. 
         FIG. 53  is a perspective view of one part of the connection unit of Embodiment 5. 
         FIG. 54  is a perspective view of one part of the connection unit of Embodiment 5. 
         FIG. 55  is a perspective view of one part of the connection unit of Embodiment 5. 
         FIG. 56  is a perspective view of a link unit and an angle fixing unit of Embodiment 5. 
         FIG. 57  is a perspective view of the link unit and the angle fixing unit of Embodiment 5. 
         FIG. 58  is a perspective view of the link unit and the angle fixing unit of Embodiment 5. 
         FIG. 59  is a perspective view of the link unit and the angle fixing unit of Embodiment 5. 
         FIGS. 60G and 60H  are explanatory views of the connection unit portion of Embodiment 5 in an enlarged cross section. 
         FIGS. 61G and 61H  are explanatory views of the connection unit portion of Embodiment 5 in an enlarged cross section. 
         FIGS. 62G and 62H  are explanatory views of the connection unit portion of Embodiment 5 in an enlarged cross section. 
         FIGS. 63G and 63H  are explanatory views of the connection unit portion of Embodiment 5 in an enlarged cross section. 
         FIG. 64  is a perspective view of one part of a connection unit of Embodiment 6. 
         FIG. 65  is a perspective view of a link unit and a pushing unit  550  of Embodiment 6. 
     
    
    
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
           1 ,  121 ,  201 ,  301 ,  401 : Mobile Telephone 
           3 ,  303 ,  403 : LID 
           5 ,  205 ,  305 ,  405 : Connection Unit 
           7 ,  307 ,  407 : Body 
           20 ,  220 ,  320 ,  420 ,  520 : Connection Body 
           30 ,  230 : Guide 
           62   a ,  62   b : Concave Part 
           77 ,  398 ,  498 : Link Pivot Attachment Part 
           98 ,  277 ,  298 ,  377 ,  477 : Guide Plate 
           100 ,  210 ,  310 ,  410 : Link Unit 
           102 ,  106 ,  211 ,  378 ,  399 ,  478 ,  499 : Pivot Attachment Projection 
           103 ,  243 ,  312   b ,  412   b : Body Side Arm 
           105 ,  251 : Slide Body 
           107 ,  212 ,  312   a ,  412   a : Lid Side Arm 
           109 : Shaft Member 
           133   a ,  133   b : Turning Shaft 
           227 ,  422   d : Shaft 
           317   a : Rolling Gear 
           322   a : Center Gear 
           331   a ,  331   b ,  431   a ,  431   b : Peripheral Surface Gear 
         La, Lb: Advance/Retreat Distance 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention will be described below with reference to the drawings. 
     Embodiment 1 
     First, a configuration of a mobile telephone  1  of Embodiment 1 will be described with a perspective view of a closed state shown in  FIG. 1 , a perspective view of an open state shown in  FIG. 2 , and a perspective view of a state in which a cover is partially detached shown in  FIG. 3 . 
     The mobile telephone  1  is configured by a lid  3 , a body  7 , and a connection unit  5  for connecting the same. The connection unit  5  is configured by a lid side unit  5   a , a body side unit  5   b , a connection body  20 , and a link unit  100 . 
     The lid side unit  5   a  and the body side unit  5   b  are screw fixed to the lid  3  and the body  7 , and integrated with the lid  3  and the body  7 . In this embodiment, the units are screw fixed with screws  89   a ,  89   b , but may be fixed through fit-in or adhesion. 
     As shown with a virtual line in  FIG. 2 , a liquid crystal display  4  serving as a display unit is arranged on the open/close inner surface of the lid  3 . 
     As shown with a virtual line, a plurality of input buttons  8  serving as operation input unit is arranged on the open/close inner surface of the body  7 . 
     When the mobile telephone  1  is in the open state, the connection body  20  is completely housed in an opening part (concave part formed in a lid side guide body  60   a ) of the lid side unit  5   a  and an opening part (concave part formed in a body side guide body  60   b ) of the body side unit  5   b , as shown in  FIG. 3 . A lid side pushing unit  40   a , a body side pushing unit  40   b , and the link unit  100  are housed in the concave part of the connection body  20 . Among them, the link unit  100  has one part slidably engaged to a guide  30 . 
       FIG. 3  shows the open state similar to  FIG. 2  with a lid side guide cover  80   a  and a body side guide cover  80   b  detached. 
     The mobile telephone  1  includes equipment, for example, a control unit such as CPU for executing various control processes (not shown), a storage unit such as non-volatile memory for storing data and a program, a display unit such as the liquid crystal display  4  for displaying image, an operation input unit such as the input button  8  for accepting input operation, a voice communication unit for performing voice communication, a data communication unit for performing data communication, an imaging part such as a CCD camera for taking pictures, a voice output unit such as a speaker for output voice, and a voice collecting unit such as a microphone for collecting voices as electronic equipment, which are in an electrically connected state. 
     According to the above configuration, the lid  3  and the body  7  can be opened and spread out or closed by the connection unit  5 . That is, they can be freely opened/closed from a fully closed state in which the surface of the liquid crystal display  4  of the lid  3  faces and superimposes the input button  8  of the body  7  to a fully open state in which the lid  3  and the body  7  are extended straightly. Therefore, the user can open/close the lid  3  and the body  7 , as necessary, and conveniently uses the mobile telephone  1  in the open state or the closed state, and carry around the mobile telephone in the closed state to prevent unintended operation. 
     A configuration of the connection unit  5  will now be described. 
       FIG. 4  is an exploded perspective view of the connection unit  5  seen from diagonally above,  FIG. 5  is an exploded perspective view of the connection unit  5  seen from diagonally below, and  FIGS. 6A to 6C  are partially enlarged explanatory views. 
     The connection unit  5  is configured by the lid side unit  5   a  attached to the lid  3  ( FIG. 2 ), the body side unit  5   b  attached to the body  7  ( FIG. 2 ), the connection body  20  housed between the lid side unit  5   a  and the body side unit  5   b , and the link unit  100  for adjusting the ratio of the advance/retreat amount of the connection body  20  into/from the lid side unit  5   a  and the body side unit  5   b.    
     In each figure, “a” is denoted on the reference numeral for components of the lid side unit  5   a , and “b” is denoted on the reference numeral for components of the body side unit  5   b . Furthermore, with regards to the connection unit  20 , “a” is denoted on the reference numeral for components that act on the lid side unit  5   a , and “b” is denoted on the reference numeral for components that act on the body side unit  5   b.    
     The lid side unit  5   a  has a width and a thickness of about the same extent as the lid  3  ( FIG. 2 ), and is configured by the lid side guide body  60   a , the lid side guide cover  80   a  attached to the front surface of the lid side guide body  60   a , and the lid side pushing unit  40   a  slidably attached to the lid side guide cover  80   a.    
     The outer shape of the lid side guide body  60   a  has a rectangular shape when seen from the connection side and a reverse L-shape in side view. A concave part  62   a  that becomes the advance/retreat space into/from which the connection body  20  advances/retreats is formed on the side connecting with the body side unit  5   b.    
     The shape of the concave part  62   a  is formed to a cavity of horizontal fan column shape in which the rectangle of a constant width (about 90% to 95% of the entire width in the present embodiment) is rotated by ¼ from the open/close inner surface to the connection side end face with the corner side of the connection side end face (lower left side of  FIG. 4 ) and the open/close inner surface (upper side of  FIG. 4 ) as the axis. 
     Therefore, a circular arc face  66   a  having a width that draws a circular arc from the open/close inner surface towards the connection side end face, and a perpendicular wall face  67   a  upstanding at right angle from both left and right ends of the circular arc face  66   a  towards the axis core of the circular arc are formed on the connection side of the lid side guide body  60   a , where the two left and right wall faces  67   a  and the circular arc face  66   a  configure an advance/retreat guide  68   a.    
     A concave part that becomes concave towards left and right outer sides at positions spaced apart by a constant distance towards the axis core from the circular arc face  66   a  is formed in each wall face  67   a , which concave part forms a slip-out preventing projection groove  65   a  having a fan shape in side view. 
     A locking side  64   a  upstanding at right angle by a constant distance towards the inner side in the axial direction is connected to the connection side end of each slip-out preventing projection groove  65   a.    
     Two fit-in grooves  71   a  for fitting in the lid side guide cover  80   a  are formed on the left and the right at the open/close outer side portion (portion on the side opposite to the connection side) of the lid side guide body  60   a . A screw hole  72   a  for screw fixing the lid side unit  5   a  to the lid  3  is formed at the center of each fit-in groove  71   a . The screw  89   a  inserted to the screw hole  81   a  of the lid side guide cover  80   a  and is screw-fit to the screw hole  72   a , whereby the lid side guide body  60   a  and the lid side guide cover  80   a  are fixed. The screw  89   a  is further screw-fit to a screw hole (not shown) formed in the lid  3 , whereby the lid side unit  5   a  is fixed to the lid  3 . 
     The lid side guide cover  80   a  and the body side guide cover  80   b  may not be formed with screw holes  81   a ,  81   b , and may be fixed through methods other than screw fixation. 
     The outer shape of the lid side guide cover  80   a  is formed to a plate form of rectangular shape having the same size in plan view as the lid side guide body  60   a , where chamfering is performed on the connection side end on the front surface to form an inclined part  88   a . Two screw holes  81   a  are symmetrically formed near the open/close outer side of the front surface. 
     As shown in  FIG. 5 , the slip-out prevention turning shaft  85   a , a slide stabilizing guide  91   a , a push direction regulating guide  86   a , and a spring locking projection  87   a  are symmetrically arranged in order from the outer side on the connection side at the back surface of the lid side guide cover  80   a . A link pivot attachment part  77  is arranged between the push direction regulating guide  86   a  on the left side and the slip-out prevention turning shaft  85   a.    
     The link pivot attachment part  77  is arranged in an upstanding manner so as to project downward at the back surface of the lid side guide cover  80   a , and a pivot attachment hole  78  passing through in the left and right direction is formed near the center. The pivot attachment hole  78  is formed within a range of the same distance as a thickness D (see  FIG. 2 ) of the lid side unit  5   a  from the connection side end face of the lid side unit  5   a.    
     The slip-out prevention turning shaft  85   a  is arranged at a position proximate to the side surface of the lid side guide cover  80   a , and is formed to a horizontal semi-circular cylinder shape. 
     The push direction regulating guide  86   a  is formed by a circular cylinder projection arranged in an upstanding manner at right angles on the back surface of the lid side guide cover  80   a.    
     The spring locking projection  87   a  is arranged in an upstanding manner on the back surface of the lid side guide cover  80   a , and is formed by a projection shorter than the push direction regulating guide  86   a . The spring locking projection  87   a  is inserted to one end of the coil spring  59   a , which is one type of elastic body. 
     The slide stabilizing guide  91   a  is a circular arc shaped guide of ¼ circle that becomes a concentric circle with the slip-out prevention turning shaft  85   a , and is symmetrically arranged on the back surface of the lid side guide cover  80   a.    
     A slip-out preventing projection housing groove  84   a  having a rectangular shape long in the connecting direction (direction from upper right to lower left of  FIG. 4 , direction from lower right to upper left of  FIG. 5 ) is symmetrically arranged proximate to the side of the open/close outer side from the slip-out prevention turning shaft  85   a  and  85   b.    
     A fit-in projection  82   a  projecting in a ring form is symmetrically arranged at the vicinity of the open/close outer side of the back surface of the lid side guide cover  80   a , and the screw hole  81   a  is formed at the center of each fit-in projection  82   a.    
     The lid side pushing unit  40   a  is configured by a lid side pushing base  41   a , a roller  44   a , and a coil spring  59   a.    
     The lid side pushing base  41   a  is formed to a column shape that is entirely long in the width direction, and two spring attachment parts  42   a  to which the coil spring  59   a  is extensibly attached are symmetrically arranged on the open/close inner surface side (upper side of  FIG. 4 ). 
     A guide hole  43   a  passing from the open/close inner surface (upper side of  FIG. 4 ) to the open/close outer surface (lower side of  FIG. 4 ) is formed further on the outer side of the spring attachment part  42   a . The push direction regulating guide  86   a  (see  FIG. 5 ) of the lid side guide cover  80   a  is inserted to the guide hole  43   a . The lid side pushing base  41   a  then can move forward and backward from the front surface (upper side of  FIGS. 4 and 5 ) to the rear surface (lower side of  FIGS. 4 and 5 ) while maintaining a parallel state without rattling. 
     The circular disc shaped roller  44   a  with thickness is symmetrically and coaxially axial supported at both side surfaces of the lid side pushing base  41   a . The roller  44   a  is arranged at a position the outer peripheral surface projects to the lower side from the bottom surface of the pushing base  41 . 
     The connection body  20  has a side wall  28  raised at right angles arranged at left and right side ends of a slide plate  27  of a substantially semicircular shape. 
     Shaft contacting grooves  21   a ,  21   b  cut to a circular arc shape when seen from the lower right of  FIG. 4  are connected in a connecting direction at the center of each upper surface of the side wall  28 , and the slip-out preventing projections  22   a ,  22   b  are symmetrically arranged in the connecting direction on the outer side of the connecting direction. 
     As shown in  FIG. 5 , the outer periphery of the slide plate  27  has the circular arc outer peripheral surface  29   a  formed to a circular arc having the lid turning axis (not shown) or the center of the circular arc of the shaft contacting groove  21   a  as an axis core, and a circular arc outer peripheral surface  29   b  formed to a circular arc having a body turning axis (not shown) or the center of the circular arc of the shaft contacting groove  21   b  as an axis core symmetrically connected in the connecting direction. The circular arc outer peripheral surface  29   a  surface corresponds to the circular arc face  66   a  of the lid side guide body  60   a , and the circular arc outer peripheral surface  29   b  surface corresponds to the circular arc face  66   b  of the body side guide body  60   b.    
     As shown in the enlarged perspective view of  FIG. 6A , the inner periphery of the slide plate  27  has a circular arc inner peripheral surface  24   a  curved on the inner side of a constant distance from the circular arc outer peripheral surface  29   a  with the lid turning axis as the axis core, and a circular arc inner peripheral surface  24   b  curved on the inner side of a constant distance from the circular arc outer peripheral surface  29   b  with the body turning axis as the axis core symmetrically connected in the connecting direction. 
     A locking concave part  25   b  of the same circular arc shape as the roller  44   b  ( FIG. 4 ) or of a circular arc shape smaller than the roller  44   b  is arranged lined in the connecting direction at the circular arc inner peripheral surface  24   b . A locking concave part  23   b  is also formed at the end on the front surface side (end on lower side of  FIG. 4 ) of the circular arc inner peripheral surface  24   b.    
     In this embodiment, the locking concave part  23   b  and the locking concave part  25   b  are arranged only on the body side, but the locking concave part  23   a  (not shown) and the locking concave part  25   a  (not shown) may be arranged on the lid side. 
     A curved w-shaped convex part  35  is symmetrically arranged on each inner surface of the left and right side walls  28 . The slide stabilizing grooves  34   a ,  34   b  of circular arc shape are formed at a portion sandwiched by a curved outer side surface of the convex part  35  and the inner surface of the slide plate  27 . As shown in the cross sectional view of  FIG. 6B , a slide stabilizing guide  91   a  of the lid side guide cover  80   a  engages the slide stabilizing groove  34   a . The connection body  20  is then smoothly and stably advanced and retreated while drawing a circular arc from the concave part  62   a  of the lid side unit  5   a.    
     The guide  30  rising perpendicular towards the open/close inner surface at a position slightly apart from the side wall  28  on the left side is arranged on the inner surface of the connection body  20 . The guide  30  has a slide space  32  at the center formed perpendicularly and in parallel. 
     As shown in the perspective view of  FIG. 6C , the link unit  100  is configured by a shaft member  109 , a lid side arm  107  for inserting the shaft member  109 , a slide body  105 , a body side arm  103 , and a slip-out preventing cap  101 . 
     The shaft member  109  has an attachment convex part  111  arranged at one end of a shaft part  112  of cylindrical shape, and a slip-out preventing shaft head  113  arranged at the other end. 
     The lid side arm  107  has a shaft insertion hole  108  formed at one end and a pivot attachment projection  106  arranged at the other end. The shape of the lid side arm itself is curved and formed to a substantially L-shape in left side view of  FIG. 6C . 
     The slide body  105  has a square column shape with the corners cut off, and is formed with a shaft insertion hole  115  for inserting the shaft member  109 . Two opposing surfaces (horizontal surfaces) of square column shape contact the opposing surface of the guide  30  (see  FIG. 6B ) of the connection body  20 , and slides while being stabilized in the up and down direction. That is, the slide body  105  is slidably and movably supported by the guide  30  in a slidable manner. 
     The body side arm  103  has a shaft insertion hole  104  formed at one end, and a pivot attachment projection  102  arranged at the other end. The shape of the body side arm  103  itself is curved and formed to a substantially L-shape in right side view of  FIG. 6C . 
     The slip-out preventing cap  101  has a ring shape, and is attached with the attachment convex part  111  of the shaft member  109 . 
     Therefore, the shaft part  112  of the shaft member  109  is inserted to the shaft insertion hole  108  of the lid side arm  107 , the shaft insertion hole  115  of the slide body  105 , and the shaft insertion hole  104  of the body side arm  103  in this order. The slip-out preventing cap  101  is attached and fixed to the attachment convex part  111  of the shaft member  109 . The body side arm  103 , the slide body  105 , and the lid side arm  107  are thereby united while being independently turnable with the shaft member  109  as the axis. The united link unit  100  has a substantially w shape when seen from the side view of  FIG. 6C . 
     The pivot attachment projection  102  of the body side arm  103  is pivotally attached to the pivot attachment hole  99  of the guide plate  98 , and the pivot attachment projection  106  of the lid side arm  107  is pivotally attached to the pivot attachment hole  78  of the link pivot attachment part  77 . 
     The body side unit  5   b  shown in  FIGS. 4 and 5  has a width and a thickness of about the same extent as the body  7  (see  FIG. 2 ), and is configured by a body side guide body  60   b , a body side guide cover  80   b  attached to the front surface of the body side guide body  60   b , and a body side pushing unit  40   b  slidably attached to the body side guide cover  80   b . Each of such elements are configured symmetric to the connecting direction with the lid side unit  5   a  as described above other than the non-symmetric portion described below, and thus the description thereof will be omitted. 
     The non-symmetric portion is a portion that does not have the link pivot attachment part  77  (see  FIG. 5 ) arranged at the body side guide cover  80   b , and instead, has the guide plate  98  with the slide stabilizing guide  91   b  on the left side formed to a thick thickness, and a pivot attachment hole  99  passing through in the left and right direction formed near the center of the guide plate  98 . The pivot attachment hole  99  is arranged within a range of the same distance as the thickness D (see  FIG. 2 ) of the body side unit  5   b  from the connection side end face of the body side unit  5   b.    
     In this embodiment, the connection body  20 , the guide body  60  ( 60   a ,  60   b ), and the guide cover  80  ( 80   a ,  80   b ) are formed with metal members, and the pushing base  41  ( 41   a ,  41   b ) and the roller  44  ( 44   a ,  44   b ) are formed with resin members, but are not limited thereto, and may be formed with appropriate raw materials. 
     The connection unit  5  is completed by combining each element configured as above. 
     The opening/closing operation of the connection unit  5  performed when the connection body  20  advances/retreats into/from the lid side unit  5   a  and the body side unit  5   b , and the opening/closing operation of the mobile telephone  1  will now be described. 
       FIG. 7  is a perspective view of one part of the connection unit  5  in the open state,  FIG. 8  is a perspective view of one part of the connection unit  5  slightly changed towards the closing direction from the open state,  FIG. 9  is a perspective view of one part of the connection unit  5  further changed towards the closing direction, and  FIG. 10  is a perspective view of one part of the connection unit  5  in the closed state.  FIG. 7  to  FIG. 10  show views seen from the lower left position in  FIG. 5 . 
       FIG. 11  is an enlarged cross sectional view of the connection unit  5  portion in the open state,  FIG. 12  is an enlarged cross sectional view of the connection unit  5  portion slightly changed towards the closing direction from the open state,  FIG. 13  is an enlarged cross sectional view of the connection unit  5  portion further changed towards the closing direction, and  FIG. 14  is an enlarged cross sectional view of the connection unit  5  portion in the closed state.  FIG. 11  to  FIG. 14  show cross sectional views taken along line A-A in  FIG. 3 . 
       FIGS. 15A to 15D  are explanatory views describing a mobile telephone  1  in each state changing from the open state to the closed state in a perspective view. 
     In the open state, the lid  3  attached with the lid side unit  5   a  (see  FIG. 11 ) and the body  7  attached with the body side unit  5   b  are opened 180 degrees forming a rectangular solid body as a whole, as shown in  FIG. 7 ,  FIG. 11 , and  FIG. 15A . 
     In this case, the connection body  20  is completely housed in the concave part  62   a  (see  FIG. 4 ) of the lid side unit  5   a  and the concave part  62   b  in the body side unit  5   b , and cannot be visibly recognized from the outside. As shown in  FIG. 11 , the slide body  105  of the link unit  100  approaches the base of the guide  30  the most. 
     Furthermore, the roller  44   b  of the body side pushing unit  40   b  is locked by contacting the locking concave part  25   b  (see  FIG. 4 ) of the connection body  20 . Therefore, the lid side unit  5   a  and the body side unit  5   b  do not transition to the closed state with slight force due to the biasing force of the coil spring  59   b , and the open state can be maintained. In  FIG. 4 , the locking concave part  25   b  is formed only on the body side pushing unit  40   b  side, but the locking concave part may also be formed on the lid side pushing base  41   a  side. In this case, the roller  44   a  of the lid side pushing unit  40   a  is locked at the locking concave part, and the open state can be maintained with a stronger force. 
     When the user manually applies force so that the lid  3  and the body  7  are folding operated from the open state in the closing direction, the roller  44   b  moves out from the locking concave part  25   b  at the point the relevant force exceeds the biasing force of the coil spring  59   b , whereby the lid  3  attached with the lid side unit  5   a  (see  FIG. 11 ) and the body  7  attached with the body side unit  5   b  transition to a slightly bent state, as shown in  FIG. 8 ,  FIG. 12 , and  FIG. 15B . When the roller  44   b  moves out from the locking concave part  25   b , the user feels a clicking feeling or a satisfactory operation feeling. 
     In transitioning towards the closing direction, the lid side unit  5   a  turns with the slip-out prevention turning shaft  85   a  (see  FIG. 8 ) as a virtual rotation axis, and the body side unit  5   b  turns with the slip-out prevention turning shaft  85   b  (see  FIG. 8 ) as a virtual rotation axis. The pivot attachment projection  102  of the body side arm  103  and the pivot attachment projection  106  of the lid side arm  107  turn in conjunction with the shaft member  109  as the center. 
     According to such turning, the link pivot attachment part  77  and the guide plate  98  separate as shown in  FIG. 8 , and the interval W between the pivot attachment projection  102  of the body side arm  103  and the pivot attachment projection  106  of the lid side arm  107  becomes wider than in the open state as shown in  FIG. 12 . Thus, the slide body  105  of the link unit  100  slidably moves in a straight line from the base towards the distal end side of the guide  30  in the slide space  32  of the guide  30 . Therefore, the ratio between the advance/retreat distance La (see  FIG. 12 ) the connection body  20  advances from the lid side unit  5   a  and the advance/retreat distance Lb (see  FIG. 12 ) the connection body  20  advances from the body side unit  5   b  becomes one to one, and thus equally advances. A stable and smooth operation feeling is thereby obtained. 
     When folding operated further in the closing direction, the state transitions to the bent state, as shown in  FIG. 9 ,  FIG. 13 , and  FIG. 15C . In the middle of transitioning, the interval W becomes a maximum when the virtual turning axis  31   a  of the lid side unit  5   a  and the virtual turning axis  31   b  of the body side unit  5   b  are positioned on a line connecting the pivot attachment projection  102  of the body side arm  103  and the pivot attachment projection  106  of the lid side arm  107 , as shown in  FIG. 13 , and thereafter, the interval W becomes smaller. Meanwhile, the slide body  105  of the link unit  100  continues to move from the base towards the distal end of the guide  30  in the slide space  32  of the guide  30 . The ratio of the advanced amount of the connection body  20  from the lid side unit  5   a  and the advanced amount of the connection body  20  from the body side unit  5   b  is maintained to one to one, and thus is always equally advanced. 
     When further folding operated in the closing direction, the state transitions to a completely folded closed state, as shown in  FIG. 10 ,  FIG. 14 , and  FIG. 15D . As shown in  FIG. 14 , the slide body  105  of the link unit  100  is positioned in the slide space  32  at a position closest to the distal end of the guide  30 . 
     The lid side arm  107  and the body side arm  103  are curved and formed so that the side surfaces on the opposing sides thereof become concave. Thus, a gap X is ensured between the body side arm  103  and the lid side arm  107 , and the lid side guide cover  80   a  and the body side guide cover  80   b  are held in the gap X. 
     When transitioning from the closed state to the open state, operation completely opposite to that in transitioning towards the closing direction is performed. 
     According to such an operation, the connection body  20  advances/retreats drawing a circular arc with respect to the lid side unit  5   a  and the body side unit  5   b , and a mobile telephone  1  having a novel configuration in which the lid  3  and the body  7  open/close can be provided. 
     In opening/closing, the connection body  20  equally advances/retreats with respect to the lid side unit  5   a  and the body side unit  5   b  by the function of the link unit  100 , and a stable operation symmetric at the center of the folding can be performed. 
     The connection body  20  slidably turns and advances/retreats with the circular arc outer peripheral surface  29   a  (see  FIG. 5 ) contacting the circular arc face  66   a  of the lid side guide body  60   a  (see  FIG. 4 ), and thus advances/retreats without being caught. In particular, when the slide stabilizing guide  91   a  (see  FIG. 6A ) arranged on the lid side guide cover  80   a  and the stabilizing groove  34   a  (see  FIG. 6B ) arranged on the connection body  20  engage, a more stable slide turn can be realized, and a smooth advancement/retreatment can be reliably realized. 
     The concave part  62   a  and  62   b  are arranged in the connection part of the lid  3  and the connection part of the body  7 , respectively, where one end side of the connection body  20  is attached to advance into and retreat from the concave part  62   a , and the other end side of the connection body  20  is attached to advance into and retreat from the concave part  62   b . Therefore, in the fully open state, the connection body  20  can be housed in the concave parts  62   a ,  62   b  and be hidden, whereby the appearance of the mobile telephone  1  improves. 
     The connection body  20  can be advanced/retreated in a circular arc form from the concave part  62  ( 62   a ,  62   b ) by arranging the advance/retreat guide  68  ( 68   a ,  68   b ) for advancing/retreating the connection body  20  while drawing a circular arc with the slip-out prevention turning shaft  85  ( 85   a ,  85   b ) as a virtual axis core at the lid side unit  5   a  and the body side unit  5   b , and arranging the side wall  28  and the circular outer peripheral surface  29  ( 29   a ,  29   b ) on the connection body  20 . In the open state, the connection body  20  is housed in the concave part  62 , and in transitioning from the open state to the closed state, the connection body  20  advances in a circular arc form from the concave part  62  thereby allowing the lid  3  and the body  7  to be in the closed state. 
     The advance/retreat guide  68  is formed with different circular arc axes with the axis of the circular arc face  66   a  on the lid  3  side as the lid turning axis  31   a  (see  FIG. 13 ) and the axis of the circular arc face  66   b  on the body  7  side as the body turning axis  31   b , whereby a moderate opening/closing operation can be realized in the fully closed state, the fully opened state, and the state in between. 
     A configuration of arranging the locking concave parts  23   b ,  25   b  and the pushing unit  40   b  for locking the advancement/retreatment of the connection body  20  with respect to the concave part  62  when the open/close angle of the lid  3  and the body  7  becomes a constant angle, and fitting and locking the roller  44   b  of the pushing unit  40   b  into the locking concave  23   b ,  25   b  by the biasing force of the coil spring  59   b  is adopted. Therefore, the lid  3  and the body  7  can be stabilized at a constant angle of 0° and 180°, and the operability of the user improves. The locking open/close angle is not limited thereto, and the locking concave part may be formed to lock the advancement/retreatment at other angles, or the locking concave part may be formed while setting three or more angles for locking advancement/retreatment. 
     The force for stabilizing the lid  3  and the body  7  at a constant angle can be easily adjusted by the biasing force of the coil spring  59  by using the coil spring  59  ( 59   a ,  59   b ) for providing the biasing force to the pushing unit  40 , and an open/close mechanism of a moderate clicking feeling can be easily provided. 
     Furthermore, from the fully open state to the closed state (up to right before the fully closed state), the connection body  20  can be prevented from slipping out from the lid side unit  5   a  and the body side unit  5   b  since the slip-out prevention turning shafts  85   a ,  85   b  are contacting the shaft contacting grooves  21   a ,  21   b . In the fully closed state, the connection body  20  can be prevented from slipping out from the lid side unit  5   a  and body side unit  5   b  since the slip-out preventing projections  22   a ,  22   b  are contacting the locking sides  64   a ,  64   b.    
     The pushing unit for positioning the open/close position includes the lid side pushing unit  40   a  and the body side pushing unit  40   b , but may only include either one. In this case, a satisfactory operation feeling for symmetrically opening/closing is obtained by the link unit  100 . 
     The circular arc face  66   a  is provided to slidably advance/retreat the connection body  20  in a circular arc form, and thus is not limited to being configured with a plane, and may be formed to other shapes by arranging a plurality of circular arc shaped rails in the width direction etc. The two wall faces  67   a  are provided so that the connection body  20  does not rattle while sliding, and thus are not limited to perpendicular faces, and may be formed to other shapes. 
     The slip-out preventing projection groove  65   a  and the locking side  64   a , and the slip-out preventing projection  22   a  of the connection body  20  are provided to prevent the connection body  20  from slipping out from the lid-side unit  5   a , and thus are not limited to such shape and may be formed to other shapes. For instance, the concave part may be formed at one part of the circular arc face  66   a  to serve as the slip-out preventing projection groove  65   a  and the locking side  64   a  may be arranged on the connection end face  61   a  side of the slip-out preventing projection groove  65   a  instead of arranging the slip-out preventing projection groove  65   a  and the locking side  64   a  at the side in the width direction. In this case, the slip-out preventing projection  22   a  of the connection body  20  is preferably arranged not on the side in the width direction of the connection body  20  but on the side end in the advancing/retreating direction. 
     The locking concave parts  23 ,  25  may not be arranged in the slide plate  27 , and may be arranged on the inner surface of the side wall  28 . In this case, the roller  44  is formed with a spherical body and biased towards the outer side in the width direction so as to be locked at the locking concave part arranged on the inner surface of the side wall  28 . The mobile telephone  1  can be positioned at a predetermined open/close angle with such configuration, and a satisfactory clicking feeling can be obtained. 
     The roller  44  may be non-rotatably formed with a slidable shape and raw material. In this case as well, the opening/closing operation is smoothly performed, and the open/close angle can be locked. 
     In the fully open state, a configuration of hiding the connection body  20  so as to be completely invisible is adopted, but a hole or a groove may be formed on the connection side of the lid side guide cover  80   a  and the body side guide cover  80   b , so that the connection body  20  is partially visible even in the fully open state. In this case as well, a hinge will not project out and be seen as in the prior art, and a mobile telephone  1  of a smart design can be provided. 
     The lid  3  and the lid side guide body  60   a  are configured as separate bodies but may be integrally formed. The body  7  and the body side guide body  60   b  are configured as separate bodies but may be integrally formed. 
     Embodiment 2 
     Embodiment 2 will now be described. 
       FIG. 16  is a perspective view of a mobile telephone  121  of Embodiment 2, and  FIG. 17  is a partially exploded enlarged perspective view of the mobile telephone  121  of Embodiment 2. 
     In this case, a lid side unit  125   a  is fixed to a lid  3 , a body side unit  125   b  is fixed to a body  7 , and the lid side unite  125   a  and the body side unit  125   b  configure a connection unit  125 . 
     A side wall member  131  is symmetrically arranged on the outer side of the side wall  28  of the connection body  20  to be housed in the connection unit  125  in the open state. The side wall member  131  has a bearing  132  arranged on the inner surface side (upper side of  FIG. 16 ), and turning shafts  133   a ,  133   b  are arranged in parallel to the bearing  132 . The turning shafts  133   a ,  133   b  are positioned at locations where the slip-out prevention turning shaft  85   a  of the lid side guide cover  80   a  and the slip-out prevention turning shaft  85   b  of the body side guide cover  80   b  in Embodiment 1 exist. Slip-out preventing projections  134   a ,  134   b  having the same effect as the slip-out preventing projections  22   a ,  22   b  (see  FIG. 4 ) are formed on the side wall member  131 . 
     A lid side guide cover  180   a  and a body side guide cover  180   b  have a configuration similar to the lid side guide cover  80   a  and the body side guide cover  80   b  in Embodiment 1 other than that groove holes  152   a ,  152   b  are formed at locations where the slip-out prevention turning shaft  85   a  (Embodiment 1) and the slip-out prevention turning shaft  85   b  (Embodiment 1) exist, and bearing holes  151   a ,  151   b  for bearing the turning shafts  133   a ,  133   b  are formed at the side surface of the groove holes  152   a ,  152   b.    
     A guide body similar to the lid side guide body  60   a  and the body side guide body  60   b  of Embodiment 1 is arranged in the mobile telephone  121 , but the illustration thereof is omitted in  FIG. 17 . 
     Other components are the same as Embodiment 1, and thus the same reference numerals are denoted for the same components and detailed description thereof will be omitted. 
     According to the above configuration, opening/closing in a novel structure can be realized, and a more stable turn can be realized compared to the virtual axis of Embodiment 1. 
     The connection body  20  is prevented from slipping out from the lid side unit  5   a  and the body side unit  5   b.    
     Looking at the outer appearance of the mobile telephone  121 , the bearing  132  is slightly visible on the inner side surface in the open state, but other portions are not visible, and a solid rectangular shape is obtained as a whole in the open state. 
     Embodiment 3 
     Embodiment 3 will now be described. 
       FIG. 18  is a plan view of a mobile telephone  201  of Embodiment 3,  FIG. 19  is an exploded perspective view of a connection unit  205  seen from diagonally above,  FIG. 20  is an exploded perspective view of the connection unit  205  seen from diagonally below,  FIG. 21  is an explanatory view of a link unit  210  in an exploded perspective view, and  FIG. 22  is a perspective view of a connection body  220 . 
     The mobile telephone  201  includes the lid  3  and the body  7  same as the mobile telephone  1  of Embodiment 1. A lid side connection unit  205   a  corresponding to the lid side unit  5   a  (see  FIG. 2 ) of Embodiment 1 is attached to the lid  3 , and a body side connection unit  205   b  corresponding to the body side unit  5   b  (see  FIG. 2 ) of Embodiment 1 is attached to the body  7 . 
     The connection body  220  (see  FIG. 19 ) and the link unit  210  are housed in the connection part of the lid side connection unit  205   a  and the body side connection unit  205   b  in the open state. The link unit  210 , the connection body  220 , the lid side connection unit  205   a , and the body side connection unit  205   b  configure a connection unit  205 . 
     The lid side connection unit  205   a  is configured by the lid side guide cover  280   a  and the lid side guide body  60   a , and the body side connection unit  205   b  is configured by the body side guide cover  280   b  and the body side guide body  60   b.    
     The lid side guide cover  280   a  is the same as the lid side guide cover  80   a  of Embodiment 1 other than that the pushing direction regulating guide  86   a  (see  FIG. 5 ) and the spring locking projection  87   a  of Embodiment 1 are not arranged, and a guide plate  277  (see  FIG. 20 ) projecting downward is arranged. 
     A pivot attachment hole  278  passing through in the width direction of the mobile telephone  201  is formed in the guide plate  277 . 
     The body side guide cover  280   b  is the same as the body side guide cover  80   b  of Embodiment 1 other than that the pushing direction regulating guide  86   b  (see  FIG. 5 ) and the spring locking projection  87   b  of Embodiment 1 are not arranged, and a guide plate  298  (see  FIG. 20 ) projecting downward is arranged in place of the guide plate  98 . 
     A pivot attachment hole  299  passing through in the width direction of the mobile telephone  201  is formed in the guide plate  298 . 
     The link unit  210  (see  FIG. 21 ) corresponds to the link unit  100  (see  FIG. 6C ) of Embodiment 1, and is configured by a lid side arm  212 , a coil spring  215 , a locking convex body  221 , a shaft  227 , a locking guide body  234 , a body side arm  243 , and a slide body  251 . 
     The lid side arm  212  corresponds to the lid side arm  107  (see  FIG. 6C ) of Embodiment 1, where a shaft insertion hole  214  (see  FIG. 21 ) is formed at one end of the arm bent to a substantially L-shape and a pivot attachment projection  211  is formed at the other end. The shaft insertion hole  214  is formed with an engagement strip  213  that engages a cut-out surface  226  of the shaft  227  so as to rotate with the inserted shaft  227 . 
     The coil spring  215  is one type of an elastic body, and is partially or entirely housed in the concave part  225  (see  FIG. 21B ) formed in the locking convex body  221 . 
     The locking convex body  221  has a shaft insertion hole  223  formed at the center, and a perpendicular surface  222  formed at one part of the side wall of the shaft insertion hole  223 . A locking projection  224  projecting in the axial direction is formed at one end face (face on the side contacting with the locking guide body  234 ) of the shaft insertion hole  223 . A concave part  225  is formed at the other end of the shaft insertion hole  223 . 
     The shaft  227  corresponds to the shaft member  109  (see  FIG. 6C ) of Embodiment 1, and is entirely formed to a rod form of substantially cylindrical shape with the cut-out surface  226  formed on one side and an inserting projection  228  formed at the other side. 
     The locking guide body  234  has a shaft insertion hole  233  formed at the center, where locking guides  231 ,  236  projecting in the axial direction along the vicinity of the circumference are arranged at one end face (face on the side contacting the locking convex body  221 ) of the shaft insertion hole  233 . A concave part  238  is formed on the other end of the shaft insertion hole  233 , and a cut-out part  239  is formed on one side part. 
     The body side arm  243  corresponds to the body side arm  103  (see  FIG. 6C ) of Embodiment 1, where the shaft insertion hole  241  is formed at one end of the arm having a substantially L-shape, and a pivot attachment projection  242  is formed at the other end. 
     The slide body  251  corresponds to the slide body  105  (see  FIG. 6C ) of Embodiment 1, and the entire shape is formed to a substantially solid rectangular shape, where linear guide grooves  252 ,  252  are arranged in parallel and in symmetric at the center of one surface and the opposite surface, and a shaft insertion hole  253  for inserting the shaft  227  is formed in a direction orthogonal to the guide groove  252 . 
     The link unit  210  configured as above has an angle fixing function for fixing the open/close angle, which angle fixing function is realized with an angle fixing unit  240  configured by the coil spring  215 , the locking convex body  221 , and the locking guide body  234 . 
     That is, the locking convex body  221  is constantly biased towards the locking guide body  234  side by the biasing force of the coil spring  215 , where the locking projection  224  rides over the locking guides  231 ,  236 , slidably moves thereon and drops by the relative rotation of the locking convex body  221  and the locking guide body  234 , and angle fixation is realized at the dropped position. While the locking projection  224  is riding over the locking guide  231 , the angle is maintained by the biasing force of the coil spring  215  by freely stopping the rotation at an arbitrary angle. 
     The connection body  220  corresponds to the connection body  20  (see  FIG. 4 ) of Embodiment 1, and is the same as the connection body  20  of Embodiment 1 other than that the guide  230  and the slide space  232  corresponding to the guide  30  and the slide space  32  of Embodiment 1 are arranged near the center of the connection body  220 , and the locking concave part  23   b , the circular arc inner peripheral surface  24   b , and the locking concave part  25   b  of Embodiment 1 are omitted. The guide  230  is formed to a thin thickness compared to Embodiment 1, and is configured so that the guide grooves  252 ,  252  (see  FIG. 21 ) contact the inner side of the guide  230 ,  230  and the slide body  251  slidably moves. 
     Other components are the same as Embodiment 1, and thus the same reference numerals are denoted for the same components and the description thereof will be omitted. 
     The opening/closing operation of the connection unit  205  executed when the connection body  220  advances/retreats with respect to the lid side connection unit  205   a  and the body side connection unit  205   b , and the opening/closing operation of the mobile telephone  201  will now be described. 
       FIG. 23  is a bottom view of one part of the connection unit  205  in the open state,  FIG. 24  is a perspective view of one part of the connection unit  205  slightly changed towards the closing direction from the open state, and  FIG. 25  is a perspective view of one part of the connection unit  205  in the closed state.  FIG. 23  to  FIG. 25  are views seen from the lower right position in  FIG. 20 . 
       FIG. 26  is an enlarged cross sectional view of the connection unit  205  portion in the open state,  FIG. 27  is an enlarged cross sectional view of the connection unit  205  portion slightly changed towards the closing direction from the open state, and  FIG. 28  is an enlarged cross sectional view of the connection unit  205  portion in the closed state.  FIG. 26  to  FIG. 28  are cross sectional views taken along line B-B of  FIG. 18 . 
       FIG. 29  is an enlarged perspective view of a locking guide body  234  arranged on the angle fixing unit  240  for enhancing the operation feeling of the opening/closing operation of the mobile telephone  201 . 
     The open/closed state of the entire mobile telephone  201  corresponds to the explanatory view of  FIG. 15  of Embodiment 1, and thus the description will be made using  FIG. 15 . 
     As shown in  FIG. 23  and  FIG. 26 , in the open state, the lid  3  attached with the lid side connection unit  205   a  (see  FIG. 26 ) and the body  7  attached with the body side connection unit  205   b  are in the state opened 180 degrees, and a rectangular solid shape is obtained as a whole, as shown in  FIG. 15A  of Embodiment 1. 
     The connection body  220  is completely housed in the concave part  62   a  (see  FIG. 19 ) of the lid side connection unit  205   a  and the concave part  62   b  (reference numeral omitted in  FIG. 19 ) of the body side connection unit  205   b , and is not visible from the outside. 
     As shown in  FIG. 26 , the slide body  251  of the link unit  210  becomes closest to the base of the guide  230 . 
     In this case, the state of the angle fixing unit  240  has the locking projection  224  of the locking convex body  221  positioned at position P 8  (see  FIG. 29 ) of the locking guide body  234 . More specifically, the locking guide body  234  is formed with a locking guide  231  projecting to a constant height in a circular arc shape at a range of about forty percent along the circumference of the locking guide body  234  and having the end inclined, and a locking guide  236  of hill shape projecting to a height of about the same extent as the locking guide  231  with a slight interval from the locking guide  231 . The position P 8  is positioned adjacent to one end of the locking guide  236 . 
     The locking convex body  221  is biased so as to push the locking guide body  234  by the biasing force of the coil spring  215  (see  FIG. 21 ). Thus, even is the locking projection  224  rides on the locking guide body  234  and attempts to move to position P 6  through position P 7 , it will not ride over with a slight force, and the lid side connection unit  205   a  and the body side connection unit  205   b  will not transition to the closed state. Therefore, the open state is stably maintained. 
     When the user manually applies force to fold the lid  3  and the body  7  to the closing direction from the above open state, the locking projection  224  rides over the locking guide  236  through position P 7  and transitions to position P 5  through position P 6  at the point the relevant force exceeds the biasing force of the coil spring  215 . As shown in  FIG. 24  and  FIG. 27 , the lid  3  attached with the lid side connection unit  205   a  (see  FIG. 26 ) and the body  7  attached with the body side connection unit  205   b  transition to a slightly bent state (e.g., about 170° or 160°). 
     Describing the operation feeling in this case, since position P 7  is inclined, the state transitions to the closed state as if being taken in while the locking projection  224  is positioned at position P 7 , and the closed state is reliably maintained. 
     The locking projection  224  rides over the locking guide  236  through the position P 7 , so that the user feels a clicking feeling or a satisfactory operation feeling, and thereafter transitions to position P 5  as if being taken in through position P 6 . 
     Thus, when transitioning in the closing direction, the lid side connection unit  205   a  turns with the slip-out prevention turning shaft  85   a  (see  FIG. 24 ) as a virtual rotation axis, and the body side connection unit  205   b  turns with the slip-out prevention turning shaft  85   b  (see  FIG. 24 ) as a virtual rotation axis. In this case, the pivot attachment projection  242  of the body side arm  243  and the pivot attachment projection  211  of the lid side arm  212  turn symmetrically in conjunction with the shaft  227  as the center. 
     According to such turn, the interval W between the pivot attachment projection  242  of the body side arm  243  and the pivot attachment projection  211  of the lid side arm  212  becomes wider than in the open state, as shown in  FIG. 27 . Thus, the slide body  251  of the link unit  210  slidably moves in a straight line from the base towards the distal end side of the guide  230  through the slide space  232  of the guide  230 . Therefore, the ratio between the advance/retreat distance La (see  FIG. 27 ) the connection body  220  advances from the lid side connection unit  205   a  and the advance/retreat distance Lb (see  FIG. 27 ) the connection body  220  advances from the body side connection unit  205   b  becomes one to one, and thus equally advances. A stable and smooth operation feeling is thereby obtained. 
     When folding operated further in the closing direction, the locking projection  224  passes position P 4  and rides over the locking guide  231  to transition to position P 3 , and the lid  3  and the body  7  transition to a further bent state. In the middle of transitioning, the interval W becomes a maximum when the virtual turning axis  31   a  (see  FIG. 27 ) of the lid side connection unit  205   a  and the virtual turning axis  31   b  of the body side connection unit  205   b  are positioned on a line connecting the pivot attachment projection  242  of the body side arm  243  and the pivot attachment projection  211  of the lid side arm  212 , and thereafter, the interval W becomes smaller. Meanwhile, the slide body  251  of the link unit  210  continues to move from the base towards the distal end of the guide  230  in the slide space  232  of the guide  230 . The ratio of the advanced amount of the connection body  220  from the lid side unit  205   a  and the advanced amount of the connection body  220  from the body side unit  205   b  is maintained to a one to one, and thus is always equally advanced. 
     The position P 3  is on a plane orthogonal to a direction the coil spring  215  biases, and is at a projecting position. Thus, the frictional force increase since the biasing force of the coil spring  215  is strongly applied while the locking projection  224  is positioned at position P 3 . As a result, a so-called free stop in which the open/close angle of the lid  3  and the body  7  is maintained regardless of which position the locking projection  224  is arranged in the position P 3  is realized. 
     When further folding operated in the closing direction, the locking projection  224  transitions to position P 1  through position P 2 , and a completely folded closed state is obtained, as shown in  FIG. 25  and  FIG. 28 . As shown in  FIG. 28 , the slide body  251  of the link unit  210  is positioned in the slide space  232  at a position closest to the distal end of the guide  230 . 
     The body side arm  243  and the lid side arm  212  are bent and formed so that the side surfaces on the opposing sides thereof become concave. Thus, a gap X is ensured between the body side arm  243  and the lid side arm  212 , and the lid side guide cover  280   a  and the body side guide cover  280   b  are held in the gap X. 
     When transitioning from the closed state to the open state, operation completely opposite to that in transitioning towards the closing direction is performed. 
     According to such an operation, the connection body  220  advances/retreats drawing a circular arc with respect to the lid side unit  205   a  and the body side unit  205   b . A mobile telephone  201  of a novel configuration in which the lid  3  and the body  7  open/close can be provided. 
     In opening/closing, the connection body  220  equally advances/retreats with respect to the lid side unit  205   a  and the body side unit  205   b  by the function of the link unit  210 , and a stable operation symmetric at the center of the folding can be performed. 
     The connection body  220  slidably turns and advances/retreats with the circular arc outer peripheral surface  29   a  (see  FIG. 20 ) contacting the circular arc face  66   a  of the lid side guide body  60   a  (see  FIG. 19 ), and thus advances/retreats without being caught. In particular, when the slide stabilizing guide  91   a  (see  FIG. 19 ) arranged on the lid side guide cover  280   a  and the stabilizing groove  34   a  (see  FIG. 22 ) arranged on the connection body  220  engage, a more stable slide turn can be realized, and a smooth advancement/retreatment can be reliably realized. 
     The concave part  62   a  and  62   b  are arranged in the connection part of the lid  3  and the connection part of the body  7 , respectively, where one end side of the connection body  220  is attached to advance into and retreat from the concave part  62   a , and the other end side of the connection body  220  is attached to advance into and retreat from the concave part  62   b . Therefore, in the fully open state, the connection body  220  can be housed in the concave parts  62   a ,  62   b  and be hidden, whereby the appearance of the mobile telephone  201  improves. 
     The connection body  220  can be advanced/retreated in a circular arc form from the concave part  62  ( 62   a ,  62   b ) by arranging the advance/retreat guide  68  ( 68   a ,  68   b ) for advancing/retreating the connection body  220  while drawing a circular arc with the slip-out prevention turning shaft  85  ( 85   a ,  85   b ) as a virtual axis core in the lid side unit  205   a  and body side unit  205   b , and arranging the side wall  28  and the circular outer peripheral surface  29  ( 29   a ,  29   b ) on the connection body  220 . In the open state, the connection body  220  is housed in the concave part  62 , and in transitioning from the open state to the closed state, the connection body  220  advances in a circular arc form from the concave part  62  thereby allowing the lid  3  and the body  7  to be in the closed state. 
     The advance/retreat guide  68  is formed with different circular arc axes with the axis of the circular arc face  66   a  on the lid  3  side as the lid turning axis  31   a  (see  FIG. 27 ) and the axis of the circular arc face  66   b  on the body  7  side as the body turning axis  31   b , whereby a moderate opening/closing operation can be realized in the fully closed state, the fully opened state, and the state in between. 
     The lid  3  and the body  7  can be stabilized at a constant angle of 0°, 170° (or 160° etc.) and 180° by arranging the angle fixing unit  240  for locking the advancement/retreatment of the connection body  220  with respect to the concave part  62  when the open/close angle of the lid  3  and the body  7  becomes a constant angle, and the operability of the user improves. The locking open/close angle is not limited thereto, and the locking guides  231 ,  236  may be formed to lock the advancement/retreatment at other angles, or the locking guides  231 ,  236  may be formed while setting two or four or more angles for locking advancement/retreatment. 
     Furthermore, from the fully opened state to the closed state (up to right before the fully closed state), the connection body  220  can be prevented from slipping out from the lid side unit  205   a  and the body side unit  205   b  since the slip-out prevention turning shafts  85   a ,  85   b  are contacting the shaft contacting grooves  21   a ,  21   b . In the fully closed state, the connection body  220  can be prevented from slipping out from the lid side unit  205   a  and body side unit  205   b  since the slip-out preventing projections  22   a ,  22   b  are contacting the locking sides  64   a ,  64   b.    
     Compared to a case of adopting the pushing unit  40  of Embodiment 1, the space on the inner side of the connection body  220  can be widely ensured by adopting the angle fixing unit  240 , whereby the degree of freedom in housing the connection cable for electrically connecting the electronic equipment in the lid  3  and the electronic equipment in the body  7  is enhanced. 
     The circular arc face  66   a  is provided to slidably advance/retreat the connection body  220  in a circular arc form, and thus is not limited to being configured with a plane, and may be formed to other shapes by arranging a plurality of circular arc shaped rails in the width direction. Furthermore, the two wall faces  67   a  are provided so that the connection body  220  does not rattle while sliding, and thus are not limited to perpendicular faces, and may be formed to other shapes. 
     The slip-out preventing projection groove  65   a  and the locking side  64   a  are provided to prevent the connection body  220  from slipping out from the lid-side unit  205   a , and thus are not limited to such shape and may be formed to other shapes and may be formed at one part of the circular arc surface  66   a . For instance, one part of the circular arc face  66   a  may be formed to a concave shape in a circular arc form up to right in front of the connection end face  61   a  along the advancing/retreating direction to serve as the slip-out preventing projection groove  65   a  and the locking side  64   a  may be arranged on the connection end face  61   a  side of the slip-out preventing projection groove  65   a . In this case, the slip-out preventing projection  22   a  of the connection body  220  is preferably arranged on the upper side end at the front surface of the connection body  220 . 
     In the fully open state, a configuration of hiding the connection body  220  so as to be completely invisible is adopted, but a hole or a groove may be formed on the connection side of the lid side guide cover  280   a  and the body side guide cover  280   b , so that the connection body  220  is partially visible even in the fully open state. In this case as well, a hinge will not project out and be seen as in the prior art, and a mobile telephone  201  of a smart design can be provided. 
     Embodiment 4 
     Embodiment 4 will now be described. 
       FIG. 30  is a plan view of a mobile telephone  301  of Embodiment 4,  FIG. 31A  is a front view of the mobile telephone  301 ,  FIG. 31B  is a plan enlarged cross sectional view of the inside of a connection unit  305 ,  FIG. 32  is an exploded perspective view of a connection unit  305  seen from diagonally above,  FIG. 33  is an exploded perspective view of the connection unit  305  seen from diagonally below,  FIG. 34  is a perspective view of a connection body  320 , and  FIG. 35  is a perspective view of one part of the connection unit  305  in the open state seen from below. 
     The mobile telephone  301  includes a lid  303  similar to the lid  3  of the mobile telephone  1  of Embodiment 1 and a body  307  similar to the body  7  of the mobile telephone  1  of Embodiment 1. A lid side unit  305   a  corresponding to the lid side unit  5   a  (see  FIG. 2 ) of Embodiment 1 is arranged in the lid  303 . A body side unit  305   b  corresponding to a body side unit  5   b  (see  FIG. 2 ) of Embodiment 1 is arranged in the body  307 . 
     A connection body  320  (see  FIG. 33 ) and a link unit  310  (see  FIG. 33 ) are housed in a connection part of the lid side unit  305   a  and the body side unit  305   b  in the open state. The link unit  310 , the connection body  320 , the lid side unit  305   a  and the body side unit  305   b  configure a connection unit  305 . 
     The lid side unit  305   a  is configured by a lid side guide cover  380   a  and a lid side guide body  360   a , and the body side unit  305   b  is configured by a body side guide cover  380   b  and a body side guide body  360   b.    
     The lid side guide cover  380   a  is the same as the lid side guide cover  380   a  of Embodiment 1 other than that a link pivot attachment part  398  is arranged in place of the link pivot attachment part  77  (see  FIG. 5 ) of Embodiment 1. The body side guide cover  380   b  is the same as the body side guide cover  380   b  of Embodiment 1 other than that a guide plate  377  is arranged in place of the guide plate  98  of Embodiment 1. 
     A pivot attachment projection  399  projecting towards the inner side in the width direction of the mobile telephone  301  is arranged on the link pivot attachment part  398 , and a pivot attachment projection  378  projecting towards the inner side in the width direction of the mobile telephone  301  is arranged on the guide plate  377 . 
     The link unit  310  is configured by the lid side link unit of the lid side unit  305   a  side and a body side link unit of the body side unit  305   b . As shown in  FIG. 35 , the lid side link unit is configured by a lid side arm  312   a  having one end axially supported at the pivot attachment projection  399  of the link pivot attachment part  398 , a rolling gear  317   a  axially supported in parallel to a pivot axis of the pivot attachment projection  399  at the other end of the lid side arm  312   a , a center gear  322   a  gearing with the rolling gear  317   a  and having a parallel rotation axis, and a peripheral surface gear  331   a  (see  FIG. 34 ) having the teeth lined in a circular arc shape with the rotation axis of the center gear  322   a  as the center and being formed on the inner surface of the connection body  320 . 
     The body side link unit is configured symmetric to the lid side link unit and is configured by a body side arm  312   b  having one end axially supported at the pivot attachment projection  378  of the link pivot attachment part  377 , a rolling gear  317   b  axially supported in parallel to a pivot axis of the pivot attachment projection  378  at the other end of the body side arm  312   b , a center gear  322   b  gearing with the rolling gear  317   b  and having a parallel rotation axis, and a peripheral surface gear  331   b  having the teeth lined in a circular arc shape with the rotation axis of the center gear  322   b  as the center and being formed on the inner surface of the connection body  320  (see  FIG. 34 ). The lid side arm  312   a  and the body side arm  312   b  are supported in a rolling manner so that the rolling gear  317   a  and the rolling gear  317   b  can roll while gearing with the peripheral surface gear  331   a  and the peripheral surface gear  331   b , respectively. 
     As shown in  FIG. 34 , the peripheral surface gear  331   a  and the peripheral surface gear  331   b  having the teeth of the gear arranged in a circular arc shape are arranged parallel in the left and right direction with different center axes and with a constant interval at the inner surface of the connection body  320 . 
     A bearing  333   a  having a shaft hole  332   a  formed on the extended line of the center axis of the peripheral surface gear  331   a  and a bearing  333   b  having a shaft hole  332   b  formed on the extended line of the center axis of the peripheral surface gear  331   b  are arranged upright between the peripheral surface gear  331   a  and the peripheral surface gear  331   b  at the bottom on the inner side of the connection body  320 . A shaft body  321   a  (see  FIG. 32 ) is inserted to the shaft hole  332   a  of the bearing  333   a  to rotatably bear the center gear  322   a , and a shaft body  321   b  is inserted to the shaft hole  332   b  of the bearing  333   b  to rotatably bear the center gear  322   b.    
     Furthermore, on the inner side of the connection body  320 , locking concave parts  341   a ,  342   a , a rolling rail  343   a , and a locking concave part  344   a  are arranged in this order from the inner side to the outer side as a guide rail on which the roller  44   a  of the lid side pushing unit  40   a  rolls. 
     In symmetric thereto, locking concave parts  341   b ,  342   b , a rolling rail  343   b , and a locking concave part  344   b  are arranged in this order from the inner side to the outer side as a guide rail on which the roller  44   b  of the lid side pushing unit  40   b  rolls. 
     Other components are the same as Embodiment 1, and the same reference numerals are denoted for the same components and the detailed description thereof will be omitted. 
     An opening/closing operation of the connection unit  305  executed by advancing/retreating the connection body  320  with respect to the lid side unit  305   a  and the body side unit  305   b , and an opening/closing operation of the mobile telephone  301  will be described below. 
       FIG. 35  is a perspective view of one part of the connection unit  305  in the open state,  FIG. 36  is a perspective view of one part of the connection unit  305  slightly changed towards the closing direction from the open state,  FIG. 37  is a perspective view of one part of the connection unit  305  further changed in the closing direction, and  FIG. 38  is a perspective view of one part of the connection unit  305  in the closed state.  FIG. 35  to  FIG. 38  are views seen from the lower right position in  FIG. 33 . 
       FIG. 39  is a perspective view of the link unit  310  and the pushing unit  40  ( 40   a ,  40   b ) in the open state,  FIG. 40  is a perspective view of the link unit  310  and the pushing unit  40  slightly changed towards the closing direction from the open state,  FIG. 41  is a perspective view of the link unit  310  and the pushing unit  40  further changed in the closing direction, and  FIG. 42  is a perspective view of the link unit  310  and the pushing unit  40  in the closed state. 
       FIG. 43  is an explanatory view of the connection unit  305  portion in the open state in an enlarged cross section,  FIG. 44  is an explanatory view of the connection unit  305  portion slightly changed towards the closing direction from the open state in an enlarged cross section,  FIG. 45  is an explanatory view of the connection unit  305  portion further changed in the closing direction in an enlarged cross section, and  FIG. 46  is an explanatory view of the connection unit  305  portion in the closed state in an enlarged cross section. In  FIG. 43  to  FIG. 46 , (C) shows a cross sectional view taken along a line C-C in  FIG. 30 , (D) shows a cross sectional view taken along a line D-D in  FIG. 30 , and (E) shows a cross sectional view taken along line E-E in  FIG. 30 . 
     First, in the open state, as shown in  FIG. 35  and  FIG. 43 , the lid  303  arranged with the lid side unit  305   a  (see  FIG. 43 ) and the body  307  arranged with the body side unit  305   b  are in a state opened 180 degrees, and one rectangular solid shape as a whole is obtained as shown in  FIG. 15A  in Embodiment 1. 
     (D) and (E) in the figure are cross sectional views seen from the side opposite to (C), and are shown with the left and the right sides reversed. 
     The connection body  320  is completely housed in the concave part  62   a  (see  FIG. 32 ) of the lid side unit  305   a  and the concave part  62   b  of the body side unit  305   b , and is not visible from the outside. As shown in  FIG. 43C , the lid side arm  312   a  of the connection unit  305  is in a state closest to the horizontal state, where the rolling gear  317   a  axially supported at the distal end is positioned near the end on the body side unit  305   b  side of the peripheral surface gear  331   a  on the side opposite to the axial center of the peripheral surface gear  331   a  when seen from the pivot attachment projection  399  axially supporting the lid side arm  312   a.    
     Similarly, as shown in  FIG. 43D , the body side arm  312   b  is in a state closest to the horizontal state, where the rolling gear  317   b  axially supported at the distal end is positioned near the end on the lid side unit  30   a  side of the peripheral surface gear  331   b  on the side opposite to the axial center of the peripheral surface gear  331   b  when seen from the pivot attachment projection  378  axially supporting the lid side arm  312   b.    
     In this case, the lid side arm  312   a  and the body side arm  312   b  cross in side view. 
     As shown in  FIG. 43E , the roller  44  ( 44   a ,  44   b ) of the pushing unit  40  ( 40   a ,  40   b ) contacts the locking concave part  341  ( 341   a ,  341   b ) (see  FIG. 34 ) of the connection body  320 . Therefore, the lid side unit  305   a  and the body side unit  305   b  transition to the closed state with a small force by the biasing force of the coil spring  59  ( 59   a ,  59   b ), and can be maintained in the open state. 
     When the user manually applies force so that the lid  303  and the body  307  is folding operated from the open state in the closing direction, the roller  44  moves out from the locking concave part  341  at the point the relevant force exceeds the biasing force of the coil spring  59 . The lid  303  attached with the lid side unit  305   a  and the body  307  attached with the body side unit  305   b  transition to a slightly bent state, as shown in  FIG. 36 ,  FIG. 40 , and  FIG. 44 . When the roller  44  moves out from the locking concave part  341 , the user feels a clicking feeling or a satisfactory operation feeling. 
     In transitioning towards the closing direction, the lid side unit  305   a  turns with the slip-out prevention turning shaft  85   a  (see  FIG. 36 ) as the virtual rotation axis, and the body side unit  305   b  turns with the slip-out prevention turning shaft  85   b  (see  FIG. 36 ) as the virtual rotation axis. 
     As shown in  FIG. 44C , the rolling gear  317   a  rolls on the peripheral surface gear  331   a  while gearing with the gear of the peripherals surface gear  331   a , and moves towards the lid side unit  305   a . The rolling gear  317   a  rotates the center gear  322   a  during such movement. 
     In symmetric thereto, the rolling gear  317   b  rolls on the peripheral surface gear  331   b  while gearing with the gear of the peripheral surface gear  331   b , and moves towards the body side unit  305   b , as shown in  FIG. 44D . The rolling gear  317   b  rotates the center gear  322   b  during such movement. 
     The center gear  322   a  and the center gear  322   b  gear with each other, and reverse operate by the same rotation amount. Therefore, the lid side arm  312   a  and the body side arm  312   b  constantly has the same rotation amount and symmetrically rotate, where the ratio between the advance/retreat distance La (see  FIG. 44 ) the connection body  320  advances from the lid side unit  305   a  and the advance/distance Lb (see  FIG. 44 ) the connection body  320  advances from the body side unit  305   b  becomes one to one, and advances from thus equally advances. A stable and smooth operation feeling is thereby obtained. 
     At the angle moved in such slightly closed state, the roller  44  of the pushing unit  40  each contacts the locking concave part  342  and is rotation locked, as shown in  FIG. 44E . Therefore, the open/close angle of the mobile telephone  301  stabilizes once at an angle of 170° and 160°. 
     When folding operated further in the closing direction, the state transitions to a bent state as shown in  FIG. 37 ,  FIG. 41 , and  FIG. 45 . During such transition as well, the ratio of the amount the connection body  320  advances from the lid side unit  305   a  and the amount the connection body  320  advances from the body side unit  305   b  is maintained at a ratio of one to one, and always equally advances. 
     In this case, as shown in  FIG. 45E , the roller  44  of the pushing unit  40  constantly strongly receives the biasing force of the coil spring  59  ( 59   a ,  59   b ) as it rides on the rolling rail  343 . The rolling rail  343  is formed such that the radius to the rolling rail  343  having the slip-out prevention turning shaft  85   a ,  85   b  or the center of rotation as the center extends towards each end on the lid  303  side and the body  307  side from the center of the connection body  320 . Thus, the roller  44  smoothly rolls in the closing direction by the biasing force of the coil spring  59 , and naturally transitions towards the closing direction as if being taken in. 
     When naturally transitioned in the closing direction or further folding operated in the closing direction, the state transitions to a completely folded closed state, as shown in  FIG. 38 ,  FIG. 42 , and  FIG. 46 . In this case, as shown in  FIG. 46 , the rolling gear  317   a  is positioned on the opposite side in the open state, that is, near the end on the lid side connection unit  305   a  side at the peripheral surface gear  331   a . The rolling gear  317   b  is positioned on the opposite side in the open state, that is, near the end on the body side connection unit  305   b  side at the peripheral surface gear  331   b.    
     Therefore, as shown in  FIG. 46C , the line connecting the axis center of the shaft hole  332   a  (axis center of the center gear  322   a ), the axis center of the rolling gear  317   a , and the axis center of the pivot attachment projection  399  has a substantially L shape. Furthermore, as shown in  FIG. 46D , a line connecting the axis center of the shaft hole  332   b , the axis center of the rolling gear  317   b , and the axis center of the pivot attachment projection  378  has a substantially L shape symmetric to the above substantially L shape. In this case, the lid side arm  312   a  and the body side arm  312   b  are in a state close to a parallel state without crossing in side view. The roller  44  of the pushing unit  40  contacts the locking concave part  344  and is locked, and a fully closed state is maintained by the biasing force of the coil spring  59 . 
     Accordingly, an appropriate space is ensured between the lid side arm  312   a  and the body side arm  312   b , so that the thickness of the lid side guide cover  380   a  and the thickness of the body side guide cover  380   b  are housed within the width of the space, and the state transitions to the fully closed state. 
     When transitioning from the closed state to the open state, the operation completely the opposite of that in transitioning in the closing direction is performed. 
     According to the above configuration, the connection body  320  advances/retreats drawing a circular arc with respect to the and the lid side unit  305   a  and the body side unit  305   b , and a mobile telephone  301  having a novel configuration in which the lid  303  and the body  307  open/close is provided. 
     In opening/closing, the connection unit  320  equally advances/retreats with respect to the lid side unit  305   a  and the body side unit  305   b  by the function of the link unit  310 , and a stable operation symmetric at the center of folding can be performed. 
     The connection body  320  slidably turns and advances/retreats with the circular arc outer peripheral surface  29   a  (see  FIG. 33 ) contacting the circular arc face  66   a  of the lid side guide body  360   a  (see  FIG. 32 ), and thus can advances/retreats without being caught. In particular, when the slide stabilizing guide  91   a  (see  FIG. 32 ) arranged on the lid side guide cover  380   a  and the stabilizing groove  34   a  (see  FIG. 34 ) arranged on the connection body  320  engage, a more stable slide turn can be realized, and a smooth advancement/retreatment can be reliably realized. 
     The concave part  62   a  are  62   b  are arranged in the connection part of the lid  303  and the connection part of the body  307 , respectively, where one end of the connection body  320  is attached in an advance into and retreat from in the concave part  62   a , and the other end of the connection body  320  is attached to advance into and retreat from the concave part  62   b . Therefore, in the fully open state, the connection body  320  can be housed in the concave parts  62   a ,  62   b  and be hidden, whereby the appearance of the mobile telephone  301  improves. 
     The connection body  320  can be advanced/retreated in a circular arc form from the concave part  62  ( 62   a ,  62   b ) by arranging the advance/retreat guide  68  ( 68   a ,  68   b ) for advancing/retreating the connection body  320  while drawing a circular arc with the slip-out prevention turning shaft  85  ( 85   a ,  85   b ) as a virtual axis core at the lid side unit  305   a  and the body side unit  305   b , and arranging the side wall  28  and the circular outer peripheral surface  29  ( 29   a ,  29   b ) on the connection body  320 . In the open state, the connection body e 20  is housed in the concave part  62 , and in transitioning from the open state to the closed state, the connection body  320  advances in a circular arc form from the concave part  62  thereby allowing the lid  303  and the body  307  to be in the closed state. 
     Similar to Embodiment 1, the advance/retreat guide  68  is formed with different circular arc axes with the axis of the circular arc face  66   a  on the lid  303  side as the lid turning axis  31   a  (see  FIG. 4  of Embodiment 1) and the axis of the circular arc face  66   b  on the body  307  side as the body turning axis  31   b  (see  FIG. 4  of Embodiment 1), whereby a moderate opening/closing operation can be realized in the fully closed state, the fully opened state, and the state in between. 
     The locking concave part  341  ( 341   a ,  341   b ),  342  ( 342   a ,  342   b ),  344  ( 344   a ,  344   b ), and the pushing unit  40  ( 40   a ,  40   b ) for locking the advancement/retreatment of the connection body  320  with respect to the concave part  62  when the open/close angle of the lid  303  and the body  307  becomes a constant angle are arranged. The open/close angle of the lid  303  and the body  307  can then be stabilized at a constant angle of 0°, 170° (or 160°), and 180°, and the operability for the user improves. The locking open/close angle is not limited thereto, and the locking concave parts  341 ,  342 ,  344  may be formed to lock the advancement/retreatment at other angles, or the locking concave parts  341 ,  342 ,  344  may be formed while setting two or four or more angles for locking advancement/retreatment. 
     The force for stabilizing the lid  303  and the body  307  at a constant angle can be easily adjusted by the biasing force of the coil spring  59  by using the coil spring  59  ( 59   a ,  59   b ) for applying the biasing force to the pushing unit  40 , and the open/close mechanism having satisfactory clicking feeling can be easily provided. 
     Furthermore, from the fully open state to the closed state (right before fully closed state), the connection body  320  can be prevented from slipping out from the lid side unit  305   a  and the body side unit  305   b  since the slip-out prevention turning shaft  85   a ,  85   b  are contacting the shaft contacting groove  21   a ,  21   b . In the fully closed state, the connection body  320  can be prevented from slipping out from the lid side unit  305   a  and the body side unit  305   b  since the slip-out preventing projections  22   a ,  22   b  are contacting the locking sides  64   a ,  64   b.    
     The pushing unit for positioning the open/close position includes the lid side pushing unit  40   a  and the body side pushing unit  40   b , but may only include either one. In this case as well, a satisfactory operation feeling for symmetrically opening/closing is obtained by the link unit  310 . 
     The circular arc face  66   a  is provided to slidably advance/retreat the connection body  320  in a circular arc form, and thus is not limited to being configured with a plane, and may be formed to other shapes by arranging a plurality of circular arc shaped rails in the width direction. The two wall faces  67   a  are provided so that the connection body  320  does not rattle while sliding, and thus are not limited to perpendicular faces, and may be formed to other shapes. 
     The slip-out preventing projection groove  65   a  and the locking side  64   a  are provided to prevent the connection body  320  from slipping out from the lid-side unit  305   a , and thus are not limited to such shape and may be formed to other shapes, and furthermore, may be formed at one part of the circular arc face  66   a . For instance, one part of the circular arc face  66   a  may be formed to a concave shape in a circular arc form up to right in front of the connection end face  61   a  along the advancing/retreating direction to serve as the slip-out preventing projection groove  65   a  and the locking side  64   a  may be arranged on the connection end face  61   a  side of the slip-out preventing projection groove  65   a . In this case, the slip-out preventing projection  22   a  of the connection body  320  is preferably arranged on the upper side end at the front surface of the connection body  320 . 
     The locking concave parts  341 ,  342  and  344  may not be arranged in the slide plate  27 , and may be arranged on the inner surface of the side wall  28 . In this case, the roller  44  is formed with a spherical body and biased towards the outer side in the width direction so as to be locked at the locking concave part arranged on the inner surface of the side wall  28 . According to such configuration as well, the mobile telephone  301  can be positioned at a predetermined open/close angle, and a satisfactory clicking feeling can be obtained. 
     The roller  44  may be non-rotatably formed with a slidable shape and raw material. In this case as well, the opening/closing operation is smoothly performed, and the open/close angle can be locked. 
     In the fully open state, a configuration of hiding the connection body  320  so as to be completely invisible is adopted, but a hole or a groove may be formed on the connection side of the lid side guide cover  380   a  and the body side guide cover  380   b , so that the connection body  320  is partially visible even in the fully open state. In this case as well, a hinge will not project out and be seen as in the prior art, and a mobile telephone  301  of a smart design can be provided. 
     Embodiment 5 
     Embodiment 5 will now be described. 
       FIG. 47  is a plan view of a mobile telephone  401  of Embodiment 5,  FIG. 48A  is a front view of the mobile telephone  401 ,  FIG. 48B  is a plan enlarged cross sectional view of the inside of a connection unit  405 ,  FIG. 49  is an exploded perspective view of a connection unit  405  seen from diagonally above,  FIG. 50  is an exploded perspective view of the connection unit  405  seen from diagonally below,  FIG. 51  is a perspective view of a connection body  420 , and  FIG. 52  is a perspective view of one part of the connection unit  405  in the open state seen from below. 
     The mobile telephone  401  includes a lid  403  similar to the lid  303  of the mobile telephone  301  of Embodiment 4 and a body  407  similar to the body  7  of the mobile telephone  301  of Embodiment 4. A lid side unit  405   a  corresponding to the lid side unit  305   a  (see  FIG. 2 ) of Embodiment 4 is arranged in the lid  403 , and a body side unit  405   b  corresponding to a body side unit  305   b  (see  FIG. 2 ) of Embodiment 4 is arranged in the body  407 . 
     A connection body  420  (see  FIG. 50 ) and a link unit  410  are housed in a connection part of the lid side unit  405   a  and the body side unit  405   b  in the open state. The link unit  410 , the connection body  420 , the lid side unit  405   a  and the body side unit  405   b  configure a connection unit  405 . 
     The lid side unit  405   a  is configured by a lid side guide cover  480   a  and a lid side guide body  460   a , and the body side unit  405   b  is configured by a body side guide cover  480   b  and a body side guide body  460   b.    
     The lid side guide cover  480   a  is the same as the lid side guide cover  380   a  of Embodiment 4, and a link pivot attachment part  498  similar to the link pivot attachment part  398  is arranged. The body side guide cover  480   b  is the same as the body side guide cover  380   b  of Embodiment 4 other than that a guide plate  477  similar to the guide plate  377  of Embodiment 4 and of different position is arranged. 
     A pivot attachment projection  499  projecting towards the inner side in the width direction of the mobile telephone  401  is arranged on the link pivot attachment part  498 , and a pivot attachment projection  478  projecting towards the inner side in the width direction of the mobile telephone  401  is arranged on the guide plate  477 . 
     The link unit  410  is configured by the lid side link unit of the lid side unit  405   a  side and a body side link unit of the body side unit  405   b . As shown in  FIG. 52 , the lid side link unit is configured by a lid side arm  412   a  having one end axially supported at the pivot attachment projection  499  of the link pivot attachment part  498 , a rolling gear  417   a  axially supported in parallel to a pivot axis of the pivot attachment projection  499  at the other end of the lid side arm  412   a , a center gear  422   a  gearing with the rolling gear  417   a  and having a parallel rotation axis, and a peripheral surface gear  431   a  (see  FIG. 51 ) having the teeth lined in a circular arc shape with the rotation axis of the center gear  422   a  as the center and being formed on the inner surface of the connection body  420 . 
     The link pivot attachment part  498  is similar to the link pivot attachment part  398  of Embodiment 4, the lid side arm  412   a  is similar to the lid side arm  312   a  of Embodiment 4, and the rolling gear  417   a  is similar to the rolling gear  317   a  of Embodiment 4. The center gear  422   a  corresponds to the center gear  322   a  of Embodiment 4, and is configured by connecting the gears  422   e ,  422   c  having the same gear size with the shaft  422   d . Therefore, the gears  422   e ,  422   c  are integrally rotated, and the center gear  422   a  acts as one gear. 
     The body side link unit is configured symmetric to the lid side link unit and is configured by a body side arm  412   b  having one end axially supported at the pivot attachment projection  478  of the guide plate  477 , a rolling gear  417   b  axially supported in parallel to a pivot axis of the pivot attachment projection  478  at the other end of the body side arm  412   b , a center gear  422   b  gearing with the rolling gear  417   b  and having a parallel rotation axis, and a peripheral surface gear  431   b  (see  FIG. 51 ) having the teeth lined in a circular arc shape with the rotation axis of the center gear  422   b  as the center and being formed on the inner surface of the connection body  420 . 
     The guide plate  477  is similar to the guide plate  377  of Embodiment 4, the lid side arm  412   b  is similar to the lid side arm  312   b  of Embodiment 4, the rolling gear  417   b  is similar to the rolling gear  317   b  of Embodiment 4, and the center gear  422   b  is similar to the center gear  322   b  of Embodiment 4. 
     An angle fixing unit  440  is connected to the center gear  422   b . The angle fixing unit  440  corresponds to the angle fixing unit  240  of Embodiment 3, and is configured by a locking guide body  461  including a coil spring  463  similar to the coil spring  215  of Embodiment 3, a locking convex body  462  similar to the locking convex body  221  of Embodiment 3, and a locking guide (not shown) similar to the locking guide  231 ,  236  of the locking guide body  234  of Embodiment 3. A shaft body  421   b  is inserted to the coil spring  463 , the locking convex body  462 , and the locking guide body  461  in this order. 
     As shown in  FIG. 51 , the peripheral surface gear  431   a  similar to the peripheral surface gear  331   a  of Embodiment 3, and the peripheral surface gear  431   b  similar to the peripheral surface gear  331   b  of Embodiment 3 are arranged parallel in the left and right direction with different center axes and with a constant interval at the inner surface of the connection body  420 . The spaced interval is wider than in Embodiment 3. 
     Bearings  433   a ,  433   b  similar to the bearings  333   a ,  333   b  of Embodiment 3 are arranged upright between the peripheral surface gear  431   a  and the peripheral surface gear  431   b  at the bottom on the inner side of the connection body  420 . A bearing  451  including an axial hole  452  coaxial with the shaft center of a shaft hole  432   b  of the bearing  433   b  is formed upright in parallel to the bearing  433   b . A shaft body  421   b  is rotatably supported as shown in  FIG. 49  between the bearing  451  and the bearing  433   b , and the shaft body  421   b  is attached to the angle fixing unit  440 . The angle fixing unit  440  has the locking guide body  461  attached so as not to rotate at the bearing  433   b , and the locking convex body  462  attached so as to integrally rotate with the shaft body  421   b . The shaft body  421   b  is attached so as to integrally rotate with the center gear  422   b , and thus the locking convex body  462  integrally rotates with the center gear  422   b  and the locking guide body  461  is always non-rotatable, whereby the angle fixing function described in Embodiment 3 is realized. 
     Other components are the same as Embodiment 3 and Embodiment 4, and the same reference numerals are denoted for the same components and the description thereof will be omitted. 
     An opening/closing operation of the connection unit  405  executed by advancing/retreating the connection body  420  with respect to the lid side unit  405   a  and the body side unit  405   b , and an opening/closing operation of the mobile telephone  401  will be described below. 
       FIG. 52  is a perspective view of one part of the connection unit  405  in the open state,  FIG. 53  is a perspective view of one part of the connection unit  405  slightly changed towards the closing direction from the open state,  FIG. 54  is a perspective view of one part of the connection unit  405  further changed in the closing direction, and  FIG. 55  is a perspective view of one part of the connection unit  405  in the closed state.  FIG. 52  to  FIG. 55  are views seen from the lower right position in  FIG. 50 . 
       FIG. 56  is a perspective view of the link unit  410  and the angle fixing unit  440  in the open state,  FIG. 57  is a perspective view of the link unit  410  and the angle fixing unit  440  slightly changed towards the closing direction from the open state,  FIG. 58  is a perspective view of the link unit  410  and the angle fixing unit  440  further changed in the closing direction, and  FIG. 59  is a perspective view of the link unit  410  and the angle fixing unit  440  in the closed state. 
       FIG. 60  is an explanatory view of the connection unit  405  portion in the open state in an enlarged cross section,  FIG. 61  is an explanatory view of the connection unit  405  portion slightly changed towards the closing direction from the open state in an enlarged cross section,  FIG. 62  is an explanatory view of the connection unit  405  portion further changed in the closing direction in an enlarged cross section, and  FIG. 63  is an explanatory view of the connection unit  405  portion in the closed state in an enlarged cross section. In  FIG. 60  to  FIG. 63 , (G) shows a cross sectional view taken along a line G-G in  FIG. 47 , and (H) shows a cross sectional view taken along a line H-H in  FIG. 47 . 
     (G) and (H) are cross sections seen from opposite sides, and thus are shown in a left-right reversed state. 
     Regarding the opening/closing operation described in each figure, the opening/closing operation of the link unit  410  is the same as that of the link unit  310  of Embodiment 4, and the opening/closing operation of the angle fixing unit  340  is the same as that of the angle fixing unit  240  of Embodiment 3, and thus the detailed description thereof will be omitted. 
     According to the mobile telephone  401  of Embodiment 5, the effect same as the link unit  310  of Embodiment 4 and the effect same as the angle fixing unit  240  of Embodiment 3 are obtained. 
     Embodiment 6 
     Embodiment 6 will now be described. Embodiment 6 is substantially the same as Embodiment 4, and the pushing unit  550  ( 550   a ,  550   b ) of a spherical body  552  ( 552   a ,  552   b ) is used in place of the pushing unit  40  of the roller  44  of Embodiment 4. 
       FIG. 64  is a perspective view of one part of the connection unit  305  (see  FIG. 30  of Embodiment 4) in the open state seen from the lower side, and  FIG. 65  is a perspective view of the link unit  310  and the pushing unit  550  in the open state. 
     As shown in  FIG. 64 , the lid side pushing unit  550   a  is configured by a tubular part  551   a  formed projecting towards the lower side at the back surface of the lid side guide cover  580   a  corresponding to the lid side guide cover  380   a  of Embodiment 4, a coil spring  553   a  housed in the tubular part  551   a , and a spherical body  552   a  biased towards the opening part on the lower side at the tubular part  551   a  by the coil spring. 
     The body side pushing unit  550   b  is configured by a tubular part  551   b  formed projecting towards the lower side at the back surface of the body side guide cover  580   b  corresponding to the body side guide cover  380   b  of Embodiment 4, a coil spring  553   b  housed in the tubular part  551   b , and a spherical body  552   b  biased towards the opening part on the lower side at the tubular part  551   b  by the coil spring  553   b.    
     As shown in  FIG. 65 , on the inner side of the connection body  520 , locking concave parts  541   a ,  542   a , a rolling rail  543   a , and a locking concave part  544   a  are arranged in this order from the inner side to the outer side as a guide rail on which the spherical body  552   a  of the lid side pushing unit  550   a  rolls. 
     Symmetrically, locking concave parts  541   b ,  542   b , a rolling rail  543   b , and a locking concave part  544   b  are arranged in this order from the inner side to the outer side as a guide rail on which the spherical body  552   b  of the body side pushing unit  550   b  rolls. 
     These correspond to the locking concave parts  341   a  ( 341   b ),  342   a  ( 342   b ), the rolling rails  343   a  ( 343   b ), and the locking concave parts  344   a  ( 344   b ) in Embodiment 4, and are the same as in Embodiment 4 other than being formed to a wide width. 
     Other components are the same as Embodiment 4, and the same reference numerals are denoted for the same components and the detailed description thereof will be omitted. 
     According to the above configuration, the link unit  310  performs the same opening/closing operation as in Embodiment 4, and obtains the same effects as in Embodiment 4. 
     The spherical body  552  of the pushing unit  550  rolls with the locking concave parts  541 ,  542 , the rolling rail  543 , and the locking concave part  544  as the guide rail, and thus effects same as the pushing unit  40  of Embodiment 4 are obtained. 
     The space on the inner side of the connection body  520  can be widely ensured by using the pushing unit  550  compared to when the pushing unit  40  of Embodiment 4 is used. Thus, the degree of freedom in housing the connection cable for electrically connecting the electronic equipment in the lid  303  and the electronic equipment in the body  307  is enhanced. 
     In the correspondence of the configuration of the invention and the above embodiments, a mobile terminal of the invention corresponds to the mobile telephone  1 ,  1   a  of the embodiment; and similarly, a first casing corresponds to the lid  3 ,  303 ,  403 ; a connection mechanism corresponds to the connection unit  5 ,  205 ,  305 ,  405 ; a second casing corresponds to the body  7 ,  307 ,  407 ; a connection member corresponds to the connection body  20 ,  220 ,  320 ,  420 ,  520 ; an opening part corresponds to the concave part  62   a ,  62   b ; an advance/retreat ratio stabilization part corresponds to the link unit  100 ,  210 ,  310 ,  410 ; a second casing side connection corresponds to pivot attachment of the pivot attachment projection  102  and the guide plate  98 ; a second casing side arm corresponds to the body side arm  103 ,  243 ,  312   b ,  412   b ; a connection member side connection corresponds to engagement of the slide body  105  ( 251 ) and the guide  30  ( 230 ); a first casing side connection corresponds to a pivot attachment of the pivot attachment projection  106  and the link pivot attachment part  77 ; a first casing side arm corresponds to the lid side arm  107 ,  212 ,  312   a ,  412   a ; a pivot attachment part corresponds to the shaft member  109  and the shaft  227 ; a turning shaft of the first casing side corresponds to the turning shaft  133   a ; a turning shaft of the second casing side corresponds to the turning shaft  133   b , an advance/retreat amount corresponds to the advance/retreat distance La, Lb; and a constant ratio corresponds to one to one; but the present invention is not limited only to the configuration of the above embodiments, and numerous other embodiments may be contrived. 
     INDUSTRIAL APPLICABILITY 
     The present invention is not limited to the above-described mobile telephone, and is applicable to other mobile telephones and mobile terminals such as PDA.