Abstract:
A bi-axial swivel assembly allows the rotation of a bracket around the longitudinal axis of a support shaft when the restriction cam lies inside an imaginary reference plane. The attitude of the bracket is allowed to change around the longitudinal axis of the support shaft. Only if the bracket allows the restriction cam get off a recess, the perpendicular surface serves to prevent the restriction cam from protruding outside the imaginary reference plane. The attitude of the bracket can be prevented from changing around the rotation axis perpendicular to the longitudinal axis. The bi-axial swivel assembly allows the wire to penetrate through first and second hollow spaces. When the bracket rotates around the longitudinal axis, the wire is only forced to suffer from a slight torsion within the first hollow space. The wire can be protected from a larger flexure.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an electronic apparatus such as a cellular or mobile phone terminal. In particular, the invention relates to a cellular phone terminal of a so-called flip or clamshell type.  
         [0003]     2. Description of the Prior Art  
         [0004]     A cellular or mobile phone terminal of a so-called clamshell type, including a bi-axial swivel assembly, is well known as disclosed in Japanese Patent Application Publication 2005-023958. The cellular phone terminal includes a main enclosure and a display enclosure. The bi-axial swivel assembly includes a support shaft fixed to the main enclosure. A support member is supported on the support shaft for relative rotation. A bracket is coupled to the support member for relative rotation around the rotation axis perpendicular to an imaginary plane including the longitudinal axis of the support shaft. The display enclosure is coupled to the bracket.  
         [0005]     An annular groove is formed around the support shaft. A pair of parallel imaginary planes serve to define the opposite sides of the groove. The imaginary planes extend perpendicular to the longitudinal axis of the support shaft. Recesses are defined in the sides of the groove at a predetermined angular position. The recesses in cooperation defines an enlarged section of the groove. When the display enclosure takes a standard attitude, a cam member integral with the bracket is located inside a space between the parallel imaginary planes. The cam member is allowed to move along the groove over the entire length. The bracket is allowed to rotate around the support shaft over an angular range of 180 degrees, for example. When the display enclosure rotates around the rotation axis by 90 degrees from the standard attitude, the cam member protrudes outside a space between the parallel imaginary planes. The cam member is only allowed to move in the groove within the enlarged section. The rotation of the display enclosure is thus restricted around the support shaft. Moreover, the standard attitude of the display enclosure can always be maintained when the cam member stays outside the enlarged section in the groove.  
         [0006]     Electric connection must be established between the display enclosure and the main enclosure in the aforementioned cellular phone terminal. A wire is wound around the bracket in the direction around the rotation axis so as to establish the electric connection. The wire is forced to suffer from a larger flexure every time the display enclosure or bracket rotates around the rotation axis. The wire is also forced to suffer from a larger flexure every time the display enclosure rotates around the support shaft. The wire in this manner suffer from a frequent load.  
       SUMMARY OF THE INVENTION  
       [0007]     It is accordingly an object of the present invention to provide a bi-axial swivel assembly capable of relieving a load applied to a wire.  
         [0008]     According to a first aspect of the present invention, there is provided a bi-axial swivel assembly comprising: a pair of coaxial bearings located at positions distanced from each other; a pair of support shafts respectively supported on the bearings for relative rotation; a first hollow space extending at least within one of the support shafts in the axial direction of the support shaft, said first hollow space penetrating through the bearing corresponding to the one of the support shafts; a support member interposed between the support shafts, said support member coupled with the support shafts based on integral formation; a tube supported on the support member, said tube extending along the rotation axis perpendicular to an imaginary plane including the longitudinal axis of the support shaft; a second hollow space extending within the tube in the axial direction of the tube, said second hollow space penetrating through at least the support member; a bracket supported on the tube for relative rotation around the rotation axis; a perpendicular surface defined on at least one of the bearings along an imaginary reference plane perpendicular to the longitudinal axis of the support shaft; a restriction cam coupled to the bracket, said restriction cam extending in the centrifugal direction of the rotation axis, said restriction cam lying inside the imaginary reference plane when the bracket takes a first attitude, said restriction cam protruding outside the imaginary reference plane when the bracket takes a second attitude established through rotation by 90 degrees around the rotation axis from the first attitude; and a recess formed on the perpendicular surface, said recess receiving the restriction cam protruding outside the imaginary reference plane.  
         [0009]     The bi-axial swivel assembly allows the rotation of the bracket and support shafts around the longitudinal axis of the support shaft as long as the restriction cam lies inside the imaginary reference plane. The attitude of the bracket is allowed to change relative to the bearings around the longitudinal axis of the support shaft. Only if the restriction cam is located off the recess, the perpendicular surface serves to prevent the restriction cam from protruding outside the imaginary reference plane. The restriction cam is prevented from rotation around the rotation axis. The attitude of the bracket can also be prevented from changing around the rotation axis. On the other hand, when the restriction cam is positioned within the recess, the restriction cam is allowed to protrude outside the imaginary reference plane through the rotation around the rotation axis. The bracket is thus allowed to rotate around the rotation axis over the angular range of 90 degrees. The attitude of the bracket is allowed to change around the rotation axis at specific position around the longitudinal axis of the support shaft.  
         [0010]     The bi-axial swivel assembly allows the wire to penetrate through the first and second hollow spaces. Even in the case where the bracket rotates around the longitudinal axis of the support shaft, the wire is only forced to suffer from a slight torsion within the first hollow space. The wire can be protected from a larger flexure. Even in the case where the bracket rotates around the rotation axis, the wire is only forced to suffer from a slight torsion within the second hollow space. The wire can be protected from a larger flexure also in this case. The wire can in this manner relieved from a load to the utmost. Disconnection and short of the wire can be avoided.  
         [0011]     The support member may support the tube at a position off the longitudinal axis of the support shaft in the bi-axial swivel assembly. The bi-axial swivel assembly of the type enables a reliably provision of the first hollow space on the longitudinal axis of the support shaft. This enables the location of the wire closest to the longitudinal axis of the support shaft. The wire is thus reliably prevented from a larger flexure.  
         [0012]     The bi-axial swivel assembly of the type can be incorporated into an electronic apparatus such as a cellular or mobile phone terminal. The cellular phone terminal may comprise: first and second enclosures; a pair of coaxial bearings attached to the first enclosure at positions distanced from each other; a pair of support shafts respectively supported on the bearings for relative rotation; a first hollow space extending at least within one of the support shafts in the axial direction of the support shaft, said first hollow space penetrating through the bearing corresponding to the one of the support shafts; a support member interposed between the support shafts, said support member coupled with the support shafts based on integral formation; a tube supported on the support member, said tube extending along the rotation axis perpendicular to an imaginary plane including the longitudinal axis of the support shaft; a second hollow space extending within the tube in the axial direction of the tube, said second hollow space penetrating through at least the support member; a bracket supported on the tube for relative rotation around the rotation axis; a perpendicular surface defined on at least one of the bearings along an imaginary reference plane perpendicular to the longitudinal axis of the support shaft; a restriction cam coupled to the bracket, said restriction cam extending in the centrifugal direction of the rotation axis, said restriction cam lying inside the imaginary reference plane when the bracket takes a first attitude, said restriction cam protruding outside the imaginary reference plane when the bracket takes a second attitude established through rotation by 90 degrees around the rotation axis from the first attitude; and a recess formed on the perpendicular surface, said recess receiving the restriction cam protruding outside the imaginary reference plane.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The above and other objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments in conjunction with the accompanying drawings, wherein:  
         [0014]      FIG. 1  is a perspective view schematically illustrating a cellular or mobile phone terminal as an example of an electronic apparatus;  
         [0015]      FIG. 2  is a side view schematically illustrating a display enclosure rotating around a vertical axis in an upright attitude on a main enclosure;  
         [0016]      FIG. 3  is a perspective view schematically illustrating the structure of a bi-axial swivel mechanism according to a first embodiment of the present invention from a front viewpoint;  
         [0017]      FIG. 4  is a perspective view schematically illustrating the structure of the bi-axial swivel mechanism from a rear viewpoint;  
         [0018]      FIG. 5  is an enlarged plan view schematically illustrating the relationship between a restriction cam and cam members designed to restrict the rotation of the display enclosure around the vertical axis;  
         [0019]      FIG. 6  is an enlarged plan view schematically illustrating the relationship between the restriction cam and the cam members when the display enclosure rotates around the horizontal axis;  
         [0020]      FIG. 7  is a perspective view schematically illustrating the structure of the bi-axial swivel mechanism keeping a bracket in an upright attitude around the horizontal axis;  
         [0021]      FIG. 8  is an enlarged plan view schematically illustrating the restriction cam rotating around the vertical axis when the swivel mechanism keeps the bracket in the upright attitude;  
         [0022]      FIG. 9  is an enlarged plan view schematically illustrating the restriction cam contacting with the cam members when the display enclosure rotates around the horizontal axis;  
         [0023]      FIG. 10  is a perspective view schematically illustrating the structure of the bi-axial swivel mechanism when the bracket rotates farthest around the horizontal axis;  
         [0024]      FIG. 11  is an exploded view schematically illustrating the structure of the bi-axial swivel mechanism;  
         [0025]      FIG. 12  is a schematic view schematically illustrating the relationship between a stationary cam member and a movable cam member;  
         [0026]      FIG. 13  is a schematic view schematically illustrating the relationship between the stationary cam member and the movable cam member;  
         [0027]      FIG. 14  is a schematic view schematically illustrating the relationship between the stationary cam member and the movable cam member;  
         [0028]      FIG. 15  is a sectional view taken along an imaginary plane including the vertical axis;  
         [0029]      FIG. 16  is an exploded view schematically illustrating the structure of a bi-axial swivel mechanism according to a second embodiment of the present invention;  
         [0030]      FIG. 17  is an exploded view schematically illustrating the structure of a bi-axial swivel mechanism according to a third embodiment of the present invention; and  
         [0031]      FIG. 18  is an exploded view schematically illustrating the structure of a bi-axial swivel mechanism according to a fourth embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]      FIG. 1  schematically illustrates a cellular or mobile phone terminal  11  of a so-called flip or clamshell type as an example of an electronic apparatus. The cellular phone terminal  11  includes a transmitter  12  and a receiver  13 . The transmitter  12  has a main enclosure  14  serving as a first enclosure according to the present invention. A printed circuit board, not shown, is incorporated within the main enclosure  14 . Processing circuits, such as a central processing unit (CPU) and a memory, are mounted on the printed circuit board as conventionally known. Input keypads  15 , such as an on-hook key, an off-hook key, ten keys, and the like, are embedded in the front flat surface of the transmitter  12 . The CPU operates in response to the manipulation of the input keypads  15 . The main enclosure  14  may be molded from a reinforced resin material, for example.  
         [0033]     The receiver  13  has a display enclosure  16  serving as a second enclosure according to the present invention. A flat display panel such as a liquid crystal display (LCD) panel  17  is incorporated within the display enclosure  16 . A screen opening  18  is defined in the front flat surface of the display enclosure  16 . The screen of the LCD panel  17  is placed within the screen opening  18 . Various texts and graphics are displayed on the screen of the LCD panel  17  in response to the operation of the CPU. The display enclosure  16  may be molded from a reinforced resin material, for example.  
         [0034]     The microphone hole  19  is defined in the front flat surface of the main enclosure  14 . A microphone is embedded in the microphone hole  19 . A speaker hole  21  is defined in the front flat surface of the display enclosure  16 . A speaker is embedded in the speaker hole  21 . The user of the cellular phone terminal  11  talks to the microphone so as to establish a voice call. The speaker reproduces the voice of the other side.  
         [0035]     The transmitter  12  is coupled to the receiver  13  through a bi-axial swivel mechanism  22 . The swivel mechanism  22  realizes the rotation around a horizontal axis  23  between the transmitter  12  and the receiver  13 . The horizontal axis  23  is set in parallel with the front flat surface of the main enclosure  14  at the end of the front flat surface of the main enclosure  14 . The rotation around the horizontal axis  23  enables superposition of the receiver  13  over the transmitter  12 . The phone flip is in this manner closed in the cellular phone terminal  11 . The screen of the LCD panel  17  is overlaid on the front flat surface of the main enclosure  14 .  
         [0036]     As is apparent from  FIG. 2 , the swivel mechanism  22  also realizes the rotation around a vertical axis  24  between the transmitter  12  and the receiver  13 . The vertical axis  24  is set in parallel with the front flat surface of the display enclosure  16 . The vertical axis  24  is allowed to rotate around the horizontal axis  23  in an attitude set perpendicular to the horizontal axis  23 . The back surface of the receiver  13  is allowed to face forward through the rotation around the vertical axis  24 . When the cellular phone terminal  11  is then folded through the rotation around the horizontal axis  23 , the screen of the LCD panel  17  is exposed outward.  
         [0037]     As shown in  FIG. 3 , the swivel mechanism  22  includes a pair of sockets or bearings  26 ,  26  according to a first embodiment of the present invention. The bearings  26  are located at coaxial positions distanced from each other. The bearings  26  may be punched out of a metallic plate, for example. The bearings  26  are fixed to the main enclosure  14 . Screws, not shown, are employed for fixation of the bearings  26 , for example. The screws penetrate through corresponding screw holes  26   a  for engagement of the tip ends with the main enclosure  14 .  
         [0038]     A shaft member  27  is supported on the bearings  26  for relative rotation. The shaft member  27  includes a pair of support shafts  28 ,  28  respectively supported on the corresponding bearings  26 . A support member  29  is located between the support shafts  28 ,  28  at a position off the longitudinal axis of the shaft member  27 . An inside space  31  is defined around the longitudinal axis of the shaft member  27  at a position adjacent to the support member  29 . The support member  29  is coupled with the support shafts  28 ,  28  based on integral formation. The support member  29  and the support shafts  28 ,  28  in this manner form the shaft member  27  as a one-piece component. The longitudinal axis of the shaft member  27  corresponds to the aforementioned horizontal axis  23 .  
         [0039]     A bracket  32  is coupled to the support member  29  for relative rotation around the aforementioned vertical axis  24 . The bracket  32  is coupled to the display enclosure  16 . Screws, not shown, are employed to connect the bracket  32  to the display enclosure  16 , for example. The screws penetrate through screw holes  32   a  for engagement of the tip ends with the display enclosure  16 .  
         [0040]     A shaft cover or sleeve  33  is located between the bracket  32  and the support member  29 . The sleeve  33  is immobilized to the bracket  32 . Specifically, when the bracket  32  rotates around the vertical axis  24 , the sleeve  33  is forced to rotate around the vertical axis  24  along with the bracket  32 .  
         [0041]     As is apparent from  FIG. 4 , a first hollow space  34  is define in one of the support shafts  28 . The first hollow space  34  is designed to penetrate through the support shaft  28  along the horizontal axis  23 . The first hollow space  34  thus penetrates through the corresponding bearing  26 . The inner end of the first hollow space  34  opens in the aforementioned inside space  31  of the support member  29 . A coaxial cable  35  can thus be guided from the inside space  31  toward the outside of the bearing  26  through the first hollow space  34 .  
         [0042]     As shown in  FIG. 4 , the bracket  32  is attached to a tube  36  for relative rotation around the vertical axis  24 . The tube  36  is fixed to the support member  29  in a coaxial relation with the vertical axis  24 . A second hollow space  37  is defined in the tube  36 . The second hollow space  37  penetrates through the tube  36  in the axial direction of the tube  36 . The inner end of the second hollow space  37  opens in the aforementioned inside space  31  of the support member  29 . The coaxial cable  35  can thus be guided from the inside space  31  toward the outside of the bracket  32  through the second hollow space  37 . The coaxial cable  35  is consequently guided from the bearing  26  to the bracket  32  along the horizontal axis  23  and the longitudinal axis of the tube  36 .  
         [0043]     A cam member  38  is mounted on each of the support shafts  28 . The cam member  38  is immobilized to the corresponding bearing  26 . The cam members  38  are designed to respectively define perpendicular surfaces  38   a ,  38   a  opposed to each other. The perpendicular surfaces  38   a  are defined along parallel reference planes perpendicular to the horizontal axis  23 , respectively. The perpendicular surfaces  38   a  define a groove  39  extending around the horizontal axis  23 . The groove  39  has a uniform width.  
         [0044]     A recess  41  is formed on the individual perpendicular surface  38   a  at a predetermined angular position. The recesses  41 ,  41  serve to define an enlarged section in the groove  39 . The angular position of the recesses  41  may depend on the position of the vertical axis  24  or sleeve  33  established when the receiver  13  is set upright from the transmitter  12 , as shown in  FIG. 2 .  
         [0045]     A restriction cam  42  is formed on the outer periphery of the sleeve  33 . The restriction cam  42  is designed to extend in the centrifugal direction of the vertical axis  24 . The restriction cam  42  is defined around the vertical axis  24  based on the outline of the sleeve  33 . As shown in  FIG. 5 , parallel flat surfaces  44 ,  44  are defined on the restriction cam  42 . The parallel flat surfaces  44 ,  44  respectively extend within parallel imaginary planes set tangent to an imaginary cylinder  43  coaxial to the vertical axis  24 . The parallel imaginary planes are set perpendicular to the horizontal axis  23 . The diameter of the imaginary cylinder  43  is set in accordance with the distance between the parallel reference planes. When the parallel flat surfaces  44 ,  44  lie inside a space between the parallel reference planes, the restriction cam  42  is allowed to move along the groove  39  over the entire length.  
         [0046]     The restriction cam  42  allows establishment of curved surfaces  45 ,  45  between the parallel flat surfaces  44 ,  44 . The curved surfaces  45  are located outside the imaginary cylinder  43 . A large-seized imaginary cylinder  46  coaxial to the vertical axis  24  may be described to form the curved surfaces  45 ,  45 . The diameter of the large-sized imaginary cylinder  46  may be set equal to the extent of the enlarged section of the groove  39 .  
         [0047]     When the receiver  13  and the transmitter  12  are widely opened as shown in  FIG. 1 , the bracket  32  is positioned at a first position around the horizontal axis  23  as shown in  FIG. 3 . The bracket  32  takes a standard attitude around the vertical axis  24  prior to the positioning around the horizontal axis  23 . In this case, the flat surfaces  44  of the restriction cam  42  are respectively set in parallel with the parallel reference planes, as shown in  FIG. 6 , the flat surfaces  44  stay in a space between the parallel reference planes. The bracket  32  is thus allowed to rotate around the horizontal axis  23 . Here, the bracket  32  is completely prevented from rotation around the vertical axis  24 .  
         [0048]     When the receiver  13  is set to stand upright from the transmitter  12  as shown in  FIG. 2 , the bracket  32  is positioned at a second position around the horizontal axis  23  as shown in  FIG. 7 . The restriction cam  42  is in this case located in the enlarged section of the groove  39  as shown in  FIG. 5 . The enlarged section allows the rotation of the restriction cam  42  around the vertical axis  24 . This enables the rotation of the bracket  32  namely the display enclosure  16  around the vertical axis  24 . The bracket  32  thus takes a halfway attitude around the vertical axis  24 . The restriction cam  42  protrudes outside a space between the parallel reference planes as shown in  FIG. 8 , for example. The movement of the restriction cam  42  is restricted within the enlarged section of the groove  39  as is apparent from  FIG. 9 . The bracket  32  namely the display enclosure  16  is thus prevented from rotation around the horizontal axis  23 . The display enclosure  16  of the halfway attitude is reliably prevented from colliding against the main enclosure  14 . The main enclosure  14  is surely prevented from damages caused by such collision or contact.  
         [0049]     When the receiver  13  is overlaid on the transmitter  12 , the bracket  32  is positioned at a third position around the horizontal axis  23  as shown in  FIG. 10 . The bracket  32  is forced to take the standard attitude around the vertical axis  24  prior to the positioning around the horizontal axis  23  in the same manner as described above. The flat surfaces  44 ,  44  of the restriction cam  42  are located in a space between the parallel reference planes as described above. The bracket  32  is thus allowed to rotate around the horizontal axis  23 . The bracket  32  namely the display enclosure  16  is completely prevented from rotation around the vertical axis  24 . This serves to reliably prevent collision or contact between the receiver  13  and the transmitter  12  in response to the rotation around the vertical axis  24 .  
         [0050]     Here, a further detailed description will be made on the structure of the swivel mechanism  22 . A first rotation restriction mechanism  51  is established between the tube  36  and the sleeve  33 , as shown in  FIG. 11 . The first rotation restriction mechanism  51  includes an annular stationary cam member  52  coupled to the tube  36  for immobility relative to the tube  36  around the vertical axis  24 . The stationary cam member  52  may tightly be mounted around the tube  36 . An annular movable cam member  53  is superposed on the stationary cam member  52 . The movable cam member  53  may be mounted around the tube  36  for relative rotation around the vertical axis  24 . The movable cam member  53  is coupled to the sleeve  33 . A relative rotation is prevented between the movable cam member  53  and the sleeve  33  around the vertical axis  24 . A Bellville spring  54  is interposed between the bracket  32  and the movable cam member  53 . The Bellville spring  54  serves to urge the stationary cam member  52  against the movable cam member  53 . The stationary cam member  52 , the movable cam member  53  and the Bellville spring  54  are received in the inside space of the sleeve  33 .  
         [0051]     A second rotation restriction mechanism  56  is established between the cam member  38  and the bearing  26  around one of the support shafts  28 . The second rotation restriction mechanism  56  includes an annular stationary cam member  57  mounted around the support shaft  28  for relative rotation around the horizontal axis  23 . A movable cam member  58  is superposed on the stationary cam member  57 . The movable cam member  58  may be coupled with the support shaft  28  for immobility relative to the support shaft  28  around the horizontal axis  23 . A coil spring  59  is interposed between the bearing  26  and the movable cam member  58 . The coil spring  59  serves to urge the movable cam member  58  against the stationary cam member  57 . The stationary cam member  57 , the movable cam member  58  and the coil spring  59  are received in the inside space of a cam casing  61 . The cam casing  61  is coupled to the bearing  26  for immobility relative to the bearing  26  around the horizontal axis  23 . The stationary cam member  57  may likewise be coupled to the cam casing  61  for immobility relative to the cam casing  61  around the horizontal axis  23 .  
         [0052]     As shown in  FIG. 12 , a swell  63  is formed on the stationary cam member  52 ,  57 . The swell  63  swells toward the corresponding movable cam member  53 ,  58  from an imaginary plane  62  perpendicular to the horizontal axis  23  or the vertical axis  24 . A depression  64  is formed on the movable cam member  53 ,  58 . The depression  64  retreats from the imaginary plane  62 . The depression  64  includes first and second inclined surfaces  64   a ,  64   b . The first inclined surface  64   a  is formed to extend upward from the bottom of the depression  64  toward the imaginary plane  62  around the horizontal axis  23  or the vertical axis  24 . The inclined surface  64   a  extends upward from the bottom surface of the depression  64  toward the imaginary plane  62 . The second inclined surface  64   b  is formed to extend downward from the imaginary plane  62  toward the bottom of the depression  64 . The shape of the depression  64  may correspond with that of the swell  63 . Since the Bellville spring  54  or the coil spring  59  serves to urge the movable cam member  53 ,  58  against the stationary cam member  52 ,  57 , the swell  63  received in the depression  64  enables restriction to a relative rotation of the movable cam member  53 ,  58 . This results in a clicking movement of the movable cam member  53 ,  58 .  
         [0053]     When the movable cam member  53 ,  58  rotates in response to the rotation of the display enclosure  16  or the bracket  32 , as shown in  FIG. 13 , for example, the swell  63  of the stationary cam member  52 ,  57  slides along the first inclined surface  64   a  of the movable cam member  53 ,  58 . The movable cam member  53 ,  58  is distanced from the stationary cam member  52 ,  57  in response to the rotation of the movable cam member  53 ,  58  based on the inclination of the first inclined surface  64   a . Elastic force is thus stored up in the Belleville spring  54  or the coil spring  59  in response to the movement of the movable cam member  53 ,  58 . The movable cam member  53 ,  58  is in this manner urged against the stationary cam member  52 ,  57 . If restraint is released from the display enclosure  16  or the bracket  32  around the horizontal axis  23  or the vertical axis  24 , the first inclined surface  64   a  develops a driving force in the reverse direction around the horizontal axis  23  or the vertical axis  24 . The driving force is kept developed until the swell  63  is completely received in the depression  64 . The display enclosure  16  is in this manner allowed to enjoy an elastic restriction to the movement around the horizontal or vertical axis  23 ,  24 .  
         [0054]     When the swell  63  of the stationary cam member  52 ,  57  reaches the second inclined surface  64   b  in the adjacent depression  64 , as shown in  FIG. 14 , the inclination of the second inclined surface  64   b  allows the movable cam member  53 ,  58  to approach the stationary cam member  52 ,  57  during the rotation of the movable cam member  53 ,  58 . In this case, the second inclined surface  64   b  develops a driving force acting on the movable cam member  53 ,  58  for rotation. If restraint is released from the display enclosure  16  or the bracket  32  around the horizontal axis  23  or the vertical axis  24 , the movable cam member  53 ,  58 , namely the display enclosure  16 , is thus forced to rotate around the vertical or horizontal axis  24 ,  23  until the swell  63  is completely received in the depression  64 . The movement of the swell  63  is restricted within the adjacent depressions  64 ,  64 .  
         [0055]     As shown in  FIG. 15 , a gap  65  may further be formed in the support shaft  28 . The gap  65  is continuous with the inside space  31 . The gap  65  serves to establish a wider opening of the first hollow space  34 . The assembling of the coaxial cable  35  can thus be accomplished with a higher efficiency.  
         [0056]      FIG. 16  schematically illustrates a swivel mechanism  22   a  according to a second embodiment of the present invention. The swivel mechanism  22   b  allows provision of the cam member  38  only on one of the support shafts  28 . The cam member  38  may be coupled to the bearing  26  for immobility relative to the bearing  26  around the horizontal axis  23  with the assistance of the cam casing  61  in the manner as described above. The first hollow space  34  is defined in the other support shaft  28  as described above. The second hollow space  37  is defined in the tube  36 . Like reference numerals are attached to structure or components equivalent to those of the aforementioned first embodiment.  
         [0057]      FIG. 17  schematically illustrates a swivel mechanism  22   b  according to a third embodiment of the present invention. The tube  36  is supported on the shaft member  27  or support member  29  for relative rotation around the vertical axis  24  in this swivel mechanism  22   b . The tube  36 , the sleeve  33 , the movable cam member  53  and the bracket  32  are thus forced to rotate all together. The stationary cam member  52  may be coupled to the support member  29  for immobility relative to the support member  29  around the vertical axis  24 . The first hollow space  34  is defined in the support shaft  28  in the same manner as described above. The second hollow space  37  is defined in the tube  36 . Like reference numerals are attached to structure or components equivalent to those of the aforementioned first embodiment. The cam member  38  may be mounted only on one of the support shafts  28  in the swivel mechanism  22   b  in the same manner as the aforementioned second embodiment.  
         [0058]      FIG. 18  schematically illustrates a swivel mechanism  22   c  according to a fourth embodiment of the present invention. The swivel mechanism  22   c  allows provision of the first rotation restriction mechanism  51  outside the sleeve  33 . The first hollow space  34  is defined in the support shaft  28  in the same manner as described above. The second hollow space  37  is defined in the tube  36 . Like reference numerals are attached to structure or components equivalent to those of the aforementioned first embodiment. The cam member  38  may be mounted only on one of the support shafts  28  in the swivel mechanism  22   c  in the same manner as the aforementioned second embodiment. The movable cam member  53 , the sleeve  33  and the bracket  32  may be forced to rotate all together around the vertical axis  24 . Otherwise, the tube  36  may also be forced to rotate around the vertical axis  24  along with the movable cam member  53 , the sleeve  33  and the bracket  32 .