Abstract:
A hinge mechanism comprises a follower, a cam and a first spring. The first spring is spiral, one end of the first spring is mounted to the follower, another end of the first spring is mounted to the cam. The cam rotates relative to the follower about a rotating axis, the first spring is compressed to accumulate elastic force, until the line connecting two ends of the first spring is parallel to the rotating axis where the first spring is mostly compressed to accumulate maximum of the elastic force and the hinge mechanism is in an intermediate state. Once the cam is rotated over the intermediate state, the first spring is expanded under previously accumulated elastic force, which drive the cam continuously rotated relative to the follower.

Description:
BACKGROUND 
     1. Technical Field 
     The exemplary embodiment relates to hinge mechanisms and, particularly to hinge mechanisms used in portable electronic devices. 
     2. Description of Related Art 
     Portable radiotelephones having two housings joined by a type of hinge that allows the housings to fold upon one another are known in the art. Some folding radiotelephones have most of the electronic components installed in one housing called the main housing and fewer electronic components installed in the other housing, called the cover. Other folding radiotelephones may have all electronics components installed in the body with the cover serving only to cover the keypad, or both keypad and display of the phone. 
     Some known portable cellular radiotelephones utilize a hinge mechanism having a spring, a cam and a follower assembled into a cylindrically hollow can via an open end thereof and held in assemblage by a cap coupled to the can over the open end. The assembled hinge is disposed in a cavity of cover and a cavity of body. This hinge mechanism may be desirable to some radiotelephone manufacturers because it can be purchased as a separate unit, thereby eliminating the steps associated with assembling the hinge during manufacturing. However, the number of parts used is large and the cost of the hinge mechanism is high. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the exemplary hinge mechanism and portable electronic device using the hinge mechanism. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment. 
         FIG. 1  is schematic view of a portable electronic device in an open position configured in accordance with the exemplary embodiment. 
         FIG. 2  is an exploded, schematic view of the exemplary embodiment of the hinge mechanism used in the portable electronic device shown in  FIGS. 1 and 2 . 
         FIG. 3  is similar to  FIG. 2 , but showing the hinge mechanism in another view. 
         FIG. 4  is an assembled and partially cutaway view of the hinge mechanism shown in  FIG. 3 . 
         FIG. 5  is a schematic view of which a cam rotates relative to a follower in an intermediate state. 
         FIG. 6  is a schematic view of the hinge mechanism shown in  FIG. 5  in an open position. 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiment of a foldable, portable electronic device  200  of the exemplary embodiment is shown in  FIG. 1 . The portable electronic device  200  includes three portions, a cover  102 , a body  104  and a hinge mechanism  100  joining the cover  102  to the body  104 .  FIG. 1  shows the cover  102  in an “open” position such that a user of the portable electronic device  200  can listen via earpiece  1022  and speak into microphone  1042 . The body  104  includes a keypad  1044  having a plurality of buttons  1046 . The keypad  1044  may also have additional buttons  1046  such as power, function, send, and other buttons associated with communication commands. The body  104  also has an antenna  1048  that enables the portable electronic devices  200  communicating with a base station (not shown) of the portable electronic device system. The body  104  further includes a port  1050  that allows the portable electronic device  200  to connect with external components, for example, a battery charger, external antenna, keypad, speaker or microphone. 
     When the portable electronic device  200  is assembled, the hinge mechanism  100  is disposed in a barrel portion  1024  of the cover  102 . The cover  102 , with the hinge mechanism  100  received therein, is rotatably coupled between two knuckles  1052 ,  1054  of the body  104 . The design of hinge mechanism  100  allows the cover  102  to be held in a closed position, and at an obtuse angle in the open position. 
     Referring to  FIGS. 2 to 4 , the hinge mechanism  100  includes a main shaft  10 , a stationary element, such as a follower  20 , three moveable elements, such as a cam  30 , a first spring  40  and a second spring  50 , a cylindrically hollow can  60  and a washer  70 . The cam  30 , the first spring  40  and the second spring  50  are assembled into the can  60 . The follower  20  and the cam  30  are connected together via the first spring  40  and the second spring  50 . The main shaft  10  passes through the follower  20 , the cam  30  and the can  60  and held in assemblage by the washer  70  latched with the main shaft  10 . 
     The main shaft  10  includes a first cylindrical shaft  12  and a second cylindrical shaft  14  protruding outwardly from one end of the first shaft  12 . The first shaft  12  is larger than the second shaft  14 , so a first resisting surface  16  (seen  FIG. 3 ) is formed between the first shaft  12  and the second shaft  14 . The second shaft  14  has an annular groove  142  radially defined in a distal end thereof and surrounding the second shaft  14 . The groove  142  is configured to latch the washer  70  therein. 
     The follower  20  includes a substantially elliptical resisting portion  21 , a retaining portion  22  protruding outwardly from one end of the resisting portion  21 , a shaft portion  23  protruding outwardly from another end of the resisting portion  21 . The follower  20  has a first hole  24  longitudinally defined in a center of the retaining portion  22  and a second hole  25  longitudinally defined in a center of the shaft portion  23 . The first hole  24  has the same shape as the first shaft  12  with a smaller size than the first shaft  12 . The first hole  24  is configured to firmly accommodate the first shaft  12 . The second hole  25  is communicated with the first hole  24  and has the same shape and size as the second shaft  14 . The second hole  25  is configured to accommodate the second shaft  14 . The first hole  24  is large than the second hole  25 , so a second resisting surface  26  is formed between the first hole  24  and the second hole  25 . The second resisting surface  26  is configured to resist against the first resisting surface  16 . 
     The retaining portion  22  mates with an aperture (not shown) in one of the knuckles  1052 ,  1054  of the body  104  of a portable electronic device  200 . The retaining portion  22  is shaped to be received in the aperture and lock the hinge mechanism  100  in place. The shaft portion  23  is a hollow cylinder and rotatably accommodated in the can  60 . The follower  20  has a first securing trough  232  and a second securing trough  234  symmetrically defined a distal end thereof facing the cam  30 . The first securing trough  232  is configured to latch with the first spring  40 . The second securing trough  234  is configured to latch with the second spring  50 . 
     The cam  30  has a third securing trough  32  and a fourth securing trough  34  symmetrically defined in an end thereof facing the follower  20 . The third securing trough  32  is configured to latch with the first spring  40 . The fourth securing trough  34  is configured to latch with the second spring  50 . The cam  30  has a first opening  36  defined therethrough, the second shaft  14  passes through the cam  30  by the first opening  36 . The inner diameter of the first opening  36  is slightly larger than the outer diameter of the second shaft  14  such that the second shaft  14  can rotate in the first opening  36  without restraint. The cam  30  has two symmetrical first flat surfaces  38  longitudinally formed an outer peripheral surface thereof. The first flat surfaces  38  are configured to mate with the can  60  so that the cam  30  rotates with the can  60 . 
     The first spring  40  includes a first spiral main body  42 , a first securing portion  44  protruding one end thereof facing the follower  20  and a second securing portion  46  protruding another end there of facing the cam  30 . The first securing portion  44  and the second securing portion  46  are both semicircular. The first securing portion  44  is rotatably latched in the first securing trough  232 , and the second securing portion  46  is rotatably latched in the third securing trough  32 . 
     The second spiral spring  50  includes a spiral second main body  52 , a third securing portion  54  protruding one end thereof facing the follower  20  and a fourth securing portion  56  protruding another end there of facing the cam  30 . The third securing portion  54  and the fourth securing portion  56  are both semicircular. The third securing portion  54  is rotatably latched in the second securing trough  234 , and the fourth securing portion  56  is rotatably latched in the fourth securing trough  34 . 
     The can  60  is a barrel including an open end  62 , a partially closed end  64  and a peripheral wall  66  connecting the open end  62  and the partially closed end  64 . The open end  62 , the partially closed end  64  and the peripheral wall  66  cooperatively enclose a space  68 . The space  68  is configured for accommodating the shaft portion  23  of the follower  20 , the first spring  40 , the second spring  50  and the cam  30 . The cross-sectional of the space  68  has the same shape and size as that of the cam  30 . The can  60  has two symmetrical second flat surfaces  662  longitudinally formed on the peripheral wall  66 . The second flat surfaces  662  are configured to mate with the first flat surface of the cam  30  so that the can  60  rotates with the cam  30 . 
     The distance between the two second flat surfaces  662  is slightly larger than the diameter of the shaft portion  23  so that the shaft portion  23  can  60  rotate in the space  68  without restraint. The partially closed end  64  has a second opening  642  defined therethrough, the second shaft  14  passes through the partially closed end  64  by the second opening  642 . 
     In assembling the hinge mechanism  100 , firstly, the first securing portion  44  of the first spring  40  is latched in the first securing trough  232 , and the second securing portion  46  of the first spring  40  is latched in the third securing trough  32 , so the first spring  40  is located between the follower  20  and the cam  30 . Secondly, the third securing portion  54  of the second spring  50  is latched in the second securing trough  234 , the fourth securing portion  56  of the second spring  50  is latched in the fourth securing trough  34 , so the second spring  50  is located between the follower  20  and the cam  30 . The follower  20 , the first spring  40 , the second spring  50  and the cam  30  is assembled into the space  68  of the can  60  via the open end  62  thereof. The first hole  24 , the second hole  25 , the first opening  36  and the second opening  642  are aligned. The main shaft  10  passes through the first hole  24 , the second hole  25 , the first opening  36  and the second opening  642 , until the first resisting surface  16  of the main shaft  10  resist against the second resisting surface  26  of the follower  20 . At this time, the first spring  40  and the second spring  50  are wound around the second shaft  14 . The resisting portion  21  of the follower  20  is resisted against the open end  62  of the can  60 . The groove  142  of the second shaft  14  extend outwardly the partially closed end  64  from the second opening  642 . Then, the washer  70  is latched into the groove  142 , so yields an assembled hinge mechanism  100 . 
     In use, the can  60  of the hinge mechanism  100  is received in slots (not shown) formed on the interior surface the barrel portion  1024  of the cover  102  so that the can  60  rotates with the cover  102  as the cover  102  is moved between the open and closed position with respect to the body  104 . The follower  20  of the hinge mechanism  100  is locked into one of the knuckles  1052 ,  1054  of the body  104  so that the follower  20  rotates with the body  104 , and does not rotate when the cover  102  is moved between the open and closed positions with respect to the body  104 . When the cover  102  is in closed state, referring to  FIG. 4 , the first spring  40  and the second spring  50  is slightly compressed, so both have a tendency to expand. Thereby, the cam  30  have a tendency to rotate relative to the follower  20  in the direction of arrow A shown in  FIG. 4 . As mentioned above, the cam  30  rotates with the can  60  which rotates with the cover  102 , and the follower  20  rotate with the body  104 , so that the cover  102  is firmly attached to the body  104 . 
     Referring to  FIGS. 4 to 6 , a force is exerted on the can  60  to make can  60  and the cam  30  rotate relative to the follower  20  in the direction of arrow B shown in  FIG. 4 . As the cam  30  rotates, the distance between the first securing portion  44  and the second securing portion  46  and the distance between the third securing portion  54  and the fourth securing portion  56  are gradually shortened, with the first spring  40  and the second spring  50  being compressed and twisted to accumulate elastic force. Once the line L 1  connecting the first securing portion  44  with the second securing portion  46  is parallel to the second shaft  14 , the first spring  40  is mostly compressed to accumulate maximum of the elastic force. Simultaneously, the line L 2  connecting the third securing portion  54  with the fourth is parallel to the second shaft  14  also, the second spring  50  is mostly compressed to accumulate maximum of the elastic force too. At this stage, the hinge mechanism  100  is in an intermediate state (seen  FIG. 5 ). 
     The can  60  is continuously rotated relative to the follower  20  in the direction of arrow B until the can  60  is rotated over the intermediate state, the first spring  40  and the second spring  50  expand under previously accumulated elastic force, which drive the can  60  and the cam  30  continuously rotated in the direction of arrow B until the hinge mechanism  100  is in a fully open state (seen  FIG. 6 ). At this time, the first spring  40  and the second spring  50  are slightly compressed, so both of which have a tendency to expand. With a result the cam  30  trends to rotate relative to the follower  20  in the direction of arrow B shown in  FIG. 4 . As mentioned above, the cam  30  rotates with the can  60  which rotates with the cover  102 , and the follower  20  rotate with the body  104 , so that the cover  102  is firmly located in open state. 
     It is to be understood, the second spring  50  can be omitted when the first spring  40  can provide enough force to make the cover  102  rotate relative to the body  104 . 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.