Abstract:
A hinge assembly ( 100 ) includes a shaft ( 10 ), a follower ( 12 ), a cam ( 20 ), a friction-reducing mechanism ( 30 ), and an urging means. The shaft includes a securing portion ( 11 ) formed thereon. The follower is connected with the shaft. The cam essentially is in the shape of a cylinder, and includes a cam surface ( 24 ) and defines a cam hole ( 22 ) extending therethrough. The cam hole receives the shaft therethrough. The friction-reducing mechanism is located around the shaft, and includes a rolling means. A first end of the urging means abuts against the shaft, and an opposite second end of the urging means biases the friction-reducing mechanism. The friction-reducing mechanism is disposed between the cam and the urging means. The cam surface of the cam is rotatably and movably engaged with the follower under force of the urging means.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to hinge assemblies and, particularly, to a hinge assembly for foldable electronic devices, such as mobile telephones, electronic notebooks, and so on.  
         [0003]     2. Discussion of the Related Art  
         [0004]     With the development of wireless communication and information processing technologies, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. These electronic devices enable consumers to enjoy the convenience of high technology services anytime and anywhere. Consumers particularly favor foldable electronic devices for their convenience.  
         [0005]     Generally, foldable electronic devices have most of the electronics in one housing, called the body. The other housing, called the cover, normally contains fewer electronic components than the body. Other foldable electronic devices have all the electronics in the body, with the cover containing no electronics. Various types of hinge assemblies are used to join a body and a cover of a foldable electronic device, so that the cover can unfold up from and fold down upon the body. Manufacturers are constantly seeking to reduce the volume, size and/or weight of portable foldable electronic devices. Thus, it is desirable that the hinge assembly coupling the main housing with the cover is modularized and miniaturized. Modularized hinge assemblies usually consist of moving parts such as a cam member, a cam follower, a shaft, and a spring, held together in a unified structure. Where either the cam member or the cam follower directly contacts the spring. The structure is easily and quickly attached to the main housing and the cover during mass production. The cam member and the cam follower always contact each other under the force of the spring.  
         [0006]     One kind of the hinge assembly includes a housing secured to a body of the mobile phone, a spring received in the housing, a rotary cam rod, and a shaft with a follower and a connecting portion. The rotary cam rod is received in the housing and engages with the housing. One end of the spring contacts an inner wall of the housing, and the other end of the spring resists one end of the rotary cam rod. The shaft passes through the rotary cam rod, the spring and a washer in that order.  
         [0007]     Although the above-described hinge assembly is suitable for some foldable electronic devices, sliding friction is produced between the spring and the rotary cam rod because of relative rotation therebetween. This wastes energy and causes abrasion of the spring and the rotary cam rod. The abrasion may eventually lead to premature malfunction or failure of the hinge assembly.  
         [0008]     What is needed, therefore, is a hinge assembly which has a relatively simple and small modularized configuration, which can be produced at low cost, and which has a relatively low amount of friction associated therewith.  
       SUMMARY OF THE INVENTION  
       [0009]     In a first preferred embodiment, a hinge assembly is provided for joining a flip cover to a main body of a foldable electronic device. The hinge assembly includes a shaft, a follower, a cam, a friction-reducing mechanism, and an urging (i.e. driving) means. The shaft includes a securing portion formed thereon. The follower is connected with the shaft. The cam is essentially cylinder shaped, and includes a cam surface defining a cam hole extending therethrough, the cam hole receiving the shaft therethrough. The friction-reducing mechanism is located around the shaft, and includes a rolling means. A first end of the urging means abuts the shaft, and an opposite second end of the urging means biases the friction-reducing mechanism. The friction-reducing mechanism is disposed between the cam and the urging means. The cam surface of the cam is rotatably and movably engaged with the follower under the driving force of the urging means.  
         [0010]     Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Many aspects of the hinge assembly can be better understood with reference 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 present hinge assembly. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0012]      FIG. 1  is a schematic, isometric view of a flip-type mobile phone including a flip cover, a main body, and a hinge assembly according to a first preferred embodiment, the hinge assembly being shown with dashed lines;  
         [0013]      FIG. 2  is an enlarged, assembled view of the hinge assembly of  FIG. 1 ;  
         [0014]      FIG. 3  is similar to  FIG. 2 , but viewed from another aspect;  
         [0015]      FIG. 4  is an exploded, isometric view of a friction-reducing mechanism of the hinge assembly of  FIG. 2 ;  
         [0016]      FIG. 5  is similar to  FIG. 4 , but viewed from another aspect; and  
         [0017]      FIG. 6  an assembled view of friction-reducing mechanism the of  FIG. 4 ; and  
         [0018]      FIG. 7  is an assembled view of the hinge assembly of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]     Referring now to the drawings,  FIG. 1  shows a flip-type mobile phone  200 , which includes a hinge assembly  100 , according to a preferred embodiment. The mobile phone  200  has a main body  202  and a flip cover  204 . The main body  202  and the flip cover  204  are pivotally connected to each other via the hinge assembly  100 . It should be noted that the hinge assembly  100  may also, for example, be used to interconnect components like a main body and a flip cover of any of a variety of different foldable devices other than the mobile phone  200 .  
         [0020]     Referring now to  FIGS. 2-3 , the hinge assembly  100  includes a shaft  10 , a cam  20 , a friction-reducing mechanism  30 , a spring  40  functioning as an elastic urging means, and a C-clip  50 . The friction-reducing mechanism  30  includes a first baffle plate  32 , a plurality of ball bearing  34  and a second baffle plate  36 . The shaft  10  extends through the cam  10 , the friction-reducing mechanism  30 , the spring  40  and the C-clip  50 , thereby integrating the hinge assembly  100  into a complete unit.  
         [0021]     The shaft  10  includes in sequence a securing portion  11  formed at one end thereof, a follower  12  adjacent the securing portion  11 , a shaft portion  13 , a neck portion  14 , and a flange portion  15 . The securing portion  11  is for engaging with the main body  202  of the mobile phone  200 . The follower  12  includes an enlarged cylindrical portion  122 , and two symmetrically opposite finger portions  124  as a cam surface extending in an axial direction and adjoining one end of the shaft portion  13 . Each finger portion  124  has a top portion  126 .  
         [0022]     The cam  20  is a generally cylindrical body and defines a central cam hole  22  extending therethrough. The cam  20  has a cam surface  24  formed at one end thereof, and a planar end surface  26  on an opposite end thereof. The cam surface  24  includes two valleys  242 , two peaks  244 , four inclined planes  246  disposed between the valleys  242  and the peaks  244 . Preferably, the valleys  242  are located 180 degrees apart from each other, with the peaks  244  are located 180 degrees from each other. The cam  20  has a protrusion  28  formed on outer peripheral wall thereof, the protrusion  28  being oriented parallel to the central axis of the cam  20 . The protrusion  28  is for engaging with the flip cover  204  of the mobile phone  200 .  
         [0023]     Referring to  FIGS. 4-6 , the first baffle plate  32  is circular ring-shaped. The first baffle plate  32  includes a first bottom portion  322 , and a first bent portion  324  formed by bending the outer periphery of the first bottom portion  322  to a one side of the first bottom portion  322 . The first bottom portion  322  has a central opening  326  extending therethrough. The first bent portion  324  has a latching protrusion  328  formed on outer periphery thereof. The first bottom portion  322  has an outer surface  3222  abutting the planar end surface  26  of the cam  20 .  
         [0024]     The plurality of ball bearings  34  cooperatively forms a ring member.  
         [0025]     The second baffle plate  36  is circular ring-shaped. The second baffle plate  36  includes a second bottom portion  362 , and a second bent portion  364  formed by bending the outer periphery of the second bottom portion  362  to a one side of the second bottom portion  362 . The second bottom portion  362  has a central opening  366  extending therethrough. The second bent portion  364  has a latching groove  368 . The latching groove  368  corresponds to the latching protrusion  328  of the first baffle plate  32 . The second bottom portion  362  has an outer surface  3622  abutting the spring  40 .  
         [0026]     The spring  40  is helical and preferably metallic, with an inner diameter larger than a diameter of the large diameter portion  13  of the shaft  10 . Thus the spring  40  can be located around the shaft  10 .  
         [0027]     In the assembly of the hinge assembly  100 , referring to  FIG. 7 , firstly, the ball bearings  34  are placed in the first baffle plate  32 . The second baffle plate  36  is adjoined with the first baffle plate  32  together to define a receiving cavity  38 , with the latching protrusion  328  of the first baffle plate  32  engaging in the latching groove  368  of the second baffle plate  36 . The ball bearings  34  are received in the receiving cavity  38 . Then, the shaft  10  passes through the cam hole  22  of the cam  20 , the central openings  326 ,  366  of the first baffle plate  32  and the second baffle plate  36 , the spring  40  and the C-clip  50 . A first end of the spring  40  resists the second bottom portion  362  of the baffle plate  36 , an opposite second end of the spring  40  resists the C-clip  50 . Because of the urging force of the spring  40  the cam surface  24  of the cam  20  will contact the finger portions  124  no matter what rotational position the cam  20  is in.. The hinge assembly  100  is thus completely assembled, as shown in  FIG. 7 .  
         [0028]     Referring to  FIGS. 1 and 7 , in use, the protrusion  28  of the cam  20  is engaged (i.e., operatively located/fixed) in a cavity (not shown) of the flip cover  204  of the mobile phone  200 , and cannot rotate relative to the flip cover  204 . The securing portion  11  of the shaft  10  is engaged in the main body  202  of the mobile phone  200 , and cannot rotate relative to the main body  202 . When the flip cover  204  of the mobile phone  200  is in a fully closed position or a fully open position, the finger portions  124  of the shaft  10  are located in the valleys  242  of the cam  20  and engage with the valleys  242 .  
         [0029]     When the flip cover  204  of the mobile phone  200  is rotated between an open position and a closed position (or vice versa), the cam  20  rotates along with the flip cover  204 , while the shaft  10  remains fixed in the main body  202  of the mobile phone  200 . As a result, the finger portions  124  ride along the inclined planes  246  of the cam surface  24  from the valleys  242  to the peaks  244  (see  FIG. 4 ). Simultaneously, the cam  20  moves axially and resists the first baffle plate  32 , which makes the first baffle plate  32  rotate relative to the second baffle plate  36 , and compresses the spring  40 . Also, the ball bearings  34  rotate and roll relative to the first baffle plate  32 . Because the first baffle plate  32  and the second baffle plate  36  resist each other via the ball bearings  34 , only rolling friction is produced between the first baffle plate  32  and the second baffle plate  36 . Once the finger portions  124  pass over the peaks  244 , the spring  40  decompresses and drives the cam  20  back toward the cylindrical portion  122 , with the finger portions  124  riding along the inclined planes  246  from the peaks  244  to the valleys  242 . The flip cover  204  is thus rotated automatically to the fully closed position (or fully open position) under the decompression force of the spring  40 . Accordingly, the flip cover  204  is moved 180 degrees relative to the main body  202 , with the finger portions  124  once again mating in the valleys  242 . In this way, the flip cover  202  is closed (or opened). Preferably, the structures of the flip cover  204  and the main body  202  are adapted to control the degree of rotation of the hinge assembly  10 , such that the finger portions  124  can be held in one or more particular locations between the valleys  242  and the peaks  244 .  
         [0030]     A main advantage of the hinge assembly  100  is that the cam  20  and the spring  40  do not directly contact each other, thereby reducing friction associated with relative rotation between the cam  20  and the spring  40  via the friction-reducing mechanism  30 . Accordingly, when the hinge assembly  100  is assembled in the mobile phone  200 , the energy required in opening the flip cover  202  of the mobile phone  200  is reduced. Furthermore, wear of the cam  20  and the spring  40  is reduced, and the working lifetime of the hinge assembly  100  is prolonged.  
         [0031]     In further alternative embodiments, the follower  12  can be a separate element that is not integrally formed with the shaft  10 . In such case, the follower  12  defines a shaft hole, and has a cam surface or finger portions. The ball bearings  34  can be replaced by another kind of rolling means such as roller bearings. The spring  40  can be made of a nonmetallic material such as plastic. Furthermore, the spring  40  can instead be another kind of elastic element or urging means known in the art, such as a resilient cylinder. The C-clip  50  can be omitted, in which case the spring  40  directly resists the flange portion  15 , and there can  20  be more than one protrusion  28 .  
         [0032]     However, when the securing portion  11  of the shaft  10  is used to connect with the flip cover  204 , and the protrusion  28  of the cam  20  is used to connect with the main body  202 . In such case, there is no relative rotation between the cam  20  and the spring  40 , whereas there is relative rotation between the C-clip  50  and the spring  40 . Accordingly, the friction-reducing mechanism  30  is disposed between the spring  40  and the C-clip  50 . Because the C-clip  50  and the spring  40  resist each other via the friction-reducing mechanism  30 , only rolling friction is produced between C-clip  50  and the spring  40 . In an alternative embodiment, the C-clip  50  can be omitted. In such case, the friction-reducing mechanism  30  is disposed between the spring  40  and the flange portion  15  of the shaft  10 .  
         [0033]     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, 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.