Abstract:
A hinge assembly ( 100 ) includes a shaft ( 10 ), a cam ( 20 ), and an elastic member ( 30 ). The shaft is in the form of a rod and provided with a projection ( 16 ). The cam includes a body ( 21 ) and a center cavity ( 23 ). The body of the cam defines a cam face ( 22 ) at one end thereof, and the projection of the shaft is engaged with the cam face. The shaft travels through the center cavity of the cam. One end of the elastic member biases relative to a distal end portion of the shaft, and an opposite end of the elastic member abuts an end of the cam opposite the cam face.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to hinge assemblies and, more particularly, to a hinge assembly for hinging together housings of foldable electronic devices such as mobile telephones, electronic notebooks, and so on.  
         [0003]     2. Discussion of the Prior Art  
         [0004]     With the development of the technologies of wireless communication and information processing, 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. Foldable electronic devices are particularly favored by consumers 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, thus the cover contains no electronics and serves only to cover a keypad and a display of the body. 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.  
         [0006]     As represented in  FIG. 4 , a conventional hinge assembly for a foldable mobile telephone  700  includes a spring  762  and two hinge pins  764 ,  768 . The hinge pins  764 ,  768  are disposed in a tubular hinge arm  742  formed at an end of a cover  74 , and corresponding bushings  722  are formed in a body  72 . The spring  762  is positioned between the hinge pins  764 ,  768 , and at all times forces the hinge pins  764 ,  768  outwardly from the cover  72  toward the body  74 .  
         [0007]     Such a hinge assembly is suitable for some foldable mobile telephones. However, the hinge assembly includes a variety of individual pieces that must be installed within the foldable mobile telephone when the foldable mobile telephone is assembled. This type of hinge does not meet the growing trend for foldable mobile telephone manufacturers to use integrated one-piece hinge assemblies, which can be quickly and easily press-fitted into foldable mobile telephone sub-assemblies during manufacturing.  
         [0008]     What is needed, therefore, is a hinge assembly which is integrated and provides easy assembly.  
       SUMMARY  
       [0009]     In a preferred embodiment herein, a hinge assembly for a foldable electronic device is provided. The hinge assembly includes a shaft, a cam, and an elastic member. The shaft is in the form of a rod and provided with a projection. The cam includes a body and a center cavity. The body of the cam defines a cam face at one end thereof, and the projection of the shaft is engaged with the cam face. The shaft travels through the center cavity of the cam. One end of the elastic member is effectively resisted by the shaft, and an opposite end of the elastic member abuts an end of the cam opposite the cam face.  
         [0010]     Other advantages and novel features of various embodiments will become more apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Other aspects of the hinge assembly can be better understood with reference to the following drawings. The components in the drawings are not necessarily scale, the emphasis instead being placed upon clearly illustrating the principles of the hinge assembly. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0012]      FIG. 1  is an isometric view of a foldable electronic device with a hinge assembly, according to a first preferred embodiment;  
         [0013]      FIG. 2  is an enlarged, exploded, isometric view of the hinge assembly of  FIG. 1 ;  
         [0014]      FIG. 3  is an assembled, isometric view of the hinge assembly of  FIG. 2 ; and  
         [0015]      FIG. 4  is an exploded, isometric view of a conventional hinge assembly for a foldable mobile telephone. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]      FIGS. 1-3  show a hinge assembly  100  according to a preferred embodiment of the present hinge system. The hinge assembly  100 , in the embodiment illustrated, is used to interconnect a body  801  and a cover  802  of a foldable electronic device  800 . The hinge assembly  100  includes a shaft  10 , a cam  20 , a compression spring  30 , and a disk  40 . The shaft  10  extends through the cam  20 , the compression spring  30 , and the disk  40 , thereby integrating the hinge assembly  100  into a complete unit. While the hinge assembly  100  is shown incorporated into the foldable electronic device  800 , it is to be understood that the hinge assembly  100  or obvious variations thereof may prove useful in other work environments (e.g., cabinet doors) as well.  
         [0017]     The shaft  10  is essentially in the form of a round rod. A keyed head  12  is formed at a first end of the shaft  10 , and an annular slot  14  and a corresponding stop plate  15  are formed at an opposite second end of the shaft  10 . The stop plate  15  may be either integrally or separately attached as part of the shaft  10 . The keyed head  12  is an irregular polygonal block. The keyed head  12  is engaged with the body  801  of the foldable electronic device  800  so that the shaft  10  is rotatable with the body  801 . A pair of projections  16  is formed on two opposite sides of the shaft  10  and adjacent the keyed head  12 . The projections  16  are advantageously generally pole-shaped and are essentially diametrically aligned with each other. Further advantageously, the pole-shape and the positioning of the projections  16  (i.e., their configuration) is chosen so as to facilitate movement thereof relative to the cam  20 . The projections  16  and the shaft  10  are either integral or separately attached. If separately attached, the shaft  10  could have a pair of holes defined in a periphery thereof, and the projections  16  of the shaft  10  could be respectively secured in the holes. Whether or not mounting holes are employed, the projections  16  could be mechanically or metallurgically fastened to the shaft.  
         [0018]     The cam  20  is essentially in the form of a modified, hollow cylinder and includes a body  21  and a center cavity  23 . The center cavity  23  is formed through the body  21  along a center axis of the cam  20 . The center cavity  23  is engaged with the shaft  10 , so that the cam  20  is both axially movable and rotatable relative to the shaft  10 . A first end of the body  21  has a cam face  22 , and an opposite second end of the body  21  has a flat face  24 . The cam face  22  has two vertical slopes  226  and two angled slopes  228 . Each angled slope  228  spans about half a circumference of the body  21  and is advantageously angled (roughly 15°-50° relative to the flat face  24 ) to promote a gradual yet significant change in loading in the compression spring  30  upon rotation of the cam  20 . Each vertical slope  226  is essentially parallel to the center axis of the cam  20 . In an alternative embodiment, each angled slope  228  spans about 160 degrees of a circumference of the body  21 . The slopes  226 ,  228  are alternatively formed, thereby establishing a pair of respective ridges  222 . A protrusion  28  is formed on a periphery of the body  21 . The protrusion  28  is cuboid and is engaged with the cover  802  of the foldable electronic device  800  so that the cam  20  is rotatable with the cover  802 .  
         [0019]     The compression spring  30  advantageously is made of metal and is spiral-shaped (i.e., a coil spring). The disk  40  is C-shaped and is elastically snap fit and thus secured on the shaft  10  in the annular slot  14 . The compression spring  30  abuts against the disk  40 . The disk  40  is retained on the length of the shaft  10  by the stop plate  15 , even under a force created by the compression spring  30 .  
         [0020]     In assembly of the hinge assembly  100 , the second end of the shaft  10  extends through the center cavity  23  of the cam  20  and the compression spring  30 , and the disk  40  is snap fit on the shaft  10  in the annular slot  14 . The compression spring  30  is located between the cam  20  and the disk  40 . One end of the compression spring  30  abuts against the disk  40 . The disk  40 , in turn, biases against the stop plate  15  due to the force of the compression spring  30  (i.e., conversely, the compression spring  30  is biased relative to the stop plate  15  in this manner). An opposite end of the compression spring  30  abuts against the flat face  24  of the cam  20 . The compression spring  30  is slightly compressed, so that the compression spring  30  continuously presses the cam face  22  of the cam  20  against the projections  16  of the shaft  10 . The hinge assembly  100  is thus completely assembled, as shown in  FIG. 3 . In this position, the projections  16  are respectively located on the angled slopes  228  of the cam  20  adjacent the ridges  222  thereof, and the cover  802  of the foldable electronic device  800  is held in a closed position by a lock mechanism (not shown).  
         [0021]     To open the foldable electronic device  800 , the lock mechanism is manually unlocked. Hence, the compression spring  30  decompresses and drives the cam  20  to move relative to the shaft  10 . The cover  802  is correspondingly rotated up from the body  801  and continuously rotated in an opening direction under the decompression force of the compression spring  30 . The cover  802  is thus opened automatically to a fully opened position, a position at which the projections  16  abut against the vertical slopes  226  of the cam  20 .  
         [0022]     To close the foldable electronic device  800 , the cover  802  is manually rotated down toward the body  801 . As such, the cam  20  moves relative to the shaft  10 . The angled slopes  228  of the cam  20  move relative to the projections  16  of the shaft  10 , with the ridges  222  approaching the corresponding projections  16 . Concurrently, the flat face  24  of the cam  20  axially moves toward the second end of the shaft  10  (i.e., toward the stop plate  15 ) and rotates relative to the shaft  10 . As a result, the compression spring  30  is compressed. When the foldable electronic device  800  is in a closed position, the cover  802  is held by the lock mechanism.  
         [0023]     It is to be understood that the compression spring  30  may alternatively be made of another material (e.g., plastic or rubber) and/or have a different configuration (e.g., leaf spring or resilient cylinder).  
         [0024]     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages. The examples hereinbefore described are merely preferred or exemplary embodiments of the invention.