FIELD OF THE INVENTION  
       [0001]     The present invention relates to hinge assemblies and, more particularly, to a hinge assembly for foldable devices such as mobile telephones, portable computers, and so on.  
       DESCRIPTION OF RELATED ART  
       [0002]     With the development of wireless communication and information processing technologies, portable electronic devices such as mobile phones and personal digital assistants (PDA) are appearing in abundance, and consumers can now enjoy the full convenience of high technology anytime and anywhere.  
         [0003]     Portable electronic devices includes several types such as bar type, flip type and folder type so as to satisfy different tastes of different people. A bar type mobile phone, since its keypad is exposed, can easily be damaged or the keypad can be pressed by mistake. A flip type mobile phone, although it was introduced to solve this problem and equipped with a flip to protect the keypad by covering it, shares another problem with the bar type mobile phone that its main body is still too long for convenient transport. Furthermore, the flip type mobile phone fails to satisfy the demand for a larger display screen required for internet access, etc. Thus, a folder type mobile phone has been introduced to shorten the length of the main body of a bar type phone or a flip type phone. However, the hinges that connect the cover and the housing can only open 150 degrees. The folder type mobile phone cannot be opened 180 degrees like a bar type mobile.  
         [0004]     Therefore, a new hinge assembly and a portable electronic device therewith are desired in order to overcome the above-described problems.  
       SUMMARY OF THE INVENTION  
       [0005]     One embodiment of the present hinge assembly includes a connecting member, two cams, two shafts and two elastic elements. The connecting member includes a first sleeve, a second sleeve and a connecting sleeve connected between the first sleeve and the second sleeve. The first sleeve and the second sleeve each have a partition board formed therein. Each partition board includes a plurality of protrusions extending therefrom with a plurality of latching grooves formed between the protrusions. Each cam has at least one latching block and defines an axial hole. Each shaft has a shaft portion. The shaft portion is structured and arranged for passing through the axial hole of each cam and rotating together with each cam. Each elastic element provides an elastic force for each cam so as to hold the cam against a corresponding partition board.  
         [0006]     Other advantages and novel features of the present hinge assembly will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     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.  
         [0008]      FIG. 1  is an exploded, isometric view of an embodiment of the present hinge assembly, as used in a mobile phone;  
         [0009]      FIG. 2  is an exploded, isometric view of the embodiment of the hinge assembly shown in  FIG. 1 ;  
         [0010]      FIG. 3  is an enlarged view of the connecting member in  FIG. 2 ;  
         [0011]      FIG. 4  is a side view of the connecting member in  FIG. 3 ;  
         [0012]      FIG. 5  is an enlarged view of the cam in  FIG. 2 ;  
         [0013]      FIG. 6  is an enlarged view of the barrel in  FIG. 2 ;  
         [0014]      FIG. 7  is a partially cross-sectional view of the hinge assembly in  FIG. 2 ;  
         [0015]      FIG. 8  is an isometric view of the mobile phone in a position corresponding to a closed state;  
         [0016]      FIG. 9  is a cut-away view of  FIG. 8  along the line IX-IX;  
         [0017]      FIG. 10  is an isometric view of the mobile phone in a position corresponding to being opened to 90 degrees;  
         [0018]      FIG. 11  is a cut-away view of  FIG. 10  along the line XI-XI;  
         [0019]      FIG. 12  is an isometric view of the mobile phone in a position corresponding to being opened to 180 degrees; and  
         [0020]      FIG. 13  is a cut-away view of  FIG. 12  along the line XIII-XIII. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0021]     Referring now to the drawings in detail,  FIG. 1  shows a hinge assembly  200 , applied to a foldable electronic device such as a folder type mobile phone  100 , for pivotably coupling a cover  110  and a housing  120 . Although proving particularly advantageous when used in foldable electronic devices, the hinge assembly  200  should not be considered limited in scope solely to an intended use environment of foldable electronic devices.  
         [0022]     The cover  110  includes an upper cover  112  and a lower cover  114 . The upper cover  112  and the lower cover  114  are each substantially a rectangular cavity with an open side, and may be clasped together so as to form the cover  110 .  
         [0023]     The upper cover  112  defines an arcuate cutout  1122  at one end thereof, which communicates the end of the upper cover  112 . The upper cover  112  has a display  16  for showing information on an upper surface thereof. Adjacent to the arcuate cutout  1122 , the upper cover  112  defines a receiving groove  1124  opposite to the display  116 . The receiving groove  1124  is substantially semi-circular.  
         [0024]     The lower cover  114  forms two symmetrically fixed cylinders  1142  at one end thereof. Each fixed cylinder  1142  is substantially cylindrical, and the two fixed cylinders  1142  are positioned opposite to each other. One of the fixed cylinders  1142  defines a reverse rotating groove  1144  with non-circular shape. The other of the fixed cylinders  1142  defines a rotating groove  1146  with a circular shape. A rectangular cavity  1140  is defined between the two fixed cylinders  1142 . An arcuate groove  1148  is defined at one end of the lower cover  114 , and communicates the cavity  1140 .  
         [0025]     The housing  120  includes an upper housing  122  and a lower housing  124 . The upper housing  122  and the lower housing  124  are respectively substantially a rectangular cavity with an open side, and may be clasped each other so as to form the housing  120 . The upper housing  122  has a keypad  126  for inputting information.  
         [0026]     The upper housing  122  defines an arcuate cutout  1222  at one end thereof, which communicates with the end of the upper housing  122 . Adjacent to the arcuate cutout  1222 , the upper housing  122  defines a receiving groove  1224  opposite to the keypad  126 . The receiving groove  1224  is substantially semi-circular.  
         [0027]     The lower housing  124  defines two symmetrically fixed cylinders  1242  at one end thereof. The cylinders  1242  are substantially cylindrical, and are positioned opposite to each other for engaging in the receiving groove  1224 . One of the fixed cylinders  1242  defines a reverse rotating groove  1244  with non-circular shape. The other of the fixed cylinders  1242  defines a rotating groove  1246  with a circular shape. A rectangular cavity  1240  is defined between the two fixed cylinders  1242 . An arcuate groove  1248  is defined at one end of the lower housing  124 , and communicates with the cavity  1240 .  
         [0028]     Referring to  FIG. 2 , the hinge assembly  200 , in the embodiment illustrated, includes a connecting member  10 , two shafts  20 , two cams  30 , two springs  40  and two barrels  50 . The shafts  20 , the cams  30 , the springs  40  and the barrels  50  are received in the connecting member  10 . The hinge assembly  200  is thus integrated into a whole.  
         [0029]     Referring also to  FIGS. 3 and 4 , the connecting member  10  is substantially H-shaped, and includes a first sleeve  12 , a second sleeve  14  and a connecting sleeve  16  perpendicularly connected with each other. The first sleeve  12  is parallel to the second sleeve  14 .  
         [0030]     The first sleeve  12  is substantially a hollow cylinder. A partition board  104  is positioned in a middle of the first sleeve  12 , thereby dividing the first sleeve  12  into two parts. The first sleeve  12  has a circular end for rotatably engaging in the rotating groove  1146 . A limiting block  102  is formed in an inner peripheral wall of the first sleeve  12 , and extends from an opposite end to the partition board  104  along an axis of the first sleeve  12 . The partition board  104  forms two symmetrically opposite first protrusions  1020  and two symmetrically opposite second protrusions  1022 . The first protrusions  1020  and the second protrusions  1022  are located around a periphery of the partition board  104 , and intersect with the peripheral wall of the first sleeve  12 . Each first protrusion  1020  and each second protrusion  1022  is substantially trapeziform in shape. A latching groove  1024  is defined between each first protrusion  1020  and each second protrusion  1022 . An axial hole  108  is defined in a middle of the partition board  104 .  
         [0031]     The second sleeve  14  is substantially a hollow cylinder. The structure of the second sleeve  14  is similar to that of the first sleeve  12 . A partition board  144  is positioned in a middle of the second sleeve  14 , thereby dividing the second sleeve  14  into two parts. The second sleeve  14  has a circular end for rotatably engaging in the rotating groove  1246 . A limiting block  142  is formed in an inner peripheral wall of the second sleeve  14 , and extends from an opposite end to the partition board  144  along an axis of the second sleeve  14 . The partition board  144  forms two symmetrically opposite third protrusions  1040  and two symmetrically opposite fourth protrusions  1042 . The third protrusions  1040  and the fourth protrusions  1042  are located around a periphery of the partition board  144 , and intersect with the peripheral wall of the second sleeve  14 . Each third protrusion  1040  and each fourth protrusion  1042  is substantially trapeziform in shape. A latching groove  1044  is defined between each third protrusion  1040  and each fourth protrusion  1042 . An axial hole  148  is defined in a middle of the partition board  144 .  
         [0032]     The height of the first protrusions  1020 , the second protrusions  1022 , the third protrusions  1040  and the fourth protrusions  1044  are respectively defined as “H 1 ”, “H 2 ”, “H 3 ”, “H 4 ”. “H 1 ”, “H 2 ”, “H 3 ” and “H 4 ” are related by the equation:
 
 H 4 =H 1 &gt;H 2 &gt;H 3.
 
         [0033]     The connecting sleeve  16  is substantially hollow cylinder, and perpendicularly communicates the first sleeve  12  and the second sleeve  14  and vice-versa. The first sleeve  12  and the second sleeve  14  respectively define a wire groove  17 ,  18  adjacent to a corresponding partition board  104 ,  144 . The wire grooves  17  and  18  are used as a passage allowing wires to connect the cover  110  and the housing  120 .  
         [0034]     Each shaft  20  includes a flange portion  22  and a shaft portion  24 . The flange portion  22  is substantially disk-like in shape, and is positioned at one end of the shaft portion  24 . The shaft portion  24  is a deformable shaft structure, and is formed by cutting two flat surfaces. One end of the shaft portion  24  opposite to the flange portion  22  defines a fixed hole  26 .  
         [0035]     Referring also to  FIG. 5 , each cam  30  is substantially disk-like in shape. Each cam  30  has two latching blocks  32  formed at one end thereof. Each latching block  32  is substantially trapeziform in shape so as to engage in corresponding latching grooves  1024 ,  1044 . Each cam  30  defines a positioning groove  34  at a peripheral wall thereof. The positioning groove  34  is located at the same side of the two latching blocks  32 . The positioning groove  34  is arcuate, and the arcuate angle is 90 degrees. Each cam  30  defines a through hole  36  with an elliptical shape in a central area thereof. The size and the shape of the through hole  36  conform with those of the shaft portion  24 .  
         [0036]     Each spring  40  is a cylindrical spring. An inner diameter of each spring  40  is larger than an outer diameter of each shaft portion  24 , thereby allowing each spring  40  to be placed around a corresponding shaft portion  24  of each shaft  20 .  
         [0037]     Referring also to  FIG. 6 , each barrel  50  includes a cylindrical portion  52  and a fixing portion  54  connected to each other. The cylindrical portion  52  defines a limiting groove  520  at a peripheral wall thereof. The limiting groove  520  is substantially arcuate, with an angle of 90 degrees between one end and the other. The cylindrical portion  52  defines a receiving hole  522  at one end thereof opposite to the fixing portion  540  and is used for receiving a corresponding spring  40 . The fixing portion  54  is a deformable shaft. An outer peripheral diameter of the fixing portion  54  is smaller than an outer diameter of the cylindrical portion  52 , thereby forming a step between them. The fixing portion  54  defines two flat surfaces  540  so that the fixing portion  54  may be engaged in the reverse rotating groove  1144  of the cover  110  or the reverse rotating groove  1244  of the housing  120 , and rotates together with the cover  110  or the housing  120 . The fixing portion  54  defines an end hole  542  and a deformable hole  544  opposite to the cylindrical portion  52 . The deformable hole  544  communicates with the receiving hole  522 .  
         [0038]     In assembly, referring to  FIG. 7 , firstly, the shaft portion  24  of one shaft  20  passes through the axial hole  108  of the partition board  104  of the first sleeve  12 , and the flange portion  22  resists one side of the partition board  104  opposite to the protrusions  1020 ,  1022 . Then, the shaft portion  24  is inserted into the through hole  36  of one cam  30 , one spring  40 , the receiving hole  522 , the deformable hole  544  and the end hole  542  of one barrel  50  in that order. Thus, the cam  30 , the spring  40  and the barrel  50  are received in the first sleeve  12 . Owing to the deformable shaft portion  24 , the shaft portion  22  may limit the rotation of the cam  30  and the barrel  50 . Each latching block  32  engages in a corresponding latching groove  1024 , and the limiting block  102  of the first sleeve  12  engages in the positioning groove  34  of the cam  30  and the limiting groove  520  of the barrel  50 . Finally, the shaft  20  is fixed at a distal end by expanded joint so as to connect the above elements. The assembled process of the second sleeve  14  is similar to that of the first sleeve  12 . Thus, the assembled process is not detailed. Accordingly, the hinge assembly  200  is thus completely assembled.  
         [0039]     The assembled hinge assembly  200  is assembled into the foldable electronic device  100 . Firstly, the lower cover  114  is positioned opposite to the lower housing  124 , with the fixed cylinder  1142  opposite to the fixed cylinder  1242 . Next, the first sleeve  12  of the hinge assembly  200  is received in the cavity  1140  of the lower cover  114 , and the second sleeve  14  is received in the cavity  1240  of the lower housing  124 . The two ends of the connecting sleeve  16  respectively engage in corresponding arcuate grooves  1148 ,  1248  so as to connect the lower cover  114  and the lower housing  124 . At the same time, the fixed portion  54  of each barrels  50  engages in a given reverse rotating groove  1144  or  1244 , and the circular ends of the first sleeve  12  and the second sleeve  14  are respectively received in their corresponding rotating grooves  1146 ,  1246 . After that, printed circuit boards are received in the foldable electronic device  100 . Wires pass through the wire groove  17 ,  18  of the connecting member  10  so as to electronically connect the cover  110  and the housing  120 . Finally, the receiving groove  1124  of the upper cover  112  receives the fixed cylinders  1142 , and one end of the connecting sleeve  16  engages in the cutout  1122 . Thus, the upper cover  112  covers the lower cover  114 . The receiving groove  1224  of the upper housing  122  receives the fixed cylinders  1242 , and the other end of the connecting sleeve  16  engages in the cutout  1222 . Thus, the upper housing  122  covers the lower housing  124 . Accordingly, the assembled process of the foldable electronic device  100  is finished.  
         [0040]     Referring to  FIGS. 8 and 9 , when the cover  110  is closed relative to the housing  120 , the latching blocks  32  of the cam  30  of the first sleeve  12  and the second sleeve  14  are respectively engaged in the latching grooves  1024 ,  1044 . Referring to  FIGS. 10 and 11 , if the cover  110  is opened relative to the housing  120 , the cover  110  firstly brings the barrel  50  in the first sleeve  12  to rotate because the heights of the first protrusions  1020 , the second protrusions  1022 , the third protrusions  1040  and the fourth protrusions  1044  are related by the equation H 4 =H 1 &gt;H 2 &gt;H 3 . The barrel  50  further brings the shaft  20  to rotate. Thus, the shaft  20  makes the cam  30  rotate together therewith. Owing to the first protrusions  1020  being larger than the second protrusions  1022 , the latching blocks  32  of the cam  30  rotate counter-clockwise relative to the first sleeve  12 . Thus, the latching blocks  32  slide away from the latching grooves  1024 , and pass over the second protrusion  1022 . Accordingly, the latching blocks  32  are engaged in the next latching groove  1024  between the first protrusion  1020  and the second protrusion  1022 . At the same time, the limiting block  102  of the first sleeve  12  rotates 90 degrees in the positioning groove  34  of the cam  30  and the limiting groove  520  of the barrel  50 . Thus, the cover  110  is opened 90 degrees relative to the housing  120 . Owing to the limiting block  102 , the cover  110  is kept at 90 degrees.  
         [0041]     If the cover  180  is opened to 180 degrees, referring to  FIGS. 12 and 13 , the limiting block  102  of the first sleeve  12  limits the rotation of the cam  30 . Thus, the latching block  32  of the second sleeve  14  slides away from the latching groove  1044 . Owing to the third protrusions  1040  being smaller than the fourth protrusions  1042 , the latching block  32  passes through the third protrusion  1040 , and is engaged in the latching groove  1044  between the fourth protrusion  1042  and the third protrusion  1040 . At the same time, the limiting block  142  of the second sleeve  14  rotates 90 degrees in both the positioning groove  34  of the cam  30  and the limiting groove  520  of the barrel  50 . Thus, the housing  120  is opened 90 degrees relative to the cover  110 . Owing to the limiting block  102 , the housing  120  is kept in 180 degrees state relative to the cover  110 .  
         [0042]     The principles of the closing process are basically the same as the cover  110  of the foldable electronic device  100  is opened. Thus, the closing process is not detailed.  
         [0043]     In an alternative embodiment, the receiving hole  522  of the barrel  50  may be omitted. Accordingly, the spring  40  directly resists an end wall of the barrel  50 .  
         [0044]     In an alternative embodiment, the first protrusion  1020 , the second protrusion  1022 , the third protrusion  120  and the fourth protrusion  122  are not limited to being trapeziform in shape. Alternatively, the configuration may be replaced by concave and convex surfaces. The latching blocks  32  may also be replaced by other structures.  
         [0045]     In an alternative embodiment, the height of the first protrusion  1020 , the second protrusion  1022 , the third protrusion  1040  and the fourth protrusion  1042  are not limited to the above relationship. Alternatively, the height of the first protrusion  1020  can be reversed to the second protrusion  1022 . Then, the housing  120  is firstly opened to an angle of 90 degrees relative to the cover  110 , and the cover  110  is further opened to an angle of 90 degrees relative to the housing  120 .  
         [0046]     Understandably, the connecting member may includes a first connecting portion configured so as to be rotatably received in the housing, a second connecting portion configured so as to be rotatably received in the cover, and a third connecting portion connecting the first connecting portion with the second connecting portion in a manner such that the first connecting portion and the second connecting portion are non-removable relative to each other. The first connecting portion and the second connecting portion respectively define a first rotation axis and a second rotation axis that are parallel to each other. A first rotation limiting unit is configured so as to be engaged between the first connecting portion and the housing in a manner so as to limit the housing to rotate within a first predetermined angle relative to the first rotating axis. A second rotation limiting unit is configured so as to be engaged between the second connecting portion and the cover in a manner so as to limit the cover to rotate within a second predetermined angle relative to the second rotating axis.  
         [0047]     As described above, the hinge assembly  200  may be opened to an angle of 90 degrees so as to view the information on the display  116 . Moreover, the foldable electronic device  100  may be also opened to an angle of 180 degrees. Accordingly, the foldable electronic device  100  is like a bar type mobile phone when opened. Therefore, the foldable electronic device combines the advantages of the bar type mobile phone and the foldable type mobile phone. Understandably, the angle of 90 degrees may be variable, and be replaced by other angles.  
         [0048]     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 merely being preferred or exemplary embodiments of the invention.
A hinge assembly ( 200) includes a connecting member ( 10), two cams ( 30), two shafts ( 20), two elastic elements ( 40) and two barrels ( 50). The connecting member includes a first sleeve ( 12), a second sleeve ( 14) and a connecting sleeve ( 16) connected between. The first sleeve and the second sleeve each have respective partition boards ( 104, 144) formed therein. Each partition board includes a plurality of protrusions extending therefrom with a plurality of latching grooves formed between the protrusions. Each cam includes at least one latching block ( 32) and defines an axial hole ( 36). Each shaft has a shaft portion ( 24), and the shaft portion is configured for passing through the axial hole of each cam. Each elastic element provides an elastic force for each cam so as to hold the cam against the protrusions.