Patent Publication Number: US-2010107369-A1

Title: Hinge assembly

Description:
CROSS REFERENCE STATEMENT 
     This application is related to co-pending U.S. patent applications, which are applications Ser. Nos. 12/261225, 12/261230, and both entitled “HINGE ASSEMBLY”. In the co-pending applications, the inventors are Jin-Xin Wang, Xiao-Bo Li and Lian-Cheng Huang. The co-pending applications have the same assignee as the present application. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to hinge assemblies and, more particularly, to a hinge assembly used in an electronic device. 
     2. Description of Related Art 
     An electronic device such as a mobile phone, a notebook computer, or a personal digital assistant, generally has a main body and a display cover pivotally mounted on the main body via a hinge assembly. 
     A typical hinge assembly includes a shaft, a cam, a cam follower and an elastic member. The cam defines a recess in a side surface, and forms a protrusion on the side surface adjoining the recess via a slanted surface. The cam follower forms a protrusion corresponding to the recess of the cam, and defines a recess corresponding to the protrusion of the cam. The cam is non-rotatably connected to the shaft. The cam follower is rotatably connected to the shaft. The elastic member is sleeved on the shaft to provide an elastic force to drive the cam follower to contact with the cam. 
     The typical hinge assembly may be retained at a predetermined position when the cam is engaged with the cam follower. When rotating the typical hinge assembly to close, the protrusion of the cam follower contacts the slanted surface of the cam, and the elastic force generated by the elastic member drives the protrusion of the cam follower to slide along the slanted surface and engage in the recess of the cam. Thus, the typical hinge assembly can be automatically closed after manually rotating to a certain position. 
     However, if the slanted surface of the cam is too steep, the protrusion of the cam follower engages in the recess of the cam too quickly. As a result, the typical hinge assembly will close suddenly, thus introducing a shock or impact to a display cover of an electronic device. If the slanted surface of the cam is too gentle, the typical hinge assembly will close slowly, or be incapable of completely closing. Moreover, the protrusion of the cam follower may easily detach from the recess of the cam. As a result, the display cover may not be stably closed on a main body of the electronic device. 
     What is needed, therefore, is a new hinge assembly that overcomes the above mentioned disadvantages. 
    
    
     
       BRIEF DESCRIPTION OF THE 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 disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and all the views are schematic. 
         FIG. 1  is an exploded, isometric view of a first embodiment of a hinge assembly, the hinge assembly including a cam and a cam follower. 
         FIG. 2  is an isometric view of the cam follower of the hinge assembly in  FIG. 1 . 
         FIG. 3  is similar to  FIG. 1 , but viewed from another aspect. 
         FIG. 4  is an assembled, isometric view of the hinge assembly in  FIG. 1 . 
         FIG. 5  is a plan view showing the cam engaging with the cam follower in a first position. 
         FIG. 6  is a plan view showing the cam engaging with the cam follower in a second position. 
         FIG. 7  is a plan view of a second embodiment of a hinge assembly, showing a cam engaging with a cam follower. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a first embodiment of a hinge assembly  10  includes a rotatable shaft  11 , a rotatable stand  12 , a fixed stand  13 , a cam  14 , a cam follower  15 , a restricting member  16 , an elastic member  17 , two friction members  18 , a washer  19  sleeved on the rotatable shaft  11 , and a fastening member  101  latched on an end of the rotatable shaft  11 . 
     Referring to  FIGS. 2 and 3 , a cross-section of the rotatable shaft  11  perpendicular to a rotating axis of the rotatable shaft  11  is double-D shaped. A flange  111  is formed on a first end of the rotatable shaft  11 , and a threaded portion  112  may be formed on a second end of the rotatable shaft  11 . A shaft head  113  extends from the flange  111  along an extending direction of the rotatable shaft  11 . 
     The rotatable stand  12  includes a flat plate  121 . The flat plate  121  defines a plurality of fixing holes  1211 . A positioning piece  122  extends substantially perpendicularly from a side of the flat plate  121 . The positioning piece  122  defines a non-circular pivot hole  1221  corresponding to the shape of the shaft head  113  of the rotatable shaft  11 . 
     The fixed stand  13  includes a fixing plate  131  and a supporting plate  132  extending substantially perpendicularly from a side of the fixing plate  131 . The fixing plate  131  defines a plurality of fixing holes  1311 . The supporting plate  132  defines a circular pivot hole  1321  in an end away from the fixing plate  131 , and an assembling hole  1322  in a middle portion. The supporting plate  332  also forms a limiting protrusion  1323 , and defines a plurality of lubricant grooves  1324  adjacent to the pivot hole  1321 . 
     The cam  14  may be substantially fan-shaped, and defines a circular cam hole  141  in a center portion. A fixing pole  142  extends from an end of the cam  14 . The cam  14  also forms two positioning protrusions  143  in a side surface. Two side walls of each positioning protrusion  143  are slanted surfaces. 
     The cam follower  15  may be substantially cylindrical. A center of the cam follower  15  defines a non-circular through hole  151  corresponding to the shape of the cross-section of the rotatable shaft  11 . The cam follower  15  defines two positioning grooves  152  in a side surface  150  corresponding to the positioning protrusions  143  of the cam  14 . Each positioning groove  152  has two side walls, each side wall includes a first slanted surface  1521  and a second slanted surface  1522  connected to each other. The first slanted surface  1521  is adjacent to the side surface  150 . The second slanted surface  1522  is adjacent to a bottom surface of the positioning groove  152 . A gradient of the first slanted surface  1521  relative to the bottom surface of the positioning groove  152  is smaller than that of the second slanted surface  1522  relative to the bottom surface of the positioning groove  152 . 
     In alternative embodiments, the positioning grooves  152  may be defined in the cam  14 , and the positioning protrusions  143  may be formed on the cam follower  15 . In addition, the number of the positioning protrusions  143  and the corresponding number of the positioning grooves  152  may be any desired number, such as one, three, four, five, or more. 
     The restricting member  16  includes a substantially circular main portion  160 . A center of the main portion  160  defines a non-circular through hole  161  corresponding to the shape of the cross-section of the rotatable shaft  11 . A restricting portion  162  is formed at an edge of the main portion  160 . In the illustrated embodiment, the restricting portion  162  is an arched protrusion extending radially from an edge of the main portion  160 . The restricting portion  162  forms a first limiting surface  1621  and a second limiting surface  1622  on opposite ends. 
     In the illustrated embodiment, the elastic member  17  is a plurality of spring washers. The elastic member  17  may be other elastic components, such as a helical spring. 
     The friction member  18  defines a circular through hole  181  in a center portion, and defines a plurality of lubricant grooves  182  in a side surface. 
     The washer  19  defines a non-circular through hole  191  in a center portion corresponding to the shape of the cross-section of the rotatable shaft  11 . 
     The fastening member  101  may be a nut to engage with the threaded portion  112  of the rotatable shaft  11 . 
     Referring also to  FIG. 4 , the rotatable shaft  11  is passed through one friction member  18 , the non-circular through hole  161  of the restricting member  16 , the pivot hole  1321  of the fixed stand  13 , the other friction member  18 , the cam hole  141  of the cam  14 , the through hole  151  of the cam follower  15 , the elastic member  17 , the washer  19 , and engaged with the fastening member  101 . The fixing pole  142  of the cam  14  is inserted into the assembling hole  1322  of the fixed stand  13 . The positioning protrusions  143  of the cam  14  engage in the corresponding positioning grooves  152  of the cam follower  15 . The shaft head  113  engages in the pivot hole  1221  of the rotatable stand  12 . Therefore, the rotatable stand  12 , the cam follower  15 , the restricting member  16 , and the washer  19  are non-rotatably connected to the rotatable shaft  11 . The fixed stand  13  and the cam  14  are rotatably connected to the rotatable shaft  11 . 
     When the hinge assembly  10  is applied in an electronic device (not shown), the rotatable stand  12  and the fixed stand  13  are fixed on a display cover and a main body of the electronic device, respectively. When opening the electronic device, the rotatable stand  12  rotates with the rotatable shaft  11 , for example, in a clockwise direction, thus driving the cam follower  15  to rotate. The positioning protrusions  143  of the cam  14  slide out from the positioning grooves  152  of the cam follower  15 . The elastic member  17  becomes compressed and provides an elastic force along the rotatable shaft  11 , thus enabling the components of the hinge assembly  10  to contact each other tightly. When the display cover reaches a desired angle, the desired angle of the display cover relative to the main body can be retained via the frictional forces generated between the components of the hinge assembly  10 . The first and second limiting surfaces  1621 ,  1622  of the restricting member  16  are configured to block the limiting protrusion  1323  of the fixed stand  13 , thus defining a rotatable range of the rotatable stand  12 . 
     When closing the electronic device, the rotatable stand  12  rotates with the rotatable shaft  11 , for example, in a counterclockwise direction, thus driving the cam follower  15  to rotate. The positioning protrusions  143  of the cam  14  are close to the positioning grooves  152  of the cam follower  15 . After the display cover is manually rotated to a certain position, the elastic force provided by the elastic member  17  drives the positioning protrusions  143  of the cam  14  to engage in the positioning grooves  152  of the cam follower  15 , thus driving the display cover to close on the main body automatically. 
     Referring to  FIGS. 5 and 6 , the positioning protrusion  143  engages with the first slanted surface  1521  of the positioning groove  152 , causing the display cover to close slowly due to the small gradient of the first slanted surface  1521 , until the positioning protrusion  143  engages with the second slanted surface  1522  of the positioning groove  152 . The display cover then closes quickly due to the large gradient of the second slanted surface  1522 , until the display cover folds on the main body. 
     Since the first slanted surface  1521  has a buffering effect to prevent the display cover from closing quickly from a large angle, the shock or impact of the display cover is minimized or avoided. In addition, the second slanted surface  1522  facilitates the display cover to close quickly at the moment of closure. This quick closure does not impart shock or cause impact to the display cover, because the angle between the display cover and the main body allowing the display cover to close quickly is very small. Moreover, the positioning protrusions  143  are stably engaged in the positioning grooves  152  due to the large gradient of the second slanted surface  1522 , so that the display cover is stably closed on the main body. 
     The angle between the display cover and the main body during the beginning of the automatic closure depends on the lengths of the first and second slanted surface  1521 ,  1522 . For example, when the angle between the display cover and the main body is about 10 degrees, the display cover begins to close slowly. When the angle between the display cover and the main body is about 2 degrees, the display cover begins to close quickly. 
     Referring to  FIG. 7 , a second embodiment of a hinge assembly  20  is similar in principle to the first embodiment of the hinge assembly  10 , except that the cam  24  forms two positioning protrusions  243  in a side surface  240 . Each positioning protrusion  243  has two side walls, each side wall includes a first slanted surface  2431  and a second slanted surface  2432  connected to each other. The first slanted surface  2431  is adjacent to a top surface of the positioning protrusion  243 . The second slanted surface  2432  is adjacent to the side surface  240 . A gradient of the first slanted surface  2431  relative to the top surface of the positioning protrusion  243  is smaller than that of the second slanted surface  2432  relative to the top surface of the positioning protrusion  243 . The cam follower  25  defines two positioning grooves  252  corresponding to the positioning protrusions  243 , and two side walls of each positioning groove  252  are slanted surfaces. 
     During the automatic closure of the display cover, the first slanted surface  2431  of the positioning protrusion  243  engages in the positioning groove  252 , causing the display cover to close slowly due to the small gradient of the first slanted surface  2431 , until the second slanted surface  2432  of the positioning protrusion  243  engages in the positioning groove  252 . The display cover then closes quickly due to the large gradient of the second slanted surface  2432 , until the display cover folds on the main body. 
     In alternative embodiments, the positioning protrusions  243  may be formed on the cam follower  25 , and the positioning grooves  252  may be defined in the cam  14 . In addition, the number of the positioning protrusions  243  and the corresponding number of the positioning grooves  252  may be any desired number, such as one, three, four, five, or more. 
     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 disclosure or sacrificing all of its material advantages.