Abstract:
A voice coil motor includes a fixing assembly and a piston assembly movably received in the fixing assembly. The fixing assembly includes a fixing frame and one or more magnetic members positioned on the fixing frame. The piston assembly includes a lens and a coil sleeved on the lens. The coil and the lens cooperatively define a receiving groove. The fixing frame forms one or more resisting portions. The fixing frame sleeves on the lens with the resisting portions engaging in the receiving groove, such that the coil together with the lens is capable of moving along the at least one resisting portion utilizing the magnetic force generated by the magnetic members.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure generally relates to voice coil motors, and particularly to a voice coil motor for a lens module. 
         [0003]    2. Description of the Related Art 
         [0004]    A voice coil motor has a small size, small power consumption and is of a low price, thus the voice coil motor is suitable for zooming or focusing a camera module. The voice coil motor includes a fixing assembly, rotary assembly positioned in the fixing assembly, and a plurality of magnetic members. In assembly of the camera module, the voice coil motor is fixed on the image sensor, and then, a barrel of the lens module is screwed into the rotary assembly. However, a threaded portion(s) needs to be formed in the rotary assembly and the barrel of the lens module, therefore, the voice coil motor is difficult to manufacture. In addition, in assembly of the camera module, an operator must spend a significant amount of time manually screwing the lens module into place, thereby resulting in lower assembly efficiency. 
         [0005]    Therefore, there is room for improvement within the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0006]    The components in the drawings are not necessarily drawn to scale, the emphasis instead placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0007]      FIG. 1  is an isometric, assembled view of an embodiment of a lens module including a support assembly, a piston assembly, and a fixing assembly. 
           [0008]      FIG. 2  is an isometric, exploded view of the lens module of  FIG. 1 . 
           [0009]      FIG. 3  is similar to  FIG. 2 , but viewed from another aspect. 
           [0010]      FIG. 4  is an isometric, exploded view of the support assembly of  FIG. 3 . 
           [0011]      FIG. 5  is an isometric, exploded view of the piston assembly of  FIG. 3 . 
           [0012]      FIG. 6  is an isometric, exploded view of the fixing assembly of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring to  FIG. 1 , an embodiment of a lens module  100  includes an image sensing unit  10  and a voice coil motor  30  is shown. Referring to  FIGS. 2 and 3 , the image sensing unit  10  includes a base plate  11  and an image sensor  13  positioned on the base plate  11 . The voice coil motor  30  is positioned on the base plate  11 , and includes a support assembly  31 , a piston assembly  33 , a fixing assembly  35 , and a front cover  39 . 
         [0014]    Referring to  FIGS. 2 through 4 , the support assembly  31  includes a support base  311  and a plurality of connecting pieces  313  positioned on the support base  311 . The support base  311  includes a main body  3111  and a plurality of support portions  3113  formed on the main body  3111 . The main body  3111  is substantially rectangular, and defines a plurality of assembly holes  3115  in an edge of the main body  3111  for receiving the connecting pieces  313 . The main body  3111  defines a circular penetrating hole  3116  in a center portion thereof, and a first assembly groove  3117  in a top surface thereof for receiving the piston assembly  33 , and a second assembly groove  3119  in a bottom surface thereof for receiving the base plate  11 . The main body  3111  further forms a plurality of positioning poles  3118  on the top surface thereof for positioning the connecting pieces  313  and the piston assembly  33 . 
         [0015]    The connecting pieces  313  are substantially L-shaped. Each connecting piece  313  includes a connecting portion  3131  and a positioning portion  3133  substantially perpendicularly extending from an end of the connecting portion  3131 . The connecting portion  3131  extends through the assembly hole  3115  of the main body  3111 , and the positioning portion  3133  defines a receiving hole  3135  for receiving the positioning pole  3118 . 
         [0016]    Referring to  FIGS. 2 ,  3  and  5 , the piston assembly  33  includes a lens  331 , a first elastic piece  335 , and a coil  337 . The lens  331  includes a main portion  3311 , an assembly portion  3313 , and a positioning portion  3314 . The assembly portion  3313  and the positioning portion  3314  are formed on opposite sides of the main portion  3311 . The main portion  3311  is positioned in the first assembly groove  3117  of the support base  311 . In the illustrated embodiment, the main portion  3311  is octagonal. The assembly portion  3313  is cylindrical, and defines an assembly hole  3315  penetrating the assembly portion  3313  and the main portion  3311 . A plurality of restricting protrusions  3317  is formed on an outer surface of the assembly portion  3313  for positioning the coil  337 . The positioning portion  3314  is substantially annular, and used for positioning the first elastic piece  335 . 
         [0017]    The first elastic piece  335  is substantially rectangular, and defines a through hole  3351 . The first elastic piece  335  defines a plurality of positioning holes  3353  for receiving the positioning poles  3118  of the support base  311 . The coil  337  is octagonal, and sleeves on the restricting protrusions  3317  of the assembly portion  3313 , thereby forming a receiving groove  3318  (see  FIG. 2 ) between the coil  337  and the lens  331 . The coil  337  is electrically connected to an outer circuit (not shown). 
         [0018]    Referring to  FIGS. 2 ,  3  and  6 , the fixing assembly  35  includes a fixing frame  351 , a second elastic piece  353 , and a plurality of magnetic members  355 . The fixing frame  351  is positioned on the support portion  3113  of the support base  311 , and sleeves on the lens  331 . The fixing frame  351  includes a top plate  3511  and a side plate  3513  which is substantially perpendicular extending from an edge of the top plate  3511 . The top plate  3511  defines a penetrating hole  3515 , and the lens  331  extends through the penetrating hole  3515 . The top plate  3511  further defines four connecting holes  3516  in the edge corners thereof. A plurality of resisting portions  3517  extend from an inner rim of the penetrating hole  3515  and towards the inner side of the fixing frame  351 . The resisting portions  3517  are received in the receiving groove  3318  of the piston assembly  33 . 
         [0019]    The second elastic piece  353  is substantially rectangular, and defines a through hole  3531  in a center portion thereof. The second elastic piece  353  further defines a plurality of limiting holes  3533  around the through hole  3531  for receiving the resisting portions  3517 . 
         [0020]    Each magnetic member  355  has a triangular prism shape, and is positioned in the inner side of the fixing frame  351 ; and each magnetic member  355  is opposite to one resisting portion  3517 . When the resisting portions  3517  are received in the receiving groove  3318  of the piston assembly  33 , the magnetic members  355  are arranged opposite to the coil  337 . In the illustrated embodiment, the fixing assembly  35  has four magnetic members  355  and four resisting portions  3517 . The magnetic members  355  are permanent magnets. 
         [0021]    The front cover  39  is fixed on the fixing frame  351 , and defines an assembly hole  391  in a center portion thereof. The front cover  39  forms a plurality of fixing poles  393  engaging in the connecting holes  3516  of the fixing frame  351 . 
         [0022]    Referring to  FIGS. 1 through 6 , in assembly of the lens module  100 , the base plate  11  of the image sensing unit  10  is positioned in the second assembly groove  3119  of the support assembly  31 . The first elastic piece  335  sleeves on the positioning portion  3314  of the lens  331 , and then the positioning portion  3314  is positioned on the support portion  3113 . The coil  337  sleeves on the restricting protrusion  3317  of the assembly portion  3313 . The magnetic members  355  are positioned in the inner side of the fixing frame  351 . The second elastic piece  353  is positioned on the resisting portions  3517  of the fixing frame  351 , and abuts the magnetic members  355 . The fixing frame  351  sleeves on the lens  331 , with the resisting portions  3517  engaging in the receiving groove  3318  of the lens  331 . Then the magnetic members  355  are arranged opposite to the coil  337 . The front cover  39  is fixed on the fixing frame  351 , with the lens  331  extending through the assembly hole  391  of the front cover  39 . 
         [0023]    In use, the coil  337  is electrically connected to the outer circuit. As a result of current applied, a magnetic force acts on the coil  337  due to the magnetic field formed by the four magnetic members  355 . Then, the lens  331  is driven to move up along the resisting portions  3517 . When the coil  337  is disconnected from the outer circuit, the magnetic force ceases, and thus the lens  331  will move down along the resisting portions  3517  simply due to force of gravity. 
         [0024]    In assembly of the lens module  100 , the coil  337  of the voice coil motor  30  is sleeved on the lens  331 , the resisting portions  3517  of the fixing frame  351  is engaged in the receiving groove  3318 , and the fixing frame  351  is positioned on the support base  311 . Therefore, the lens module  100  is very easily assembled together, and there is no need to machine a plurality of threaded portions on the lens  331  and the piston assembly  33  as found in the lens module of related art, thereby resulting in higher assembly efficiency. 
         [0025]    In alternative embodiments, the support assembly  31  can be omitted, and the image sensing unit  10  can be directly positioned on the fixing assembly  35 . The fixing assembly  35  may have only one magnetic member  355  or more than two magnetic members  355 . The fixing frame  351  may form only one resisting portion  3517  or have more than two resisting portions  3517 . 
         [0026]    While the present disclosure has been described with reference to particular embodiments, the description is illustrative of the disclosure and is not to be construed as limiting the disclosure. Therefore, various modifications can be made to the embodiments by those of ordinary skill in the art without departing from the true spirit and scope of the disclosure, as defined by the appended claims.