Abstract:
A lens actuator for driving a lens to move includes a lens barrel for accommodating the lens, a coil warped around the lens barrel, a fixed barrel, the lens barrel being received in and linearly movable relative to the fixed barrel, a plate shaped body including a through hole defined in a center thereof and a peripheral portion around the through hole, the flat spring plate&#39;s peripheral portion being fixed to one end of the fixed barrel. The fixed barrel is comprised of a permanent magnetic material.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is related to commonly-assigned co-pending application Ser. No. 12/192376, entitled “resilient plate and lens actuator with same”. Disclosure of the above-identified application is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention generally relates to lens actuators, and particularly to a voice coil motor type lens actuator and a fixing unit in the actuator. 
         [0004]    2. Description of Related Art 
         [0005]    Variable focal length lenses are widely used in optical systems. Optical systems incorporating such lenses can, for example, provide focused images of objects at varying distances without adjusting the distance between the lens and the image plane. Variable focal length lenses can also be used in optical systems that provide varying magnification without change of lenses. 
         [0006]    Generally, the optical system usually includes an actuator, such as a stepping motor, to drive the lenses. However, the step motor is relatively large in volume. Use of the step motor requires a significant amount of space for movement of the lenses, which makes the optical system bulky. 
         [0007]    Therefore, what is needed is a lens actuator adapted for driving the lenses with more compact structure and less mechanical movement. 
       SUMMARY 
       [0008]    A lens actuator for driving a lens to move includes a lens barrel for accommodating the lens, a coil warped around the lens barrel, a fixed barrel, the lens barrel being received in and linearly movable relative to the fixed barrel, a plate shaped body including a through hole defined in a center thereof and a peripheral portion around the through hole, the flat spring plate&#39;s peripheral portion being fixed to one end of the fixed barrel. The fixed barrel is comprised of a permanent magnetic material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Many aspects of the present embodiments 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 embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0010]      FIG. 1  is a schematic, isometric view of a lens actuator according to an exemplary embodiment, the lens actuator including a fixed barrel and a flat spring plate. 
           [0011]      FIG. 2  is an exploded view of the lens actuator in  FIG. 1 . 
           [0012]      FIG. 3  is a schematic, isometric view of the fixed barrel in  FIG. 2 . 
           [0013]      FIG. 4  is a schematic, isometric view of the flat spring plate in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0014]    Referring to  FIGS. 1 and 2 , a lens actuator  10 , in accordance with an exemplary embodiment, includes a housing  20 , a fixed barrel  30 , a movable unit  40 , two flat spring plates ( 50 ,  50   a ), and a board  60 . 
         [0015]    The housing  20  includes a roof plate  22 , a through hole  222  defined in the center of the roof plate  22 , two opposite first side plates  24  and two opposite second side plates  26  respectively perpendicularly extending from the four peripheral sides of the roof plate  22  and fastened to one another by a dovetail panel joint (not shown). The roof plate  22 , the first side plates  24 , and the second side plates  26  cooperatively define a cavity for accommodating the fixed barrel  30 . The housing  20  may be made of electromagnetic shield material, such as ferronickel alloy, electrically conductive plastic, surface conductive material, electrically conductive glass, etc. 
         [0016]    The fixed barrel  30  may be made of (refer to  FIG. 3 ) a permanent magnetic material, such as NdFeB alloy, Samarium-Cobalt Alloy, Alnico, etc. The fixed barrel  30  is configured to be received in the housing  20  and comprises a main body  31 . In this embodiment, the shape of a cross section of the main body  31  is square. 
         [0017]    The shape of the cross section of the main body  31  may be round, triangle, pentagon or hexagon, etc. 
         [0018]    A first accommodation room  301  is defined in the main body  31 . Four first locating pins  303  are respectively vertically protruded from the top and bottom sides of the main body  31  at each corner thereof. The first locating pins  303  are configured for locating and fastening the fixed barrel  30  to both the flat spring plate plates ( 50 ,  50   a ). A terminal groove  305  is formed on the outer wall of the main body  31 . 
         [0019]    Referring to  FIG. 2 , the movable unit  40  includes a lens barrel  41  and coils  42 . The movable unit  40  is accommodated in the first accommodating room  301  and may be movable relative to the fixed barrel  30 . The lens barrel  41  defines a second accommodating room  412  for accommodating lenses and filters (not shown). The second accommodating room  412  is a through hole. Four convex stages  416  are respectively protruded from the top and bottom sides of the lens barrel  41  at each corner thereof. A second locating pin  413  is protruded from the top surface of the each of the convex stage  416 . Two grooves  414  are defined on an outer sidewall of each convex stage  416 . The grooves  414  are configured for receiving an adhesive material therein. The two flat spring plates ( 50 ,  50   a ) are respectively glued (i.e., adhesively mounted) to the top and bottom sides of the lens barrel  41  by adhesive, so as to respectively link the two flat spring plates with the lens barrel  41 . The coils  42  are warped around the outer wall of the lens barrel  41 . 
         [0020]    Referring to  FIG. 4 , the first flat spring plate  50  comprises a plate shaped body  51 . In the present embodiment, the shape of the plate shaped body  51  is quadrate. The plate shaped body  51  includes a first edge  511   a , a second edge  511   b , a third edge  511   c , and a fourth edge  511   d . The first edge  511   a  is parallel to the third edge  511   c , and the second edge  511   b  is parallel to the fourth edge  511   d . A second through hole  510  for light passing therethrough is defined at the center of the plate shaped body  51 . A first slot  52 , a second slot  53 , a third slot  54  and a fourth slot  55  are defined in the plate shaped body  51  around the second through hole  510 . The slots ( 52 ,  53 ,  54 ,  55 ) are oriented about 90 degrees with respect to each other. 
         [0021]    The first slot  52  includes a first starting portion  521   a , a first ending portion  521   b , and a first connecting portion  521   c . The first starting portion  521   a  is parallel to the first edge  511   a . The first ending portion  521   b  is parallel to the third edge  511   c . The first connecting portion  521   c  is parallel to the second edge  511   b  and connected with the first starting portion  521   a  and the first ending portion  521   b . The length of the first ending portion  521   b  is less than or equal to that of the first starting portion  521   a . A first fixing portion  56   a  is formed between the second through hole  510  and the angular part or space between the first ending portion  521   b  and the first connecting portion  521   c.    
         [0022]    The second slot  53  includes a second starting portion  531   a , a second ending portion  531   b , and a second connecting portion  531   c . The second starting portion  531   a  is parallel to the second edge  511   b . The second ending portion  531   b  is parallel to the fourth edge  511   d . The second connecting portion  531   c  is parallel to the third edge  511   c  and connected with the second starting portion  531   a  and the second ending portion  531   b . The length of the second ending portion  531   b  is less than or equal to that of the second starting portion  531   a . A second fixing portion  56   b  is formed between the second through hole  510  and the angular part or space between the second ending portion  531   b  and the second connecting portion  531   c . The second starting portion  531   a  and the second connecting portion  531   c  are on the outer side of the first slot  52 , i.e., the second starting portion  531   a  and the second connecting portion  531   c  are closer to the second edge  511   b  and the third edge  511   c  than the first slot  52 . A first L-shaped spring portion  57   a  is arranged between the first slot  52  and the second slot  53 . The spring portion  57   a  has a uniform width throughout the length thereof. Since the L-shaped spring portion  57   a  has an angular part or space, the durability and flexibility of the first flat spring plate  50  is enhanced. 
         [0023]    The third slot  54  includes a third starting portion  541   a , a third ending portion  541   b , and a third connecting portion  541   c . The third starting portion  541   a  is parallel to the third edge  511   c . The third ending portion  541   b  is parallel to the first edge  511   a . The third connecting portion  541   c  is parallel to the fourth edge  511   d  and connected with the third starting portion  541   a  and the third ending portion  541   b . The length of the third ending portion  541   b  is less than or equal to that of the third starting portion  541   a . A third fixing portion  56   c  is formed between the second through hole  510  and the angular part or space between the third ending portion  541   b  and the third connecting portion  541   c . The third starting portion  541   a  and the third connecting portion  541   c  are on the outer side of the second slot  53 , i.e., the third starting portion  541   a  and the third connecting portion  541   c  are closer to the third edge  511   c  and the fourth edge  511   d  than the second slot  53 . A second L-shaped spring portion  57   b  is formed between the second slot  53  and the third slot  54 . 
         [0024]    The fourth slot  55  includes a fourth starting portion  551   a , a fourth ending portion  551   b , and a fourth connecting portion  551   c . The fourth starting portion  551   a  is parallel to the fourth edge  511   d . The fourth ending portion  551   b  is parallel to the second edge  511   b . The fourth connecting portion  551   c  is parallel to the first edge  511   a  and connected with the fourth starting portion  551   a  and the fourth ending portion  551   b . The length of the fourth ending portion  551   b  is less than or equal to that of the fourth starting portion  551   a . A fourth fixing portion  56   d  is formed between the second through hole  510  and the angular part or space between the fourth ending portion  551   b  and the fourth connecting portion  551   c . The fourth starting portion  551   a  and the fourth connecting portion  551   c  are on the outer side of the third slot  54 , i.e., the fourth starting portion  551   a  and the fourth connecting portion  551   c  are closer to the fourth edge  511   d  and the first edge  511   a  than the third slot  54 . A third L-shaped spring portion  57   c  is formed between the third slot  54  and the fourth slot  55 . The first starting portion  521   a  and the first connecting portion  521   c  are on the outer side of the fourth slot  55 , i.e., the first starting portion  521   a  and the first connecting portion  521   c  are closer to the first edge  511   d  and the first edge  511   a  than the fourth slot  55 . A fourth L-shaped spring portion  57   d  is formed between the fourth slot  55  and the first slot  52 . 
         [0025]    Each fixing portion ( 56   a ,  56   b ,  56   c ,  56   d ) defines a first cutout  561  at the edge of the second through hole  510  corresponding to the respective second locating pins  413 . Each fixing portion ( 56   a ,  56   b ,  56   c ,  56   d ) further defines two holes  563  set around the first cutout  561 . The two holes  563  are corresponding to the grooves  414 . The fixing portion further ( 56   a ,  56   b ,  56   c ,  56   d ) defines a second cutout  562  around the second through hole  510  for fixing one end of the coils  42  therein. 
         [0026]    A peripheral portion  58  is formed between the edges ( 511   a ,  511   b ,  511   c  and  511   d ) and the starting portions ( 521   a ,  531   a ,  541   a  and  551   a ). Four holes  582  corresponding to the respective first locating pins  303  are defined in the peripheral portion  58  in four corners. The peripheral portion  58  is fastened to the top side of the fixed barrel  30  by engagement of the holes  582  with the respective first locating pins  303 . 
         [0027]    Most of the structure of the second flat spring plate  50   a  is similar to that of the first flat spring plate  50 , except that, the first flat spring plate  50  includes a first terminal  501  perpendicular to one side thereof and the second flat spring plate  50   a  includes a second terminal  502  perpendicular to one side thereof. 
         [0028]    The lens actuator  10  may only have a first flat plate  50  or a second flat plate  50   a.    
         [0029]    The board  60  is corresponding to the housing  20  to form a corresponding room to accommodate the fixed barrel  30 , the lens barrel  40 , the first flat spring plate  50   a  and the second flat spring plate  50   a . The board  60  comprises a body  61  covered over the second flat spring plate  50   a  on the bottom side of the housing  30 , an through hole  62  corresponding to the second accommodating room  412  of the lens barrel  41 , four holes  63  respectively fastened to the first locating pins  303  at the bottom side of the fixed barrel  30 . 
         [0030]    The first terminal  501  is mounted in the terminal groove  305  of the fixed barrel  32  and electrically connected to the coils  42 . The second terminal  502  is electrically connected to the coils  42 . 
         [0031]    When an electric current is applied to the terminals  501 ,  502  and the coils  42 , the coils  42  are excited to act upon the magnets  34 , thereby receiving a magnetic force to drive the lens barrel  42  to linearly move along its central axis. 
         [0032]    When electric current is cut off from the terminals  501 ,  502 , the first flat spring plate  50  and the second flat spring plate  50   a  impart a restoring force to the lens barrel  41 , thereby returning the lens barrel  41  to its former position. 
         [0033]    Furthermore, the housing  20  and the board  60  protect the lens barrel  41  and image sensor (not shown) against dust. 
         [0034]    While certain embodiments have been described and exemplified above, various other embodiments will be apparent to those skilled in the art from the foregoing disclosure. The present invention is not limited to the particular embodiments described and exemplified but is capable of considerable variation and modification without departure from the scope of the appended claims.