Abstract:
There is provided a lens module including: an actuator moving a lens barrel in an optical axis direction; and a housing having a mounting part on which the actuator is mounted, wherein the actuator includes a piezoelectric member and a bar member vibrated by the piezoelectric member, and the bar member line-contacts the mounting part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2013-0067027 filed on Jun. 12, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a lens module, and more particularly, to a lens module in which a lens barrel moves using a smooth impact drive mechanism (SIDM) scheme. 
         [0004]    2. Description of the Related Art 
         [0005]    A high performance lens module commonly has an autofocus function in order to improve resolution. That is, such a high performance lens module includes an actuator moving a lens barrel in an optical axis direction. 
         [0006]    Two types of actuator are mainly used to move a lens barrel. One type thereof has a structure using a permanent magnet and a coil, while the other type has a structure using a piezoelectric member. Here, since the former moves the lens barrel due to a change in magnetic force generated in the coil, the lens barrel may be moved relatively rapidly. However, since a member such as a spring, or the like, for supporting the lens barrel is required, a structure of the lens module may be relatively complicated. 
         [0007]    In contrast thereto, since the latter has a comparatively simple structure and may move the lens barrel relatively rapidly, it may be effectively applied to a small lens module. However, in the latter, since it may be difficult to align and fix a position of the actuator with respect to a housing, a tilt phenomenon may occur in the lens barrel due to a mounting defect of the actuator. 
         [0008]    As the related art associated with the present invention, there is provided Patent Document 1. Patent Document 1 discloses a structure of fitting and fixing one end of a rod  42  into a hole  526  of a housing  5 . However, since the structure disclosed in Patent Document 1 is a structure in which only one end of the rod  42  is slightly fitted into the hole  526  of the housing  5 , it is difficult to improve mounting precision of the rod  42  with respect to the housing  5 , a tilt phenomenon of the lens barrel may easily occur. 
       RELATED ART DOCUMENT 
       [0000]    
       
         (Patent Document 1) KR2012-088794 A 
       
     
       SUMMARY OF THE INVENTION 
       [0010]    An aspect of the present invention provides a lens module capable of improving mounting precision of an actuator with respect to a housing. 
         [0011]    According to an aspect of the present invention, there is provided a lens module including: an actuator moving a lens barrel in an optical axis direction; and a housing having a mounting part on which the actuator is mounted, wherein the actuator includes a piezoelectric member and a bar member vibrated by the piezoelectric member, and the bar member line-contacts the mounting part. 
         [0012]    The actuator may further include a mass member coupled to the piezoelectric member. 
         [0013]    The mounting part may include: a first mounting part receiving the piezoelectric member therein; and a second mounting part contacting the bar member. 
         [0014]    The bar member may have a cylindrical shape. 
         [0015]    At least a portion of the mounting part may be a groove having a cross section having an arc shape, and a diameter of the cylindrical shape and a diameter of the arc shape may be different. 
         [0016]    At least a portion of the mounting part may be a groove line-contacting the bar member at two points and having a cross section having a polygonal shape. 
         [0017]    The bar member may have a polyprismatic shape. 
         [0018]    At least a portion of the mounting part may be a groove line-contacting the bar member at two points and having a cross section having an arc shape. 
         [0019]    At least a portion of the mounting part may be a groove line-contacting the bar member at two points and having a cross section having a polygonal shape. 
         [0020]    The lens module may further include a permanent magnet contacting coupled to the lens barrel and contacting the bar member. 
         [0021]    The lens module may further include an adhesive member applied between the mounting part and the bar member. 
         [0022]    According to another aspect of the present invention, there is provided a lens module including: a housing receiving a lens barrel therein; an actuator moving the lens barrel in an optical axis direction and including a piezoelectric member and a bar member; and a bracket mounted in the housing and supporting the actuator to be in parallel with the optical axis direction of the lens barrel, wherein the bar member line-contacts the bracket. 
         [0023]    The actuator may further include a mass member coupled to the piezoelectric member. 
         [0024]    The bracket may include: a first mounting part receiving the piezoelectric member therein; and a second mounting part contacting the bar member. 
         [0025]    The bar member may have a cylindrical shape. 
         [0026]    The bracket may be provided with a groove having a cross section having an arc shape, and a diameter of the cylindrical shape and a diameter of the arc shape may be different. 
         [0027]    The bracket may be provided with a groove line-contacting the bar member at two points and having a cross section having a polygonal shape. 
         [0028]    The bar member may have a polyprismatic shape. 
         [0029]    The bracket maybe provided with a groove line-contacting the bar member at two points and having a cross section having an arc shape. 
         [0030]    The bracket may be provided with a groove line-contacting the bar member at two points and having a cross section having a polygonal shape. 
         [0031]    The lens module may further include a permanent magnet contacting coupled to the lens barrel and contacting the bar member. 
         [0032]    The lens module may further include an adhesive member applied between the mounting part and the bar member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0034]      FIG. 1  is an exploded perspective view of a lens module according to an embodiment of the present invention; 
           [0035]      FIG. 2  is an assembled perspective view of a lens barrel and an actuator shown in  FIG. 1 ; 
           [0036]      FIG. 3  is an assembled perspective view of a housing and the actuator shown in  FIG. 1 ; 
           [0037]      FIG. 4  is a cross-sectional view of a coupling structure of the housing and the actuator taken along line A-A of  FIG. 3 ; 
           [0038]      FIGS. 5 through 8  are cross-sectional views of another coupling structure of the housing and the actuator taken along line A-A; 
           [0039]      FIG. 9  is a view showing an actuator and a bracket of a lens module according to another embodiment of the present invention; and 
           [0040]      FIG. 10  is a cross-sectional view showing a coupling structure of the bracket and a housing shown in  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0041]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
         [0042]      FIG. 1  is an exploded perspective view of a lens module according to an embodiment of the present invention;  FIG. 2  is an assembled perspective view of a lens barrel and an actuator shown in  FIG. 1 ;  FIG. 3  is an assembled perspective view of a housing and the actuator shown in  FIG. 1 ;  FIG. 4  is a cross-sectional view of a coupling structure of the housing and the actuator taken along line A-A of  FIG. 3 ;  FIGS. 5 through 8  are cross-sectional views of another coupling structure of the housing and the actuator taken along line A-A;  FIG. 9  is a view showing an actuator and a bracket of a lens module according to another embodiment of the present invention; and  FIG. 10  is a cross-sectional view showing a coupling structure of the bracket and a housing shown in  FIG. 9 . 
         [0043]    The lens module  100  according to the embodiment of the present invention may include a hosing  110 , a lens barrel  120 , and an actuator  200  as shown in  FIG. 1 . In addition, the lens module  100  may further include an image sensor unit  140 . In addition, the lens module  100  may further include a shield can. Further, the lens module  100  further may further include an additional component in addition to the above-mentioned components. For example, the lens module  100  may further include a sensor (for example, a hall sensor) sensing a relative position of the lens barrel  120  with respect to an image sensor unit. 
         [0044]    The housing  100  may be formed of a material having resistance to external impacts. For example, the housing  110  may be formed of a metal, a plastic, or another material having a predetermined degree of rigidity. However, the housing  110  is not limited to being formed of the above-mentioned material, but may be formed of another material if necessary. 
         [0045]    The housing  110  may receive the lens barrel  120  and the actuator  200  therein. More specifically, the housing  110  may be provided with a receiving part  112  receiving the lens barrel  120  therein and a mounting part  114  receiving the actuator  200  therein. 
         [0046]    The receiving part  112  may be generally formed at the center of the housing  110 . More specifically, the receiving part  112  may be penetrated in a vertical direction with respect to one surface of the image sensor unit  140 . 
         [0047]    The receiving part  112  may have a transversal cross section larger than that of the lens barrel  120 . More specifically, the receiving part  112  may have the transversal cross section larger than that of the lens barrel  120  so that the lens barrel  120  received therein may move in a vertical direction (hereinafter, referred to as an alignment direction) of an optical axis to be actively aligned. However, the transversal cross section of the receiving part  112  is not necessarily larger than that of the lens barrel  120 . That is, the receiving part  112  and the lens barrel  120  may have the same cross sectional size if necessary. 
         [0048]    The mounting part  114  may be formed at an edge adjacent to the receiving part  112 . For example, the mounting part  114  may be formed at an edge of the housing  110  as shown in  FIG. 1 . When the mounting part  114  is formed at the edge of the housing  110  as described above, space utilization efficiency of the housing  110  is increased to thereby be advantageous for miniaturization of the lens module  100 . 
         [0049]    The mounting part  114  may include a first mounting part  116  and a second mounting part  118 . 
         [0050]    The first mounting part  116  may receive a piezoelectric member  220  and a mass member  230  of the actuator  200  therein. Here, the first mounting part  116  may have a width W 1  greater than a width W of the piezoelectric member  220 . The above-mentioned condition may enable free movement of the piezoelectric member  220  disposed at the first mounting part  116 . However, the width W 1  of the first mounting part  116  and the width W of the piezoelectric member  220  may be the same as each other as long as the piezoelectric member  220  may be freely moved. In addition, the first mounting part  116  may be provided with a hole  117  opened to the outside of the housing  110 . The hole  117  may be used as a space for withdrawing a flexible substrate connected to the piezoelectric member  220 . 
         [0051]    The second mounting part  118  may receive a bar member  210  of the actuator  200  therein. Here, the second mounting part  118  may have a width W 2  greater than a diameter D of the bar member  210 . Therefore, the bar member  210  received in the second mounting part  118  may not contact a side of the second mounting part  118 . In addition, the second mounting part  118  may be provided with a groove  119  lengthily extended in a height direction of the housing  110 . The groove  119  may have a cross section having an arc shape. Here, the arc shape may have a diameter D 2 . However, a shape of the cross section of the groove  119  is not limited to the arc shape, but may have another shape if necessary. The groove  119  may contact the bar member  210 . More specifically, the groove  119  may line-contact the bar member  210  through one or more segment lengthily extended in the height direction of the housing  110 . The contact structure between the groove  119  and the bar member  210  as described above may be advantageous in aligning the bar member  210  in parallel with the height direction of the housing  110 . 
         [0052]    The lens barrel  120  may include one or more lens. More specifically, the lens barrel  120  may include one or more lens for projecting light reflected from a subject to the image sensor unit  140 . Here, optical characteristics of the lens may be determined depending on a type of lens module  100 . For example, a high resolution lens module  100  may include four or more lenses, and a low resolution lens module  100  may include three or less lenses. In addition, the lens barrel  120  may further include a stop adjusting an amount of incident light and a filter cutting off infrared rays. 
         [0053]    An inner surface of the lens barrel  120  may be coated with an anti-reflective material or a light shielding material. This configuration may decrease a phenomenon in which unnecessary light is reflected onto the inner surface of the lens barrel  120  to be incident to the image sensor unit, whereby resolution of the lens module  100  may be improved. 
         [0054]    The image sensor unit  140  may include an image sensor  142  and a substrate  144 . In addition, the image sensor unit  140  may further include one or more electronic component (for example, a passive device) required for driving the image sensor  142 . Here, the image sensor  142  may be a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) type electronic component. However, the image sensor  142  is not limited to the above-mentioned type of electronic component, but may be another type of electronic component. The substrate  144  may include a circuit pattern enabling an electrical connection between the image sensor  142  and the passive device. In addition to the passive device, the substrate  144  may further include other electronic components making an operation of the image sensor  142  relatively smooth. Meanwhile, the image sensor  142  and the passive device may be formed integrally with each other on the substrate  144 . For example, the image sensor  142  may be manufactured in a chip scale package (CSP) form. 
         [0055]    Next, the actuator  200  will be described with reference to  FIGS. 1 and 2 . 
         [0056]    The actuator  200  may include the bar member  210 , the piezoelectric member  220 , the mass member  230 , and a magnet member  240 . 
         [0057]    The bar member  210  may generally have a cylindrical shape. More specifically, the bar member  210  have a cylindrical shape in which it has a diameter D. Here, the diameter D may be different from a diameter D 2  of the groove  119  having an arc shape. For reference, although the case in which the bar member  210  has the cylindrical shape has been described in the present embodiment, the bar member  210  is not limited to having the cylindrical shape. For example, the bar member  210  may have another shape as long as it may transfer vibrations of the piezoelectric member  220  to the lens barrel  120  or the magnet member  240 . For example, the bar member  210  may be manufactured to have a prismatic shape. 
         [0058]    The bar member  210  may contact the magnet member  240 . More specifically, the bar member  210  may be closely adhered to the magnet member  240  by magnetic force. Therefore, the bar member  210  may be formed of a ferromagnetic substance easily affected by magnetic force. However, the bar member  210  is not limited to being formed of the ferromagnetic substance, but may be formed of another material if necessary. For example, the bar member  210  may be formed of a non-magnetic material. 
         [0059]    The piezoelectric material  220  may be attached to one end of the bar member  210  and provide substantial driving force enabling movement of the lens barrel  120 . More specifically, the piezoelectric member  220  may vibrate the bar member  210  in a length direction while being repeatedly expanded or contracted and bent depending on a current signal, and the vibrations of the bar member  210  may move the lens barrel  120  in an optical axis direction C-C. Here, a direction in which the lens barrel  120  is moved may be changed depending on a movement pattern of the piezoelectric member  220  vibrating the bar member  210 . 
         [0060]    The mass member  230  may be formed at one end of the piezoelectric member  220 . More specifically, the mass body  230  may be positioned at an opposite side to the bar member  210  based on the piezoelectric member  220 . The mass member  230  formed as described above may provide directionality and stability to driving force of the piezoelectric member  220 . 
         [0061]    The magnet member  240  may be coupled to the lens barrel  120 . More specifically, the magnet member  240  may be firmly attached to a side of the lens barrel  120 . The magnet member  240  configured as described above may increase close adhesion between the lens barrel  120  and the actuator  200  to transfer the driving force by the actuator  200  to the lens barrel  120 . For reference, one surface of the magnet member  240  may be provided with a groove to which the bar member  210  having the cylindrical shape may be closely adhered. 
         [0062]    Next, a coupling structure between the actuator  200  and the housing  110  will be described with reference to  FIGS. 3 and 4 . 
         [0063]    The actuator  200  may be mounted at the mounting parts  116  and  118  of the housing  110 . More specifically, the actuator  200  may be aligned by the bar member  210  contacting the second mounting part  118 . 
         [0064]    The contact between the bar member  210  and the second mounting part  118  may be stably maintained in a state in which a contact area therebetween is maximized. That is, the bar member  210  having the cylindrical shape and the second mounting part  118  in which the groove  119  is formed may be maintained in the most stable state when they line-contact each other at two points P 1  and P 2  as shown in  FIG. 4 . (For reference, in a state other than the above-mentioned state, since the bar member  210  and the second mounting part  118  point-contact each other, they may not be maintained in a stable state of contact). Particularly, since the bar member  210  and the second mounting part  118  line-contact each other by the segment that is in parallel with the height direction of the housing  110 , the contact between the bar member  210  and the second mounting part  118  may align the actuator  200  to be in parallel with the height direction of the housing  110 . Therefore, according to the present embodiment, the alignment of the actuator  200  may be enabled only by mounting the actuator  200  at the mounting parts  116  and  118 . 
         [0065]    The bar member  210  and the groove  119  of the second mounting part  118  may have an adhesive  300  filled therebetween. More specifically, when the mounting of the actuator  200  is completed, the adhesive  300  may be filled in a gap between the bar member  210  and the groove  119  in order to improve reliability of coupling between the housing  110  and the actuator  200 . Here, as the adhesive  300 , a photocurable resin adhesive, a thermosetting resin adhesive, or the like, may be used. However, the adhesive  300  is not limited to the above-mentioned kind of adhesive, but may be another kind of adhesive if necessary. 
         [0066]    Meanwhile, a form in which the bar member  210  and the second mounting part  118  contact each other may be changed as shown in  FIGS. 5 and 6 . For example, the bar member  210  and the second mounting part  118  may line-contact each other at one point P 1  as shown in  FIG. 5 . In this case, the bar member  210  may have a diameter D smaller than a diameter D 2  of the groove  119 . In addition, the second mounting part  118  may have a cross section having a shape other than the arc shape, as shown in  FIG. 6 . In this case, the bar member  210  having a circular cross section and the groove  119  may easily line-contact each other. 
         [0067]    In addition, the bar member  210  may have a cross section having a shape other than the circular shape, as shown in  FIGS. 7 and 8 . For example, the bar member  210  may have a cross section having a rectangular shape, as shown in  FIGS. 7 and 8 . The bar member  210  having the above-mentioned shape may be more easily processed as compared with a bar member having a cylindrical shape. In addition, since the bar member  210  having the above-mentioned shape has the same cross sectional shape as that of the piezoelectric member  220 , it may be easily coupled to and aligned with the piezoelectric member  220 . 
         [0068]    Next, a lens module according to another embodiment of the present invention will be described with reference to  FIGS. 9 and 10 . 
         [0069]    The lens module according to the present embodiment may further include a bracket  400 . More specifically, the lens module according to the present embodiment may include the bracket  400  receiving the actuator  200  therein as shown in  FIG. 9 . 
         [0070]    The bracket  400  may have an internal space  410  capable of receiving the actuator  200  therein and be mounted at the mounting part  114  of the housing  110 . Here, the bracket  400  may line-contact the mounting part  114  as shown in  FIG. 10 . In addition, the bracket  400  and the groove  119  may have an adhesive  300  filled therebetween in order to improve reliability of coupling therebetween. 
         [0071]    In the lens module configured as described above, since the bracket  400  protects the actuator  200  from external impacts, reliability of an operation of the actuator  200  may be improved. 
         [0072]    As set forth above, according to the embodiments of the present invention, since the actuator may be precisely mounted in the housing, a tilt phenomenon of the lens barrel generated in a process of mounting the lens barrel may be significantly decreased. 
         [0073]    While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.