Patent Publication Number: US-2023138300-A1

Title: Lens Assembly

Description:
TECHNICAL FIELD 
     The disclosure relates to a lens assembly, and more particularly to an ultra-small lens assembly having an auto focus function and an optical image stabilization (OIS) function. 
     BACKGROUND ART 
     Lens assemblies which are applied to small mobile devices such as smartphones are becoming miniaturized according to developments in technology, and have an auto focus function and an optical image stabilization (OIS) function to obtain captured images of high quality. 
     The auto focus function may be a function which moves a lens module provided in the lens assembly forward or backward to automatically match a focal point to a specific subject. 
     The OIS function may be a function which detects a shaking of a mobile device (e.g., a smartphone, a tablet personal computer (PC), etc.) with a gyro sensor and corrects the focal point by minutely moving the lens module in an opposite direction of a direction to which the mobile device moves. A movement of the lens module when performing OIS may be carried out in a direction perpendicular to a direction to which a lens moves when performing auto focusing. The lens assembly may support the lens module with a plurality of metal wires having elasticity so that the lens module may move smoothly when performing OIS. 
     Recently, small mobile devices are being applied with image sensors having 108 megapixels to realize high quality images, and lens sizes applied accordingly have also increased. For example, while lenses which were previously applied have a diameter of about less than or equal to 9.1φ, lenses used together with high-definition image sensors have a diameter of greater than or equal to 15φ. As described above, a weight of the lens may also increase as the size of the lens increases. 
     Accordingly, small mobile devices have a disadvantage of an amount of electricity consumed increasing to drive a more heavier lens module according to employing the high-definition image sensor. Based on the above, there is an inconvenient disadvantage of having to charge a battery embedded in the small mobile device more often as a camera function is used more. 
     In addition, as the weight of the lens increases, there is a disadvantage of a lens focal point not being accurately maintained as the lens module is tilted because the metal wire of a fine thickness is unable to withstand the weight of the lens module and a center portion of the metal wire is bent. Further, there is a disadvantage of the camera function of the small mobile device not being performed due to being vulnerable to force such as the metal wire breaking and the like when the small mobile device is subject to an external force or dropped on a floor. 
     However, if the metal wires are formed more thickly than the existing metal wires to solve the disadvantages described above, more power is to be applied to a driving part for OIS for a normal operation because a movement width of the lens module becomes smaller compared to when existing wires of a fine thickness are used when performing OIS. The above leads to a disadvantage of power consumption of a charging battery of a small mobile device accelerating. 
     DISCLOSURE 
     Technical Problem 
     An object of the disclosure is in providing a lens assembly configured such that a plurality of hinge members supporting a lens module to be movable is formed to be strong against external force and to not be bent due to a weight of a lens for optical image stabilization (OIS). 
     Another object of the disclosure is in providing a lens assembly which can minimize power being consumed by a driving part for adjusting auto focus and OIS. 
     Technical Solution 
     To achieve the objects described above, the present disclosure provides a lens assembly including a base, a lens module disposed at an inner side of the base, driving parts for a first optical image stabilization (OIS) and a second OIS configured to move the lens module in a perpendicular direction of an optical axis direction, and a plurality of hinge members configured to support the lens module to be movable and disposed parallel to one another, and the plurality of hinge members is characterized in that a column part is gradually protruded to be convex as it nears a center and is injected molded with a synthetic resin. 
     The lens assembly may further include a support inserted in the base to be movable in the optical axis direction, and a driving part for adjusting auto focus which moves the support in the optical axis direction, and each of the plurality of hinge members may be configured so that one end part is fixed to four corners of the support, and other end part is fixed to the lens module. 
     An adhesive may be applied to a portion through which the one end part of the plurality of hinge members and the support are connected to one another, and an adhesive may be applied to a portion through which the other end part of the plurality of hinge members and the lens module are engaged to one another. 
     Each of the plurality of hinge members may be configured such that a first connection part is formed in-between the one end part and the column part and a second connection part is formed in-between the other end part and the column part, and each of the first and second connection parts is formed to a thickness thinner than a thickness of the column part. 
     The driving part for adjusting auto focus may be a piezo actuator, and the piezo actuator may include a piezoelectric device fixed to the base, and an expandable bar configured such that one end is connected to one side of the piezoelectric device and is connected to the support. 
     The support may further include a guide bar guiding a movement of the support in the optical axis direction by being connected to a corner which faces the corner at which the expandable bar is connected in a diagonal direction to be slidable. 
     Each of the plurality of hinge members may be configured such that one end part is fixed to four corners of the base, and other end part is fixed to the lens module. 
     An adhesive may be applied to a portion through which the one end part of the plurality of hinge members and the base are connected to one another, and an adhesive may be applied to a portion through which the one end part of the plurality of hinge members and the lens module are engaged with one another. 
     The lens assembly may further include a movable member which moves an image sensor disposed at a rear direction of the lens module in the optical axis direction, and a driving part for adjusting auto focus for the movable member to move in the optical axis direction. 
     The movable member may include a first portion to which the image sensor is engaged, and a second portion extended from the first portion and disposed in-between a side wall of the base and the lens module. 
     The image sensor may be mounted to one portion of a flexible printed circuit board (FPCB), and other portion of the FPCB is disposed in a folded state based on the one portion of the FPCB. 
     The driving part for adjusting auto focus may include a magnet disposed at the second portion, and a coil disposed at a side wall of the base so as to face the magnet. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is an assembled view illustrating a lens assembly according to an embodiment of the disclosure; 
         FIG.  2    and  FIG.  3    are exploded perspective views illustrating a lens assembly according to an embodiment of the disclosure; 
         FIG.  4    is perspective view illustrating a base of a lens assembly according to an embodiment of the disclosure; 
         FIG.  5    is a perspective view illustrating a support of a lens assembly according to an embodiment of the disclosure; 
         FIG.  6    is a plane view illustrating a state in which a support and a lens module of a lens assembly are engaged according to an embodiment of the disclosure; 
         FIG.  7    is a cross-sectional view taken along line A-A marked in  FIG.  6   ; 
         FIG.  8    is an enlarged perspective view illustrating a first engagement groove of a lens module to which one end of a hinge member is connected; 
         FIG.  9    is an enlarged perspective view illustrating a second engagement groove of a support to which other end of a hinge member is connected; 
         FIG.  10    is a plane view illustrating a state in which an inner cover and an outer cover of a lens assembly is omitted according to an embodiment of the disclosure; 
         FIG.  11    is a cross-sectional view taken along line B-B marked in  FIG.  10   ; 
         FIG.  12    is a view of open loop hysteresis curves compared according to whether first and second centering alignment protrusions are present; 
         FIG.  13    is a schematic view illustrating a lens assembly according to another embodiment of the disclosure; and 
         FIG.  14    and  FIG.  15    are exploded perspective views illustrating a lens assembly according to still another embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Various embodiments will be described in greater detail below with reference to the accompanied drawings. Embodiments described herein may be variously modified. A specific embodiment may be illustrated in the drawings and described in detail in the detailed description. However, the specific embodiment described in the accompanied drawing is only to assist in the easy comprehension of the various embodiments. Accordingly, it should be noted that the technical spirit of the disclosure is not limited by the specific embodiments described in the accompanied drawings, and should be interpreted to include all modifications, combinations, equivalents and/or alternatives of the embodiments included in the spirit of the disclosure and in the technical scope 
     Terms including ordinal numbers such as first and second may be used in describing various elements, but the elements are not limited by the above-described terms. The above-described terms may be used only for the purpose of distinguishing one element from another element. 
     In addition thereto, in describing the disclosure, in case it is determined that the detailed description of related known functions or configurations may unnecessarily confuse the gist of the disclosure, the detailed description thereof will be omitted. 
     A lens assembly according to an embodiment of the disclosure may be manufactured to an ultra-small size and installed in a small mobile device such as a smartphone to be used in capturing an image. 
     The lens assembly according to an embodiment of the disclosure will be described in detail below with reference to the drawings. 
       FIG.  1    is an assembled view illustrating the lens assembly according to an embodiment of the disclosure,  FIG.  2    and  FIG.  3    are exploded perspective views illustrating the lens assembly according to an embodiment of the disclosure,  FIG.  4    is perspective view illustrating a base of the lens assembly according to an embodiment of the disclosure, and  FIG.  5    is a perspective view illustrating a support of the lens assembly according to an embodiment of the disclosure. 
     Referring to  FIG.  1    to  FIG.  3   , a lens assembly  1  according to an embodiment of the disclosure may include a base  10 , a support  30  which moves a lens module  50  in a Z-axis direction (herein, the Z-axis direction may mean an optical axis direction) for auto focusing, a lens module  50  which is disposed at an inner side of the support  30  and includes a lens part  51  formed of a plurality of lenses, a plurality of hinge members  40  configured such that the lens module  50  connects the support  30  and the lens module  50  for the lens module  50  to be movable along a X-Y plane based on the support  30  for OIS, an inner cover  60  configured to prevent the lens module  50  from separating from the support  30 , and an outer cover  70  configured to cover one side of the base  10 . 
     Referring to  FIG.  4   , the base  10  may be installed at one portion of the small mobile device (not shown), and a printed circuit board (not shown) to which an image sensor (not shown) is mounted may be disposed at a lower side (an opposite side of a side covered by the outer cover  70 ) of the base  10 . 
     The base  10  may be formed roughly as a cuboid. In addition to the cuboid, the shape of the base  10  may be appropriately changed according to a size and shape of the small mobile device to which a lens assembly  10  is installed. 
     The base  10  may be provided with a predetermined space in which the support  30  disposed at the inner side moves along the Z-axis direction, and a floor part  12  may be formed with a first light passing hole  11 . The light which passed the lens module  50  may be irradiated to the image sensor positioned at the lower side of the base  10  through the first light passing hole  11  formed at the base  10 . 
     The base  10  may have a seat part  12   a  protruded and formed at one corner from among four corners of the floor part  12 . The seat part  12   a  may be fixed with a piezo actuator  17  which will be described below. Specifically, one surface of a piezoelectric element  17   a  of the piezo actuator  17  may be fixed. 
     The piezo actuator  17  may move the support  30  forward or backward in the Z-axis direction. The piezo actuator  17  may be applied with a current through a first printed circuit board  13  disposed at the base  10 . The piezo actuator  17  may include a piezoelectric element  17   a  with a length that is variable in one direction by electric-field according to the current being applied, and an expandable bar  17   b  with one end engaged at one side of the piezoelectric element  17   a . The expandable bar  17   b  may have a thrust which moves the support  30  forward or backward in the Z-axis direction by expanding in a length direction according to a varied length of the piezoelectric element  17   a.    
     The support  30  may be formed with an engagement part  32   a  through which the expandable bar  17   b  is penetrated and inserted to one corner of the support  30  on which the piezo actuator  17  is disposed. 
     The support  30  may be guided by a guide bar  19  when moving forward or backward along the Z-axis direction by the driving of the piezo actuator  17 . The guide bar  19  may be disposed in another corner which is at a diagonally opposite side based on the one corner of the support  30  on which the piezo actuator  17  is disposed. In this case, the guide bar  19  may be engaged to an engagement protrusion  32   b  which is formed at the support  30  to be slidable. 
     The support  30  may be guided through a plurality of balls (not shown) rather than the guide bar  19 . Specifically, the plurality of balls may be disposed in a state contacting each of the base  10  and the support  30  between an inner side corner of the base  10  and an outer side corner of the support  30  corresponding thereto. In order for the support  30  to smoothly operate by a driving of the piezo actuator  17 , an inertial movement of the support  30  may be made possible by the expansion operation of the expandable bar  17   b  having a constant preload applied to the support  30  at all times. 
     Referring to  FIG.  4    and  FIG.  5   , the lens assembly may include a preload magnet  21  engaged to one surface of the support  30  and a magnetic material  22  disposed at the base  10  to face the preload magnet  21  at a certain interval. An interacting magnetic force of the preload magnet  21  and the magnetic material  22  may be exerted as a force supporting the support  30  by pulling the support  30  toward the base  10  with a certain force. Accordingly, a preload part may not only assist in a detailed realization of the inertial movement and stop operation of the support  30  when driving the piezo actuator  17 , but also eliminate a phenomenon of the support  30  being tilted. 
     When the current is applied to the piezo actuator  17 , the piezoelectric element  17   a  may be configured such that the length is varied in a direction parallel to the Z-axis direction due to the electric-field and the expandable bar  17   b  is expanded accordingly. In this case, the support  30  preloaded by a force provided from the preload part may adjust a focal point distance of a lens by performing inertial movement and moving along the Z-axis direction. 
     Specifically, the forward and backward movements of the support  30  may be carried through the following operation. If a forward direction current is repeatedly applied to the piezoelectric element  17   a , the support  30  may move forward because the expandable bar  17   b  is expanded as the piezoelectric element  17   a  repeats a stretching operation and a rapid restoration operation due to the electric-field of the forward direction current. Alternatively, if a reverse direction current is repeatedly applied to the piezoelectric element  17   a , the support  30  may move backward because the expandable bar  17   b  is contracted as the piezoelectric element  17   a  repeats the stretching operation and the rapid restoration operation due to the electric-field of the reverse direction current. 
     The support  30  may be formed in a rough cuboid shape in a size smaller than the base  10 . The support  30  may be disposed to movable forward and backward along the Z-axis direction from the inner side of the base  10  (referring to  FIG.  10   ). 
     The driving part for OIS will be described with reference to  FIG.  2    and  FIG.  3   . 
     The lens assembly according to an embodiment of the disclosure may include a driving part for a first OIS for moving the lens module  50  in an X-axis direction, and a driving part for a second OIS for moving the lens module  50  in an Y-axis direction. 
     The driving part for the first OIS may include a first coil  25  disposed at one side surface from among four side surfaces of the base  10  and a first magnet  55  disposed at one side surface from among the four side surfaces of the lens module  50 . 
     The first magnet  55  may be disposed to face the first coil  25  with a certain interval therebetween based on the lens module  50  being disposed in an inner side space of the base  10  together with the support  30 . 
     The driving part for the first OIS may move the lens module  50  in a +X-axis direction or a −X-axis direction through interaction with the first magnet  55  according to a direction of the current being applied to the first coil  25 . 
     The first coil  25  may be electrically connected to a second printed circuit board  14  installed at the base  10 . The first magnet  55  may be disposed at one side surface of the lens module  50 . In this case, in-between the first magnet  55  and the lens part  51 , a first shielding member  55   a  of a flat plate shape engaged to the lens module  50  may be disposed. The driving part for the first OIS may not be affected by an electromagnetic field generated from the driving part for the second OIS due to the first shielding member  55   a.    
     The second printed circuit board  14  may be formed with a plurality of terminals  14   a  to receive power and a control signal from the outside. The second printed circuit board  14  may be mounted with a first hall sensor (not shown). The first hall sensor may be positioned at an inner side of the first coil  25  in a closed curve shape and detect movement of the first magnet  55 , and transmit the detected signal to a control part of the small mobile device. The control part may perform control in the X-axis direction of the lens module  50  through the first hall sensor of the second printed circuit board  14  and the driving part for the first OIS. 
     The driving part for the second OIS may include a second coil  27  disposed at a side surface adjacent to the surface on which the first coil  25  is disposed from among the four side surfaces of the base  10 , and a second magnet  57  disposed at a side surface adjacent to the surface on which the first magnet  55  is disposed from among the four side surfaces of the lens module  50 . 
     The second magnet  57  may be disposed to face the second coil  27  with a certain interval therebetween based on the lens module  50  being disposed in the inner side space of the base  10  together with the support  30 . 
     The driving part for second OIS may move the lens module  50  in a +Y-axis direction or a −Y-axis direction through interaction with the second magnet  57  according to the direction of the current being applied to the second coil  27 . 
     The second coil  27  may be electrically connected to a third printed circuit board  15  installed at the base  10 . The second magnet  57  may be disposed at one side surface of the lens module  50 . In this case, in-between the second magnet  57  and the lens part  51 , a second shielding member  57   a  of a flat plate shape engaged to the lens module  50  may be disposed. The driving part for second OIS may not be affected by the electromagnetic field generated from the driving part for the first OIS due to the second shielding member  57   a.    
     The third printed circuit board  15  may be formed with a plurality of terminals  15   a  for receiving power and a control signal from the outside. The third printed circuit board  15  may be mounted with a second hall sensor (not shown). The second hall sensor may be positioned at an inner side of the second coil  27  in a closed curve shape and detect movement of the second magnet  57 , and transmit the detected signal to the control part of the small mobile device. The control part may perform control in the Y-axis direction of the lens module  50  through the second hall sensor of the third printed circuit board  15  and the driving part for the second OIS. 
     The driving parts for the first OIS and the second OIS may move the lens module  50  in the X-axis direction and the Y-axis direction and correct the position of the lens part  51  as a result of shaking hands. The lens module  50  may move in the X-axis direction due to the driving part for the first OIS, and move in the Y-axis direction due to the driving part for second OIS. Accordingly, the lens module  50  may be connected to the support  30  to be movable through the plurality of hinge members  40  which will be described below. Accordingly, the lens module  50  may move to any one position on the X-Y plane in a state supported by the support  30 . 
     The support  30  may be formed with a second light passing hole  31 . Based on the support  30  being inserted in the inner side space of the base  10 , the second light passing hole  31  may correspond to the first light passing hole  11  of the base  10 . Light which passed the lens part  51  may sequentially pass the second light passing hole  31  and the first light passing hole  11  and reach of the image sensor (not shown). 
     The plurality of hinge members  40  which support the lens module  50  to be movable in the X-axis direction and the Y-axis direction based on the support  30  will be described below. The plurality of hinge members  40  may all be formed in a same shape and four hinge members may be provided. 
       FIG.  6    is a plane view illustrating a state in which the support and the lens module of the lens assembly are engaged according to an embodiment of the disclosure,  FIG.  7    is a cross-sectional view taken along line A-A marked in  FIG.  6   ,  FIG.  8    is an enlarged perspective view illustrating a first engagement groove of the lens module to which one end of a hinge member is connected, and  FIG.  9    is an enlarged perspective view illustrating a second engagement groove of the support to which other end of the hinge member is connected. 
     The plurality of hinge members  40  may be configured such that each one end part is inserted and fixed in a plurality of first engagement grooves  33  formed at four corners of the inner side of the support  30 , and each other end part is inserted and fixed in a plurality of second engagement grooves  53  formed at the four corners of the outer side of the lens module  50 . 
     The plurality of hinge members  40  may be formed of a material having elasticity so that the plurality of hinge members may be restored to its original position when the driving parts for the first OIS and the second OIS are not operated after moving to any one point on the X-Y plane by the driving parts for the first OIS and the second OIS. 
     Specifically, it may be preferable for the plurality of hinge members  40  to be formed with a synthetic resin material (e.g., thermoplastic elastomer (TPE)) which is a nonconductor and has superior durability. 
     Because the plurality of hinge members  40  may be formed with a synthetic resin material, the plurality of hinge members may be manufactured by injection molding. Although the lens assembly of the related art, which includes wires with a very fine thickness that are formed of a metal material of the related art, has the disadvantage of wires breaking easily when an external force is applied, the hinge member according to an embodiment may not only have good durability as there is no breakage even with external force applied to the lens assembly  1 , but may also enhance a reliability of a product. 
     A structure of the hinge member  40  interconnecting the support  30  and the lens module  50  will be described in detail below with reference to  FIG.  7    to  FIG.  9   . 
     The plurality of hinge members  40  may be formed such that the shapes are all the same. Accordingly, the above will be described based on one hinge member. 
     The hinge member  40  may include a column part  43   d  having a predetermined length and thickness, a lower end part  43   a  disposed at a lower end of the column part  43   d , an upper end part  43   f  disposed at an upper end of the column part  43   d , a first connection part  43   c  formed between the column part  43   d  and the lower end part  43   a , and a second connection part  43   e  formed between the column part  43   d  and the upper end part  43   f.    
     The lower end part  43   a  of the hinge member  40  may form a first stepped part  43   b  positioned between the lower end part  43   a  and the first connection part  43   c . The first stepped part  43   b  may be formed to have a width narrower than the lower end part  43   a . The lower end part  43   a  of the hinge member  40  may be engaged to a first engagement part  33   a  of the first engagement groove  33 , and the first stepped part  43   b  may be engaged to a second engagement part  33   b  of the first engagement groove  33 . 
     The lower end part  43   a  of the hinge member  40  may not be separated from the first engagement groove  33  due to a pair of first hook protrusions  33   c  provided in the first engagement groove  33  and maintain an engaged state before applying an adhesive. 
     A first adhesive  45   a  is applied to a connecting portion between the support  30  and the hinge member  40  so that the hinge member  40  is fixed firmly to the support  30 . Accordingly, when an external force is applied to the lens assembly  1 , the hinge member  40  may be fundamentally blocked from being separated from the support  30 . 
     The upper end part  43   f  of the hinge member  40  may be formed with a second stepped part  43   g  positioned between the upper end part  43   f  and the second connection part  43   e . The second stepped part  43   g  may be formed to have a width narrower than an upper end part  43   f . The upper end part  43   f  of the hinge member  40  may be engaged to a first engagement part  53   a  of the second engagement groove  53 , and the second stepped part  43   g  may be engaged to a second engagement part  53   b  of the second engagement groove  53 . 
     The upper end part  43   f  of the hinge member  40  may not be separated from the second engagement groove  53  due to a pair of second hook protrusions  53   c  provided in the second engagement groove  53  and maintain an engaged state before applying an adhesive. 
     Second and third adhesives  45   c  and  45   d  may be applied to a connecting portion between the lens module  50  and the hinge member  40  so that the hinge member  40  may be firmly fixed to the lens module  50 . Accordingly, when an external force is applied to the lens assembly  1 , the hinge member  40  may be fundamentally blocked from being separated from the support  30 . After the first adhesive  45   a  is hardened by sequentially permeating in-between the lower end part  43   a  and the first engagement part  33   a  of the first engagement groove and in-between the first stepped part  43   b  and the second engagement part  33   b  of the first engagement groove, the connecting portion between the support  30  and the hinge member  40  may be firmly fixed. 
     After the second adhesive  45   c  is hardened by sequentially permeating in-between an upper end part  43   f  and a first engagement part  53   a  of the second engagement groove and in-between the second stepped part  43   g  and the second engagement part  33   b  of the first engagement groove, the connecting portion between the support  30  and the hinge member  40  may be firmly fixed. The second adhesive  45   c  may have a same viscosity as with the first adhesive  45   a.    
     The third adhesive  45   d  may be applied to encase the second connection part  43   e  at a lower part of the second engagement groove  53 . The third adhesive  45   d  may be a damping bond, and may be maintained roughly in a gel state even after hardening is completed after application. 
     The first adhesive  45   a  may fix the support  30  and the hinge member  40 , and the second adhesive  45   c  may perform the role of fixing the lens module  50  and the hinge member  40 . Based on the third adhesive  45   d  being applied to encase the second connection part  43   e , the second connection part  43   e  may be elastically bent at a predetermined angle so that movement by the lens module  50  on the X-Y plane is possible. Accordingly, the third adhesive  45   d  may perform the role of a damper which absorbs external force applied to the lens assembly or force generated in a control process. 
     The hinge member  40  may be adhesively fixed to the support  30  after being first adhesively fixed to the lens module  50 . In this case, the second and third adhesives  45   c  and  45   d  may be applied to each connecting portion of the hinge member  40  and the lens module  50  in a state in which the upper end part  43   f  of the hinge member  40  is inserted in the second engagement groove  53 . Then, the first adhesive  45   a  may be applied to the connecting portion of the hinge member  40  and the support  30  in a state in which the lower end part  43   a  of the hinge member  40  is inserted in the first engagement groove  33 . 
     Alternatively, based on the hinge member  40  being fixed to the lens module  50  after first being adhesively fixed to the support  30 , the first and third adhesives  45   a  and  45   d  may be applied to each connecting portion of the hinge member and the support  30  in a state in which the lower end part  43   a  of the hinge member  40  is inserted in the first engagement groove  33 . At this time, the third adhesive  45   d  may be applied to encase the first connection part  43   c  so as to not interfere with the first connection part  43   c  being bent, and perform the role of the damper which is capable of absorbing the external force applied to the lens assembly  1 . Then, the second adhesive  45   c  may be applied to the connecting portion of the hinge member  40  and the lens module  50  in a state in which the upper end part  43   f  of the hinge member  40  is inserted in the second engagement groove  53 . 
     In the embodiment, although both ends of the hinge member  40  have been described as each being fixed by the adhesive to the support  30  and the lens module  50  as an example, it may also be possible for both ends to be engaged in a pressed state without the adhesive. 
     The first and second connection parts  43   c  and  43   e  may be formed thinner than the column part  43   d . Accordingly in-between the lower end part  43   a  and the column part  43   d , and in-between the upper end part  43   f  and the column part  43   d  may be bent at a predetermined angle. As described above, when the driving parts for the first OIS and the second OIS are operated, the lens module  50  may move smoothly to a X-axis and a Y-axis according to the first and second connection parts  43   c  and  43   e  being bent. In addition, the first and second connection parts  43   c  and  43   e  may be stored to its original shape by elastic force based on power to the driving parts for the first OIS and the second OIS being blocked. 
     The column part  43   d  may be formed in a shape with a center portion that is convex overall according to having a shape which gradually increases in thickness as it nears the center from each of the upper end and the lower end of the column part. In this case, a longitudinal section of the column part  43   d  may be roughly an elliptical shape, and a cross section may be roughly a circular shape. 
     Meanwhile, size of lens which is applied to the small mobile device is being increased for high resolution capturing. Accordingly, when the size of the lens is increased, the weight of the lens is also increased. Because the wire hinge of metal material used in the related art is bent by its own malleability in case the weight of the lens module  50  is heavy, controlling the position of the lens module  50  has been difficult. However, in the embodiment, because the column part  43   d  uses the hinge member  40  which is in the convex shape, a rigidity of the hinge member  40  may be greatly enhanced, and the hinge member  40  may not be bent even if the weight of the lens module  50  is increased. 
     A structure of an inner cover  60  will be described in detail below with reference to  FIG.  10    and  FIG.  11   . 
     The inner cover  60  may prevent the lens module  50  inserted in the support  30  from separating from the support  30 . The inner cover  60  may be formed with a third light passing hole  61  through which an upper part of the lens part  51  may be exposed. 
     The inner cover  60  may be detachably engaged to the support  30  to cover a portion of an opening of the support  30  for inserting the lens module  50  inside the support  30 . In this case, the inner cover  60  may be formed with a plurality of engagement parts  63  which is snap engaged to a plurality of engagement protrusions  36  formed at an outer side surface of the support  30 . 
     According to the inner cover  60  is seated around the opening of the support  30 , because there is a predetermined interval with an upper surface of the lens module  50 , the lens module  50  is not contacted when moving in the X-axis and Y-axis directions. 
     The inner cover  60  may include first and second centering alignment protrusions  65  and  67  which are disposed spaced apart to form an angle perpendicular with each other. The first and second centering alignment protrusions  65  and  67  may perform a role of aligning the lens module  50  to a center position when the driving parts for the first OIS and the second OIS are not in operation. 
     The first centering alignment protrusion  65  may be formed with an embossing so as to protrude toward the first magnet  55 . In this case, the first centering alignment protrusion  65  may be disposed at a position corresponding to the first magnet  55  according to a disposition direction of the first magnet  55 , and may be formed to a length which is the same or shorter than the length of the first magnet  55 . 
     The second centering alignment protrusion  67  may be disposed in a roughly perpendicular direction based on the first centering alignment protrusion  65 , may be formed with embossing to protrude toward the second magnet  57 . In this case, the second centering alignment protrusion  67  may be disposed at a position corresponding to the second magnet  57  along the disposition direction of the second magnet  57 , and may be formed to a length which is the same or shorter than the length of the second magnet  57 . 
     Based on the inner cover  60  being formed of the magnetic material, a gravitational force may be in action at all times in-between the inner cover  60  and the first and second magnets  55  and  57 . The first centering alignment protrusion  65  may be protruded and formed more closely to the first magnet  55  than an interval between the one surface (surface facing the lens module  50 ) of the inner cover  60  and the first magnet  55 . Like the first centering alignment protrusion  65 , the second centering alignment protrusion  67  may be protruded and formed more closely to the second magnet  57  than an interval between the one surface (surface facing the lens module  50 ) of the inner cover  60  and the second magnet  57 . 
     Accordingly, based on the first and second magnets  55  and  57  fixed to the lens module  50  when the driving parts for first OIS and second OIS are not in operation being moved to a position corresponding to the respectively corresponding first and second centering alignment protrusions  65  and  67 , the lens module  50  may be naturally aligned to a centering position. 
     The above may be verified through an open loop hysteresis curve shown in  FIG.  12   . A distance value L 1  corresponding to a certain current value of when (a) there are first and second centering alignment protrusions  65  and  67  may be shown significantly smaller than a distance value L 2  of when (b) there are no first and second centering alignment protrusions  65  and  67 . Accordingly, in the embodiment in which the first and second centering alignment protrusions  65  and  67  are formed in the inner cover  60 , it is shown that the centering of the lens module  50  may be easier. 
     The lens assembly  1  according to an embodiment as described above may form the first and second centering alignment protrusions  65  and  67  of a simple shape through a simple embossing processing to the inner cover  60  without having a complicated separate centering structure for the centering of the lens module  50 . Accordingly, not only is precise controlling of the lens module  50  of a product is made easy, but reliability in the product may also be enhanced. 
     The outer cover  70  may be engaged to the base  10 , and cover the inner cover  60 . The outer cover  70  may also be formed with a fourth light passing hole  71  through which the upper part of the lens part  51  may be exposed. The outer cover  70  may be formed with a metal material capable of shielding electromagnetic waves. 
     A lens assembly according to another embodiment of the disclosure will be described below with reference to  FIG.  13   .  FIG.  13    is a schematic view illustrating the lens assembly according to another embodiment of the disclosure. 
     A lens assembly  100  according to another embodiment of the disclosure may include a base  110 , a movable member  130 , a lens module  150  provided with a lens part  151 , and a plurality of hinge members  140  which support the lens module  150  to be movable along the X-Y plane based on the base  110 . 
     Because the plurality of hinge members  140  has the same structure as with the plurality of hinge members  40  provided in the lens assembly  1  according to an embodiment of the disclosure, the detailed description will be omitted. 
     The plurality of hinge members  140  may be configured such that each one end part is fixed to inner four corners  113  of the base  110 , and each other end part is fixed to outer four corners  153  of the lens module  150 . In this case, the plurality of hinge members  140  may be configured such that both end parts are firmly fixed to the base  110  and the lens module  150  through an adhesive. 
     The lens assembly  100  according to another embodiment of the disclosure may be configured such that the lens module  150  is not moved forward or backward along the Z-axis direction (optical axis direction) for adjusting auto focus. The auto focus may be adjusted by an operation in which an image sensor  160  is moved forward to be adjacent to the lens module  150  based on the Z-axis direction or moved backward to be farther from the lens module  150 . 
     Based on realizing auto focus adjustment through a method of the image sensor  160  moving forward or backward, because the image sensor  160  which is lighter in weight than the lens is moved, an amount of power being consumed accordingly may be decreased. 
     The image sensor  160  may be disposed at a lower side of the lens module  150 , and engaged to a first portion  135  of the movable member  130  to move forward or backward in the Z-axis direction by the movable member  130 . The image sensor  160  may be inserted in an engagement hole formed at the first portion  135 . 
     A back surface of the image sensor  160  may be mounted to a one portion  163  of a flexible printed circuit board (FPCB). A other portion  161  of the FPCB may be configured such that an end part is moved out to an outer side of the base  110  in a state folded by 180 degrees based on the one portion  163 . In this case, the end part of the other portion  161  of the FPCB may be disposed with a connector  165 . The connector  165  may be connected with a separate connector (not shown) which is connected to a distal end of an external power wiring or a signal wiring. 
     Accordingly, because the FPCB is easily deformed when the movable member  130  to which the image sensor  160  is engaged is moved in the Z-axis direction, it does not interfere in the movement of the movable member  130 . 
     The movable member  130  may include a second portion  137  which is extended and formed at the first portion  135 , and disposed in-between a side wall  117  of the base  110  and one side of the lens module  150  moving forward or backward in the Z-axis direction. 
     In-between the second portion  137  and the side wall  117  of the base  110 , a plurality of balls  132  may be disposed. The plurality of balls  132  may perform a guide role for the movable member  130  to move forward or backward along the Z-axis direction based on the base  110 . The second portion  137  and the side wall  117  of the base  110  may be formed with a V-shape groove (not shown) through which the plurality of balls  132  is guided. 
     The driving part for adjusting the auto focus to move the movable member  130  may include a magnet  120  which is engaged to the second portion  137  and coil  121  which is disposed at the side wall  117  of the base  100  to face the magnet  120 . The coil  121  may be mounted to the printed circuit board (not shown) installed at the base  110 . 
     The driving part for adjusting the auto focus may move the movable member  130  in a Z-axis direction or a −Z-axis direction through interaction with the magnet  120  according to a direction (one direction or reverse direction thereof) of the current applied to the coil  121 . 
     On the printed circuit board on which the coil  121  is disposed, a plurality of terminals for receiving power and a control signal from the outside may be formed, and a hall sensor  123  for detecting a position of the movable member  130  and controlling may be mounted. 
     The hall sensor  123  may detect a movement of the magnet  120  by being disposed to be surrounded by coil  121  formed in a closed curve, and transmit the detected signal to a control part (not shown) of a small electronic device. The control part may perform control in the Z-axis direction of the support through the hall sensor  123  and the driving part for adjusting the auto focus. 
     The lens assembly  100  according to another embodiment of the disclosure may include a driving part for a first OIS (not shown) which moves the lens module  150  in the X-axis direction and a driving part for a second OIS (not shown) which moves the lens module  150  in the Y-axis direction for OIS. 
     The driving parts for the first OIS and the second OIS provided in the lens assembly  100  according to another embodiment of the disclosure may be formed of the same structure as with the driving parts for the first OIS and the second OIS provided in the lens assembly  1  according to an embodiment of the disclosure described above. 
     For example, the coils of the driving parts for the first OIS and the second OIS may be each disposed at two side surfaces adjacent to the base  110 , and the magnets of the driving parts for the first OIS and the second OIS may be each disposed at two side surfaces of the lens module  150  to correspond to each coil. 
       FIG.  14    and  FIG.  15    are exploded perspective views illustrating a lens assembly according to still another embodiment of the disclosure. 
     A lens assembly  200  may be the same in most configurations and different in a part of the configurations with the lens assembly  10  described above. Accordingly, in describing the configuration of the lens assembly  200 , the configurations different from the above described lens assembly  10  will be mainly described. 
     Referring to  FIG.  14    and  FIG.  15   , the lens assembly  200  may include a base  210 , a support  230  which moves a lens module  250  in the Z-axis direction (in the disclosure, the Z-axis direction may mean an optical axis direction) for auto focusing, a lens module  250  which is disposed at an inner side of the support  230  and includes a lens part  251  configured of a plurality of lenses, a plurality of hinge members  240  configured such that the lens module  250  connects the support  230  and the lens module  250  for the lens module  250  to be movable along the X-Y plane based on the support  230  for OIS, an inner cover  260  configured to prevent the lens module  250  from separating from the support  230 , and an outer cover  270  which covers one side of the base  210 . 
     Each hinge member  240  may be configured such that one end part is engaged to a first engagement groove  233  of the support  230 , and other end part is engaged to a second engagement groove  253  of the lens module  250 . In this case, the one end part of each hinge member  240  and the first engagement groove  233  may be adhered and fixed by an adhesive, and the other end part of the hinge member  240  and the second engagement groove  253  may be adhered and fixed by the adhesive. Specifically, a damper bond may be used at a connection part of the hinge member. 
     The lens assembly  200  may include a driving part for adjusting auto focus which is configured of coils  215  and magnets  235  rather than a piezo actuator to adjust auto focus. The coil  215  may be disposed on one surface at an inner side of the base  210 , and the magnet  235  may be disposed on one surface at an outer side of the support  230  to correspond to the coil  215  with a certain interval therebetween. 
     The support  230  may move forward or backward along the Z-axis direction by the driving part for adjusting auto focus. At this time, the support  230  may be guided by a plurality of first balls  221  and a plurality of second balls  223 . 
     The plurality of first balls  221  may be disposed in a respectively contacted state in-between a first corner part  210   a  of the inner side of the base  210  and a first guide surface  230   a  of the support  230  corresponding thereto. 
     The plurality of second balls  223  may be disposed in a diagonal direction based on the plurality of first balls  221 . In this case, the plurality of second balls  223  may be disposed in a respectively contacted state in-between a second corner part  210   b  of the inner side of the base  210  and a second guide surface  230   b  of the support corresponding thereto. 
     The driving part for the first OIS may include a first coil  225  which is disposed at one side surface from among four side surfaces of the base  210 , and a first magnet  255  which is disposed at one side surface from among four side surfaces of the lens module  250 . 
     The driving part for second OIS may include a second coil  227  which is disposed at a side surface adjacent to the surface on which the first coil  225  is disposed from among the four side surfaces of the base  210 , and a second magnet  257  which is disposed at a side surface adjacent to the surface on which the first magnet  255  is disposed from among the four side surfaces of the lens module  250 . 
     In the base  210 , two printed circuit boards  211  and  213  may be disposed at opposite sides from each other. One printed circuit board  211  may have a plurality of first terminals  211   a , and the other printed circuit board  213  may have a plurality of second terminals  213   a . Based on the size of the lens assembly  200  being manufactured to an ultra-small type, soldering work may be conveniently performed if the plurality of first terminals  211   a  and the plurality of second terminals  213   a  are positioned at opposite sides to each other. 
     While the disclosure has been shown and described with reference to the exemplary embodiments thereof, the disclosure is not limited to the embodiments specifically described and various modifications may be made therein by those skilled in the art to which this disclosure pertains without departing from the spirit and scope of the disclosure, and such modifications shall not be understood as separate from the technical concept or outlook of the present disclosure. 
     INDUSTRIAL APPLICABILITY 
     The disclosure relates to an ultra-small lens assembly having an auto focus function and an optical image stabilization (OIS) function.