PATENT DOCUMENT

Publication Number: US-9134503-B2
Application Number: US-201213660725-A
Country: US
Kind Code: B2

Title: VCM OIS actuator module

Abstract:
A lens actuator module including an autofocus (AF) mechanism capable of moving a lens according to at least three degrees of freedom and an optical image stabilization (OIS) mechanism capable of moving the lens according to at least two degrees of freedom. The AF mechanism may have a coil and a magnet assembly for driving movement of the lens according to the at least three degrees of freedom. The optical image stabilization (OIS) mechanism may include a coil and a magnet assembly for driving movement of the lens according to the at least two degrees of freedom.

Claims:
What is claimed is: 
     
       1. A lens actuator module comprising:
 an autofocus (AF) mechanism operable to move a lens according to at least three degrees of freedom during an AF operation, the AF mechanism having a coil and a magnet assembly for driving movement of the lens according to the at least three degrees of freedom; 
 an optical image stabilization (OIS) mechanism operable to move the lens according to at least two degrees of freedom during an OIS operation, the at least two degrees of freedom different from the at least three degrees of freedom, the OIS mechanism having a coil and a magnet assembly for driving movement of the lens according to the at least two degrees of freedom; and 
 a flexure assembly positioned between the AF mechanism and the OIS mechanism, the flexure assembly having a set of AF springs attached to the AF mechanism to allow for movement of the AF mechanism and a set of OIS springs attached to the OIS mechanism to allow for movement of the OIS mechanism. 
 
     
     
       2. The lens actuator module of  claim 1  wherein the coil and magnet assembly of the AF mechanism comprises at least four separate coils that may be driven with an electric current and at least four separate magnets, wherein the coils and the magnets together control the focus position of the lens. 
     
     
       3. The lens actuator module of  claim 1  wherein the at least three degrees of freedom comprise movement of the lens in a direction parallel to an optical axis of the lens relative to an image sensor, and rotation of the lens relative to the image sensor about two axes orthogonal to the optical axis. 
     
     
       4. The lens actuator module of  claim 2  wherein the four separate coils are mounted on the lens or a lens carrier, and the four magnets are mounted on a fixed support structure of the AF mechanism. 
     
     
       5. The lens actuator module of  claim 1  wherein the coil and magnet assembly of the OIS mechanism comprises at least four separate coils and at least four separate magnets, wherein the coils and the magnets together move the lens to compensate for user handshake. 
     
     
       6. The lens actuator module of  claim 1  wherein the at least two degrees of freedom comprise movement of the lens in at least two different directions orthogonal to an optical axis. 
     
     
       7. The lens actuator module of  claim 1  further comprising:
 an upper spring assembly to suspend the lens or a lens carrier on the AF mechanism. 
 
     
     
       8. The lens actuator module of  claim 1  wherein each magnet comprises at least two regions that are poled in opposite directions so as to generate Lorentz forces in the same direction on both sides of each corresponding coil. 
     
     
       9. The lens actuator module of  claim 1  wherein the OIS mechanism further comprises:
 a plurality of ball bearings positioned between a moving portion of the OIS mechanism and a fixed portion of the OIS mechanism to minimize parasitic motions of the OIS mechanism and limit OIS mechanism movements to directions orthogonal to an optical axis of the lens. 
 
     
     
       10. The lens actuator module of  claim 9  wherein the plurality of ball bearings are maintained in contact with the moving portion and the fixed portion by a magnetic attraction between OIS mechanism magnets of the magnetic assembly, which are mounted on the moving portion of the OIS mechanism, and a magnetic material the forms part of the fixed portion of the OIS mechanism. 
     
     
       11. The lens actuator module of  claim 1  wherein the actuator module is dimensioned for use within a miniature camera of a hand-held device. 
     
     
       12. A lens actuator module comprising:
 an autofocus (AF) mechanism capable of moving a lens according to at least three degrees of freedom, the AF mechanism comprising (1) a first portion having a plurality of AF coils positioned around a lens carrier, and (2) a second portion having a plurality of AF magnets positioned within a yoke member, wherein the yoke member is positioned around the second portion such that the AF magnets are along a side of the AF coils opposite the lens carrier and the first portion is movable with respect to the second portion; 
 an optical image stabilization (OIS) mechanism operable to move the lens according to at least two degrees of freedom, the at least two degrees of freedom different from the at least three degrees of freedom, the OIS mechanism comprising (1) a base member having a plurality of OIS coils positioned around the base member, wherein the OIS coils are orthogonal to the AF coils, and (2) a plurality of OIS magnets attached to a bottom side of the first portion and positioned over the OIS coils so as to move the first portion according to the at least two degrees of freedom with respect to the base member; and 
 a flexure assembly positioned between the AF mechanism and the OIS mechanism, the flexure assembly having a set of AF springs attached to the AF mechanism to allow for movement of the AF mechanism and a set of OIS springs attached to the OIS mechanism to allow for movement of the OIS mechanism.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The application claims the benefit of the earlier filing date of U.S. Provisional Patent Application No. 61/668,612, filed Jul. 6, 2012 and incorporated herein by reference. 
    
    
     FIELD 
     An embodiment of the invention is directed to an actuator module for a camera that may be integrated within a mobile electronic device such as a smart phone. Other embodiments are also described and claimed. 
     BACKGROUND 
     Miniature cameras are becoming increasingly common in mobile electronic devices such as smartphones. There is a constant drive to improve performance of such cameras, while still maintaining the same envelope. Demands on improvements to performance of such miniature cameras are constant, as are demands for continued miniaturization, given the added features and devices added to such mobile electronic devices. In particular, high image quality requires the lens motion along the optical axis to be accompanied by minimal parasitic motion in the other degrees of freedom, particularly tilt about axes orthogonal to the optical axis. This requires the suspension mechanism to be stiff to such parasitic motions. However, given the need to control the lens position with a resolution of 1 micron, such suspension mechanisms must account for friction. Further to this, there is a strong desire, for a given size of camera, to fit bigger lenses and image sensors to improve image quality, and hence there is a desire to reduce the size of components such as actuators. 
     One feature augmentation that is now standard in such miniature cameras is autofocus (AF) whereby the object focal distance is adjusted to allow objects at different distances to be in sharp focus at the image plane and captured by the digital image sensor. There have been many ways proposed for achieving such adjustment of focal position, however most common is to move the whole optical lens as a single rigid body along the optical axis. Positions of the lens closer to the image sensor correspond to object focal distances further from the camera. 
     The incumbent actuator technology for such cameras is the voice coil motor (VCM). The VCM technology, as compared to other proposed technologies, has the key advantage of being simple, and therefore being straightforward to design. For such actuators, a current carrying conductor in a magnetic field experiences a force proportional to the cross product of the current in the conductor and the magnetic field, this is known as the Lorentz force. The Lorentz force is greatest if the direction of the magnetic field is orthogonal to the direction of the current flow, and the resulting force on the conductor is orthogonal to both. The Lorentz force is proportional to the magnetic field density and the current through the conductor. Coils of the conductor are used to amplify the force. For actuator operation, either the magnet (or more typically magnets) or the coil is mounted on a fixed support structure, while the other of the magnet (or magnets) or coil is mounted on the moving body, whose motion is being controlled by the actuator. 
     Successful actuators have been designed both ways around (i.e., with the magnets fixed or the coil fixed), however, the more usual configuration is where the magnets are fixed, and the coil is moving. Representatively, the coil is mounted around a lens carrier or, in some cases, the lens itself. This is the most desirable configuration because the relatively heavy magnets are stationary, and hence their inertia can be avoided. The moving lens carrier is attached to the fixed support structure by an attachment mechanism that allows the lens carrier to move substantially along the optical axis, without parasitic motions, while resisting the Lorentz force of the actuator. In this way the Lorentz ‘force’ is translated into a lens carrier ‘displacement’ by the attachment mechanism. 
     Another feature augmentation that is desirable in miniature cameras is optical image stabilization (OIS). OIS is a mechanism that stabilizes an image, which may be unstable due to user handshake, by varying the optical path to the sensor. The incorporation of OIS into current miniature camera VCM actuator architecture, however, has been impractical due to compromises between size, power and performance. 
     SUMMARY 
     An embodiment of the invention is an actuator module suitable for use in a camera, more specifically, a miniature camera. The actuator module may include a mechanism to provide an AF function and a mechanism to provide an OIS function. In one embodiment, the AF mechanism may be configured with four separate magnets and four separate coils positioned around a lens carrier. Each coil can deliver a force on one corner of the lens carrier along the optical axis. In this way, if the four coils are driven appropriately with a common mode current they can provide the forces needed to focus the lens. However, if driven differentially, they can actively tilt the lens to compensate for parasitic lens tilt. 
     The actuator module further incorporates an OIS mechanism configured to shift the lens carrier (and, in one embodiment, the AF mechanism attached to the lens carrier) in directions orthogonal to the optical axis. Such motions can substantially correct for handshake motions in the center of the image. Using this method of OIS, the associated image sensor substrate can remain stationary, substantially simplifying the camera manufacture, size and packaging in the mobile handheld device. The OIS mechanism may include, among other features, four separate coils and four separate magnets positioned at corners of an OIS base member. The OIS base member may be dimensioned to be positioned below the lens carrier. The OIS coils may be positioned orthogonal to the AF coils so that they shift the lens carrier in directions orthogonal to the optical axis. 
     The combination of the AF mechanism and OIS mechanism within a single actuator module allows the actuator module to modify the position of the lens relative to the image sensor along five different axes (i.e., 5 degrees of freedom (DOF)). Representatively, the lens may be shifted or translated along at least three different axes and rotated about at least two different axes. For example, the AF mechanism and/or the OIS mechanism may move the lens linearly in a direction parallel to the optical axis (DOF1), linearly in a direction parallel to a first lateral axis orthogonal to the optical axis (DOF2), linearly in a direction parallel to a second lateral axis orthogonal to the first lateral axis and to the optical axis (DOF3), rotate the lens about the first lateral axis (DOF4) and/or rotate the lens about the second lateral axis (DOF5). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments disclosed herein are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. 
         FIG. 1  is a perspective view of one embodiment of an actuator module. 
         FIG. 2  is a perspective view of the internal components of one embodiment of an actuator module. 
         FIG. 3A  is a perspective view of one embodiment of an autofocus mechanism moving portion. 
         FIG. 3B  is a perspective view of one embodiment of a lens carrier for an autofocus mechanism moving portion. 
         FIG. 3C  is a perspective view of one embodiment of a lens carrier and coil configuration for an autofocus mechanism moving portion. 
         FIG. 3D  is a perspective view of one embodiment of a lower flexure assembly for an autofocus mechanism moving portion. 
         FIG. 4A  is a perspective view of one embodiment of an autofocus mechanism moving portion attached to an autofocus mechanism fixed portion. 
         FIG. 4B  is a perspective view of one embodiment of a yoke assembly for an autofocus mechanism fixed portion. 
         FIG. 4C  is a perspective view of one embodiment of a yoke and magnet assembly for an autofocus mechanism fixed portion. 
         FIG. 4D  is a perspective view of one embodiment of an autofocus mechanism moving portion attached to an autofocus mechanism fixed portion. 
         FIG. 4E  is a perspective view of one embodiment of an autofocus mechanism moving portion attached to an autofocus mechanism fixed portion. 
         FIG. 4F  is a perspective view of one embodiment of an autofocus mechanism moving portion attached to an autofocus mechanism fixed portion. 
         FIG. 5A  is a perspective view of one embodiment of an optical image stabilization mechanism fixed portion. 
         FIG. 5B  is a perspective view of one embodiment of a conductive base portion for an optical image stabilization mechanism fixed portion. 
         FIG. 5C  is a perspective view of one embodiment of a conductive base portion and an insulating base portion for an optical image stabilization mechanism fixed portion. 
         FIG. 5D  is a perspective view of one embodiment of a coil assembly mounted to an optical image stabilization mechanism fixed portion. 
         FIG. 5E  is a perspective view of one embodiment of an optical image stabilization mechanism moving portion. 
         FIG. 5F  is a perspective view of one embodiment of a magnet assembly for an optical image stabilization mechanism moving portion. 
         FIG. 5G  is a perspective view of one embodiment of a magnet assembly for an optical image stabilization mechanism moving portion. 
         FIG. 6  is a schematic view of one embodiment of an actuator coil and magnet configuration. 
         FIG. 7  is a perspective view of one embodiment of an autofocus actuator coil and magnet configuration. 
         FIG. 8  is a schematic view of an electrical connection configuration of one embodiment of an autofocus coil and magnet configuration. 
         FIG. 9A  is a cross sectional side view of one embodiment of a lens and spring assembly along a second lateral axis of an actuator module used during an autofocus operation. 
         FIG. 9B  is a cross sectional side view of one embodiment of a lens and spring assembly along a second lateral axis of an actuator module during an autofocus operation. 
         FIG. 9C  is a cross sectional side view of one embodiment of a lens and spring assembly along a second lateral axis of an actuator module during a tilting operation. 
         FIG. 9D  is a cross sectional side view of one embodiment of a lens and spring assembly along a first lateral axis of an actuator module used during an autofocus operation. 
         FIG. 9E  is a cross sectional side view of one embodiment of a lens and spring assembly along a first lateral axis of an actuator module during a tilting operation. 
         FIG. 10A  is a top view of one embodiment of a lens and spring assembly of an actuator module used during an optical image stabilization operation. 
         FIG. 10B  is a top view of one embodiment of a lens and spring assembly of an actuator module during a shifting operation along a first lateral axis. 
         FIG. 10C  is a top view of one embodiment of a lens and spring assembly of an actuator module during a shifting operation along a second lateral axis. 
         FIG. 11  is a perspective view of one embodiment of an implementation of an actuator module within a mobile device. 
     
    
    
     DETAILED DESCRIPTION 
     In this section we shall explain several preferred embodiments with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the embodiments is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description. 
     The present invention makes use of VCM technology and presents an actuator architecture having improved power consumption, performance, reduced size, and extra functionality, including OIS.  FIG. 1  illustrates a perspective view of one embodiment of an actuator module. Actuator module  100  may have integrated therein a mechanism to provide the AF function and a mechanism to provide the OIS function. The AF mechanism is configured to both move the lens along the optical axis and actively tilt the lens. The lens tilt may be used to compensate for parasitic lens movements due to, for example, tilting of the device within which actuator module  100  is implemented (e.g., mobile electronic device  1100  illustrated in  FIG. 11 ). The OIS mechanism is configured to move (e.g., shift) the lens in directions orthogonal to the optical axis to correct for handshake motions in the center of the image. By shifting, as opposed to tilting the entire camera (e.g., the lens and image sensor together as a rigid body), the associated image sensor substrate  101  can remain stationary, substantially simplifying both camera manufacture, size and packaging in the mobile electronic device. In particular, if the entire camera is tilted, a separate space must be added beneath the image sensor substrate to account for this movement. This, in turn, increases the size of the camera and introduces the difficult task of getting multiple electrical connections off the moving image sensor substrate without reducing OIS performance. It is contemplated, however, that in other embodiments, the whole camera including the lens and image sensor may be tilted together using the AF and OIS mechanisms. 
     In effect, actuator module  100  is able to control the position of lens  102  relative to the image sensor  101  in five axes (i.e., 5 degrees of freedom (DOF)). In other words, actuator module  100  can both shift and tilt lens  102  to achieve both AF and correct for any image distortion due to the shifting OIS function. The 5 degrees of freedom are as follows: linear position along the optical axis (DOF1) as illustrated by arrow  106 , linear position along a first lateral axis orthogonal to the optical axis (DOF2) as illustrated by arrow  108 , linear position along a second lateral axis orthogonal to the first lateral axis and to the optical axis (DOF3) as illustrated by arrow  110 , rotation about a first axis orthogonal to the optical axis (DOF4) as illustrated by arrow  112  and rotation about a second axis orthogonal to the first axis and to the optical axis (DOF5) as illustrated by arrow  114 . The first axis of DOF4 and the second axis of DOF5 may be the same or different than the first lateral axis of DOF2 and the second lateral axis of DOF3, respectively. 
     It is noted that a sixth DOF, which is rotation about the optical axis illustrated by arrow  106 , is also possible. The sixth DOF may be useful, for example, in embodiments where the lens is not rotationally symmetrical about the optical axis illustrated by arrow  106 . 
     During operation, lens  102  may be moved linearly (e.g., shifted), tilted and/or rotated about any one or more of the axes illustrated in  FIG. 1  using actuator module  100 . Representatively, in one embodiment, lens  102  may shifted in a direction parallel to the optical axis  106 , tilted about axes orthogonal to the optical axis (e.g., axis  108  or axis  110 ), and rotated about an appropriate center of rotation (e.g., rotated as illustrated by arrow  112  and/or arrow  114 ) to achieve a desired AF or OIS position. 
     The addition of the controllable lens tilt DOFs provides several advantages. For example, during a factory calibration of actuator module  100 , offset currents can be applied to the AF coils, as will be described in more detail below, to tilt lens  102  and hence compensate for any static tilt errors between lens  102  and the associated image sensor  101 . Such static tilt errors may be due to manufacturing variations caused by part and assembly tolerances. In addition, as the orientation of the camera, within which actuator module  100  is implemented, is changed, the lens may tilt parasitically relative to the image sensor. This may occur where the lens is suspended on a resilient spring flexure and the lens center of gravity is not located at the point that would apply balanced loads to the spring flexures. By making use of an accelerometer found in the electronic device in which actuator module  100  is implemented, to determine the orientation of the camera, it is possible to provide offset currents to the coils to compensate for the tilt and maintain low tilt between lens  102  and the associated image sensor  101 . 
     Actuator module  100  may be enclosed within a housing  104  as further illustrated in  FIG. 1 . Housing  104  may be a substantially hollow, rectangular structure dimensioned to contain each of the components of actuator module  100 . In one embodiment, housing  104  may have a substantially circular opening through which lens  102  may be positioned and an open bottom such that it can be easily positioned over the components of actuator module  100 . Housing  104  may be made of any material suitable for containing components of actuator module  100 , for example, any substantially rigid material suitable for containing and protecting the components such as a substantially rigid plastic material. 
     In one embodiment, housing  104  may be, for example, a screening that encloses the AF and OIS mechanisms and provides drop-test end-stops limiting the motion of the mechanisms during impact. In this aspect, housing  104  may be made of a substantially rigid material, for example, a metal, such as deep-drawn steel, or injection molded plastic. In one embodiment, a metal screening may be used to minimize the material thickness. In the case of a metal screening, an insulating coating may further be provided to avoid electrical short-circuits to the various conduits, such as the springs. 
       FIG. 2  illustrates a perspective view of one embodiment of actuator module  100  with housing  104  removed. From this view, it can be seen that AF mechanism  202  and OIS mechanism  204  are positioned one on top of the other. Representatively, as illustrated in  FIG. 2 , AF mechanism  202  is positioned on top of OIS mechanism  204 . AF mechanism  202  may include lens carrier  212  mounted within AF yoke  222 . Lens  102  may be mounted within lens carrier  212  such that movement of lens carrier  212  by AF mechanism  202  during an autofocus operation or OIS mechanism  204  during an OIS operation moves the associated lens  102 . OIS mechanism  204  may include an OIS base  230  dimensioned to support each of the OIS mechanism components, for example, OIS magnets  226 A,  226 B,  226 C positioned at each corner of OIS mechanism  204 . In addition to supporting the various OIS components, OIS base  230  may also provide a support base along which AF mechanism  202  can shift during an OIS operation as will be described in more detail below. Each of the AF mechanism  202  and OIS mechanism  204  may have a substantially rectangular overall shape with substantially similar footprints such that they can be enclosed within housing  104  previously discussed in reference to  FIG. 1 . 
     The various components making up AF mechanism  202 , according to one embodiment, will now be described in more detail in reference to  FIGS. 3A-3D  and  FIGS. 4A-4F . More specifically,  FIGS. 3A-3D  illustrate various features of a moving portion of AF mechanism  202  which can be attached to, and is capable of moving with respect to, a fixed portion of AF mechanism  202 . The fixed portion of AF mechanism  202  will be described in reference to  FIGS. 4A-4F . 
       FIG. 3A  illustrates a top perspective view of one embodiment of an AF mechanism moving portion. When AF yoke  222  is removed, as illustrated in  FIG. 3A , it can be seen that AF mechanism moving portion  302  includes lens carrier  212 , AF coils  214 A,  214 B,  214 C and  214 D positioned around the circumference of lens carrier  212  and a lower flexure  224 . A lower flexure stiffener  232  may further be attached to lower flexure  224 . The lower flexure stiffener  232  may provide support to lower flexure  224  and also serve as a mounting bracket for mounting of AF mechanism moving portion  302  to OIS base  230  as illustrated in  FIG. 2 . 
       FIG. 3B  illustrates a top perspective view of lens carrier  212  with the AF coils and lower flexure removed. From this view, it can be seen that lens carrier  212  is a substantially cylindrical structure dimensioned to support a lens (e.g., lens  102 ) and allow for movement of the lens along one or more of the desired degrees of freedom. In this aspect, lens carrier  212  may include an open center dimensioned to receive the lens and various guide and pin members dimensioned to connect lens carrier  212  to various components used to drive movement of lens carrier  212 . Representatively, lens carrier  212  may have guide members  240 A,  240 B and  240 C extending from its outer circumferential wall which are dimensioned to support AF coils  214 A,  214 B and  214 C, respectively. It is noted that a fourth guide member (not shown), which is substantially similar to the illustrated guide members, is also provided along a back side of lens carrier  212  to support AF coils  214 D. The guide members  240 A,  240 B and  240 C are dimensioned to fit within an open center of each of AF coils  214 A,  214 B,  214 C and  214 D such that the coils are vertically oriented around lens carrier  212  as illustrated in  FIG. 3A . This vertical orientation of AF coils  214 A,  214 B,  214 C and  214 D facilitates movement of lens carrier  212 , and in turn the associated lens, in a direction parallel to an optical axis of the lens positioned therein during the AF operation (i.e., according to DOF1) and/or rotation or tilting of the lens along axis orthogonal to the optical axis (i.e., according to DOF4 or DOF5). Although not illustrated, the ends of the wires forming the AF coils  214 A,  214 B,  214 C and  214 D can be connected to external terminals, which can be wrapped onto pins  244 A,  244 B on two sides of the lens carrier  212 . The other ends of the wires can be bonded into channels  246 A,  246 B,  246 C and  246 D formed within lens carrier  212  and brought to the top of the lens carrier  212  and folded into the middle of the part for later connection with the AF upper flexure  420  (see  FIG. 4A ). 
     Guide members  240 A,  240 B and  240 C may be integrally formed with lens carrier  212  or may be separate structures attached to lens carrier  212  according to any suitable technique (e.g., bonding, welding, adhesive or the like). It is to be understood that although a specific number of guide members  240 A,  240 B and  240 C (e.g., four) having particular geometric shapes are described and/or illustrated in  FIG. 3B , any number of guide members  240 A,  240 B and  240 C having any shape suitable for supporting AF coils  214 A,  214 B,  214 C and  214 D in the manner described are contemplated. In the illustrated embodiment, the guide members  240 A,  240 B,  240 C and a fourth guide member (not shown) are evenly spaced around the outer circumference of lens carrier  212 . It is contemplated, however, that in other embodiments, the guide members may be unevenly spaced with respect to one another around the circumference of lens carrier  212 . 
     Lens carrier  212  may further include upper guide pins  242 A,  242 B,  242 C and  242 D extending from a top surface of lens carrier  212 , which facilitate attachment of lens carrier  212  to an AF upper flexure, as will be described in more detail in reference to  FIG. 4A . Lower guide pins  244 A and  244 B may further be provided along a circumference of lens carrier  212 . Lower guide pins  244 A and  244 B may extend from the outer wall of lens carrier in a substantially perpendicular direction and be used to align lens carrier  212  with AF lower flexure  224  as illustrated in  FIG. 3A . Upper guide pins  242 A,  242 B,  242 C and  242 D and/or lower guide pins  244 A and  244 B may be integrally formed with lens carrier  212  or may be separate structures attached to lens carrier  212  according to any suitable technique (e.g., bonding, welding, adhesive or the like). It is to be understood that although a specific number of upper guide pins  242 A,  242 B,  242 C and  242 D and/or lower guide pins  244 A and  244 B having particular geometric shapes are illustrated in  FIG. 3B , any number of upper guide pins  242 A,  242 B,  242 C and  242 D and/or lower guide pins  244 A and  244 B having any shape suitable for attaching and/or aligning lens carrier with or to the desired structure may be used. Representatively, although only two lower guide pins  244 A and  244 B are illustrated along a front side of lens carrier  212 , it is contemplated that additional lower guide pins (e.g., 2 more lower guide pins substantially similar to lower guide pins  244 A and  244 B) may be positioned along the back side of lens carrier  212  in a similar manner. Alternatively, a single lower guide pin may extend from one or more sides of lens carrier  212 . 
     Lens carrier  212  having AF coils  214 A,  214 B,  214 C and  214 D attached thereto, is attached to and sits on top of AF lower flexure  224 . AF lower flexure  224  will now be described in more detail in reference to  FIG. 3D . AF lower flexure  224  may have various spring and flexure structures incorporated therein that facilitate movement of lens carrier  212 , and the associated lens, according to the desired degrees of freedom previously discussed in reference to  FIG. 1 . The AF lower flexure  224  can be attached (e.g., bonded) on the bottom side of the lens carrier  212  according to any suitable attachment mechanism or system. For example, in one embodiment, AF lower flexure  224  is attached to the bottom of lens carrier  212  by aligning pins (not shown) extending from the bottom side of lens carrier  212  with holes  253 A and  253 B formed within free ends  252 A,  252 B,  252 C and  252 D of AF lower flexure  224 . 
     AF lower flexure  224  carries several functions, including functions in the AF mechanism  202  and OIS mechanism  204 . In one embodiment, AF lower flexure  224  may include several lower flexure assemblies  224 A,  224 B,  224 C and  224 D (e.g., four flexure assemblies when installed into the actuator module  100 ), such that there is one lower flexure assembly  224 A,  224 B,  224 C and  224 D positioned in each corner of the actuator module  100 . AF lower flexure  224  may be manufactured as a single component from a sheet material (e.g., a sheet of metal material), where the sprue (not shown) is removed during the course of manufacture. Each of the four flexure assemblies may have a portion mounted to the lens carrier  212 , and a portion mounted to the AF mechanism fixed portion. Representatively, free ends  252 A,  252 B,  252 C and  252 D may be mounted to lens carrier  212  and fixed mount portions  256 A,  256 B,  256 C and  256 D may be mounted to the AF mechanism fixed portion. In some embodiments, to facilitate mounting, each of the free ends  252 A,  252 B,  252 C and  252 D and fixed mount portions  256 A,  256 B,  256 C and  256 D may include holes dimensioned to receive pins or posts extending from the structures to which they are to be mounted to. 
     Between these two mounting regions, each of the lower flexure assemblies  224 A,  224 B,  224 C and  224 D may include AF lower springs  248 A,  248 B,  248 C and  248 D, respectively. One or more of the AF lower springs  248 A,  248 B,  248 C and  248 D may be a spring beam which suspends the lens carrier  212  on the fixed part of the AF mechanism  202 . AF lower springs  248 A,  248 B,  248 C and  248 D may help to minimize tilt and other parasitic motions of the associated lens as well as a spring force resisting the VCM force. In this aspect, each of AF lower springs  248 A,  248 B,  248 C and  248 D may have any shape and dimensions suitable to provide actuator module  100  with a desired level of stiffness in the optical axis direction (e.g., axis  106 ), high stiffness to motions orthogonal to the optical axis (e.g., axes  108  and  110 ), and yet be capable of withstanding deformations in directions orthogonal to the optical axis, such as during lens insertion and drop-testing. 
     Each of the lower flexure assemblies  224 A,  224 B,  224 C and  224 D may further include terminal ends  254 A,  254 B,  254 C and  254 D which extend from OIS springs  250 A,  250 B,  250 C and  250 D and attach to the OIS base  230 . Each of OIS springs  250 A,  250 B,  250 C and  250 D are positioned between their respective terminal ends  254 A,  254 B,  254 C and  254 D and the region mounted to the AF mechanism fixed portion (i.e., fixed mount portions  256 A,  256 B,  256 C and  256 D). OIS springs  250 A,  250 B,  250 C and  250 D are dimensioned to form part of a linking region that links the AF mechanism fixed portion to a fixed portion of the OIS mechanism. OIS springs  250 A,  250 B,  250 C and  250 D are further dimensioned to accommodate the relative motions of OIS mechanism  204  in planes orthogonal to the optical axis of an associated lens. In other words, OIS springs  250 A,  250 B,  250 C and  250 D are capable of accommodating motions in two orthogonal directions (e.g., in directions parallel to first lateral axis  108  and second lateral axis  110 ), and providing the appropriate return forces for such motions so as to resist the VCM forces. In some embodiments, in order to accommodate the motion in the two orthogonal directions, OIS springs  250 A,  250 B,  250 C and  250 D may be bent into a substantially “L” shaped structure as illustrated in  FIG. 3D . 
     The functions of the AF lower springs  248 A,  248 B,  248 C and  248 D and the OIS springs  250 A,  250 B,  250 C and  250 D may therefore, in some embodiments, be combined into a single component. Such combination is advantageous, both for packaging reasons, and further because it provides a conduit to route electrical connections from the AF mechanism  202  to the bottom of the actuator module  100 , and ultimately the associated image sensor substrate. In particular, given that the AF lower flexure  224  is split into four regions, it can accommodate four electrical connections all the way to the lens carrier  212 , onto which the AF coils  214 A,  214 B,  214 C and  214 D are mounted. In this aspect, only four electrical connections can easily be made to the AF mechanism  202 , and there are four AF coils  214 A,  214 B,  214 C and  214 D, each with two terminals that can be used to control at least three degrees-of-freedom. 
     In addition, in the illustrated embodiment, OIS springs  250 A,  250 B,  250 C and  250 D are substantially symmetrical, thereby nominally eliminating parasitic twisting forces. The four AF coils  214 A,  214 B,  214 C and  214 D and their associated magnets may also be symmetric around the lens carrier  212  so as not to introduce parasitic tilting torques. They can, however, be controlled so as to actively tilt the associated lens as desired. Still further, functions are combined in several of the components to eliminate complexity. For example, the AF lower flexure  224  forms both the AF lower springs  248 A,  248 B,  248 C,  248 D and OIS springs  250 A,  250 B,  250 C,  250 D. 
     Note that the AF lower flexure  224  may, in some embodiments, already have mounted on its terminal ends  254 A,  254 B,  254 C and  254 D one or more lower flexure stiffeners  232 A and  232 B that help to attach the flexure assemblies together thereby stabilizing AF lower flexure  224 . Materials and/or coatings for lower flexure stiffeners  232 A and  232 B are chosen to maintain electrical isolation between the two terminals (e.g., terminal ends  254 A and  254 B or terminal ends  254 C and  254 D) to which they are connected. In addition, one or more of mounting terminals  258 A,  258 B,  258 C and  258 D may extend from lower flexure stiffeners  232 A and  232 B to facilitate mounting of AF lower flexure  224  over OIS base  230 . 
     Once the AF mechanism moving portion  302  is assembled as illustrated in  FIG. 3A , the terminals of AF coils  214 A,  214 B,  214 C and  214 D are soldered to pads on the AF lower flexure  224  to complete the AF mechanism moving portion  302 . For example, each of AF coils  214 A,  214 B,  214 C and  214 D is wrapped onto the respective posts  244 A,  244 B (there are also two posts on the other side of lens carrier  212  which cannot be seen from this view), which locates them mechanically. They are then soldered onto the lower flexure free ends  252 A- 252 D, respectively. The other end of each coil is run into the respective channels  246 A- 246 D to locate them (as described earlier), before all being soldered to the AF upper flexure  420 . In one embodiment, indentations  270 A,  270 B may be made within corresponding portions of AF upper flexure  420  (see  FIG. 2 ), where the wires in the channels are brought up onto the top surface of the AF upper flexure  420  for soldering. 
     Features of the AF mechanism fixed portion will now be described in reference to  FIGS. 4A-4F .  FIG. 4A  illustrates a top perspective view of AF mechanism fixed portion  402  attached to AF mechanism moving portion  302 . AF mechanism fixed portion  402  may include AF yoke  222 , which is mounted over AF mechanism moving portion  302 . An AF upper flexure  420  may be attached to a top surface of AF yoke  222 . As can be seen from  FIG. 4B , AF yoke  222  is a substantially rectangular frame type structure which includes corner support members  403 A,  403 B,  403 C and  403 D over each corner. Since AF upper flexure  420  also has a rectangular profile, it can be supported along its corner by each of corner support members  403 A,  403 B,  403 C and  403 D such that it is suspended over AF upper flexure  420 . 
     AF upper flexure  420  may include AF upper springs  422 A,  422 B,  422 C and  422 D which extend across each corner and suspend associated carrier support members  424 A and  424 B at their ends. Representatively, each of AF upper springs  422 A,  422 B,  422 C and  422 D may be attached at one end to a wall of AF upper flexure  420  and at an opposite end to one end of the associate carrier support member  424 A or  424 B. Carrier support members  424 A and  424 B are in turn attached to lens carrier  212  by, for example, inserting upper guide pins  242 A,  242 B,  242 C and  242 D extending from the top surface of lens carrier  212  through corresponding holes formed within support members  424 A and  424 B. Terminals of AF coils  214 A,  214 B,  214 C and  214 D can be soldered to AF upper flexure  420  to make electrical connection between all of the AF upper springs  422 A,  422 B,  422 C and  422 D. AF upper flexure  420  can be electrically isolated from the AF yoke  222  by, for example, conformally coating the AF yoke  222 . 
     AF upper springs  422 A- 422 D along with AF lower springs  248 A- 248 D suspend lens carrier  212  on the AF mechanism fixed portion  402 . The combination of the AF upper springs  422 A- 422 D and AF lower springs  248 A- 248 D together provides a relatively low stiffness along the optical axis, and a relatively high stiffness in directions orthogonal to the optical axis. Since AF upper springs  422 A- 422 D and AF lower springs  248 A- 248 D are disposed relative to each other along the optical axis, a stiffness is provided which prevents undesired tilting (e.g., rotation of the associated lens about axes orthogonal to the optical axis). 
     As can be seen from the bottom perspective view of yoke  222  illustrated in  FIG. 4C , AF magnets  416 A,  416 B,  416 C and  416 D are mounted and bonded into the AF yoke  222 . In this aspect, AF yoke  222  is a substantially square frame like structure having side walls that form corners as illustrated in  FIG. 4B . AF magnets  416 A,  416 B,  416 C and  416 D may be mounted into each of the corners as illustrated in  FIG. 4C . AF magnets  416 A,  416 B,  416 C and  416 D may, in one embodiment, be substantially triangular structures which are dimensioned to fit within the corners of AF yoke  222 . 
     The AF mechanism moving portion  302  is then mounted to the AF mechanism fixed portion  402  by aligning holes formed through fixed mount portions  256 A,  256 B,  256 C and  256 D of AF lower flexure  224  with the pins  404 A,  404 B,  404 C and  404 D extending from the bottom of each of AF magnets  416 A,  416 B,  416 C and  416 D (e.g., two on each AF magnet). Once the holes are aligned with the pins, AF lower flexure  224  can be inserted onto the bottom of AF mechanism fixed portion  402 , which in turn positions lens carrier  212  within the central opening of AF yoke  222  as illustrated by  FIG. 4D . Pins  404 A,  404 B,  404 C and  404 D may also be used to position AF base member  418  over AF lower flexure  224  as illustrated by  FIG. 4E . It is noted that although pins  404 A,  404 B,  404 C and  404 D are illustrated, it is contemplated that any type of mechanism suitable for aligning and attaching AF mechanism fixed portion  402  with AF mechanism moving portion  302  (e.g., bolts, clamps, welding or the like) may be used. 
     AF base member  418  may serve several different purposes. Representatively, AF base member  418  may form part of the support structure joining the AF mechanism  202  to the OIS mechanism  204 . AF base member  418  may also serve as a mechanical end-stop for the lens carrier  212  during drop-testing. Still further, AF base member  418  may form a magnetic yoke, which largely separates the magnetic fields from the AF mechanism  202  and the OIS mechanism  204 . In this aspect, AF base member  418  may be a substantially planar frame-like structure positioned between AF lower flexure  224  and the OIS magnets. AF base member  418  may be made of any material suitable for performing the above-described functions. For example, AF base member  418  may be made of a metal material such as a magnetic stainless steel material or the like. 
       FIG. 4F  illustrates a top perspective view of AF yoke  222  positioned over AF mechanism moving portion  302  with AF upper flexure  420  removed. As can be seen from this view, AF mechanism moving portion  302  sits within and is surrounded by AF yoke  222 . AF upper flexure  420  can be attached (e.g., bonded) to lens carrier  212  and AF yoke  222  as illustrated in  FIG. 4A  to form the complete AF mechanism  202 . 
     Various aspects of the OIS mechanism  204  will now be described in reference to  FIGS. 5A-5G .  FIGS. 5A and 5B  show OIS mechanism  204  having OIS base member  502  which, during operation, is positioned below each OIS magnet  226 A,  226 B and  226 C, as illustrated in  FIG. 2 . OIS base member  502  may be considered the OIS mechanism fixed portion in that it remains substantially stationary during actuator operation. OIS base member  502  may include a conductive base portion  504 , an insulating base portion  506 , OIS coils  512 A,  512 B,  512 C and  512 D and one or more of ball bearings  514 A,  514 B, and  514 C. OIS base member  502  may be a substantially rectangular structure dimensioned to receive OIS coils  512 A,  512 B,  512 C and  512 D at each of its corners. OIS base member  502  may form the bottom of the complete actuator module. The underside surface of OIS base member  502  may form the mounting bond surface for the associated image sensor  101  when the actuator module  100  is integrated into a complete camera. 
     In one embodiment, the OIS base member  502  is an over-molding, having a conductive base portion  504 , which is placed in an injection molding machine, and around which an insulating base portion  506  can be molded. OIS base member  502  may have any size and shape suitable for mounting within actuator module  100 , for example, a substantially square shape with an open center portion. In one embodiment, conductive base portion  504  can be split into twelve conductive bodies as illustrated in  FIG. 5B . Representatively, conductive base portion  504  may include four side conductive bodies  508 A,  508 B,  508 C and  508 D and eight corner conductive bodies  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G and  510 H. Side conductive bodies  508 A,  508 B,  508 C and  508 D may be positioned along the sidewalls of insulating base portion  506  and corner conductive bodies  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G and  510 H may be positioned at the corners of insulating base portion  506 . Although side conductive bodies  508 A,  508 B,  508 C and  508 D and corner conductive bodies  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G and  510 H are separate structures, they may be manufactured as a single component held together in a sprue on a sheet (not shown). Once the insulating base portion  506 , which can be made of, for example, a plastic material, is over-molded around the conductive base portion  504 , the sprue is removed, splitting the conductive base portion  504  into the twelve separated conductive bodies  508 A,  508 B,  508 C,  508 D and  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G,  510 H. Although twelve conductive bodies are illustrated, it is contemplated that more or less of the conductive bodies may be provided within OIS base member  502 . For example, the only side conductive bodies or only corner conductive bodies may be present in OIS base member  502 . Conductive bodies  508 A,  508 B,  508 C,  508 D and  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G,  510 H may have any sizes and shapes suitable for positioning within the desired region of OIS base member  502 , but in general are relatively thin elongated structures. In addition, although in one embodiment, the above-described over-molding technique is used to form OIS base member  502 , it is contemplated that other techniques suitable for forming an OIS base member having a conductive portion and an insulating portion may be used. For example, the conductive portion and the insulating portion may be separately formed and attached to one another after they are formed, for example, by soldering one to the other. 
       FIGS. 5C and 5D  show the other components mounted on the insulating base portion  506 . Representatively, as can be seen from  FIG. 5C , each of the corners of insulating base portion  506  include recessed regions having a pair of pins  520 A,  520 B,  520 C and  520 D extending therefrom. It is noted that although pairs of pins are illustrated in each corner, a single pin or more than two pins may be present in each corner, for example three pins. These recessed regions with pins  520 A,  520 B,  520 C and  520 D therein are dimensioned to align and support OIS coils  512 A,  512 B,  512 C and  512 D as illustrated in  FIG. 5D . In one embodiment, each of OIS coils  512 A,  512 B,  512 C and  512 D may be substantially the same and may be positioned in a substantially horizontal orientation such that their openings are positioned around pins  520 A,  520 B,  520 C and  520 D as illustrated. It is to be understood, however, that although pin type structures are illustrated, any type of alignment structure could be used to position OIS coils along OIS base member  502  according to the desired orientation (e.g., elongated structures similar to guide members  240 A,  240 B,  240 C and  240 D). 
     Since, in one embodiment, each of OIS coils  512 A,  512 B,  512 C and  512 D are mounted on the fixed portion of the OIS mechanism  204  (e.g., OIS base member  502 ), OIS magnets  526 A,  526 B,  526 C and  526 D can in turn be mounted to a movable portion of actuator module  100  such that they are movable with respect to OIS base member  502 . Representatively, OIS magnets  526 A,  526 B,  526 C and  526 D may be mounted to a bottom surface of AF base member  418 , which forms the bottom of AF mechanism  202 , as illustrated by  FIG. 5E . Such configuration may be desirable where, as in the instant embodiment, each of OIS coils  512 A,  512 B,  512 C and  512 D require two electrical connections therefore 8 connections total must be routed through the associated mounting portion. It is contemplated, however, that in other embodiments, each of OIS coils  512 A,  512 B,  512 C and  512 D may be mounted to the moving portion and the magnets mounted to the fixed portion. 
     OIS magnets  526 A,  526 B,  526 C and  526 D may be dimensioned to overlap the corners of OIS base member  502  such that they are aligned over each of OIS coils  512 A,  512 B,  512 C and  512 D. To facilitate alignment of OIS magnets  526 A,  526 B,  526 C and  526 D between AF base member  418  of AF mechanism  202  and OIS base member  502 , recesses may be formed in one or more of the top or bottom side of the magnets. Since the OIS magnets  526 A,  526 B,  526 C and  526 D may be sintered from metal, adding recesses to these components may save space and reduce complexity. The recesses may be dimensioned to align with and receive pins or posts extending from base member  418  of AF mechanism  202  and OIS base member  502 . Representatively, in one embodiment, the top side of one or more of OIS magnets  526 A,  526 B,  526 C and  526 D, for example OIS magnet  526 A, may include a pair of top side recesses  540  as illustrated in  FIG. 5F , which are dimensioned to align with and receive, for example, the pair of pins  404 A which extend from AF magnet  416 A and extend through AF base member  418  as described in reference to  FIG. 4E . A pair of bottom side recesses  542  may further be formed within a bottom side of one or more of OIS magnets  526 A,  526 B,  526 C and  526 D, for example OIS magnet  526 A as illustrated in  FIG. 5G . Bottom side recesses  542  may be dimensioned to align with and receive ball bearings  514 A,  514 B and  514 C, which are positioned along the top surface of OIS base member  502 . Ball bearings  514 A,  514 B and  514 C may be placed in recesses in the OIS insulating base portion  506 . In one embodiment, there are three ball bearings  514 A,  514 B and  514 C placed in three recesses formed near corners of insulating base portion  506 . It is contemplated, however, that more or less than three ball bearings may be used. Ball bearings  514 A,  514 B and  514 C guide the motion of the moving portion of the OIS mechanism  202  so that substantially all motion of the OIS mechanism  202  relative to the image sensor is in a plane orthogonal to the optical axis. 
     It is to be understood that for proper operation of OIS mechanism  204 , contact must be maintained between the ball bearings  514 A,  514 B and  514 C and the OIS conductive base portion  504  (which is the fixed portion of the OIS mechanism), and ball bearings  514 A,  514 B and  514 C and the moving portion of the OIS mechanism (i.e., portion with OIS magnets  526 A- 526 D). In one embodiment, to maintain such contact, an attractive force is applied between the OIS mechanism moving portion (i.e., portion with OIS magnets  526 A- 526 D) and the fixed portion (i.e., OIS base member  502 ). The attractive force can be supplied by the magnetic attraction between the conductive bodies  508 A,  508 B,  508 C,  508 D and  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G,  510 H, which may be made of a magnetic material such as a metal, in the conductive base portion  504  and the OIS magnets  526 A- 526 D. 
     In addition, surfaces on the conductive bodies  508 A,  508 B,  508 C,  508 D and  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G,  510 H in the OIS base member  502  form the contact surfaces with ball bearings  514 A,  514 B and  514 C. In this way the rolling friction is minimized, and the contact surfaces will remain flat during drop test impact when high loads are potentially applied through these contact surfaces that may indent a plastic surface. 
     In one embodiment, eight of corner conductive bodies  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G,  510 H in the OIS base member  502  form contact terminals for OIS coils  512 A,  512 B,  512 C and  512 D. Representatively, corner conductive bodies  510 A,  510 B,  510 C,  510 D,  510 E,  510 F,  510 G,  510 H may form contact terminals  560 A,  560 B,  560 C,  560 D,  560 E,  560 F and  560 G, which route electrical connections to the underside of the OIS base member  502 , where they can be subsequently soldered to pads on the image sensor substrate. The ends of the OIS coils  512 A,  512 B,  512 C and  512 D can be soldered to these terminal pads. In this aspect, OIS conductive base portion  504  serves several functions. Representatively, conductive base portion  504  provides bearing surfaces for ball bearings  514 A,  514 B and  514 C, a magnetic attraction functionality for OIS magnets  526 A,  526 B,  526 C and  526 D and contact terminals for the OIS coils  512 A,  512 B,  512 C and  512 D. 
     In one embodiment, OIS base member  502  may be assembled by positioning OIS coils  512 A,  512 B,  512 C and  512 D over base pins  520 A,  520 B,  520 C and  520 D and bonding the OIS coils  512 A,  512 B,  512 C and  512 D to OIS base member  502 . The ends of OIS coils  512 A,  512 B,  512 C and  512 D may be soldered to terminal pads on the OIS base member  502 . Ball bearings  514 A,  514 B and  514 C are then placed in recesses formed within insulating base portion  506 . 
     In one embodiment, the OIS mechanism moving portion, which is illustrated in  FIGS. 5E-5G , and consists of the OIS magnets  526 A,  526 B,  526 C and  526 D, may be formed by bonding the OIS magnets to the underside of the AF base member  418  using the pins in the corners to locate the OIS magnets  526 A,  526 B,  526 C and  526 D. 
     Once assembled, the AF mechanism  202  with OIS magnets  526 A,  526 B,  526 C and  526 D attached thereto can then be mounted on the OIS mechanism fixed portion, in other words OIS base member  502 , as illustrated in  FIG. 2 . Terminals of the AF lower flexure  224  can be bonded to the OIS base member  502 . 
     Actuator assembly is then completed by positioning housing  104  over the combined AF and OIS mechanism assembly and bonding housing  104  to OIS base member  502 . The resulting actuator module  100  provided includes several important features that improve actuator performance. Namely, since there are OIS and AF coils and magnets in each corner, uncontrolled asymmetric actuator forces are kept to a minimum. This in turn means that there is little need to account for large twisting forces (torques around the optical axis) from the OIS mechanism. In addition, the OIS springs  250 A- 250 D on lower flexure  224  are symmetric, thereby nominally eliminating parasitic twisting forces. The four AF coils  214 A- 214 D and the AF magnets  416 A- 416 D are also symmetric around the lens carrier  212  so as not to introduce parasitic tilting torques. They can, however, be controlled so as to actively tilt the lens as desired. Still further, functions are combined in several of the components to eliminate complexity. In particular, OIS magnets  526 A- 526 D have features (e.g., recesses  542 ) to locate ball bearings  514 A- 514 C. The AF lower flexure  224  forms both the AF lower springs  248 A- 248 B and OIS springs  250 A- 250 D. In addition, the OIS base member  502  includes a metal component (i.e., conductive base portion  804 ) that serves several functions. Namely, conductive base portion  504  can act as the OIS yoke to hold the mechanism together through magnetic attraction; act as one half of the contact surfaces for the ball bearings  514 A- 514 C; and act as the terminals for the OIS coils  512 A- 512 D. 
     With the actuator architecture described herein, actuator module  100  can be used to drive a relatively large lens within a camera having a relatively small overall camera footprint. For example, actuator module  100  is suitable for use with a lens having a 6.2 mm diameter thread at the top, a 6.5 mm diameter at the bottom and a camera having an overall camera footprint of less than 8.5 mm square. 
     It is further noted that actuator module  100  makes it possible to apply offset currents to the OIS coils to generate shifting forces on lens  102  (see  FIG. 1 ) to both compensate for lateral alignment errors between lens  102  and the image sensor due to manufacturing variations, and lens sag. Lens sag may occur when the camera is in different orientations, as determined by the accelerometer in the mobile electronic device. 
     For example, in one embodiment, to correct for the ‘lens sag’ and/or ‘lens tilt’ associated with different camera orientations, the sag and tilt may be assessed for each of the three possible orthogonal orientations of the optical axis, each in either direction (i.e., six total), one of which includes the camera oriented vertically upwards. In one embodiment, relative sag and tilt values for each of the three orthogonal orientations, using the negative values for the opposite directions, may be stored within, for example a controller (e.g., a microprocessor) of the hand-held device. Then for a given camera orientation, as assessed by the direction of gravity by the accelerometer, the actual sag and tilt would be assumed to be a linear combination of the three stored values of sag and tilt (or their opposites) for the different direction components. 
     A tilting resonant structure within the gyroscope found within the electronic mobile device can then be used to assess the applied angular velocity of the device, as occurs during handshake. The gyroscope can output either an analogue voltage signal for each axis measured, or a digital signal. In either case, a controller such as a microprocessor within the hand-held device receives, stores and then computes the integration of the gyroscope data stream over time, so as to calculate the angle of the hand-held device. The gyroscope is a dynamic device for measuring angular velocity and therefore has a lower limit to the frequency bandwidth over which it can accurately assess angular velocity. As a result, the gyroscope cannot distinguish different static angles, and its accuracy degrades at progressively lower frequencies. For this reason, the integrated gyroscope data is then filtered using a ‘high pass filter’ to substantially remove the inaccurate low frequency data. Depending on the design of filter, it may progressively remove angular information below 1 Hz or 0.1 Hz. 
     Actuator module  100  may be controlled with quasi-static bias currents, so that at low frequency the relative lens position between the lens and image sensor is maintained. This accounts for the fact that the quasi-static information from the gyroscope has been removed. The orthogonal streams of angular data, appropriately integrated and filtered from the gyroscope, may then be transformed and mapped to account for any differences in the orientation of the gyroscope as compared to the movement axes of the OIS mechanism  204 . The resulting data represents the changes in angle of the camera about axes that are orthogonal to the optical axis, and orthogonal to the line of action of each OIS movement direction (e.g., diagonally across the camera). 
     A further mapping associated with the amount of lens shift required to compensate for a given handshake tilt, and to account for the movement of the OIS mechanism associated for a given drive current, may then be performed. Each actuator module  100  may be calibrated for each movement direction, with these calibration values stored for each camera. In addition, there may also be a further mapping, potentially also calibrated for each actuator module  100 , where a given change in tilt is actively applied to the lens for a given applied change in OIS mechanism position. In this way, a given drive to the linear OIS mechanism will produce a proportional drive to the tilting mechanism. 
     After these mapping operations, the movement for each OIS direction that corresponds with a given camera angle (imparted by handshake) is thus assessed. Based on this assessment, the drive signal corresponding with the negative of this movement is applied to each OIS axis (and potentially the associated tilt axis), as appropriate, to compensate for the handshake motion. 
     To realize these the various tilting, rotating and shifting movements described herein, the coils and magnets for both the AF mechanism and OIS mechanism are placed in the corners of actuator  100  and, in turn, the generally cuboid camera. Such positioning minimizes the size of the camera as compared to the size of lens  102 . More specifically, the typically single AF coil is split into four separate bodies (e.g., AF coils  214 A- 214 D), so as to avoid extending the coil around the sides of the lens carrier. This, in turn, maximizes the size of the lens carrier in the footprint of the camera. The advantages to such a configuration are that the current in one half of the coil is flowing in the opposite direction to the current in the other half, relative to the magnet. In order to maintain high space efficiency, it is therefore necessary to pole the two halves of the magnet in opposite directions, so that the resulting Lorentz force on each half of the coil is in the same direction. In one embodiment, the magnet is formed as a single structure with each half poled in opposite directions. In an alternative embodiment, the magnet can be split into two pieces, and each piece poled in opposite directions and then joined together. This same basic structure is repeated for the OIS magnet and coil arrangement in the corner, although mounted orthogonally, so as to generate the forces in the desired directions. 
     This basic configuration is best illustrated in  FIGS. 6 and 7 .  FIG. 6  is a schematic representation of an AF magnet and associated AF coil.  FIG. 7  is a perspective view of the same basic actuator structure of  FIG. 6 . The AF magnet and AF coil are incorporated into actuator module  100  as previously discussed. 
     It can be seen in  FIGS. 6 and 7  that the upper and lower halves of each AF magnet  416  (as viewed in the Figures) are poled in different directions. In this aspect, the upper part of each AF magnet  416  present a south pole to the associated AF coil  214 , whereas the lower part presents a north pole (although the opposite poling is also contemplated). 
     Due to the relative orientation of each AF coil  214 , it may be seen that the top half of AF coil  214  carries a current flowing ‘into’ the page in  FIG. 6 , and the bottom half of the AF coil  214  carries a current flowing ‘out’ of the page. Given the poling of AF magnet  416 , this produces a net ‘upward’ Lorentz force on both halves of AF coil  214 , relative to AF magnet  416 . Reversing the direction of the current flow will reverse the direction of the Lorentz force. 
       FIG. 7  shows AF magnet  416  and AF coil  214  from one corner of the AF mechanism  202 . It is to be understood, however, that the basic mechanism is identical for the AF magnet and AF coil in each corner of the AF mechanism. 
       FIG. 8  shows the connection scheme for the AF coils and Table 10 below shows an example of how the different connections can be used to drive the AF coils. Referring to  FIG. 8 , electrically, one terminal of each of AF coils  214 A- 214 D is connected together, and the other terminal of each of AF coils  214 A- 214 D is connected to one of the terminals of the corresponding AF lower spring (e.g., springs  248 A- 248 D). In one embodiment, the AF coil terminals, which are all connected together, are all connected to the AF upper flexure  420 , which acts to electrically connect all these terminals together. AF upper flexure  420  may be formed from a sheet material, for example, a sheet of metal material. In one embodiment, both AF upper flexure  420  and AF lower flexure  224 , which includes the AF lower springs  248 A- 248 D, are formed from sheets of material and are configured so that the notional planes of the sheets of the two spring members, when undeformed (i.e., in a resting state), are parallel to each other. AF upper flexure  420  and AF lower flexure  224  may be separated from each other along the optical axis so that one is mounted further from the image sensor and the other closer. When AF upper flexure  420  is driven, there are four separate parts to the drive signal that are driven sequentially. The frequency of cycling through these signals can be chosen so that it is a higher frequency than can cause vibrations of the lens carrier  212  that would degrade image quality, and ideally ultrasonic to avoid any acoustic noise. 
     For each drive pulse in the cycle, two of AF coils  214 A- 214 D are driven, and hence two terminals are active and the remaining two terminals are held at high impedance (effectively open-circuit). Within each drive pulse various actual drive signals are possible. Representatively, there may be a linear drive current in which one terminal is at a drive voltage and the other connected to ground. Depending on the direction of the lens motion, the direction of current flow can be changed. In this aspect, either terminal could be at the drive voltage with the other grounded. This may mean that the analogue output of the driver may include an H-bridge to allow for driving current in both directions. Still further, the drive signal may be a pulse width modulated (PWM) drive signal in which the direction of current flow may be altered depending on the direction of travel. The AF coils  214 A- 214 D may, however, be driven from a constant voltage supply, with the VCM force controlled by the current ‘on’ time during one or more pulses (depending on the PWM drive frequency). 
     An exemplary drive scheme is illustrated in Table 1 below. 
     
       
         
           
               
               
               
               
               
             
               
                   
                   
               
               
                   
                 Terminal 1 
                 Terminal 2 
                 Terminal 3 
                 Terminal 4 
               
               
                   
                   
               
             
            
               
                   
                 +ve 
                 −ve 
                 Hi Imp 
                 Hi Imp 
               
               
                   
                 Hi Imp 
                 Hi Imp 
                 −ve 
                 +ve 
               
               
                   
                 +ve 
                 Hi Imp 
                 −ve 
                 Hi Imp 
               
               
                   
                 Hi Imp 
                 −ve 
                 Hi Imp 
                 +ve 
               
               
                   
                   
               
            
           
         
       
     
     The drive scheme as illustrated in Table 1 shows that for each of the four drive pulses, two of AF coils  214 A- 214 D that are adjacent to each other are driven. In this way, when two such AF coils (e.g.,  214 A and  214 D or  214 B and  214 C) are driven, they impart a force on the lens carrier  212  along the optical axis. This force is offset from the net reaction force from the spring flexures, for example AF upper springs  422 A- 422 B and AF lower springs  248 A- 248 D, which therefore also applies a torque to the lens carrier  212  about a first axis. 
     In the next (or previous) pulse, the two of AF coils (e.g.,  214 A and  214 D or  214 B and  214 C) on the opposite side of the lens carrier  212  are driven. For the nominal design, if the two opposite pairs of AF coils (e.g., AF coils  214 A and  214 D) are driven with the same signal, the torques will cancel out, meaning no net tilt to the lens carrier  212 . However, if there is an offset between the two signals, there will be a net torque which tends to tilt (or rotate) the lens carrier  212  about the first axis (e.g., axis  108 ). 
     In the following (and/or previous) pair of pulses, two of the AF coils  214 A- 214 D are mated with their adjacent AF coils  214 A- 214 D on the other sides, so as to allow the lens carrier  212  to tilt around a second axis (e.g., axis  110 ), which is orthogonal to the first axis (e.g., axis  108 ). This scheme allows all four AF coils  214 A- 214 D to be driven, and three degrees of freedom (e.g., movement parallel to the optical axis (DOF1), rotation about the first lateral axis  108  (DOF4) and rotation about the second lateral axis  110  (DOF5)) to be controlled with only a total of four external electrical connections. Alternatively, a linear drive scheme may be used in which each of AF coils  214 A- 214 D are driven at the same time. 
     An exemplary drive scheme for OIS operation (e.g., shift the lens carrier, and associated lens, according to DOF2 and DOF3 to compensate for user handshake) will now be described. For example, in one embodiment, all four OIS coils  512 A- 512 D are electrically connected together so that coils in the opposite corners are connected electrically in series. One pair of diagonally opposite OIS coils (e.g. OIS coils  512 D and  512 B) is driven from an entirely independent current source driver from the other pair (e.g. OIS coil  512 A and  512 C). Thus, electrically, the OIS system looks like ‘two’ separate coils, with separate current sources. A particular drive current may then correspond to a particular position. Representatively, in one embodiment, the drive scheme is a first order simple drive scheme in which the drive current is proportional to the desired position. Other more complex models are possible, including corrections for hysteresis and linearity, and potentially the dynamics of the system when operating at higher frequencies. 
     Movement of the lens according to each of DOF1-DOF5 will now be described in reference to  FIGS. 9A-9E  and  FIGS. 10A-10C . Representatively,  FIGS. 9A-9E  illustrate cross sectional side views of a lens attached to some of the AF lower springs of the AF mechanism  202 .  FIGS. 10A-10C  illustrate cross sectional side views of a lens attached to some of the OIS springs of the OIS mechanism  204 . It is noted that not all of the springs and other components forming the AF mechanism  202  and OIS mechanism  204  are shown for ease of illustration and understanding of the configuration and movement of the springs and moving lens, however, are present according to the embodiments previously discussed. 
     Representatively,  FIG. 10A  illustrates a side cross sectional view along second lateral axis  110 , thus from this view AF lower springs  248 A and  248 B are shown connected to lens  102 . Although not shown for ease of illustration, lens  102  may be held within lens carrier  212  and the AF lower springs  248 A and  248 B attached to a portion of the lens carrier  212 . In  FIG. 10A , actuator module  100  may be in a resting state (e.g., no power is being applied) such that lens  102  is in a substantially horizontal position and AF lower springs  248 A and  248 B are substantially undeformed. Actuator module  100  may be actuated (e.g., power applied) during, for example an autofocus operation such that lens  102  moves in a direction parallel to optical axis  106  as illustrated in  FIG. 10B . In other words, lens  102  moves up (or down) according to DOF  1  as illustrated by arrow  1002 . AF lower springs  248 A and  248 B in turn are deformed (e.g. stretched) in either an upward (or downward) direction as shown. As previously discussed, AF mechanism  202  may also be used to tilt lens  102 . Representatively, as illustrated in  FIG. 10C , which is also a view along second lateral axis  110 , when lens  102  is rotated about second lateral axis  110  as illustrated by arrow  1004 , it tilts such that AF lower spring  248 B deforms in an upward direction and AF lower spring  248 A remains in a substantially undeformed (e.g. horizontal) configuration. Rotation about second lateral axis  110 , as illustrated by arrow  1004 , achieves lens  102  movement according to DOF4.  FIG. 10D  illustrates another cross sectional view of the AF lower springs and lens associated with AF mechanism  202 , however, this view is along first lateral axis  108  so that DOF5 can be shown. Representatively, from this view along first lateral axis  108  AF lower spring  248 B and  248 C can be seen connected to lens  102 .  FIG. 10D  illustrates these aspects when actuator  100  is in a resting state thus lens  102  and AF lower springs  248 B and  248 C are in a substantially horizontal, undeformed orientation. Once a power is applied, lens  102  may be rotated about first lateral axis  108  as shown by arrow  1006  such that lens  102  tilts and AF lower spring  248 C deforms (e.g. stretches) in an upward direction while AF lower spring  248 B remains in a substantially resting, undeformed position (e.g., horizontal). Rotation about first lateral axis  108 , as illustrated by arrow  1006 , achieves lens  102  movement according to DOF5. 
       FIGS. 10A-10C  illustrate a top view of lens  102  connected to two of the OIS springs, namely OIS springs  250 A and  250 B.  FIG. 10A  illustrates lens  102  and OIS springs  250 A and  250 B in a resting position in which lens  102  is not being shifted according to an OIS operation.  FIG. 10B  illustrates shifting of lens  102  in a direction parallel to first lateral axis  108  to achieve DOF2. Representatively, lens  102  is shifted to the left (or right) such that OIS springs  250 A and  250 B are modified from their substantially “L” shaped resting configuration to accommodate the lens shift.  FIG. 10C  illustrates shifting of lens  102  in a direction parallel to second lateral axis  110  to achieve DOF3. Representatively, lens  102  is shifted in a backward (or forward) direction such that OIS springs  250 A and  250 B deform (e.g. expand) to accommodate the lens shift. Although OIS springs  250 C and  250 D are not illustrated, it is to be understood that a configuration of the remaining springs would be deformed in a similar manner depending upon the direction in which lens  102  shifts. 
     An exemplary process for assembling actuator module  100  and operating actuator module  100  has been described herein. It is to be understood, however, that these are only exemplary processes for assembling and operating actuator module and that any one or more of the steps may be performed in a different order, or other processes may be suitable to achieve the same results. 
       FIG. 11  illustrates one implementation of the actuator described herein. Representatively, actuator module  100  may be mounted within a miniature camera contained within a mobile electronic device  1100 . Here, the user is making a manual or touch selection on the touch screen viewfinder, which is previewing an object of interest  1114 , at which the camera lens system  1102 , having actuator module  100  therein, is aimed. The selection may be in the form of a target graphic  1104  such as a contour that may be drawn by the user on the touch screen  1106 . Alternatively, the selection or target graphic  1104  may be a fixed frame or a fixed solid area that moves with the user&#39;s finger across the screen  1106 . During an AF operation, the actuator module  100  moves the lens element mounted therein so that the object of interest  1114  is in focus, e.g., according to DOF1. Actuator module  100  may also move the lens element to compensate for lens sag, which could be caused by the user tilting the mobile device while trying to capture an image. Such movement could be according to DOF4 or DOF5. Still further, actuator module  100  may shift the lens element during an OIS operation to compensate for user handshake, e.g., according to DOF2 and/or DOF3. A flash element  1110  may further be provided to illuminate the object of interest  1114 . Once the user determines that the object of interest  1114  is in focus, the user can capture the image by pressing virtual shutter button icon  1108 . 
     While certain embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that the invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. For example, although the actuator is described for use in a miniature camera, it is contemplated that the size and dimensions of the actuator can be scaled to accommodate any size camera or other device requiring movement of a lens or other component similar to that caused by the actuator described herein. Still further, although use of the actuator in a mobile device is disclosed, it is further contemplated that the actuator may be used to drive movement of a lens element within any kind of camera, e.g., still and/or video, integrated within any kind of electronic device or a camera that is not integrated into another device. Representative non-mobile devices may include a desktop computer, a television or the like. The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20121025
Publication Date: 20150915
Grant Date: 20150915
Priority Date: 20120706
Inventors: TOPLISS RICHARD J.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04N23/55", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N23/57", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N23/687", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N23/57", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N23/55", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N23/687", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B2205/0007", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04N5/23287", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N5/2257", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N5/2254", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B3/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B5/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B2205/0069", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/646", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B7/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G03B2205/0069", "inventive": false, "first": false, "tree": "[]"}, {"code": "G03B3/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B7/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B7/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G03B2205/0007", "inventive": false, "first": false, "tree": "[]"}, {"code": "G03B2205/0007", "inventive": false, "first": false, "tree": "[]"}, {"code": "G03B5/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B3/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/646", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B5/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B2205/0069", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/646", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 49878259