PATENT DOCUMENT

Publication Number: US-8730599-B2
Application Number: US-201213632963-A
Country: US
Kind Code: B2

Title: Piezoelectric and MEMS actuator

Abstract:
A micro-electro-mechanical systems (MEMS) lens actuator having a support frame including a stationary outer portion surrounding an inner receiving portion. A piezoelectric drive member is positioned within the inner receiving portion and attached to the stationary outer portion. A first movable lens support member and a second movable lens support member are frictionally engaged with opposing ends of the piezoelectric drive member at a contact point along each of the opposing ends using a preload force at the contact point. The piezoelectric drive member may have a first actuation mode which drives movement of the first movable lens support member and the second movable lens support member in a same direction and a second actuation mode which drives movement of the first movable lens support member and the second movable lens support member in different directions.

Claims:
What is claimed is: 
     
       1. A micro-electro-mechanical systems (MEMS) lens actuator comprising:
 a support frame having a stationary outer portion surrounding an inner receiving portion; 
 a piezoelectric drive member positioned within the inner receiving portion and attached to the stationary outer portion, the piezoelectric drive member having a first actuation mode and a second actuation mode; and 
 a first movable lens support member and a second movable lens support member frictionally engaged with opposing ends of the piezoelectric drive member at a contact point along each of the opposing ends using a preload force at the contact point, wherein in the first actuation mode, the piezoelectric drive member is capable of moving the first movable lens support member and the second movable lens support member in a same direction and in the second actuation mode, the piezoelectric drive member is capable of moving the first movable lens support member and the second movable lens support member in different directions. 
 
     
     
       2. The lens actuator of  claim 1  wherein the support frame is substantially planar and the piezoelectric drive member remains substantially within the plane of the support member in the first actuation mode and the second actuation mode. 
     
     
       3. The lens actuator of  claim 1  wherein the outer portion is substantially rectangular and a mounting arm extends into the inner receiving portion from one of a top wall or a bottom wall of the outer portion such that the piezoelectric drive member is suspended within the inner receiving portion. 
     
     
       4. The lens actuator of  claim 1  wherein one of the first movable lens support member and the second movable lens support member comprise a resilient support member positioned at an end of the piezoelectric drive member, wherein the resilient support member frictionally engages an end of the piezoelectric drive member using a preload force caused by loading of the piezoelectric drive member within the inner receiving portion and actuation of the piezoelectric drive member moves the resilient support member along an axis perpendicular to a direction of the preload force. 
     
     
       5. The lens actuator of  claim 1  further comprising:
 an electrostatic position sensor to detect movement of the movable lens support member. 
 
     
     
       6. The lens actuator of  claim 1  further comprising:
 a resilient flexure extending from the stationary outer portion of the support frame to the movable lens support member to minimize parasitic tilting of the movable lens support member in a direction away from a plane of the support frame. 
 
     
     
       7. The lens actuator of  claim 1  wherein the piezoelectric drive member is a substantially rectangular piezoelectric plate having an extension mode, a symmetrical bending mode and an anti-symmetric bending mode. 
     
     
       8. The lens actuator of  claim 7  wherein the extension mode represents a linear elongation along a length of the piezoelectric plate. 
     
     
       9. The lens actuator of  claim 7  wherein the symmetrical bending mode represents movement of opposing ends of the piezoelectric plate in phase with respect to one another. 
     
     
       10. The lens actuator of  claim 7  wherein the anti-symmetric bending mode represents movement of opposing ends of the piezoelectric plate in anti-phase with respect to one another. 
     
     
       11. The lens actuator of  claim 7  wherein the piezoelectric drive member comprises a plurality of electrodes electrically coupled to the piezoelectric plate, wherein in the first actuation mode, the piezoelectric plate is in the extension mode and the symmetrical bending mode, and in the second actuation mode, the piezoelectric plate is in the extension mode and the anti-symmetric bending mode. 
     
     
       12. The lens actuator of  claim 1  wherein in the first actuation mode, the first movable lens support member and the second movable lens support member move an associated lens in a direction parallel to an optical axis of the lens. 
     
     
       13. The lens actuator of  claim 1  wherein in the second actuation mode, the first movable lens support member and the second movable lens support member tilt an associated lens. 
     
     
       14. A micro-electro-mechanical systems (MEMS) lens actuator comprising:
 a support frame having a substantially planar outer portion surrounding an inner receiving portion; 
 a piezoelectric drive member suspended within the inner receiving portion such that it is surrounded by the stationary outer portion, the piezoelectric drive member having a first actuation mode and a second actuation mode; and 
 a first movable lens support member and a second movable lens support member positioned within the support frame and frictionally engaging opposing ends of the piezoelectric drive member, wherein in the first actuation mode, the piezoelectric drive member moves the first movable lens support member and the second movable lens support member such that an associated lens moves according to a first degree of freedom, and in the second actuation mode, the piezoelectric drive member moves the first movable lens support member and the second movable lens support member such that the associated lens moves according to a second degree of freedom different than the first degree of freedom. 
 
     
     
       15. The lens actuator of  claim 14  wherein the first degree of freedom is a translation motion. 
     
     
       16. The lens actuator of  claim 14  wherein the second degree of freedom is a rotational motion. 
     
     
       17. The lens actuator of  claim 14  wherein one of the first actuation mode and the second actuation mode allow the actuator to perform an autofocus operation. 
     
     
       18. The lens actuator of  claim 14  wherein one of the first actuation mode and the second actuation mode allow the actuator to perform an optical image stabilization operation. 
     
     
       19. An actuator module for driving a lens assembly, the actuator module comprising:
 a support frame having a stationary outer portion surrounding an inner receiving portion, the stationary outer portion having a top wall, a bottom wall and opposing side walls positioned around the inner receiving portion; 
 a mounting arm extending into the inner receiving portion from one of the top wall or the bottom wall, the mounting arm dimensioned to suspend a piezoelectric drive member within the inner receiving portion; 
 a resilient support member positioned at an end of the piezoelectric drive member, wherein the resilient support member frictionally engages an end of the piezoelectric drive member using a preload force caused by loading of the piezoelectric drive member within the inner receiving portion and actuation of the piezoelectric drive member moves the resilient support member along an axis perpendicular to a direction of the preload force; 
 an electrostatic position sensor having a stationary portion and a movable portion, the stationary portion attached to the stationary outer portion of the support frame and the movable portion attached to the resilient support member to detect movement of the resilient support member along the axis; and 
 a resilient flexure extending from the stationary outer portion of the support frame to the resilient support member to minimize tilting of the resilient support member in a direction away from the axis. 
 
     
     
       20. The actuator module of  claim 19  wherein the actuator module is integrally formed from a silicon wafer as a single unit. 
     
     
       21. The actuator module of  claim 19  wherein the resilient support member is a first resilient support member positioned at one end of the piezoelectric drive member, the actuator module further comprising:
 a second resilient support member positioned at an opposing end of the piezoelectric drive member. 
 
     
     
       22. The actuator module of  claim 19  wherein the piezoelectric drive member is a substantially rectangular piezoelectric plate suspended along a middle portion by the mounting arm. 
     
     
       23. The actuator module of  claim 22  wherein a bearing member is attached to an end of the piezoelectric plate so as to provide a point of contact between the resilient support member and the piezoelectric plate. 
     
     
       24. The actuator module of  claim 19  wherein the electrostatic position sensor is an electrostatic comb drive. 
     
     
       25. The actuator module of  claim 19  further comprising:
 a resilient inner frame member positioned within the inner receiving portion, the resilient inner frame member dimensioned to resiliently engage opposing ends of the piezoelectric drive member.

Description:
FIELD 
     An embodiment of the invention is directed to a micro-electro-mechanical system (MEMS) actuator for a camera module that may be integrated within a mobile electronic device such as a smartphone. Other embodiments are also described and claimed. 
     BACKGROUND 
     Miniature cameras are becoming increasingly common in mobile electronic devices such as smartphones. For such high-end miniature cameras, it is common to incorporate 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 to be 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 in a direction parallel to the optical axis. Positions of the lens closer to the image sensor correspond to object focal distances further from the camera. 
     Demands on improvements to performance of such miniature cameras are constant, as are demands for continued miniaturization. In particular, high image quality requires the lens motion in a direction parallel to the optical axis to be accompanied by minimal parasitic motion in the other degrees of freedom. As a result, the lens motion is limited to single degree of freedom, for example in a direction parallel to the optical axis, with no tilt about axes orthogonal to the optical axis. This requires the lens suspension mechanism to be stiff to such parasitic motions. However, given the need to control the lens position to around 1 micron, such suspension mechanisms must also account for friction. 
     Various types of autofocus actuators have been proposed for use in miniature cameras. One exemplary autofocus actuator is a piezoelectric actuator, which uses ultrasonic vibrations to drive lens movement. Existing piezoelectric actuators, however, are relatively large in size and costly to manufacture. 
     SUMMARY 
     An embodiment of the invention is a MEMS actuator that incorporates a piezoelectric plate driven at ultrasonic frequencies to move a body of interest. In embodiments where the MEMS actuator is used in a camera, for example a miniature camera, the body of interest may be a lens. The actuator support frame may be fabricated largely from a silicon wafer with virtually all of the required actuating structures integrally formed within the frame. In one embodiment, the frame may be a relatively thin structure, with a rectangular profile. The thin rectangular profile in combination with the piezoelectric plate yields a complete actuator that is very thin in one direction, making it possible to package next to a large lens. 
     The actuator is further configured to deliver controlled motion in at least two different degrees of freedom, for example, a translational motion and a rotational motion. Representatively, the actuator is capable of moving an associated lens along its optical axis to achieve an autofocus (AF) function (i.e., translation motion). In another embodiment, the actuator could be used to deliver optical image stabilization (OIS) functionality (i.e., rotational motion). In particular, the actuator can tilt one or more of the lens and image sensor within the associated camera in such a way to compensate for user handshake. The OIS functionality allows for longer exposure times in lower light conditions. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments 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. 1A  is a top plan view of one embodiment of an actuator attached to a lens assembly. 
         FIG. 1B  is a front plan view of the actuator of  FIG. 1A . 
         FIG. 1C  is a front plan view of the piezoelectric drive member of  FIG. 1A  according to a first actuation mode. 
         FIG. 1D  is a front plan view of the lens assembly and support members of  FIG. 1A  when moved by the piezoelectric drive member in the first actuation mode. 
         FIG. 1E  is a front plan view of the piezoelectric drive member of  FIG. 1A  according to a second actuation mode. 
         FIG. 1F  is a front plan view of the lens assembly and support members of  FIG. 1A  when moved by the piezoelectric drive member in the second actuation mode. 
         FIG. 2A  is a plan view of one embodiment of an actuator having a piezoelectric drive member. 
         FIG. 2B  is a plan view of one embodiment of the actuator of  FIG. 2A  with the piezoelectric drive member removed. 
         FIG. 2C  illustrates a plan view of some of the components of the actuator illustrated in  FIG. 2A  which are used to support the piezoelectric drive member. 
         FIG. 2D  illustrates a plan view of some of the components of the actuator illustrated in  FIG. 2A  which move the associated lens assembly. 
         FIG. 2E  illustrates a plan view of the position sensors of the actuator illustrated in  FIG. 2A  which move the associated lens assembly. 
         FIG. 2F  illustrates a magnified view of the position sensors of  FIG. 2E . 
         FIG. 3A  is a perspective view of one embodiment of a piezoelectric drive member in a linear elongation mode. 
         FIG. 3B  is a perspective view of one embodiment of a piezoelectric drive member in a symmetrical second order bending mode. 
         FIG. 3C  is a perspective view of one embodiment of a piezoelectric drive member in an anti-symmetrical second order bending mode. 
         FIG. 4  is a plan view of one embodiment of an electrode configuration for the piezoelectric drive member of  FIG. 2 . 
         FIG. 5A  is a perspective view of one embodiment of an actuator integrated within a camera module for an AF operation. 
         FIG. 5B  is a perspective view of one embodiment of a pair of actuators integrated within a camera module for an OIS operation. 
         FIG. 5C  is a perspective view of one embodiment of three actuators integrated within a camera module for an AF and OIS operation. 
         FIG. 6  is a perspective view of one embodiment of an implementation of an actuator within a mobile device. 
     
    
    
     DETAILED DESCRIPTION 
     In this section we shall explain several preferred embodiments of this invention 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 invention 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 of the invention 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. 
       FIG. 1A  illustrates a top cross-sectional view of one embodiment of an actuator attached to a lens assembly. Actuator  100  may be configured for use in a camera, more specifically a miniature camera. In the case of a camera implementation, one or more of actuator  100  can be used to deliver a controlled motion to a lens assembly  116  or other imaging component associated with the camera (e.g., an image sensor) to drive an AF and/or OIS operation. In this aspect, actuator  100  may be configured to drive movement of, in one embodiment, lens assembly  116  according to at least two different degrees of freedom. One of the degrees of freedom may be a translational motion in which actuator  100  moves lens assembly  116  in a direction parallel to its optical axis during an AF operation. Another degree of freedom may be a rotational motion in which actuator  100  rotates or tilts lens assembly  116  about rotational axis  118  during an OIS operation. Rotational axis  118  may be orthogonal to optical axis  120 . Since actuator  100  may be used to deliver controlled movement according to two degrees of freedom, the same (or similar) actuator architecture can be used for both AF and OIS functions (or other camera functions, such as panning). 
     Referring now in more detail to  FIG. 1A , actuator  100  includes a support frame  102  which can support and contain therein each of the actuator components. Support frame  102  may be mounted within a camera module associated with lens assembly  116 . Since actuator  100  may be implemented within a relatively small device such as a miniature camera, it is desirable for the actuator footprint to remain as small as possible. Support frame  102  may therefore be formed by a MEMS structure fabricated from a silicon wafer, which undergoes various etching and deposition processes to create a single integrally formed module that includes virtually all of the actuator components necessary to drive movement of the desired object (e.g., lens assembly  116 ). Since support frame  102  is formed from a silicon wafer, support frame  102  and the components formed therein, have a substantially flat and relatively thin profile. In this aspect, actuator  100  has an overall size and shape that can be packaged next to, and used with, lenses of a variety of sizes, including larger lenses. 
     Lens support members  104  and  106  are formed inward from the end portions of support frame  102 . Lens support members  104  and  106  frictionally engage opposing ends of piezoelectric drive member  108 , which is positioned within support frame  102 , between lens support members  104  and  106 . Lens assembly  116  is mounted to lens support members  104 ,  106  by, for example, guide members  112 ,  114 . Guide members  112 ,  114  may have some compliance to protect any associated components during a drop-test. Lens assembly  116  may be mounted such that its rotational axis  118 , for the purposes of an OIS functionality, is perpendicular to a longitudinal axis of piezoelectric drive member  108  and the optical axis  120  is orthogonal to rotational axis  118 . 
     Piezoelectric drive member  108  may be electronically connected to a piezoelectric drive circuit  110  which can be used to apply a voltage to piezoelectric drive member  108 . Application of a voltage to piezoelectric drive member  108  in turn deforms piezoelectric drive member  108  causing it to move lens assembly  116  according to the desired degree of freedom. 
       FIG. 1B  illustrates a front plan view of actuator  100  of  FIG. 1A . From this view, it can be seen that each of the lens support members  104 ,  106  and piezoelectric drive member  108  are supported within support frame  102 . In one embodiment, piezoelectric drive member  108  may be a substantially rectangular plate like structure. Piezoelectric drive member  108  may be fixedly attached at its center region to support frame  102  by mounting arms  122 ,  124 . The ends of piezoelectric drive member  108  facing lens support members  104 ,  106 , however, are free to move. As will now be described in more detail in reference to  FIG. 1C  to  FIG. 1E , movement of the ends of piezoelectric drive member  108  drives movement of the abutting lens support members  104 ,  106 , and in turn, lens assembly  116 . 
       FIG. 1C  illustrates movement of piezoelectric drive member  108  according to a first actuation mode. To achieve the first actuation mode, a voltage is applied to piezoelectric drive member  108 . The voltage symmetrically deforms piezoelectric drive member  108  as illustrated and causes the ends to move along an elliptical path at high frequency. In particular, in the illustrated embodiment, end  126  moves in a counter clockwise direction along elliptical path  130  and end  128  moves in a clockwise direction along elliptical path  132 . Since the center portion of piezoelectric drive member  108  is fixedly attached to support frame  102  as previously discussed, the center portion remains stationary. Assuming this movement, also referred to as a vibration, occurs at a frequency higher than lens support members  104 ,  106  can respond to, owing to their inertia, it will drive movement of the lens support members  104 ,  106 . Lens support members  104 ,  106  will move in a direction that is parallel to optical axis  120  and that is the same as the elliptical motion at a point furthest from the center of piezoelectric drive member  108 , and hence with the highest normal load and highest friction. In other words, when end  126  of piezoelectric drive member  108  is at a 3 o&#39;clock position  134  of elliptical path  130 , a frictional force between end  126  and lens support member  104  is highest. This in turn, pushes lens support member  104  upward as illustrated by  FIG. 1D . Similarly, when end  128  is at a 9 o&#39;clock position  136  of elliptical path  132 , a frictional force between end  128  and lens support member  106  is highest. This in turn, drives lens support member  106  upward as further illustrated by  FIG. 1D . Since both lens support members  104 ,  106  move in an upward direction, lens assembly  116  will also move in this direction along optical axis  120  to achieve the AF functionality. Although piezoelectric drive member  108  is shown driving lens assembly  116  upward in the first actuation mode, it is contemplated that ends  126 ,  128  may be symmetrically deformed in an opposite direction and/or elliptical path direction to move lens assembly  116  in an opposite direction. 
       FIGS. 1E and 1F  illustrate movement of piezoelectric drive member  108  according to a second actuation mode that can be used to tilt lens assembly  116 . In particular, as can be seen from this embodiment, when the voltage is applied, piezoelectric drive member  108  is anti-symmetrically deformed. In this case, both of ends  126  and  128  move in a clockwise direction along elliptical path  138  and elliptical path  140 , respectively. This in turn, causes lens support member  104  to move in a downward direction and lens support member  106  to move in an upward direction. Movement of lens support members  104 ,  106  in opposite directions rotates or tilts lens assembly  116  in a clockwise direction along rotational axis  118  to achieve an OIS functionality. It is to be recognized that ends  126 ,  128  may also be driven along a counterclockwise elliptical path to tilt lens assembly  116  in a counter clockwise direction. Thus, as can be understood from the foregoing discussion, both a translational and a rotational movement, in other words two different degrees of freedom, can be achieved using actuator  100 . 
     With this general overview of the operation of actuator  100  in mind, the structure of one embodiment of actuator  100  and the various components used to support piezoelectric drive member  108  and drive movement of lens assembly  116  will now be described in more detail in reference to  FIG. 2A-2E .  FIG. 2A  is a plan view of one embodiment of an actuator. As previously discussed, actuator  100  may be a MEMS actuator configured for use in a device such as a camera, more specifically a miniature camera, or any other miniature device requiring movement according to at least two degrees of freedom. The two degrees of freedom may be, for example, a translational and a rotational motion. For example, in the AF mode, actuator  100  moves the associated lens in a direction parallel to its optical axis (e.g., translational motion) while in the OIS mode, actuator  100  rotates the associated lens along an axis perpendicular to the optical axis (e.g., rotational motion) thereby tilting the lens to compensate for user handshake. It is noted that actuator  100  may also move the image sensor in the OIS mode to compensate for user handshake. 
     Support frame  102  may be a MEMS support structure, which supports and contains each of the actuator components therein. Various metallic electrode layers to route electrical connections to the components may also be formed within support frame  102 . Since support frame  102  is formed from a silicon wafer, support frame  102  and the components formed therein, have a substantially flat and relatively thin profile. In one embodiment, support frame  102  may have a rectangular shape and each of the actuator components may be formed within the bounds of the support frame  102 . It is noted, however, that although a rectangular support frame  102  is illustrated in  FIG. 2A , support frame  102  may have other shapes, for example, a square, triangular, circular or elliptical shape. 
     Support frame  102  may include an outer portion  204  that can be mounted (e.g., screwed, welded or the like) to a support member of, for example, a camera body at points  246 . Outer portion  204  defines an inner receiving portion  206 . The inner receiving portion  206  is substantially open and is dimensioned to contain the various actuator components as can be more clearly seen in  FIG. 2B  in which piezoelectric drive member  108  is removed. In one embodiment, inner receiving portion  206  is dimensioned to contain piezoelectric drive member  108 , as illustrated in  FIG. 2A , and each of the actuator components needed to support piezoelectric drive member  108  and drive movement of the desired object (e.g., a lens). Each of these components will now be described in more detail in reference to  FIG. 2C  and  FIG. 2D . 
       FIG. 2C  illustrates a plan view of some of the components of actuator  100  illustrated in  FIG. 2A  which are used to support a piezoelectric drive member within inner receiving portion  206 .  FIG. 2D  illustrates a plan view of the remaining components of actuator  100  illustrated in  FIG. 2A  which move the associated lens assembly. It is noted that any of the components omitted from  FIG. 2C  and  FIG. 2D  are still present in actuator  100  as illustrated in  FIG. 2A . They are simply omitted from these views for ease of illustration. 
     The piezoelectric drive member support components illustrated in  FIG. 2C  include mounting arm  122 , mounting arm  124  and inner frame member  220 . Mounting arm  122  and mounting arm  124  may be used to suspend the piezoelectric drive member  108  within inner receiving portion  206  as illustrated in  FIG. 2A . In this aspect, mounting arm  122  may extend into inner receiving portion  206  from a top wall  208  of the support frame outer portion  204 . Mounting arm  124  may extend into the inner receiving portion  206  from a bottom wall  210  of the support frame of outer portion  204 . Mounting arm  122  and mounting arm  124  may be aligned with one another and extend from a center portion of their respective walls. Mounting arm  122  can be attached to the top side of piezoelectric drive member  108  and mounting arm  124  can be attached to the bottom side of piezoelectric drive member  108  to thereby mount piezoelectric drive member  108  to support frame  102  along its middle region. Since only the middle region is restrained by mounting arms  122 ,  124 , the ends regions of piezoelectric drive member  108  are free to move. 
     Mounting arms  122 ,  124  may have the same shape and/or dimensions or a different shape and/or dimension. Representatively, in one embodiment, mounting arms  122 ,  124  may be ‘T-shaped’ support structures that are bonded onto the middle region of piezoelectric drive member  108  during assembly. The T-shape may provide a sufficient bond area between mounting arms  122 ,  124  and piezoelectric drive member  108  without overly limiting movement of piezoelectric drive member  108 . In particular, the arms of the T&#39;s can be thinly manufactured so as to minimize any increase in stiffness along the bonding region. Mounting arms  122 ,  124  may, however, have any shape and size sufficient to suspend piezoelectric drive member  108  within inner receiving portion  206  while still limiting the movement of as small a portion of the piezoelectric drive member  108  as possible. The T-shape increases the bond area, whilst the arms of the T&#39;s are thin to minimize the increase in stiffness. 
     One or more of mounting arms  122 ,  124  may be a stationary structure. Alternatively, one or more of mounting arms  122 ,  124  may have a resilient configuration so as to account for the manufacturing tolerances of piezoelectric drive member  108  in a width direction. In the embodiment illustrated in  FIG. 2C , mounting arm  122  is a resilient structure while mounting arm  124  is stationary. Representatively, mounting arm  122  may include a spring member  222  integrated within its length dimension such that when piezoelectric drive member  108  is positioned between mounting arms  122 ,  124 , mounting arm  122  can contract to accommodate a piezoelectric drive member  108  having a width greater than the distance between the ends of mounting arms  122 ,  124 . 
     Inner frame  220  may further be positioned within inner receiving portion  206  to support piezoelectric drive member  108 . Inner frame  220  may be dimensioned to surround opposing ends of piezoelectric drive member  108 . Since opposing ends of piezoelectric drive member  108  must be free to move during operation of actuator  100 , inner frame member  220  should be a relatively compliant structure that can move along with the opposing ends. In addition, inner frame member  220  should be resilient along its length dimension so that it can accommodate piezoelectric drive member  108  and generate a pre-load force between contact surfaces of piezoelectric drive member  108  and an adjacent lens support member. 
     Representatively, in one embodiment, inner frame member  220  includes a first resilient frame member  224  that extends around one end of piezoelectric drive member  108  and a second resilient frame member  226  that extends around the opposing end. First resilient frame member  224  and second resilient frame member  226  combined may form a receiving space having similar dimensions to piezoelectric drive member  108 . For example, resilient frame member  224  and resilient frame member  226  may form rectangular shaped pockets with interfacing openings, such that combined, they form a rectangular receiving space. First resilient frame member  224  may be positioned to one side of mounting arms  122 ,  124  and second resilient frame member  226  may be positioned on another side of mounting arms  122 ,  124 . In this aspect, piezoelectric drive member  108  is evenly positioned between each of frame members  224 ,  226 . First resilient frame member  224  may include spring members  228 ,  230  and second resilient frame member  226  may include spring members  232 ,  234 . In one embodiment, spring members  228 ,  230 ,  232 ,  234  may be formed within ends of their respective frame members  224 ,  226  attached to the support frame outer portion  204 . Spring members  228 ,  230 ,  232 ,  234  allow inner frame member  220  to expand to accommodate insertion of piezoelectric drive member  108 . 
     In one embodiment, end bearings  236 ,  238  are positioned at ends of inner frame member  220  and bonded to piezoelectric drive member  108  once it is inserted within inner frame member  220 . End bearings  236 ,  238  provide a bearing surface between each of the opposing ends of piezoelectric drive member  108  and an adjacent lens support member. In this aspect, end bearings  236 ,  238  may have any size and shape suitable for attaching to ends of piezoelectric drive member  108  positioned within inner frame member  220 , for example, a rectangular shape. In some embodiments, end bearings  236 ,  238  may have a protrusions  240 ,  242 , respectively, such that a single contact point is formed between each of the opposing ends of piezoelectric drive member  108  and the adjacent lens support member. In one embodiment, end bearings  236 ,  238  may be integrally formed within inner frame  220  during a manufacturing process. Alternatively, end bearings  236 ,  238  may be separately formed structures attached to inner frame  220  by, for example, a chemical bonding process. 
     In addition to each of the previously discussed components that are used to support piezoelectric drive member  108 , support frame  102  may further contain various components that cause the desired object (e.g., a lens) to move in response to the vibrational movement of the piezoelectric drive member as previously discussed in reference to  FIGS. 1A-1F . These components will now be described in reference to  FIG. 2D . 
     Representatively, actuator  100  includes lens support member  104  and lens support member  106  as previously discussed in reference to  FIGS. 1A and 2A . Lens support member  104  and lens support member  106  are configured to move in response to vibrational forces generated by piezoelectric drive member  108 . Lens support member  104  and lens support member  106  are in turn mounted to a lens assembly (not illustrated) of the camera such that they can move the lens assembly in response to the piezoelectric drive member  108 . 
     In one embodiment, lens support member  104  extends inwardly from a side wall  214  of support frame  102  and lens support member  106  extends inwardly from an opposing side wall  212  of support frame  102 . Lens support member  104  and lens support member  106  may include bearing members  248 ,  256 , respectively. Bearing members  248 ,  256  contact end bearings  236 ,  238 , respectively, along opposing ends of the piezoelectric drive member  108  as illustrated in  FIG. 2A . 
     Lens support member  104  may further include movable end support  250 . Movable end support  250  is positioned near side wall  214  and is resiliently connected to bearing member  248  by pre-load members  252 ,  254 . Pre-load members  252 ,  254  are spring-like structures that suspend bearing member  248  in front of movable end support  250  and bias bearing member  248  in a direction of the piezoelectric drive member. Representatively, pre-load members  252 ,  254  can be oppositely oriented ‘V’ shaped structures. One end of each of the ‘V’ shaped structures can be attached to movable end support  250  while the other end is attached to bearing member  248 . In this aspect, the ‘V’ shaped structures will compress upon application of an outward force (i.e., an outward force in a direction of side wall  214 ) and expand back to a natural configuration when the force is removed. In particular, as can be seen from  FIG. 2B , prior to insertion of piezoelectric drive member  108 , pre-load members  252 ,  254  are in a natural or non-compressed configuration. When piezoelectric drive member  108  is inserted into inner frame  220  as shown in  FIG. 2A , pre-load members  252 ,  254  compress to apply a pre-load force to lens support members  104 ,  106  so as to allow the appropriate friction between the surfaces, and the ability to transfer the forces to the associated lens assembly. 
     It is noted that although V-shaped pre-load members  252 ,  254  are illustrated, pre-load members  252 ,  254  may be formed by any type of resilient member suitable to perform the desired function, e.g., a coiled spring. 
     Similarly, lens support member  106  may include movable end support  258 . Movable end support  258  may be resiliently connected to bearing member  256  by pre-load members  260 ,  262 . Pre-load members  260 ,  262  may be similar to pre-load members  252 ,  254 . Pre-load members  260 ,  262  may suspend bearing member  256  in front of movable end support  258  and bias bearing member  256  in a direction of the piezoelectric drive member. In this aspect, when the piezoelectric drive member is loaded into inner frame member  220 , bearing end  236  frictionally engages bearing member  248  at a contact point and bearing end  238  frictionally engages bearing member  256  at a contact point as illustrated in  FIG. 2A . 
     Each of bearing members  248 ,  256  and movable end supports  250 ,  258  are capable of a vertical motion as illustrated by arrows  264 ,  266 . Pre-load members  252 ,  254 ,  260 ,  262  are configured such that the vertical motion of bearing members  248 ,  256  is substantially identical to the vertical motion of movable end supports  250 ,  258 . Thus, during operation, a vibrational movement of piezoelectric drive member  108  causes one or both of bearing members  248 ,  256  to move in a vertical direction this in turn moves one or both of the movable end supports  250 ,  258  vertically (i.e. along an axis perpendicular to a direction of the preload force). The lens assembly can be mounted to movable end supports  250 ,  258  such that the vertical movement of one or both of movable ends supports  250 ,  258  causes a translational (e.g., vertical) or rotational (e.g., tilting) movement of the lens assembly. Bearing members  248 ,  256  and movable end supports  250 ,  258  may have any size and shape suitable for supporting a lens assembly and causing movement of the lens assembly in response to a movement of the piezoelectric drive member. In the illustrated embodiment, bearing members  248 ,  256  and movable end supports  250 ,  258  face one another and are formed by a base member having side walls extending therefrom. Other configurations, however, are contemplated. 
     Each of lens support member  104  and lens support member  106  is suspended within inner receiving portion  206  by one or more of resilient flexures  268 ,  270 ,  272 ,  274 . Representatively, in one embodiment, lens support member  104  is suspended from top wall  208  of support frame  102  by resilient flexure  268  and from bottom wall  210  by resilient flexure  270 . Lens support member  106  is suspended from top wall  208  by resilient flexure  272  and bottom wall  210  by resilient flexure  274 . Each of resilient flexures  268 ,  270 ,  272 ,  274  are configured such that they are relatively compliant to motions orthogonal to the bearing surfaces (e.g., interfacing surfaces of bearing member  248  and end bearing  236 ), and yet stiff in the direction resisting a pre-load force of the piezoelectric drive member. For example, in one embodiment, each of resilient flexures  268 ,  270 ,  272 ,  274  may be substantially ‘L’ shaped structures in which the short arm is attached to the respective top or bottom wall of support frame  102  and the long arm is attached at its end to the respective movable end support  250 ,  258 . The flexures resist the pre-load force largely by tension along the long arm portion of the structure. 
     In addition, resilient flexures  268 ,  270 ,  272 ,  274  are configured to resist parasitic tilting of the respective movable end supports  250 ,  258  ‘out of the plane’ of support frame  102 . This in turn, prevents tilting of the lens assembly attached to movable end supports  250 ,  258  in a similar direction. This may be accomplished by, for example, increasing a thickness of the short arm portion  276  of each of resilient flexures  268 ,  270 ,  272 ,  274 , which is attached to support frame  102 , such that it is thicker than the long arm portion  278 . Short arm portion  276  is therefore substantially stiff during operational loads, but will deflect slightly during drop test and impact to allow movable end supports  250 ,  258  to hit the sideways end-stops  292  without breaking the long arm portion  278 , which is in tension. This aspect is particularly important since actuator  100  may be implemented within a mobile device, which must be operable even after being dropped on a hard surface. In particular, manufacturing specifications require that mobile devices withstand what is commonly referred to as a “drop test.” The drop test requires that the mobile device remain operable after being dropped multiple times from a specified distance above a concrete surface. Dropping of the device in this manner subjects the various components within the device to large impact forces. 
     The motion of lens support members  104 ,  106  may be monitored by position sensors  280 ,  282  as illustrated by  FIG. 2E  and the magnified view of  FIG. 2F . Position sensors  280 ,  282  are positioned between lens support members  104 ,  106  and their respective adjacent side walls  212 ,  214 . In one embodiment, position sensors  280 ,  282  are electrostatic position sensors such as comb capacitive position sensors. As can be seen from  FIG. 2F , position sensor  282  may have a stationary portion  296  attached to support frame  102  and a movable portion  294  attached to the movable end support  258  of lens support member  106 . Stationary portion  296  may have fingers  295  which interlock with fingers  293  extending from movable portion  294 . As lens support member  106  moves in the vertical direction, the movable portion  294  of sensor  282  also moves. The movement of the movable portion  294  with respect to the stationary portion  296  is then used to determine the degree of movement of the associated lens assembly. Although details of position sensor  282  are illustrated in  FIG. 2F , it is contemplated that position sensor  280  is identical to position sensor  282  and therefore may also include a stationary portion attached to support frame and a movable portion attached to movable end support  250  of lens support member  104  to monitor movement of the associate lens assembly. 
     In one embodiment, position sensors  280 ,  282  are decoupled from lens support members  104 ,  106  to reduce parasitic motion of position sensors  280 ,  282 . Representatively, there may be some parasitic motion of lens support members  104 ,  106  towards the center of support frame  102  as resilient flexures  268 ,  270 ,  272 ,  274  (see  FIG. 2D ) deflect by several microns. Such movement may interfere with the operation of position sensors  280 ,  282  since the movable portion of positions sensors  280 ,  282  are attached to lens support members  104 ,  106 . In particular, the gaps between the fingers of the movable portion  294  and stationary portion  296  may be smaller than the degree of parasitic motion of lens support members  104 ,  106  on its four-bar-link suspension (i.e., resilient flexures  268 ,  270 ,  272 ,  274 ). 
     Decoupling is achieved by mounting position sensors  280 ,  282  to respective frame side walls using one or more of re-entrant flexures  284 ,  286 ,  288 ,  290  and flexure arms  283 ,  285 ,  287 ,  289 , respectively. Re-entrant flexures  284 ,  286 ,  288 ,  290  are substantially resilient structures that allow the movable portion of the respective position sensor  280 ,  282  to move in the desired direction (e.g., in a direction parallel to the optical axis). Flexure arms  238 ,  285 ,  287 ,  289  are substantially rigid structures used to attach the desired portion of position sensors  280 ,  282  to the re-entrant flexure  284 ,  286 ,  288 ,  290 . The movable portion  294  of each of position sensors  280 ,  282  is attached to the respective movable end support  250 ,  258  using a support beam  298  as illustrated in  FIG. 2F . A similar support beam would be used with respect to position sensor  280 . Since the movable sensor portion  294  is attached to the movable end support  250  or  258 , when the movable end support  250  and/or  258  moves, movable sensor portion  294  also moves to a similar degree. This movement may be monitored to determine the degree of movement and/or position of movable end support  250  or  258 , an in turn the associated lens assembly. 
     Support beam  298  may be a substantially ‘L’ shaped structure that is compliant in the direction of the parasitic motion (i.e., horizontal motion of movable end support  258  to the right as viewed in  FIG. 2F ), but stiff in the direction of desired motion (i.e., vertical motion of movable end support in  FIG. 2F ) of movable end supports  250 ,  258 . It is noted that the short length of the short arm of support beam  298 , which is orthogonal to the long arm in this case is not useful operationally, but helps to prevent drop-test failure by providing some compliance to allow some relative vertical motion between movable portion  294  and movable end support  258 . 
     In addition, by suspending position sensor  280  and position sensor  282  from support frame  102  using re-entrant flexures  284 ,  286  and re-entrant flexures  288 ,  290 , respectively, the nominal parasitic motion of one flexure (e.g., a translational motion in a horizontal direction as viewed from  FIG. 2F ) is cancelled by the nominal parasitic motion of the other. Thus, re-entrant flexures  284 ,  286  and re-entrant flexures  288 ,  290  are configured so that they nominally generate no parasitic motions, and hence maintain the alignment between the movable portion  284  and stationary portion  296  of the position sensors  280 ,  282 . 
     Returning to  FIG. 2A , as can be seen from this view, loading of piezoelectric drive member  108  within inner frame  220  causes inner frame  220  to expand to accommodate a length of piezoelectric drive member  108 . This in turn pushes end bearing  236  and end bearing  238  into contact with bearing member  248  and bearing member  256 , respectively. As previously discussed, bearing members  248 ,  256  are resiliently connected to movable end supports  250 ,  258 , respectively, by pre-load members  252 ,  254 ,  260 ,  262 . Upon compression, pre-load members  252 ,  254 ,  260 ,  262  provide the pre-load force between the bearing surfaces (i.e., surfaces of end bearings  236 ,  238  and bearing members  248 ,  256 ) so as to allow the appropriate friction between the surfaces, and the ability to transfer the forces to the associated lens assembly. End bearings  236 ,  238  have protrusions  240 ,  242 , respectively, such that the pre-load force is applied at a single contact point on each of end bearings  236 ,  238 . 
     The configuration and actuation modes of the piezoelectric drive member  108  will now be described in more detail in reference to  FIGS. 3A-3C . In one embodiment, piezoelectric drive member  108  may be formed by a piezoelectric beam or plate having a substantially rectangular shape. It is contemplated, however, that piezoelectric drive member  108  may have other shapes and sizes depending upon the configuration of actuator  100 . It is further contemplated that piezoelectric drive member  108  may be formed by a single piezoelectric plate structure or multiple plate like structures bonded together. Electrodes are positioned along the beam or plate structure as illustrated in  FIG. 4  to drive movement of piezoelectric drive member  108 . 
       FIGS. 3A-3C  show the relevant resonant modes of piezoelectric drive member  108  that are excited to drive actuator  100 . In one embodiment, there are three resonant modes. The three resonant modes may be a linear elongation mode along the length of the piezoelectric drive member  108  ( FIG. 3A ), a second order bending mode where the two sides of piezoelectric drive member  108  move in phase (symmetrical) ( FIG. 3B ) and a second order bending mode where the two side of piezoelectric drive member  108  move in anti-phase with each other (anti-symmetrical) ( FIG. 3C ). The aspect ratio of piezoelectric drive member  108  is optimized so that these resonant modes all occur at very similar frequencies. For example, in one embodiment, where piezoelectric drive member  108  has a length of around 4.7 mm and a width of 1 mm, the piezoelectric material of piezoelectric drive member  108  results in resonant frequencies around 480 kHz. Since the phase of the response of piezoelectric drive member  108  varies right at resonance, a suitable drive frequency is one slightly different from all three modes. Representatively, in one embodiment, a drive frequency slightly below the lowest of the three modes may be used so that all modes operate in phase with the drive signal. 
     The electrode configuration allows for more than one mode to be excited at a time when driven. It may be appreciated that if the elongation mode shown in  FIG. 3A  and the bending mode shown in  FIG. 3B  are excited at the same time, the free ends of piezoelectric drive member  108  will move along an elliptical path, in the same direction, at high frequency. This may be referred to herein as the first actuation mode, which was previously discussed in reference to  FIG. 1C . Assuming this occurs at a frequency that is higher than one or more of lens support members  104 ,  106  can respond to, owing to its inertia, this motion will tend to drive lens support member  104  and lens support member  106  along a direction substantially normal to the bearing surface of end bearings  236 ,  238  and in the direction that is the same as the elliptical motion when furthest from the fixed center of piezoelectric drive member  108 , and hence with highest normal load and highest friction. This in turn, will result in a translational motion of the associated lens assembly in a direction parallel to its optical axis (i.e., an AF operation). 
     Alternatively, if the elongation mode shown in  FIG. 3A  and the bending mode shown in  FIG. 3C  are excited at the same time, the free ends of piezoelectric drive member  108  will move along an elliptical path, each in opposite directions. This may be referred to herein as the second actuation mode, which was previously discussed in reference to  FIG. 1E . Assuming this occurs at a frequency that is higher than one or more of lens support member  104  and lens support member  106  can respond to, this motion will tend to drive lens support member  104  in a direction opposite lens support member  106 . This in turn, will result in a rotational motion of the associated lens assembly (e.g., an OIS operation). 
       FIG. 4  illustrates a schematic view of one embodiment of an electrode configuration of piezoelectric drive member  108 . In particular, the illustrated electrode allows for piezoelectric drive member  108  to drive two of the previously discussed modes at the same time. Representatively, electrodes  401 ,  402 ,  403 ,  404  and  405  are configured so as to drive nine different regions of piezoelectric drive member  108  with nine different signals. To reduce the drive voltage, piezoelectric drive member  108  can be formed as a co-sintered multi-layer plate, with at least one, and in some embodiments, plural, internal electrodes. In such a configuration, it is possible to achieve the same effect with a number of different directions of electric field between the various electrodes, depending on how the device is poled and then driven. Nevertheless the advantage of this configuration is that the piezoelectric material in each region is driven so as to produce the same net deformation as would have been the case were there only external electrodes on either side of piezoelectric drive member  108  driven with a voltage to produce the equivalent electric field. It is contemplated, however, that in other embodiments, external electrodes only on either side of piezoelectric drive member  108  may be used to drive movement. 
     When driven with such an electric field ‘through the thickness’ of piezoelectric drive member  108 , the material deforms in different directions. It is noted that deformations through the thickness are not important to the operation of piezoelectric drive member  108 . The deformations that are important are in the plane of piezoelectric drive member  108  and support frame  102 . Considering the simplified case where there are only external electrodes in the pattern of nine regions, which are connected to appropriate voltage sources, an applied electric field in one region will cause shrinkage or expansion in the plane of piezoelectric drive member  108  and support frame  102 , depending on the direction of the applied electric field. This is in comparison to the poling direction of piezoelectric drive member  108 . Such deformation is proportional to the ‘d31’ strain coefficient, which equates electric field applied to resulting strain. 
     Given the mode shapes of the resonant modes, and the operation of the actuator  100 , any deformations across the width of piezoelectric drive member  108  do not effect operation. The important direction is along the length of piezoelectric drive member  108 . 
     Representatively, consider electrode  405 , this electrode drives the central ‘third’ of piezoelectric drive member  108  (the exact proportion can be optimized to balance the movement of the modes). If electrode  405  is driven with an electric signal at a frequency close to the elongation mode shown in  FIG. 3A , it may be appreciated that the resulting strain couples very well with this resonant mode, and hence the mode will be excited. If the drive frequency is somewhat below the resonant frequency, the resulting motion will be close to being ‘in phase’ with the drive signal. 
     Consider another embodiment where electrodes  401  and  403  are driven with the same signal, and electrodes  402  and  404  are driven with the same single that is opposite to the signal applied to electrodes  401  and  403 . It may be appreciated that locally, one side of piezoelectric drive member  108  will expand, while the other contracts, causing a bending action. Since all these electrodes are split into two regions, the sense of this bending will be different towards the center than at the ends, corresponding with the bending mode of  FIG. 3B  (i.e., the symmetrical bending mode). In this case, it may be appreciated that these signals will couple well into the symmetrical bending mode shown in  FIG. 3B . 
     Likewise, if electrode  401  and electrode  403  are driven with opposite sense drive signals, as are electrode  402  and electrode  404 , yet, electrode  401  and electrode  402  are also driven with opposite signals, this drive will couple well into the anti-symmetric bending mode shown in  FIG. 3C . 
     Whether the signal used to drive electrode  405  is the same or opposite to the signal use to drive electrode  401  will determine in which direction the elliptical of the ends of the piezoelectric drive member  108  will follow. This in turn will determine which direction lens support member  104  and lens support member  106  at each end will be moved. 
     It may also be appreciated that whether the electrodes are driven to couple to the symmetrical mode of  FIG. 3B  or the anti-symmetrical mode of  FIG. 3C  will determine whether lens support member  104  and lens support member  106  will be moved in the same direction or the opposite direction. In this way, it is possible to realize an actuator that can control the motion of the associated lens assembly in two degrees of freedom; in this case one linear and one rotary. 
     Given an appreciation of the basic operation of piezoelectric drive member  108 , some of the further features of actuator  100  as a whole will now be described with reference to an exemplary assembly process. Representatively, in one embodiment, support frame  102 , including the various inner components illustrated in  FIGS. 2A-2E , is fabricated from a silicon wafer. Actuator  100  may be assembled by positioning support frame  102  on an assembly jig, which has pins that interface with hole  201  formed in mounting arm  122 , and each of the pair of holes  203 ,  205  in end bearings  236 ,  238 , respectively as illustrated in  FIG. 2B . The jig is then manipulated to pull the silicon structures away from the placement region of the piezoelectric drive member, so as to make room for the drive member. In one embodiment, each planar dimension of piezoelectric drive member  108  is accurate to +/−50 μm. In this way, the mounting arm  122  may be moved ‘upwards’ by about 100 μm, since the nominal position has an interference of about 50 μm. Each end bearing  236 ,  238  is moved by around 325 μm, as there is nominally about 300 μm interference between the end bearings  236 ,  238  and piezoelectric drive member  108 . In this way, the movement of end bearings  236 ,  238 , compresses the structure of the pre-load members  252 ,  254 ,  260 ,  262 , as illustrated in  FIG. 2 . 
     It is also noted that in moving end bearings  236 ,  238  to accommodate piezoelectric drive member  108  and generate the pre-load force on the contact surfaces (e.g., lens support members  104 ,  106 ), it is necessary to stretch inner frame  220  on which end bearings  236 ,  238  are mounted. Inner frame  220  is stretched using spring members  228 ,  230 ,  232 ,  234  as illustrated in  FIG. 2A  in which piezoelectric drive member  108  is inserted into inner frame  220 . 
     In terms of providing electrical connections to position sensors  280 ,  282 , various configurations are possible. Representatively, in one embodiment, the half of each of position sensors  280 ,  282  mounted to support frame  102  (e.g., stationary portion  296 ) can be split into two electrode regions, with half the fingers in each. Then the fingers in the moving half (e.g., movable portion  294 ) are all connected together electrically. In this way, in one embodiment, the comb is configured as two capacitors in series, where the central conductor is floating. This means that no electrical signal is required to be routed off the moving part of the comb. 
     Regarding the electrical connections to the various portions of the piezoelectric drive member  108 , various configurations are contemplated. In one embodiment, the electrode configurations on piezoelectric drive member  108  may be routed such that all the connections are to the center of one side of member  108 , e.g., proximate to mounting arm  124 . Corresponding tracks may be deposited on portions of support frame  102  adjacent to this region. These are then joined during the fabrication process, possibly through a soldering process, or using conductive adhesive, or potentially even a wire-bonding process. In this way the troublesome requirement for multiple electrical connections to both drive piezoelectric drive member  108  and position sensors  280 ,  282  is accommodated. To connect actuator  100  to the appropriate power supply and drive electronics (e.g., piezoelectric drive circuit  110  illustrated in  FIG. 1A , it may be advantageous to connect a flexible printed circuit (FPC) to support frame  102 , with appropriate terminal pads. The power supply may supply an alternating current (AC) or a direct current (DC) to drive movement of piezoelectric drive member  108 . 
       FIGS. 5A-5C  illustrate possible implementations of the actuator within a miniature camera.  FIG. 5A  illustrates an actuator and camera configuration for an AF functionality. Representatively, in one embodiment, actuator  100  is mounted on one side of a camera module  502  having lens assembly  504 . In this case, lens assembly  504  may be connected to lens support member  104  and lens support member  106  as previously discussed in reference to  FIG. 1A . For the AF operation, only one degree-of freedom is required (e.g., a translation motion in a direction parallel to the lens optical axis  120 ). Thus, although actuator  100  is capable of driving a rotational movement of lens assembly  504  about rotational axis  118 , which is orthogonal to optical axis  120 , movement about rotational axis  118  is not required for AF. It is noted that since only one degree of freedom is needed for AF, the anti-symmetric bending mode of piezoelectric drive member  108  as illustrated in  FIG. 3C  is not required. In this aspect, the electrodes attached to piezoelectric drive member  108  could be configured into seven regions required to drive the first actuation mode as described in reference to  FIG. 1C , rather than the nine regions illustrated in  FIG. 4 . Actuator  100  may, however, operate according to the second actuation mode, in which case, lens assembly  504  may tilt or rotate about rotational axis  118 . 
       FIG. 5B  illustrates an actuator and camera configuration for an OIS functionality. For an OIS functionality, which is used to compensate for user handshake, it is desirable for lens assembly  504  to be rotatable about two different axes orthogonal to each other and to the optical axis. Thus, in one embodiment, two of actuator  100  may be used. Actuator  100 - 1  may be mounted on one side of camera module  502  and actuator  100 - 2  may be mounted on an opposite side. In this case, lens support members  104  and  106 , as previously discussed in reference to, for example  FIG. 1A , may be connected to a structure that contains both the lens assembly and image sensor, and possibly a different AF actuator, in order to move the whole camera module is if it were a rigid body. OIS motion would consist of tilting this rigid body about one or more rotational axes  118 ,  512 , which are orthogonal to the optical axis  120 . The two actuators may act in concert to deliver a rotational degree of freedom about both rotational axes  118 ,  512 . In this aspect, lens assembly  504  can tilt about two different rotational axes  118 ,  512  to compensate for user handshake. 
     In one embodiment, each of actuators  100 - 1  and  100 - 2  may have two controlled degrees of freedom (one linear, and one rotary) to achieve the OIS function. In another embodiment, the OIS functionality is achieved by tilting the whole camera with two actuators  100 - 1  and  100 - 2 , each with one controlled degree of freedom. It is noted, however, that according to the latter embodiment, a real pivot point (like a ball and socket) about which the two actuators would need to pivot the camera is required. According to the former embodiment, no pivot point is required, rather it would be a ‘virtual pivot’. It is for this reason that the two actuators may have two controlled degrees of freedom each. The use of the virtual pivot means that the point of rotation can be in the middle of the camera, close to the center of gravity. In this way the camera is ‘suspended’ on the two OIS actuators, and no real pivot is needed. A real pivot would need to be under the camera, out of the optical path, which may, however, add to the camera height. 
       FIG. 5C  illustrates an actuator and camera configuration for an AF and OIS functionality. Representatively, to achieve both the AF and OIS functionality, three of actuators may be mounted to camera module  502 . Actuator  100 - 2  may be mounted along one side of camera module  502  to deliver an AF functionality as described in reference to  FIG. 5A . Two additional actuators  100 - 1  and  100 - 3  may be mounted along opposing sides of camera module  502  to deliver an OIS functionality as described in reference to  FIG. 5B . It is noted, however, that although three actuators  100 - 1 ,  100 - 2  and  100 - 3  are illustrated for driving both the AF and OIS operation, it is contemplated that in an alternative embodiment, two actuators may be used to deliver both AF and OIS functionality. Representatively, two actuators, for example, actuators  100 - 1  and  100 - 2  positioned on adjacent sides of camera module  502  may be capable of driving movement of lens assembly  504  about optical axis  120  and rotational axes  118 ,  512 . In particular, actuator  100 - 1  and actuator  100 - 2  may be used together or separately to drive movement of lens assembly  504  about optical axis  120  during an AF operation. Actuator  100 - 1  may also be used to rotate lens assembly  502  about rotational axis  118  while actuator  100 - 2  can be used to rotate lens assembly  504  about rotational axis  512  during an OIS operation. 
       FIG. 6  illustrates one implementation of the actuator described herein. Representatively, actuator  100  may be mounted within a miniature camera contained within a mobile device  600 . Here, the user is making a manual or touch selection on the touch screen viewfinder, which is previewing an object of interest  614 , at which the camera lens system  602 , having actuator  100  therein, is aimed. The selection may be in the form of a target graphic  604  such as a contour that may be drawn by the user on the touch screen  606 . Alternatively, the selection or target graphic  604  may be a fixed frame or a fixed solid area that moves with the user&#39;s finger across the screen  606 . The actuator  100  moves the lens element mounted therein so that the object of interest  614  is in focus. A flash element  610  may further be provided to illuminate the object of interest  614 . Once the user determines that the object of interest  614  is in focus, the user can capture the image by pressing virtual shutter button icon  608 . 
     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 as a MEMS device 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. In addition, the actuator may be formed from a material other than a silicon wafer, or the different actuator components may be formed from different materials and assembled after formation to form the actuator. The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20121001
Publication Date: 20140520
Grant Date: 20140520
Priority Date: 20121001
Inventors: TOPLISS RICHARD J.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B7/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B13/0075", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B26/0858", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/648", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B13/0075", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B7/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B26/0858", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/648", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 50384939