Patent Publication Number: US-2021173171-A1

Title: Optical element driving mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority of U.S. Provisional Patent Application No. 62/944,496, filed 6 Dec. 2019, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Field of the Disclosure 
     The present invention relates to a driving mechanism, and more particularly to an optical element driving mechanism. 
     Description of the Related Art 
     The design of today&#39;s electronic devices is continually moving toward miniaturization, so that various elements or structures of optical modules used in such applications as imaging must be continuously reduced in size in order to achieve miniaturization. Therefore, how to design a miniature optical element driving mechanism has become an important issue. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     An embodiment of the invention provides an optical element driving mechanism having an optical axis and including a fixed portion, a movable portion, and a driving assembly. The movable portion is movable relative to the fixed portion. The driving assembly drives the movable portion to move relative to the fixed portion. The driving assembly moves in a first direction to move the movable portion in a second direction, wherein the first direction is different from the second direction. 
     According to some embodiments of the present disclosure, the first driving assembly includes a piezoelectric element, a transmission element, a clamping element, a conversion element, two first magnetic elements and a second magnetic element. The piezoelectric element has a circular plate shape extending in a third direction and the second direction. The transmission element is connected to the piezoelectric element. The clamping element is clamped to the transmission element, and movable relative to the transmission element. The conversion element is connected to the clamping element. Two first magnetic elements are disposed on the conversion element. The second magnetic element is disposed on the movable portion. Each of the first magnetic elements has a first magnetic pole direction, and the first magnetic pole direction is neither parallel nor perpendicular to the first direction, the second direction, and the third direction. The second magnetic element has a second magnetic pole direction, and the second magnetic pole direction is parallel to the second direction. When viewed along the third direction, the first magnetic elements do not overlap, one of the first magnetic elements is closer to the piezoelectric element than the other first magnetic element, and one of the first magnetic elements is closer to a light incident surface than the other first magnetic element, and the second magnetic element is between the first magnetic elements. When viewed along the first direction, the first magnetic elements partially overlap. When viewed along the second direction, the first magnetic elements do not overlap. The transmission element is moved along the first direction by the piezoelectric element, and the clamping element and the conversion element are moved along the first direction by the transmission element, and the movable portion is driven to move along the second direction by a force between the first magnetic elements and the second magnetic element. 
     According to some embodiments of the present disclosure, when viewed along the third direction, the second magnetic element at least partially overlaps one of the first magnetic elements. 
     According to some embodiments of the present disclosure, when viewed along the third direction, the second magnetic element does not overlap any one of the first magnetic elements. 
     According to some embodiments of the present disclosure, the driving assembly further includes four intermediate elements contacting the conversion element and the fixed portion. The fixed portion has a fixed-portion-first-sliding surface and a fixed-portion-second-sliding surface, the conversion element has a conversion-element-first-sliding surface and a conversion-element-second-sliding surface, and the conversion-element-first-sliding surface faces the fixed-portion-first-sliding surface, the fixed-portion-first-sliding surface and the conversion-element-first-sliding surface are perpendicular to the second direction, the conversion-element-second-sliding surface faces the fixed-portion-second-sliding surface, and the conversion-element-second-sliding surface and the fixed-portion-second-sliding surface are perpendicular to the second direction. The fixed-portion-first-sliding surface is closer to the light incident surface than the fixed-portion-second-sliding surface and the conversion-element-first-sliding surface, and the conversion-element-second-sliding surface is closer to the light incident surface than the fixed-portion-second-sliding surface. The fixed-portion-first-sliding surface has a fixed-portion-first-sliding rail extending in the first direction, the conversion-element-first-sliding surface has two first grooves, the first grooves and the fixed-portion-first-sliding rail accommodate parts of two of the intermediate elements. The fixed-portion-second-sliding surface has a fixed-portion-second-sliding rail extending in the first direction, the fixed-portion-second-sliding rail extends in a direction parallel to the first direction, and the conversion-element-second-sliding surface has two second grooves, and the second grooves and the fixed-portion-second-sliding rail accommodate parts of the other two intermediate elements. When viewed along the second direction, the fixed-portion-first-sliding rail at least partially overlaps the fixed-portion-second-sliding rail. 
     According to some embodiments of the present disclosure, when viewed along the third direction, the intermediate elements do not overlap, and when viewed along the first direction, the intermediate elements at least partially overlap, and when viewed along the second direction, the intermediate elements at least partially overlap. 
     According to some embodiments of the present disclosure, the fixed portion has a first limiting surface, the movable portion has a second limiting surface, and the first limiting surface and the second limiting surface are configured to restrict a movement range of the conversion element in the first direction. 
     According to some embodiments of the present disclosure, the optical element driving mechanism further includes a guiding element, wherein the movable portion has a first sliding groove, and an inner wall of the first sliding groove is covered with a coating, and the guiding element is fixedly disposed on the fixed portion and at least partially located in the first sliding groove of the movable portion to make the movable portion move along the guiding element. When viewed along the third direction, the guiding element and the conversion element at least partially overlap. The movable portion further has a second sliding groove, and the first sliding groove and the second sliding groove are at least closed-typed or non-closed-typed. The movable portion has a top surface and a bottom surface, the fixed portion has an inner top wall and an inner bottom wall, the top surface faces the inner top wall and the bottom surface faces the inner bottom wall, the top surface, the bottom surface, the inner top wall and the inner bottom wall are perpendicular to the second direction. When viewed along the third direction, a first distance between the top surface and the inner top wall is shorter than a length of the guiding element in the second direction. When viewed along the third direction, a second distance between the bottom surface and the inner bottom wall is shorter than the length of the guiding element in the second direction. 
     According to some embodiments of the present disclosure, the guiding element has a cylindrical structure and extends in the second direction. 
     According to some embodiments of the present disclosure, the guiding element has a spherical structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of this disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  is a perspective view of an optical element driving mechanism according to an embodiment of the present disclosure. 
         FIG. 2  is an exploded view of an optical element driving mechanism according to an embodiment of the present disclosure. 
         FIG. 3  is a schematic diagram of a partial structure of an optical element driving mechanism according to an embodiment of the present disclosure. 
         FIG. 4  is a cross-sectional view of the optical element driving mechanism cut along the line A-A′ in  FIG. 1 . 
         FIG. 5  is a cross-sectional view of the optical element driving mechanism cut along the line B-B′ in  FIG. 1 . 
         FIG. 6  is a cross-sectional view of the optical element driving mechanism cut along the line C-C′ in  FIG. 1 . 
         FIG. 7  is a top view of a partial structure of an optical element driving mechanism according to an embodiment of the present disclosure. 
         FIG. 8  is a cross-sectional view of the optical element driving mechanism cut along the line D-D′ in  FIG. 1 . 
         FIG. 9  is a schematic diagram of a partial structure of an optical element driving mechanism according to another embodiment of the present disclosure. 
         FIG. 10  is a schematic diagram of a partial structure of an optical element driving mechanism according to another embodiment of the present disclosure. 
         FIG. 11  is a schematic diagram of the force acting between a first magnetic element and a second magnetic element in different states. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     In the following detailed description, for the purposes of explanation, numerous specific details and embodiments are set forth in order to provide a thorough understanding of the present disclosure. The specific elements and configurations described in the following detailed description are set forth in order to clearly describe the present disclosure. It will be apparent, however, that the exemplary embodiments set forth herein are used merely for the purpose of illustration, and the inventive concept can be embodied in various forms without being limited to those exemplary embodiments. In addition, the drawings of different embodiments can use like and/or corresponding numerals to denote like and/or corresponding elements in order to clearly describe the present disclosure. However, the use of like and/or corresponding numerals in the drawings of different embodiments does not suggest any correlation between different embodiments. The directional terms, such as “up”, “down”, “left”, “right”, “front” or “rear”, are reference directions for accompanying drawings. Therefore, using the directional terms is for description instead of limiting the disclosure. 
     In this specification, relative expressions are used. For example, “lower”, “bottom”, “higher” or “top” are used to describe the position of one element relative to another. It should be appreciated that if a device is flipped upside down, an element at a “lower” side will become an element at a “higher” side. 
     The terms “about” and “substantially” typically mean +/−20% of the stated value, more typically +/−10% of the stated value and even more typically +/−5% of the stated value. The stated value of the present disclosure is an approximate value. When there is no specific description, the stated value includes the meaning of “about” or “substantially”. 
     Refer to  FIG. 1  and  FIG. 2 .  FIG. 1  is a perspective view of an optical element driving mechanism  1  according to an embodiment of the present disclosure. Some elements are shown as transparent by dotted lines to clearly show the configuration of each element.  FIG. 2  is an exploded view of the optical element driving mechanism  1  according to an embodiment of the disclosure. The optical element driving mechanism  1  has an optical axis O and includes a fixed portion  100 , a movable portion  200 , a driving assembly  300 , an adhesive element  400  (refer to  FIG. 6 ), and two guiding elements  500 . The driving assembly  300  is moved in a first direction D 1 , which causes the movable portion  200  to move in a second direction D 2 . The first direction D 1  is different from the second direction D 2 . In this embodiment, the first direction D 1  is perpendicular to the second direction D 2 , and the second direction D 2  is parallel to the optical axis O. In this embodiment, the optical element driving mechanism  1  has an auto focusing (AF) function, but it is not limited to this. In some embodiments, the optical element driving mechanism  1  may also have auto focusing and optical image stabilization (OIS) functions. 
     The fixed portion  100  is a housing S, which includes a top shell  110  and a base  120 . The top shell  110  includes an outer top wall  110 A, four side walls  110 B, and an inner top wall  110 C (as shown in  FIG. 8 ). The base  120  includes an outer bottom wall  120 A, an inner bottom wall  120 B, a fixed-portion-first-sliding surface  122 , a fixed-portion-first-sliding rail  122 A, a fixed-portion-second-sliding surface  123 , and a fixed-portion-second-sliding rail  123 A, a first connecting surface  124 , and a second connecting surface  125 . The top shell  110  has a hollow structure, and the top shell  110  may be combined with the base  120  to form the housing S of the optical element driving mechanism  1 , wherein the top shell  110  constitutes the outer top wall  110 A and four side walls  110 B of the housing S, and the base  120  constitutes the outer bottom wall  120 A of the housing S. It should be understood that the top shell  110  and the base  120  are respectively formed with a top shell opening  111  and a base opening  121 , the center of the top shell opening  111  corresponds to the optical axis O, and the base opening  121  corresponds to an image sensing element (not shown) disposed outside the optical element driving mechanism  1 . External light may enter the top shell  110  through the top shell opening  111 , and then may pass through an optical element (not shown) and the base opening  121 , and then may be received by the image sensing element to generate a digital image signal. 
     The movable portion  200  may be connected to the optical element and move relative to the fixed portion  100 . In some embodiments, the movable portion  200  is a holder  200  having a cylindrical main body portion  210 , a first sliding groove portion  220 , and a second sliding groove portion  230 . The first sliding groove portion  220  and the second sliding groove portion  230  extend from the main body portion  210 . The main body portion  210  has a through hole  211 , a side wall  212 , a top surface  213 , and a bottom surface  214 . The first sliding groove portion  220  has a first sliding groove  221 , and the second sliding groove portion  230  has a second sliding groove  231 . Wherein, the through hole  211  forms a threaded structure corresponding to another threaded structure on the outer peripheral surface of the optical element, so that the optical element may be secured in the through hole  211 . 
     Refer to  FIG. 2  and  FIG. 3 .  FIG. 3  is a schematic diagram of a partial structure of the optical element driving mechanism  1  according to an embodiment of the present disclosure. The driving assembly  300  includes a piezoelectric element  310 , a transmission element  320 , a clamping element  330 , a conversion element  340 , two first magnetic elements  350 , a second magnetic element  360 , and four intermediate elements  370 . The movable portion  200  and the conversion element  340  in  FIG. 3  are shown as transparent by dotted lines to clearly show the configuration of each element. 
     In some embodiments, the piezoelectric element  310  has a circular plate shape extending in a third direction D 3  and the second direction D 2 . The third direction D 3  is perpendicular to the first direction D 1 , and the third direction D 3  is perpendicular to the second direction D 2 . The piezoelectric element  310  includes two piezoelectric ceramic plates  311  and an elastic material sheet  312 , and the elastic material sheet  312  is disposed between the two piezoelectric ceramic plates  311 . The transmission element  320  is connected to the piezoelectric element  310 . In more detail, the transmission element  320  is fixed at the center of the piezoelectric ceramic plate  311 . The transmission element  320  is a cylindrical long axis, and the direction of the long axis is parallel to the first direction D 1 . The clamping element  330  is clamped to the transmission element  320 . The clamping element  330  is made of an elastic material and has an arc shape. This arc shape matches the shape of the long shaft (transmission element  320 ) so that the long shaft may pass through the clamping element  330  and the clamping element  330  may be clamped on the long axis. The conversion element  340  is connected to the clamping element  330 . In more detail, a part of the clamping element  330  is embedded in the conversion element  340 , but it is not limited this. In some embodiments, the conversion element  340  and the clamping element  330  are integrally formed. 
     The two first magnetic elements  350  are disposed on the conversion element  340 . In more detail, the conversion element  340  has a conversion-element side wall  341 , and the conversion-element side wall  341  is provided with two recesses to accommodate the two first magnetic elements  350 . The two first magnetic elements  350  respectively have a first magnetic pole direction M 1 . The first magnetic pole direction M 1  is not parallel or perpendicular to the first direction D 1 , the second direction D 2 , and the third direction D 3 . When viewed along the first direction D 1 , the two first magnetic elements  350  partially overlap, and when viewed along the second direction D 2 , the two first magnetic elements  350  do not overlap. When viewed along the third direction D 3 , the two first magnetic elements  350  do not overlap. One of the two first magnetic elements  350  is closer to the piezoelectric element  310  than the other, and one of the two first magnetic elements  350  is closer to an light incident surface I than the other. 
     A second magnetic element  360  is disposed on the movable portion  200 . In more detail, as shown in  FIG. 3 , the first sliding groove portion  220  has a first-sliding-groove-portion side wall  222 , and the first-sliding-groove-portion side wall  222  is provided with a concave portion to accommodate the second magnetic element  360 , and the first-sliding-groove-portion side wall  222  faces the conversion-element side wall  341  (the conversion-element side wall  341  is shown in  FIG. 2 ). The second magnetic element  360  has a second magnetic pole direction M 2 , and the second magnetic pole direction M 2  is parallel to the second direction D 2 . When viewed along the third direction D 3 , the second magnetic element  360  is between the two first magnetic elements  350 . In some embodiments, the second magnetic element  360  at least partially overlaps one of the two first magnetic elements  350 , but it is not limited this. In other embodiments, the second magnetic element  360  does not overlap any one of the two first magnetic elements  350 . 
     Refer to  FIG. 2  and  FIG. 4  to  FIG. 6 .  FIG. 4  is a cross-sectional view of the optical element driving mechanism  1  cut along the line A-A′ in  FIG. 1 .  FIG. 5  is a cross-sectional view of the optical element driving mechanism  1  cut along the line B-B′ in  FIG. 1 .  FIG. 6  is a cross-sectional view of the optical element driving mechanism  1  cut along the line C-C′ in  FIG. 1 . The conversion element  340  has a conversion-element-first-sliding surface  342  and a conversion-element-second-sliding surface  343 . The conversion-element-first-sliding surface  342  faces the fixed-portion-first-sliding surface  122 , and the fixed-portion-first-sliding surface  122  and the conversion-element-first-sliding surface  342  is perpendicular to the second direction D 2 . The conversion-element-second-sliding surface  343  faces the fixed-portion-second-sliding surface  123 , and the conversion-element-second-sliding surface  343  and the fixed-portion-second-sliding surface  123  are perpendicular to the second direction D 2 . 
     As shown in  FIGS. 2, 4, and 6 , the fixed-portion-first-sliding surface  122  is closer to the light incident surface I than the fixed-portion-second-sliding surface  123  and the conversion-element-first-sliding surface  342 . The fixed-portion-first-sliding surface  122  has the fixed-portion-first-sliding rail  122 A extending in the first direction D 1 . The conversion-element-first-sliding surface  342  has two first grooves  342 A, and the two first grooves  342 A respectively accommodate two intermediate elements  370 . A first groove  342 A and the fixed-portion-first-sliding rail  122 A accommodate a part of an intermediate element  370 . In other words, the intermediate elements  370  contact the conversion element  340  and the fixed portion  100 . The intermediate elements  370  are movably disposed between the first groove  342 A and the fixed-portion-first-sliding rail  122 A. The first groove  342 A limits a movement range of the intermediate elements  370 . The friction between the conversion-element-first-sliding surface  342  and the fixed-portion-first-sliding surface  122  may be reduced by disposing the intermediate elements  370  on the fixed-portion-first-sliding rail  122 A. 
     As shown in  FIG. 2 ,  FIG. 5 , and  FIG. 6 , the conversion-element-second-sliding surface  343  is closer to the light incident surface I than the fixed-portion-second-sliding surface  123 . Similar to the conversion-element-first-sliding surface  342  and the fixed-portion-first-sliding surface  122  described above, the conversion-element-second-sliding surface  343  has two second grooves  343 A, and the fixed-portion-second-sliding surface  123  has the fixed-portion-second-sliding rail  123 A extending in the first direction D 1 . The two second grooves  343 A accommodate two intermediate elements  370 . A second groove  343 A and the fixed-portion-second-sliding rail  123 A accommodate a part of an intermediate element  370 . That is, the intermediate elements  370  are movably disposed between the second groove  343 A and the fixed-portion-second-sliding rail  123 A, and the second groove  343 A limits the movement range of the intermediate elements  370 . The friction between the conversion-element-second-sliding surface  343  and the fixed-portion-second-sliding surface  123  may be reduced by disposing the intermediate elements  370  on the fixed-portion-second-sliding rail  123 A. 
     When viewed along the second direction D 2 , the fixed-portion-first-sliding rail  122 A and the fixed-portion-second-sliding surface  123  at least partially overlap. When viewed along the third direction D 3 , the intermediate elements  370  do not overlap. When viewed along the first direction D 1 , the intermediate elements  370  at least partially overlap, and when viewed along the second direction D 2 , the intermediate elements  370  at least partially overlap. 
     In this embodiment, two intermediate elements  370  are disposed on a side of the conversion element  340  that is close to the light incident surface I, and the other two intermediate elements  370  are disposed on an opposite side of the conversion element  340  that is far away from the light incident surface I. The intermediate element  370  may move more stably in the sliding rail with the configuration described above compared with only one intermediate element  370  disposed on the two sides, or one intermediate element  370  disposed on only one side. But it is not limited to this, the number or configuration of the intermediate element  370  may be changed as required. In some embodiments, the intermediate elements  370  are fixedly disposed on the conversion element  340 . In some embodiments, the intermediate elements  370  may not be provided, and the friction is reduced by changing the material between the two sliding surfaces. 
     Refer to  FIG. 6  and  FIG. 7 .  FIG. 7  is a top view of a partial structure of the optical element driving mechanism  1  according to an embodiment of the present disclosure. The adhesive element  400  may be used to connect the driving assembly  300  to the fixed portion  100 . In more detail, the base  120  has a first connecting surface  124  perpendicular to the first direction D 1 . The first connecting surface  124  faces the piezoelectric ceramic plate  311  of the piezoelectric element  310 , and the adhesive element  400  may be disposed between the piezoelectric ceramic plate  311  and the first connecting surface  124 . When viewed along the second direction D 2 , the first connecting surface  124  and the transmission element  320  at least partially overlap. 
     The base  120  also has a second connecting surface  125  perpendicular to the second direction D 2 . The second connecting surface  125  faces the transmission element  320 , and the adhesive element  400  may be disposed between the transmission element  320  and the second connecting surface  125 . When viewed along the second direction D 2 , the second connecting surface  125  and the transmission element  320  at least partially overlap. In this embodiment, the driving assembly  300  is connected to the fixed portion  100  by the adhesive element  400  which is a soft adhesive, so that the piezoelectric element  310  and the transmission element  320  may move along the first direction D 1  relative to the base  120  in a specific range. 
     Refer to  FIG. 7  to  FIG. 9 .  FIG. 8  is a cross-sectional view of the optical element driving mechanism  1  cut along the line D-D′ in  FIG. 1 .  FIG. 9  is a schematic diagram of a partial structure of the optical element driving mechanism  1 ′ according to another embodiment of the present disclosure. As shown in  FIG. 7 , two cylindrical guiding elements  500  are fixedly disposed on the base  120  of the fixed portion  100  and respectively pass through the first sliding groove  221  and the second sliding groove  231  of the movable portion  200 . An inner wall  221 A of the first sliding groove  221  is covered with a coating to reduce the friction between the guiding element  500  and the first sliding groove  221 . In this embodiment, the optical element driving mechanism  1  has a rectangular structure. When viewed along the second direction D 2 , the first sliding groove  221  and the second sliding groove  231  are arranged diagonally, and the first sliding groove  221  is arranged at a corner that is close to the conversion element  340 . When viewed along the third direction D 3 , the first sliding groove  221  and the conversion element  340  at least partially overlap. 
     In some embodiments, the first sliding groove  221  is closed-typed, that is, as shown in  FIG. 7 , the first sliding groove  221  surrounds the guiding element  500 . On the other hand, the second sliding groove  231  is non-closed-typed, as shown in  FIG. 7 , the guiding element  500  is not completely surrounded by the second sliding groove  231 . Since the first sliding groove  221  is closed-typed, a side wall  120 C of the base  120  is provided with an accommodating portion  120 D to accommodate a protruding part of the side wall  120 C that surrounds the first sliding groove  221  and is close to the base  120 . With this design structure, the space in the optical element driving mechanism  1  may be fully utilized to achieve miniaturization. And compared to a structure with only one closed-typed sliding groove, the closed-typed first sliding groove  221  may make the movable portion  200  move along the sliding groove, while the non-closed-typed second sliding groove  231  may assist in the movement of the movable portion  200  in the second direction D 2 . In addition, compared with a structure with two closed-typed sliding grooves, the non-closed-typed second sliding groove  231  may reduce the probability that the guiding element  500  cannot pass through the sliding groove during assembly due to manufacturing tolerances, thereby improving the assembly success rate of the optical element driving mechanism  1 . 
     As shown in  FIG. 8 , the top surface  205  of the movable portion  200  faces the inner top wall  110 C of the top shell  110 , and the bottom surface  206  of the movable portion  200  faces the inner bottom wall  120 B of the base  120 . The top surface  205 , the bottom surface  206 , the inner top wall  110 C and the inner bottom wall  120 B are perpendicular to the second direction D 2 . When viewed along the third direction D 3 , a first distance R 1  between the top surface  205  and the inner top wall  110 C is less than a length L of the guiding element  500  in the second direction D 2 , and a second distance R 2  between the bottom surface  206  and the inner bottom wall  120 B is less than the length L of the guiding element  500  in the second direction D 2 . That is, the movable portion  200  will not deviate from the guiding element  500  even if the movable portion  200  reaches the maximum movement range since the guiding element  500  is long enough. 
     However, the guiding element  500  and the sliding groove are not limited to the structures described above, and the configuration and the number of guiding elements  500  and sliding grooves may be changed as required. For example, as shown in  FIG. 9 , in some embodiments, an optical element driving mechanism  1 ′ has a structure and elements similar to the optical driving mechanism  1 , wherein the guiding element  500 ′ has a spherical structure and is fixed on two sides of the fixed portion  100 ′. The movable portion  200 ′ has a sliding groove  208 ′, and at least a part of the guiding element  500 ′ is located in the sliding groove  208 ′, so that the occurrence of offset may be avoided when the movable portion  200  is moved in the second direction D 2 . 
     In some embodiments, the optical element driving mechanism  1  further includes a position sensing assembly (not shown) for sensing the relative movement of the fixed portion  100  and the movable portion  200 . At least a part of the position sensing assembly is disposed on the movable portion  200 , and at least another part of the position sensing assembly is disposed on the fixed portion  100 . For example, the position sensing assembly may include a sensing element and a sensing magnetic element, and the sensing element is disposed on the base  120  of the fixed portion  100 , the sensing magnetic element is disposed on the movable portion  200 . In more detail, the sensing element may be, for example, a Hall effect sensor, a magnetoresistive sensor (MR sensor), or fluxgate, etc., which are configured to sense the magnetic field of the sensing magnetic element on the holder  200  to obtain the position of the holder  200  relative to the base  120 , but it is not limited to this. For example, in some embodiments, the second magnetic element  360  may also be used as the sensing magnetic element. 
     Next, referring to  FIGS. 2, 6, 10, and 11 , the operation of the optical element driving mechanism  1  will be described.  FIG. 10  is a schematic diagram of a partial structure of the optical element driving mechanism  1 , wherein the conversion element  340  is shown as transparent by dotted lines to clearly show the configuration of each element.  FIG. 11  is a schematic diagram of the force between the first magnetic element  350  and the second magnetic element  360  in different states. When a voltage is applied to the driving assembly  300 , the circular-plated-shaped piezoelectric element  310  is deformed, for example, the piezoelectric element  310  is slowly bent outward (the center of the piezoelectric element  310  is closer to the first connecting surface  124  (the first connecting surface  124  is shown in  FIG. 6 ) than the outer circumference), so that the transmission element  320  is moved away from the piezoelectric element  310  in the first direction D 1 . At this time, there is no relative movement between transmission element  320  and the clamping element  330  since there is a static friction between the transmission element  320  and the clamping element  330 . Then, the voltage is controlled to make the piezoelectric element  310  bend inward quickly (the outer circumference of the piezoelectric element  310  is closer to the first connecting surface  124  than the center of the piezoelectric element  310 ), and the transmission element  320  therefore moves rapidly toward the piezoelectric element  310 , and overcomes the static friction between the transmission element  320  and the clamping element  330 , so that the clamping element  330  moves away from the piezoelectric element  310  in the first direction D 1  relative to the transmission element  320 . Since the conversion element  340  is connected to the clamping element  330 , the movement of the conversion element  340  in the first direction D 1  may be controlled by repeating the above steps. 
     When the first magnetic elements  350  disposed in the conversion element  340  moves in the first direction D 1  with the conversion element  340 , the force between the first magnetic elements  350  and the second magnetic element  360  also changes accordingly. As shown in a state S 1  of  FIG. 11 , when the second magnetic element  360  is at the approximate center of the two first magnetic elements  350 , the forces are balanced at this time, and the movable portion  200  remains stationary. When the first magnetic element  350  moves away from the piezoelectric element  310  in the first direction D 1 , as shown in a state S 2 , a resultant force between the two first magnetic elements  350  and the second magnetic element  360  is applied to the movable portion  200 , and the direction of the resultant force is downward which make the movable portion  200  move along the guiding element  500  in the second direction D 2  away from the light incident surface I. 
     However, when the first magnetic element  350  moves away from the piezoelectric element  310  in the first direction D 1  to a first specific distance DS 1 , as shown in state S 3 , the direction of the force applied to the movable portion  200  between the two first magnetic elements  350  and the second magnetic element  360  is changed to upward, so the movable portion  200  will not move downward. When the first magnetic element  350  is moved closer to the piezoelectric element  310  in the first direction D 1  from the first specific distance DS 1 , as shown in state S 4 , the direction of the force applied to the movable portion  200  between the two first magnetic elements  350  and the second magnetic element  360  is upward, so that the movable portion  200  moves along the guiding element  500  in the second direction D 2  toward the light incident surface I. 
     When the first magnetic element  350  moves toward the piezoelectric element  310  in the first direction D 1  to a second specific distance DS 2 , as shown in state S 5 , the direction of the force applied to the movable portion  200  between the two first magnetic elements  350  and the second magnetic element  360  is changed to downward, so the movable portion  200  will not move upward. Therefore, by controlling the movement of the driving assembly  300  in the first direction D 1 , the movement of the movable portion  200  in the second direction D 2  may be controlled. 
     It can be seen from the description above that by changing the distance between the first magnetic elements  350  and the second magnetic element  360 , the movement range of the movable portion  200  may be restricted. In this embodiment, the two first magnetic elements  350  are disposed in the conversion element  340  and the second magnetic element  360  are disposed in the movable portion  200 , but it is not limited this. In addition, the direction of the configuration of the magnetic element may also be changed as required. 
     As shown in  FIG. 7 , the base  120  of the fixed portion  100  has a side wall  120 C as a first limiting surface  120 C. The first limiting surface  120 C is perpendicular to the first direction D 1  and faces a side surface of the conversion element  340 . When the side surface of the conversion element  340  contacts the first limiting surface  120 C, the movement of the conversion element  340  may be stopped, and the movement range of the conversion element  340  away from the piezoelectric element  310  in the first direction D 1  is restricted. And by the cylindrical shape of the movable portion  200 , the side wall  202  of the movable portion  200  is used as a second limiting surface  202 . When the conversion element  340  contacts the second limiting surface  202 , it stops moving, and the movement range of the conversion element  340  toward the piezoelectric element  310  in the first direction D 1  is restricted. That is, the first limiting surface  120 C and the second limiting surface  202  are configured to restrict the movement range of the conversion element  340  in the first direction D 1 , and the movement range of the movable portion  200  in the second direction D 2  is also restricted by the first limiting surface  120 C and the second limiting surface  202 . 
     In a conventional optical element driving mechanism, the driving assembly and the movable portion move in the same direction, that is, the long axis of the transmission element is disposed parallel to the optical axis. If the movement range of the movable portion is expected to be larger, the length of the transmission element must be increased. However, it makes the optical element driving mechanism thicker in the direction of the optical axis. In contrast with the conventional optical element driving mechanism, in this embodiment, the transmission element  320  (long axis) is horizontally arranged in the optical element driving mechanism  1  (or arranged perpendicular to the optical axis O), and the piezoelectric element  310  and the conversion element  340  may be mated with the rectangular fixed portion  100  and the circular movable portion  200  and be respectively arranged at two corners of the optical element driving mechanism  1 . Therefore, the transmission element  320  may be designed to be longer without affecting the overall thickness of the optical element driving mechanism  1 , and the movable portion  200  may also have a larger movement range. In addition, the space between the holder  200  and the base  120  may be fully used, and thus a more miniaturized optical element driving mechanism  1  may be provided. 
     As described above, an embodiment of the present invention provides an optical element driving mechanism including a fixed portion, a movable portion, and a driving assembly. The movable portion is movably disposed on the fixed portion. The driving assembly is disposed on the fixed portion and drives the movable portion to move relative to the fixed portion. Therefore, a more miniaturized optical element driving mechanism may be provided that may further control the movement of the movable portion in the second direction by controlling the movement of the driving assembly in the first direction. 
     Although the embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods, and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized according to the disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. In addition, each claim constitutes a separate embodiment, and the combination of various claims and embodiments are within the scope of the disclosure.