Patent Publication Number: US-11662573-B2

Title: Actuator and optical scanning device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present invention claims priority under 35 U.S.C. § 119 to Japanese Application No. 2019-174621 filed on Sep. 25, 2019 the entire contents of which are hereby incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present disclosure relates to an actuator and an optical scanning device including the actuator. 
     BACKGROUND 
     Conventionally, a MEMS device capable of tilting relative to a substrate has been known. The MEMS device has a permanent magnet and two cores. Each of the cores has magnetic poles arranged to oppose each other with a lower portion of the permanent magnet interposed therebetween. In addition, directions in which the magnetic poles of each core oppose each other are orthogonal to each other. Then, when a current flows through each of coils arranged in each core, a magnetic field is applied to the permanent magnet by the opposing magnetic poles to tilt a support frame and a mirror structure. With such a configuration, the MEMS device can tilt the mirror about orthogonal axes. 
     In the above MEMS device, the cores intersect in a lower portion of the mirror, and thus, need to be shifted in the height direction, and it is difficult to reduce a size. In addition, the cores and the coils are arranged on an extension line of a rotation axis of the support frame and the mirror structure in a plan view, and a gap is formed between the coils adjacent to each other in the circumferential direction, and thus, a space factor of the coils also decreases. 
     SUMMARY 
     An actuator according to an example embodiment of the present disclosure includes a swing portion that is swingable about a first axis perpendicular or substantially perpendicular to a vertically extending central axis and a second axis which is perpendicular or substantially perpendicular to the first axis and intersects with the central axis; a frame portion that supports the swing portion so as to be swingable about the first axis; and a fixed portion that supports the frame portion so as to be swingable about the second axis. The swing portion includes a magnet in a lower portion in the central axis direction. The fixed portion includes two first stator cores, first coils attached to the two first stator cores, two second stator cores, and second coils attached to the two second stator cores. The first stator core and the second stator core respectively include tooth portions extending along the central axis, and extending portions each extending from an upper end in the central axis direction of each of the tooth portions to one side in a circumferential direction about the central axis. The tooth portions of the two first stator core and the tooth portions of the two second stator cores are arrayed alternately in the circumferential direction in each of regions of the fixed portion divided by the first axis and the second axis as viewed in the central axis direction. The first coil is in the same region as the tooth portion of the first stator core. The second coil is in the same region as the tooth portion of the second stator core. As viewed in the central axis direction, each of the extending portions of the two first stator cores includes end surfaces that face the magnet and oppose each other with the magnet interposed therebetween along the first axis. Each of the extending portions of the two second stator cores includes end surfaces that face the magnet and oppose each other with the magnet interposed therebetween along the second axis. 
     The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an optical scanning device that is an example of an actuator according to an example embodiment of the present disclosure. 
         FIG.  2    is an exploded perspective view of the optical scanning device illustrated in  FIG.  1   . 
         FIG.  3    is a cross-sectional view taken along a plane including a first axis of the optical scanning device illustrated in  FIG.  1   . 
         FIG.  4    is a cross-sectional view of the optical scanning device taken along a plane perpendicular or substantially perpendicular to  FIG.  3   . 
         FIG.  5    is a perspective view of a fixed portion. 
         FIG.  6    is a plan view of the fixed portion. 
         FIG.  7    is a perspective view of a stator core. 
         FIG.  8    is a perspective view of the stator core as viewed from a different angle from  FIG.  7   . 
         FIG.  9    is a perspective view of a swing portion as viewed from below. 
         FIG.  10    is a perspective view illustrating a step of attaching a second holder member of a holder to a shaft. 
         FIG.  11    is a perspective view illustrating a step of fixing a plate to the shaft to which the second holder member has been attached. 
         FIG.  12    is a perspective view illustrating a step of fixing the shaft to a plate portion. 
         FIG.  13    is a perspective view illustrating a step of attaching a first holder member to the second holder member. 
         FIG.  14    is a perspective view illustrating a step of attaching a magnet to the first holder member. 
         FIG.  15    is a cross-sectional view of another example of an optical scanning device according to an example embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments of the present disclosure will be described in detail with reference to the drawings. In the present specification, a central axis Cx, a first axis C 1 , and a second axis C 2  are defined as follows. In an optical scanning device  100  illustrated in  FIG.  1   , the central axis Cx extends vertically. In addition, the first axis C 1  and the second axis C 2  are perpendicular or substantially perpendicular to each other. The central axis Cx intersects with each of the first axis C 1  and the second axis C 2  at intersections with the first axis C 1  and the second axis C 2 . The second axis C 2  is always perpendicular or substantially perpendicular to the central axis Cx. In addition, the first axis C 1  is perpendicular or substantially perpendicular to the central axis Cx when an optical element  1  is stopped. In addition, the top and bottom are defined along the central axis Cx with the optical scanning device  100  illustrated in  FIG.  1    as a reference. The above-described designations of directions are used for the purpose of description, and do not limit positional relationships and directions in a use state of the optical scanning device  100 . 
       FIG.  1    is a perspective view of the optical scanning device  100  that is a use example of an actuator according to the present disclosure.  FIG.  2    is an exploded perspective view of the optical scanning device  100  illustrated in  FIG.  1   .  FIG.  3    is a cross-sectional view taken along a plane including the first axis C 1  of the optical scanning device  100  illustrated in  FIG.  1   .  FIG.  4    is a cross-sectional view of the optical scanning device  100  taken along a plane perpendicular or substantially perpendicular to  FIG.  3   . The optical scanning device  100  is one of use examples of the actuator. In the optical scanning device  100 , the optical element  1  is swung about the first axis C 1  and the second axis C 2  which are perpendicular or substantially perpendicular to each other. Note that the optical element  1  is an optical element that reflects light from a light source in the optical scanning device  100 . 
     The optical scanning device  100  reflects the light from the light source (not illustrated) on a reflecting surface  111 , which will be described below, provided on the optical element  1  which is an example of the swing portion. The reflecting surface  111  reflects the light while swinging, thereby moving the reflected light and irradiating a wide range with the light, that is, scanning the light. As illustrated in  FIGS.  1  to  4   , the optical scanning device  100  includes the optical element  1 , a frame portion  2 , a fixed portion  3 , first bearings  41 , and second bearings  42 . Next, details of each portion of the optical scanning device  100  will be described. 
       FIG.  5    is a perspective view of the fixed portion  3 .  FIG.  6    is a plan view of the fixed portion  3 . The fixed portion  3  is fixed to a mounting object such as an automobile and an unmanned aerial vehicle. As illustrated in  FIGS.  1  to  6   , the fixed portion  3  includes a pedestal portion  31 , support portions  32 , an insulator  33 , first stator cores  51 , second stator cores  52 , first coils  55 , and second coils  58 . 
     As illustrated in  FIGS.  5  and  6   , the pedestal portion  31  has a rectangular plate shape. As illustrated in  FIGS.  2  to  4   , and the like, the longitudinal direction of the pedestal portion  31  is a direction along the second axis C 2 . The pedestal portion  31  may be made of, for example, a magnetic material such as iron. The pedestal portion  31  has a pedestal hole  311  penetrating along the central axis Cx at the center. The pedestal hole  311  is a hole through which lead wires of the first coil  55  and the second coil  58  pass. Two support portions  32  are arranged on an upper surface of the pedestal portion  31  in the direction of the central axis Cx. The support portions  32  are arranged apart from each other in the direction of the second axis C 2 , and extend upward from the upper surface of the pedestal portion  31  along the central axis Cx. 
     A concave second bearing holding portion  321 , which penetrates in the direction of the second axis C 2  and is open upward, is formed at an upper end of the support portion  32 . The second bearing holding portion  321  holds the second bearing  42 . The second bearing holding portion  321  supports the frame portion  2  swingably via the second bearing  42 . That is, the fixed portion  3  supports the frame portion  2  to be swingable about the second axis C 2  perpendicular or substantially perpendicular to the first axis C 1 . As illustrated in  FIG.  6   , the support portion  32  is fixed to the pedestal portion  31  with a screw Br 2 . That is, the fixed portion  3  includes: the plate-shaped pedestal portion  31  arranged on the lower side in the direction of the central axis Cx of the swing portion used as the optical element  1 ; and the pair of support portions  32  extending from the pedestal portion  31  in the direction of the central axis Cx and arrayed in the direction of the second axis C 2 . The support portion  32  has the second bearing holding portion  321  that holds the second bearing  42  that supports a rotary protrusions  22 . The fixing of the support portion  32  to the pedestal portion  31  is not limited to the screw, and a method of being capable of firmly fixing the support portion  32  to the pedestal portion  31 , such as welding and adhesion, can be widely adopted. 
     Two first stator cores  51  and two second stator cores  52  are arranged on the upper surface of the pedestal portion  31  in the direction of the central axis Cx. That is, the fixed portion  3  has the two first stator cores  51  and the two second stator cores  52 . Note that the first stator core  51  and the second stator core  52  have the same configuration and shape. 
     Details of the first stator core  51  and the second stator core  52  will be described with reference to the drawings. Note that the first stator core  51  and the second stator core  52  have the same configuration and shape. Therefore, the first stator core  51  will be described as a representative of the first stator core  51  and the second stator core  52  in this chapter.  FIG.  7    is a perspective view of the first stator core  51 .  FIG.  8    is a perspective view of the first stator core  51  as viewed from a different angle from  FIG.  7   . 
     The first stator core  51  is a molded body formed by sintering powder of a magnetic material such as iron powder as the same member, but is not limited thereto. For example, the first stator core  51  may be a stacked body in which magnetic plates are stacked. As illustrated in  FIGS.  7  and  8   , the first stator core  51  has a tooth portion  53  and an extending portion  54 . 
     The tooth portion  53  has a columnar shape. Here, a direction in which the tooth portion  53  extends is the direction along the central axis Cx. The tooth portion  53  illustrated in  FIGS.  7  and  8    has a rectangular parallelepiped shape, but is not limited thereto. For example, the tooth portion  53  may be a cylindrical column or a column having a polygonal cross-sectional shape other than a square such as a hexagon and an octagon. 
     The extending portion  54  extends from an upper end of the tooth portion  53  in the direction of the central axis Cx to one side in the circumferential direction about the central axis Cx. The extending portion  54  has a first arm portion  541  and a second arm portion  542 . The first arm portion  541  of the extending portion  54  extends from the upper end of the tooth portion  53  in a direction perpendicular or substantially perpendicular to the tooth portion  53 . The second arm portion  542  extends from a free end of the first arm portion  541  along the central axis Cx and in a direction inclined with respect to the central axis Cx. The free end of the second arm portion  542  has an end surface  543 . The end surface  543  is a surface that intersects with, specifically, a surface that is perpendicular or substantially perpendicular to a direction in which the second arm portion  542  extends. 
     As viewed in the direction of the central axis Cx, the first arm portion  541  has an outer side surface  540  on a side opposite to the direction in which the second arm portion  542  extends. The outer side surface  540  is inclined in the same direction as the direction in which the second arm portion  542  extends. 
     The first stator core  51  has the configuration described above. In addition, the tooth portion  53  and the extending portion  54  of the first stator core  51  correspond to a tooth portion  56  and an extending portion  57  of the second stator core  52 , respectively. In addition, the first arm portion  541 , the second arm portion  542 , and the end surface  543  of the extending portion  54  of the first stator core  51  correspond to the first arm portion  571 , the second arm portion  572 , and the end surface  573  of the extending portion  57  of the second stator core  52 , respectively. 
     That is, the first stator core  51  and the second stator core  52  respectively include tooth portions  53  and  56  extending along the central axis Cx and the extending portions  54  and  57  extending from the upper ends of the tooth portions  53  and  56  in the direction of the central axis Cx to one side in the circumferential direction about the central axis Cx. 
     As described above, the first stator core  51  and the second stator core  52  of the fixed portion  3  are arranged on the upper surface of the pedestal portion  31 . The tooth portion  53  of the first stator core  51  is fixed to the pedestal portion  31  with a screw Br 1 , and the tooth portion  56  of the second stator core  52  is fixed to the pedestal portion  31  with a screw Br 1  (see  FIGS.  3    and  4 ). Fixing of the tooth portion  53  and the tooth portion  56  is not limited to the screw, and welding, adhesion, or the like may be adopted. 
     In the fixed portion  3  illustrated in  FIG.  6   , a region corresponding to the first quadrant when the first axis C 1  is the x-axis and the second axis C 2  is the y-axis will be described as a first region Ar 1 . Similarly, a region corresponding to the second quadrant, a region corresponding to the third quadrant, and a region corresponding to the fourth quadrant will be described as a second region Ar 2 , a third region Ar 3 , and a fourth region Ar 4 , respectively. 
     As illustrated in  FIGS.  5  and  6   , the tooth portions  53  of the two first stator cores  51  are arranged at opposite positions with the central axis Cx interposed therebetween as viewed in the direction of the central axis Cx. In addition, the tooth portions  56  of the two second stator cores  52  are arranged at opposite positions with the central axis Cx interposed therebetween. That is, the tooth portions  53  of the two first stator cores  51  and the tooth portions  56  of the two second stator cores  52  are arrayed alternately in the circumferential direction in each of the regions Ar 1  to Ar 4  divided by the first axis C 1  and the second axis C 2  of the fixed portions  3  as viewed in the direction of the central axis Cx. 
     The first stator core  51  and the second stator core  52  are arranged alternately in the circumferential direction. Then, the tooth portions  53  of the two first stator cores  51  are arranged at opposite positions with the central axis Cx interposed therebetween. In addition, the tooth portions  56  of the two second stator cores  52  are arranged at opposite positions with the central axis Cx interposed therebetween. 
     The end surfaces  543  of the two first stator cores  51  oppose each other in the direction of the first axis C 1 . In addition, each of the end surfaces  543  faces the magnet  13  arranged above (see  FIG.  3    and the like). That is, each of the extending portions  54  of the two first stator cores  51  have the end surfaces  543  that face the magnet  13  and oppose each other with the magnet  13  interposed therebetween along the first axis C 1  as viewed in the direction of the central axis Cx. 
     With the central axis Cx as the center, the centers of the respective tooth portions  53  in the circumferential direction are arranged at positions separated by 45° in the same direction with respect to the centers of the end surfaces  543  in the circumferential direction, here, in the counterclockwise direction in  FIG.  6   . That is, with the central axis Cx as the center as viewed in the direction of the central axis Cx, the center of the end surface  543  of each of the first stator cores  51  in the circumferential direction and the center of the tooth portion  53  of the first stator core  51  in the circumferential direction are arranged to be separated by 45 degrees in the circumferential direction. 
     As described above, the tooth portion  53  has the rectangular parallelepiped shape, and each side surface thereof is arranged parallel to the first axis C 1  and the second axis C 2 . In  FIG.  6   , the tooth portions  53  of the two first stator cores  51  are arranged in the first region Ar 1  and the third region Ar 3 , respectively. 
     The first arm portion  541  of the extending portion  54  of each of the first stator cores  51  extends from the upper end of the tooth portion  53  in the clockwise direction in the circumferential direction about the central axis Cx. That is, the first arm portion  541  extends in the circumferential direction from the upper end of the tooth portion  53 . The first arm portion  541  is arranged parallel to the pedestal portion  31  and is perpendicular or substantially perpendicular to the first axis C 1  as viewed in the direction of the central axis Cx. Note that the first arm portion  541  is not necessarily parallel to the pedestal portion  31 . In addition, the first arm portion  541  may intersect with the first axis C 1  at an angle other than the perpendicular as viewed in the central axis direction. 
     The second arm portion  542  extends upward in the direction of the central axis Cx from the free end of the first arm portion  541 . The second arm portion  542  approaches the central axis Cx as proceeding upward in the direction of the central axis Cx. That is, the second arm portion  542  is inclined upward as proceeding toward the central axis Cx along the first axis C 1 . As a result, the second arm portion  542  extends in a direction away from the pedestal portion  31  while approaching the central axis Cx. A surface of the second arm portion  542  close to the free end is the end surface  543 . That is, the end surface  543  is provided on the second arm portion  542 . 
     The end surfaces  573  of the two second stator cores  52  oppose each other in the direction of the second axis C 2 . In addition, each of the end surfaces  573  faces the magnet  13  arranged above (see  FIG.  4    and the like). That is, each of the extending portions  57  of the two second stator cores  52  have the end surfaces  573  that face the magnet  13  and oppose each other with the magnet  13  interposed therebetween along the second axis C 2  as viewed in the direction of the central axis Cx. 
     With the central axis Cx as the center, the centers of the respective tooth portions  56  in the circumferential direction are arranged at positions separated by 45° in the same direction with respect to the centers of the end surfaces  573  in the circumferential direction, here, in the counterclockwise direction in  FIG.  6   . That is, with the central axis Cx as the center as viewed in the direction of the central axis Cx, the center of the end surface  573  of each of the second stator cores  52  in the circumferential direction and the center of the tooth portion  56  of the second stator core  52  in the circumferential direction are arranged to be separated by 45 degrees in the circumferential direction. 
     As described above, the tooth portion  56  has the rectangular parallelepiped shape, and each side surface thereof is arranged parallel to the second axis C 2  and the first axis C 1 . In  FIG.  6   , the tooth portions  56  of the two second stator cores  52  are arranged in the second region Ar 2  and the fourth region Ar 4 , respectively. 
     The first arm portion  571  of the extending portion  57  of each second stator core  52  extends in the clockwise direction from the upper end of the tooth portion  56  in the circumferential direction about the central axis Cx. That is, the first arm portion  571  extends in the circumferential direction from the upper end of the tooth portion  56 . The first arm portion  571  is arranged parallel to the pedestal portion  31  and is perpendicular or substantially perpendicular to the second axis C 2  as viewed in the direction of the central axis Cx. Note that the first arm portion  571  is not necessarily parallel to the pedestal portion  31 . In addition, the first arm portion  571  may intersect with the second axis C 2  at an angle other than the perpendicular as viewed in the central axis direction. 
     The second arm portion  572  extends upward in the direction of the central axis Cx from the free end of the first arm portion  571  along the second axis C 2 . In addition, the second arm portion  572  approaches the central axis Cx as proceeding upward in the direction of the central axis Cx. That is, the second arm portion  572  is inclined upward as proceeding toward the central axis Cx along the second axis C 2 . As a result, the second arm portion  572  extends in a direction away from the pedestal portion  31  while approaching the central axis Cx. A surface of the second arm portion  572  close to the free end is the end surface  573 . That is, the end surface  573  is provided on the second arm portion  572 . 
     Since the extending portions  54  and  57  of the first stator core  51  and the second stator core  52  are formed in shapes respectively having the linearly extending first arm portions  541  and  571  and the second arm portions  542  and  572 , each of the first stator core  51  and the second stator core  52  has a simpler shape as compared to a configuration that extends in a curved shape. As a result, it is possible to reduce the labor and time required to manufacture the first stator core  51  and the second stator core  52 . 
     The first coil  55  and the second coil  58  are formed by winding a lead wire around the tooth portion  53  and the tooth portion  56  with the insulator  33  interposed therebetween. That is, the fixed portion  3  has the two first coils  55  attached to the two first stator cores  51 . In addition, the fixed portion  3  has the two second coils  58  attached to the two second stator cores  52 . 
     The insulator  33  is made of an insulating material. The insulator  33  covers an outer side surface of each of the tooth portion  53  and the tooth portion  56 . Then, the first coil  55  and the second coil  58  are formed by winding lead wires around the respective outer side surfaces of the tooth portion  53  and the tooth portion  56  covered by the insulator  33 . That is, the first coil  55  is arranged in the same region as the tooth portion  53  of the first stator core  51 . In addition, the second coil  58  is arranged in the same region as the tooth portion  56  of the second stator core  52 . 
     The insulator  33  insulates the conductive lead wire from each of the conductive tooth portions  53  and  56 . In the fixed portion  3 , the pedestal portion  31  is also conductive. Therefore, the insulator  33  is formed so as to be capable of being insulated from the pedestal portion  31  as well. In the insulator  33 , a plate-shaped member  331  arranged on an upper surface of the pedestal portion  31 , and a tubular members  332 , which protrudes from the plate-shaped member  331  in the direction along the central axis Cx and accommodates each of the tooth portion  53  and the tooth portion  56 , are formed using the same member. In the insulator  33 , the plate-shaped member  331  and the tubular member  332  may be formed separately. 
     The lead wire wound around each of the tooth portion  53  and the tooth portion  56  is wired below the pedestal portion  31  through the pedestal hole  311  of the pedestal portion  31 . The lead wire is connected to a control circuit such as a driver circuit (not illustrated). That is, an electromagnet is formed by forming the first coil  55  and the second coil  58  in the tooth portion  53  of the first stator core  51  and the tooth portion  56  of the second stator core  52 , respectively. When a current is applied to each of the first coil  55  and the second coil  58 , the end surface  543  and the end surface  573  serve as magnetic pole surfaces, respectively. 
     As the tooth portion  53  and the tooth portion  56  are arranged at positions shifted by 45° in the circumferential direction with respect to the end surface  543  and the end surface  573 , respectively, the first coil  55  and the second coil  58  can be arranged in a narrow region. As a result, each space factor of the first coil  55  and the second coil  58  can be increased. As a result, the optical scanning device  100  can be downsized, and a swing torque of the optical element  1  can be increased or power consumption can be reduced. 
     Details of the optical element  1  will be described with reference to the drawings.  FIG.  9    is a perspective view of the optical element  1  as viewed from below. The first axis C 1  and the second axis C 2  are perpendicular or substantially perpendicular to each other and perpendicular or substantially perpendicular to the central axis Cx. The optical element  1  is arranged to be swingable about the first axis C 1  and the second axis C 2 . That is, the swing portion used as the optical element  1  is arranged so as to be swingable about the first axis C 1  and the second axis C 2  which are perpendicular or substantially perpendicular to the vertically extending central axis Cx and are perpendicular or substantially perpendicular to each other. The optical element  1  has a plate portion  11 , a shaft  12 , the magnet  13 , a holder  6 , and two plates  7 . 
     The plate portion  11  has a plate shape whose square corner is formed into a curved surface as viewed in the direction of the central axis Cx. The plate portion  11  has the reflecting surface  111  and a protruding portion  112 . The reflecting surface  111  is formed on an upper surface of the plate portion  11  in the direction of the central axis Cx. The reflecting surface  111  reflects light emitted from a light source (not illustrated). The plate portion  11  is made of metal such as stainless steel and an aluminum alloy. The reflecting surface  111  is formed by mirror-finishing the upper surface of the plate portion  11  in the direction of the central axis Cx. The reflecting surface  111  is not limited to the one formed by mirror finishing. For example, at least a part of the upper surface of the plate portion  11  may be formed by plating that reflects light. As the reflecting surface  111 , configurations capable of reflecting light from the light source can be widely adopted. 
     The protruding portion  112  has a tubular shape that extends downward from a central portion of a lower surface of the plate portion  11  in the direction of the central axis Cx. The protruding portions  112  are arranged side by side in the direction of the second axis C 2  with the shaft  12  interposed therebetween. The protruding portion  112  has a screw hole that is open downward. Plate portion fixing portions  72  of plates  7  to be described below are fixed to the protruding portions  112 . 
     The shaft  12  extends in the direction of the first axis C 1 . That is, the swing portion used as the optical element  1  has the shaft  12  extending along the first axis C 1 . Both ends of the shaft  12  in the direction of the first axis C 1  are swingably supported by the first bearing  41 . The shaft  12  is fixed to the lower surface of the plate portion  11  via the plate  7 . Details of the plate  7  will be described below. 
     As illustrated in  FIGS.  3  to  6    and the like, the magnet  13  has a plate shape with a square cross section. The magnet  13  has two first planes  131  and two second planes  132  on side surfaces thereof. The two first planes  131  are two parallel surfaces among the side surfaces of the rectangular parallelepiped, and the two second planes  132  are arranged side by side in parallel in a direction perpendicular or substantially perpendicular to a direction in which the first planes  131  are arrayed. The magnet  13  is fixed below the shaft  12  via the holder  6 . When the magnet  13  is fixed to the shaft  12 , the first planes  131  are arranged side by side in the direction of the first axis C 1 , and the second planes  132  are arranged side by side in the direction of the second axis C 2 . More specifically, each of the first planes  131  oppose each of the end surfaces  543  in the direction along the first axis C 1  (see  FIG.  3   ). In addition, each of the second planes  132  oppose each of the end surfaces  573  in the direction along the second axis C 2  (see  FIG.  4   ). 
     The magnet  13  is the rectangular parallelepiped having the square cross section, but may have a polygonal columnar shape whose cross section is octagonal or the like as long as the shape has the first plane and the second plane. In addition, the magnet  13  may have a shape that does not have the first plane and the second plane, for example, a columnar shape or an elliptical columnar shape. 
     Details of the holder  6  and the plate  7  and a procedure for assembling the optical element  1  will be described with reference to the drawings of manufacturing steps of the optical element  1 .  FIG.  10    is a perspective view illustrating a step of attaching a second holder member  62  of the holder  6  to the shaft  12 .  FIG.  11    is a perspective view illustrating a step of fixing the plate  7  to the shaft  12  to which the second holder member  62  has been attached.  FIG.  12    is a perspective view illustrating a step of fixing the shaft  12  to the plate portion  11 .  FIG.  13    is a perspective view illustrating a step of attaching a first holder member  61  to the second holder member  62 .  FIG.  14    is a perspective view illustrating a step of attaching the magnet  13  to the first holder member  61 . The optical element  1  assembled through all the steps is the optical element  1  illustrated in  FIG.  9   . 
     The holder  6  is arranged on the lower surface of the plate portion  11  in the direction of the central axis Cx. The holder  6  holds the magnet  13  and is fixed to the shaft  12 . That is, the magnet  13  is arranged in the lower portion of the swing portion in the direction of the central axis Cx. The holder  6  is made of, for example, a magnetic material such as iron. Since the holder  6  is made of the magnetic material in this manner, the holder  6  also serves as a yoke. As a result, it is possible to enhance the utilization efficiency of magnetism of the magnet  13 . 
     As illustrated in  FIGS.  9  and  13    and the like, the holder  6  has the first holder member  61  and the second holder member  62 . The second holder member  62  is fixed to the shaft  12 . As the second holder member  62 , a configuration manufactured by bending a metal plate may be adopted, but the second holder member  62  is not limited thereto. The second holder member  62  has a second bottom plate portion  621  and two second side plate portions  622 . 
     As illustrated in  FIG.  9   , the second bottom plate portion  621  extends along the lower surface of the plate portion  11  in the direction of the central axis Cx. The second bottom plate portion  621  is a long member, and the longitudinal direction thereof is the direction of the second axis C 2 . The two second side plate portions  622  extend downward in the direction of the central axis Cx from both end edges of the second bottom plate portions  621  in the direction of the first axis C 1 . The two second side plate portions  622  have the same shape and are arranged side by side in parallel to the direction of the first axis C 1 . 
     The second bottom plate portion  621  has bottom plate holes  625  that penetrate in the thickness direction. Two bottom plate holes  625  are formed side by side in the longitudinal direction. The bottom plate hole  625  has a size capable of accommodating the protruding portion  112  of the plate portion  11 . 
     A second penetrating portion  623  and two accommodation holes  624  are formed in each of the two second side plate portions  622 . The second penetrating portions  623  overlap in the direction of the first axis C 1 . As viewed in the direction of the central axis Cx, the two accommodation holes  624  of each of the second side plate portions  622  are arranged side by side in the direction of the second axis C 2  with the shaft  12  interposed therebetween. Then, each two accommodation holes  624  of the opposing second side plate portions  622  overlap in the direction of the first axis C 1 . Holder recesses  626  that are open to each end side are formed at lower ends of the respective second side plate portions  622  in the direction of the central axis Cx (see  FIG.  9   , and the like). The holder recesses  626  formed respectively in the two second side plate portions  622  also overlap in the direction of the first axis C 1 . The holder recess  626  accommodates and fixes the first holder member  61  as will be described below in detail. 
     As illustrated in  FIG.  9   , the shaft  12  extending in the direction of the first axis C 1  penetrates through the second penetrating portions  623  formed in each of the two second side plate portions  622  and is fixed. In addition, the plate portion fixing portions  72 , which will be described below, of the plates penetrate through the two accommodation holes  624  in the direction of the first axis C 1 . At this time, a plate penetrating portion  721 , which will be described below, formed in the plate portion fixing portion  72  overlaps with the screw hole formed in the protruding portion  112  in the direction of the central axis Cx. The plate portion fixing portion  72  is fixed to the protruding portion  112  with a screw Sc 1 . Details of fixing of the plate  7 , that is, the plate portion fixing portion  72  and the plate portion  11  will be described below. 
     As illustrated in  FIG.  9   , the first holder member  61  is fixed to a lower end of the second holder member  62  in the direction of the central axis Cx. The first holder member  61  has a first bottom plate portion  611  and two first side plate portions  612 . The first bottom plate portion  611  expands along the lower surface of the plate portion  11 . The first bottom plate portion  611  is a long member, and the longitudinal direction thereof is the direction of the first axis C 1 . The two first side plate portions  612  extend downward in the direction of the central axis Cx from both end edges of the first bottom plate portions  611  in the direction of the second axis C 2 . The two first side plate portions  612  have the same shape and are arranged side by side in parallel to the direction of the second axis C 2 . 
     Each of the two first side plate portions  612  has a first penetrating portion  613 . The pair of first penetrating portions  613  penetrates each of the first side plate portions  612  in the thickness direction. The first penetrating portions  613  overlap in the direction of the second axis C 2 . A lower portion of the first side plate portion  612  below the first penetrating portion  613  in the direction of the central axis Cx is closed. In other words, the first penetrating portion  613  is a through-hole whose periphery is closed. Then, the lower portion of the first side plate portion  612  below the first penetrating portion  613  is a magnet pressing portion  614  in the direction of the central axis Cx. It suffices that the magnet pressing portion  614  is in contact with a lower surface of the magnet  13 , and a part thereof may be separated. That is, the first penetrating portion  613  may have a notched shape whose lower portion is open. 
     The magnet  13  is partially accommodated inside the pair of first penetrating portions  613 . That is, the pair of first penetrating portions  613  form a magnet accommodating portion  63 . Then, the lower surface of the magnet  13  in the direction of the central axis Cx is covered by the magnet pressing portion  614 . Note that the magnet pressing portion  614  may be in contact or may be in non-contact with the lower surface of the magnet  13  in the direction of the central axis Cx. Since the magnet pressing portion  614  covers the lower surface of the magnet  13  in the direction of the central axis Cx, the magnet  13  is unlikely to drop off with the moment generated when the optical element  1  swings about the first axis C 1  and the second axis C 2 . 
     The magnet  13  accommodated in the magnet accommodating portion  63  is fixed to the first side plate portion  612  by adhesion, for example. That is, the magnet  13  is held by the first holder member  61 . Note that the magnet  13  may be fixed to the first bottom plate portion  611  without being limited to the first side plate portion  612 . In addition, a fixing method is not limited to the adhesion. The magnet  13  is fixed to the shaft  12  via the holder  6 . The holder  6  may be omitted if the magnet  13  can be fixed to the shaft  12 . 
     The two plates  7  have the same shape. The plate  7  is manufactured by bending a metal plate. The plate  7  has a thickness smaller than a thickness of the plate portion  11 . The plate  7  fixes the plate portion  11  and the shaft  12 . The plate  7  has a shaft fixing portion  71 , the plate portion fixing portion  72 , and a connecting portion  73 . 
     The shaft fixing portion  71  is a plate that expands along the lower surface of the plate portion  11  in the direction of the central axis Cx. The shaft fixing portion  71  is a long member, and the longitudinal direction thereof is the direction along the first axis C 1 . An end on one side in the longitudinal direction of the shaft fixing portion  71  has an overhanging portion  711  overhanging along the plate portion  11  in the direction of the second axis C 2 . The shaft  12  is fixed to a lower surface of the shaft fixing portion  71  in the direction of the central axis Cx. A method of fixing the shaft  12  to the shaft fixing portion  71  can be, for example, welding, but is not limited thereto. The shaft fixing portion  71  is arranged between the lower surface of the plate portion  11  and the shaft  12 . 
     The plate portion fixing portion  72  is a plate that extends along the lower surface of the plate portion  11  in the direction of the central axis Cx. The plate portion fixing portion  72  has a long shape, and the longitudinal direction thereof extends in the direction of the first axis C 1 . The plate portion fixing portion  72  is located below the shaft fixing portion  71  in the direction of the central axis Cx. In addition, the shaft fixing portion  71  and the plate portion fixing portion  72  are arranged to be shifted in the direction of the first axis C 1  and shifted in the direction of the second axis C 2  as viewed in the direction of the central axis Cx. That is, the shaft fixing portion  71  overlaps with the shaft  12  as viewed from the direction of the central axis Cx. In addition, the plate portion fixing portion  72  does not overlap with the shaft  12  as viewed from the direction of the central axis Cx. The plate portion fixing portion  72  has the plate penetrating portion  721  penetrating in the thickness direction. The connecting portion  73  connects the overhanging portion  711  of the shaft fixing portion  71  and the plate portion fixing portion  72 . The connecting portion  73  extends along the direction of the central axis Cx. 
     As viewed from the direction of the central axis Cx, the plate portion fixing portion  72  of the plate  7  is accommodated inside the two accommodation holes  624 . The two accommodation holes  624  in which the plate portion fixing portion  72  is accommodated are arranged on the same side when being divided into right and left with the shaft  12  as the reference as viewed from the direction of the central axis Cx. At this time, the shaft fixing portions  71  of the respective plates  7  extend in the opposite directions along the direction of the first axis C 1  as viewed from the second holder member  62 . Then, the shaft fixing portion  71  is fixed to the shaft  12 . That is, the two plates  7  are arranged at positions point-symmetric with each other with respect to the central axis Cx as viewed in the direction of the central axis Cx. 
     The plate penetrating portion  721  of the plate portion fixing portion  72  and the protruding portion  112  of the plate portion  11  are arranged side by side concentrically as viewed from the direction of the central axis Cx. Then, the screw Sc 1  is inserted into the plate penetrating portion  721  and screwed into the protruding portion  112  to fix the plate  7  and the plate portion  11 . As a result, the holder  6  and the plate portion  11  are also fixed. 
     The plate  7  may be omitted if a configuration capable of firmly fixing the shaft  12  and the plate portion  11  is provided. 
     The manufacturing steps of the optical element  1  will be described. As illustrated in  FIG.  10   , the shaft  12  is inserted into the second penetrating portion  623  formed on the second side plate portion  622  of the second holder member  62 . Then, the second holder member  62  is moved along the shaft  12 . The second holder member  62  is fixed to the shaft  12  at the central portion in the longitudinal direction of the shaft  12  (see  FIG.  11   ). At this time, the shaft  12  may be fixed to the second side plate portion  622  of the second holder member  62  or may be fixed to the second bottom plate portion  621 . Alternatively, the shaft  12  may be fixed to both the second bottom plate portion  621  and the second side plate portion  622 . 
     The fixing of the shaft  12  and the second holder member  62  can include, but is not limited to, welding. For example, a fixing method such as adhesion and press fitting may be adopted. A method of firmly fixing the shaft  12  and the second holder member  62  can be widely adopted. 
     As illustrated in  FIG.  11   , the plate portion fixing portion  72  of each of the plates  7  is inserted into each of the accommodation holes  624 , which are arranged so as to overlap in the direction of the first axis C 1 , from both sides in the direction of the first axis C 1  of the second holder member  62  fixed to the shaft  12 . At this time, the shaft fixing portion  71  of each of the plates  7  is arranged above the shaft  12  in the direction of the central axis Cx. Then, the shaft fixing portion  71  is fixed to the shaft  12  in a state where the plate penetrating portion  721  of the plate portion fixing portion  72  overlaps with the bottom plate hole  625  in the direction of the central axis Cx (see  FIG.  12   ). 
     In this state, the second holder member  62  is fixed to the shaft  12 . In addition, the plate portion fixing portions  72  of the two plates  7  are accommodated in the accommodation holes  624  of the second holder member  62 , and the shaft fixing portion  71  is arranged above the shaft  12  in the direction of the central axis Cx. Then, the shaft fixing portion  71  is fixed to the shaft  12 . 
     As illustrated in  FIG.  12   , the plate portion fixing portion  72  of the plate  7  is attached to the second holder member  62  fixed to the shaft  12 . The protruding portion  112  of the plate portion  11  is inserted into the two bottom plate holes  625  of the second bottom plate portion  621  of the second holder member  62 . At this time, a lower end surface of the protruding portion  112  in the direction of the central axis Cx is in contact with the plate portion fixing portion  72  of the plate  7 . Then, the screw hole formed in the protruding portion  112  and the plate penetrating portion  721  of the plate portion fixing portion  72  overlap in the direction of the central axis Cx. In this state, the screw Sc 1  is inserted into the plate penetrating portion  721  and screwed into the screw hole of the protruding portion  112 , whereby the plate portion fixing portion  72  of the plate  7  is fixed to the protruding portion  112  (see  FIG.  13   ). That is, the plate  7  fixes the plate portion  11  and the shaft  12 . 
     As illustrated in  FIG.  14   , the shaft  12  is fixed to the plate portion  11  via the plate  7 . Then, the second holder member  62  is fixed to the shaft  12 . The first holder member  61  is inserted and fixed to the holder recess  626  of the second side plate portion  622  of the second holder member  62 . When the first holder member has been attached to the holder recess  626 , the first penetrating portion  613  formed in the first side plate portion  612  is fitted between the two second side plate portions  622  of the second holder member  62  in the direction of the first axis C 1 . At this time, the first holder member  61  is fixed to the second holder member  62 . 
     The first holder member  61  is fixed to the second holder member  62  by welding a contact portion between the first side plate portion  612  and the second side plate portion  622 . However, a fixing method is not limited to welding. In addition, the disclosure is not limited to the fixing of the first side plate portion  612  and the second side plate portion  622 . A method of firmly fixing the first holder member  61  and the second holder member  62  can be widely adopted. As illustrated above, the shaft  12  fixed to the lower surface of the plate portion  11  is fixed to the holder  6 . In addition, the holder  6  is held by the plate portion  11  via the plate  7 . 
     As illustrated in  FIG.  14   , the magnet  13  is inserted into the first penetrating portion  613  formed on the first side plate portion  612  of the first holder member  61  in the direction along the second axis C 2  from a gap between the second plane  132  and the second side plate portions  622  of the second holder member  62 . Then, the magnet  13  is fixed in the state of being accommodated inside the first penetrating portion  613  (see  FIG.  9   ). The magnet  13  is fixed, for example, by adhesion. Note that the fixing of the magnet  13  is not limited to adhesion, but any fixing method that does not reduce a magnetic force of the magnet  13  is used. At this time, the first plane  131  of the magnet  13  faces the outer side in the direction of the first axis C 1 . In addition, the second plane  132  of the magnet  13  faces the outer side in the direction of the second axis C 2 . 
     That is, as viewed in the direction of the central axis Cx, the magnet  13  has the two first planes  131  opposing the end surfaces  543  of the two first stator cores  51  respectively in the direction of the first axis C 1 , and the two second planes  132  opposing the end surfaces  573  of the two second stator cores  52 , respectively, in the direction of the second axis C 2 . 
     As illustrated in  FIGS.  1  and  2    and the like, the frame portion  2  has an annular portion  21  and the rotary protrusions  22 . The annular portion  21  has a circular ring shape centered on the central axis Cx. That is, the frame portion  2  has an annular shape. The rotary protrusion  22  is a columnar shape that protrudes outward from the annular portion  21  in the direction of the second axis C 2 . That is, the frame portion  2  has a pair of rotary protrusions  22  protruding outward from ends of an outer side surface in the direction of the second axis C 2 . The annular portion  21  has first bearing holding portions  211  at ends in the direction of the first axis C 1 . The first bearing holding portion  211  is a recess that is recessed upward in the direction of the central axis Cx. The first bearing  41  is held by the first bearing holding portion  211 . 
     The rotary protrusion  22  is press-fitted and fixed in a through-hole provided in the annular portion  21 . However, the disclosure is not limited thereto, and the annular portion  21  and the rotary protrusion  22  may be formed using the same member. Then, the rotary protrusion  22  is swingably supported by the second bearing holding portion  321  formed on the support portion  32  of the fixed portion  3  via the second bearing  42 . The second bearing  42  has a sleeve  421  that holds the rotary protrusion  22  therein. The second bearing  42  is a slide bearing, but is not limited thereto, and a ball bearing or the like may be adopted. 
     The shaft  12  of the optical element  1  is swingably supported by the first bearing holding portion  211  of the annular portion  21  of the frame portion  2  via the first bearing  41 . That is, the frame portion  2  supports the swing portion used as the optical element  1  so as to be swingable about the first axis C 1 . In addition, the frame portion  2  has the first bearing holding portions  211  that are arranged at the ends in the direction of the first axis C 1  and hold the pair of first bearings  41  supporting both the ends of the shaft  12  in the direction of the first axis C 1 . The first bearing  41  has a sleeve  411  that holds the shaft  12  therein. The first bearing  41  is a slide bearing, but is not limited thereto, and a ball bearing or the like may be adopted. 
     As a result, the optical element  1  is supported by the frame portion  2  via the first bearing  41  so as to be swingable about the first axis C 1 . In addition, the frame portion  2  is swingably supported about the second axis C 2  via the second bearing  42 . Therefore, the optical element  1  is stably swingable about the first axis C 1 , and the optical element  1  is stably swingable about the second axis C 2  together with the frame portion  2 . 
     The optical scanning device  100  has the configuration described above. An operation of the optical scanning device  100  will be described hereinafter. The optical scanning device  100  supplies a current to the first coil  55  and the second coil  58  arranged in the fixed portion  3 , and causes the optical element  1  to operate by magnetic forces generated in the first stator core  51  and the second stator core  52  due to the energization of the first coil  55  and the second coil  58 , and the magnetic force of the magnet  13 . That is, the fixed portion  3  forms a magnetic circuit with the magnet  13 . The optical element  1  operates as follows. 
     For example, the magnetic field is generated inside the second stator core  52  by supplying the current to the second coil  58 . The end surface  573  of the second stator core  52  is the magnetic pole surface. The second stator core  52  has a shape that has a small change in cross-sectional area perpendicular or substantially perpendicular to magnetic flux lines generated inside (see  FIGS.  7  and  8   ). That is, as the free end of the extending portion  57  is cut by the amount of the connecting portion between the tooth portion  56  and the extending portion  57 , the change in cross-sectional area perpendicular or substantially perpendicular to the magnetic flux lines is suppressed. In this manner, a change in magnetic flux density is suppressed, and the magnetic force generated due to the energization of the second coil  58  is used efficiently. Note that the first stator core  51  having the same shape is also similar, and has the same effect. 
     As currents in opposite directions are supplied to the two second coils  58 , one of the end surfaces  573  opposing each other in the direction along the second axis C 2  serves as the N pole and the other serves as the S pole. Assuming that the lower surface of the magnet  13  in the direction of the central axis Cx is the magnetic pole surface and is the S pole, the magnet  13  is pulled toward the end surface  573  serving as the N pole, and repels the end surface  573  serving as the S pole. At this time, the shaft holding the magnet  13  is swingably supported by the frame portion  2  via the first bearing  41 . That is, the frame portion  2  supports the shaft  12  to be swingable about the first axis C 1 . Therefore, the optical element  1  having the plate portion  11  to which the shaft  12  has been fixed is inclined with the first axis C 1  as the center. Then, the optical element  1  swings about the first axis C 1  as the currents flowing to the second coils  58  are controlled to switch between the N pole and the S pole of the end surfaces  573 . 
     The holder  6  has a portion protruding downward in the direction of the central axis Cx with respect to the first axis C 1 . Therefore, as the optical element  1  swings about the first axis C 1 , the locus of a lower end of the holder  6  in the direction of the central axis Cx becomes an arc centered on the first axis C 1 . As illustrated in  FIG.  4   , the end surface  573  is inclined in a direction away from the central axis Cx as proceeding upward in the direction of the central axis Cx. Since the end surface  573  is formed in this manner, it is possible to approach the locus of the lower end of the holder  6 . As a result, a distance between the end surface  573  and the magnet  13  can be shortened, and the magnetic force generated between the second stator core  52  and the magnet  13  can be increased. 
     As illustrated in  FIG.  4   , the second plane  132  of the magnet  13  opposes the end surface  573  in the direction of the second axis C 2 . This also enables the distance between the end surface  573  and the magnet  13  to be shortened. 
     When the optical element  1  swings about the first axis C 1 , the amplitude of the end in the direction of the second axis C 2  perpendicular or substantially perpendicular to the first axis C 1  becomes the maximum. As illustrated in  FIGS.  5  and  6    and the like, the tooth portion  56  is shifted from the end surface  573  by 45° in the circumferential direction about the central axis Cx. That is, the tooth portion  56  and the second coil  58  are shifted from the first axis C 1  and the second axis C 2 . As a result, when the optical element  1  swings about the first axis C 1 , it is difficult for a portion having the maximum amplitude to interfere with the tooth portion  56  and the second coil  58 . For this reason, it is possible to reduce each retraction amount of the tooth portion  56  and the second coil  58  in the direction of the central axis Cx to suppress the interference with the optical element  1  and to suppress the height of the fixed portion  3  in the direction of the central axis Cx. As a result, the height of the optical scanning device  100  can be kept low. That is, the optical scanning device  100  can be downsized. 
     The second arm portion  572  approaches the central axis Cx as upward in the direction of the central axis Cx in the direction of the second axis C 2 . With such a shape, the interference with the optical element  1  hardly occurs when the optical element  1  swings as compared to the configuration in which the second arm portion  572  extends in the direction perpendicular or substantially perpendicular to the central axis Cx in the direction of the second axis C 2 . In addition, it is possible to form the second arm portion  572  thicker as compared to the case of extending along the central axis Cx. As a result, the second arm portion  572  is formed to be inclined so that the interference hardly occurs when the optical element  1  swings, and further, it is possible to increase the cross-sectional area perpendicular or substantially perpendicular to the magnetic flux lines. Therefore, the magnetic flux can be effectively used, and a swing angle of the optical element  1  can be increased. 
     In addition, an outer side surface  570  of the first arm portion  571  is inclined so as to approach the central axis as proceeding upward in the direction of the central axis Cx. That is, the outer side surface  570  of the first arm portion  571  has an inclined surface that approaches the central axis Cx as proceeding upward in the direction of the central axis Cx. With such an inclination, the optical element  1  is less likely to interfere with the first arm portion  571  when the optical element  1  swings. Therefore, the swing angle of the optical element  1  can be increased. Note that the inclination direction of the outer side surface  570  and the inclination direction of the second arm portion  572  are the same. 
     Similarly, the magnetic field is generated inside the first stator core  51  by supplying the current to the first coil  55 . The end surface  543  of the first stator core  51  serves as the magnetic pole surface. As currents in opposite directions are supplied to the two first coils  55 , one of the end surfaces  543  opposing each other in the direction along the first axis C 1  serves as the N pole and the other serves as the S pole. 
     The lower surface of the magnet  13  in the direction of the central axis Cx is pulled toward the end surface  543  serving as the N pole, and repels the end surface  543  serving as the S pole. The two end surfaces  543  are arranged to oppose each other in the direction of the first axis C 1  in which the shaft  12  extends. Therefore, the magnetic force generated between the magnet  13  and the end surface  543  does not cause the optical element  1  to swing about the shaft  12 . 
     On the other hand, the rotary protrusion  22  of the frame portion  2  supporting the shaft  12  via the first bearing  41  is swingably supported by the support portion  32  via the second bearing  42 . Therefore, the optical element  1  and the frame portion  2  are inclined with the second axis C 2  as the center due to the magnetic force between the two end surfaces  543  and the magnet  13 . In other words, the optical element  1  is inclined together with the frame portion  2  with the second axis C 2  as the center. Then, the optical element  1  swings about the second axis C 2  together with the frame portion  2  as the currents flowing to the first coils  55  are controlled to switch between the N pole and the S pole of the end surfaces  543 . 
     The two end surfaces  543  and the two end surfaces  573  define a quadrangular pyramid space. The magnet  13  is swung inside the quadrangular pyramid space defined by the four end surfaces. 
     The holder  6  has a portion that protrudes downward in the direction of the central axis Cx with respect to the rotary protrusion  22 . Therefore, as the optical element  1  swings about the second axis C 2  together with the frame portion  2 , the locus of a lower end of the holder  6  in the direction of the central axis Cx becomes an arc centered on the second axis C 2 . As illustrated in  FIG.  3   , the end surface  543  is inclined in a direction away from the central axis Cx as proceeding upward in the direction of the central axis Cx. Since the end surface  543  is formed in this manner, it is possible to approach the locus of the lower end of the holder  6 . As a result, a distance between the end surface  543  and the magnet  13  can be shortened, and the magnetic force generated between the second stator core  52  and the magnet  13  can be increased. 
     As illustrated in  FIG.  4   , the first plane  131  of the magnet  13  opposes the end surface  543  in the direction of the first axis C 1 . This also enables the distance between the end surface  543  and the magnet  13  to be shortened. 
     When the optical element  1  swings about the second axis C 2  together with the frame portion  2 , the amplitude of the end in the direction of the first axis C 1  perpendicular or substantially perpendicular to the second axis C 2  becomes the maximum. That is, the amplitude of the end of the first bearing  41  that rotatably supports the shaft  12  is maximized. As illustrated in  FIG.  5    and and the like, the tooth portion  53  is shifted from the end surface  543  by 45° in the circumferential direction about the central axis Cx. That is, the tooth portion  53  and the first coil  55  are shifted from the first axis C 1  and the second axis C 2 . When the optical element  1  and the frame portion  2  swing about the second axis C 2 , the first bearing  41  is less likely to interfere with the tooth portion  53  and the first coil  55 . For this reason, it is possible to reduce each retraction amount of the tooth portion  53  and the first coil  55  in the direction of the central axis Cx to suppress the interference with the first bearing  41  and to suppress the height of the fixed portion  3  in the direction of the central axis Cx. As a result, the height of the optical scanning device  100  can be kept low. That is, the optical scanning device  100  can be downsized. 
     The second arm portion  542  approaches the central axis Cx as upward in the direction of the central axis Cx in the direction of the first axis C 1 . With such a shape, the interference with the optical element  1  hardly occurs when the optical element  1  swings as compared to the configuration in which the second arm portion  542  extends in the direction perpendicular or substantially perpendicular to the central axis Cx in the direction of the first axis C 1 . In addition, it is possible to form the second arm portion  572  thicker as compared to the case of extending along the central axis Cx. As a result, the second arm portion  542  is formed to be inclined so that the interference hardly occurs when the optical element  1  swings, and further, it is possible to increase the cross-sectional area perpendicular or substantially perpendicular to the magnetic flux lines. Therefore, the magnetic flux can be effectively used, and a swing angle of the optical element  1  can be increased. 
     In addition, an outer side surface  540  of the first arm portion  541  is inclined so as to approach the central axis Cx as proceeding upward in the direction of the central axis Cx. That is, the outer side surface  540  of the first arm portion  541  has the inclined surface that approaches the central axis Cx as proceeding upward in the direction of the central axis Cx. With such an inclination, the optical element  1  is less likely to interfere with the first arm portion  541  when the optical element  1  swings. Therefore, the swing angle of the optical element  1  can be increased. The inclination direction of the outer side surface  540  and the inclination direction of the second arm portion  542  are the same. 
     The magnet  13  has the two first planes  131  opposing the respective end surfaces  543  of the first stator core  51  in the direction of the first axis C 1  and the two second planes  132  opposing the respective end surfaces  573  of the second stator core  52  in the direction of the second axis C 2 . As a result, it is possible to increase a region where the distance between the end surfaces  543  and  573  and the magnet  13  is short. As a result, it is possible to effectively use the magnetic flux, and it is possible to achieve high output or power saving. Then, when the output is increased, the swing angle of the optical element  1  can be also increased. 
     Then, the current supplied to the first coil  55  and the second coil  58  is controlled by the control circuit (not illustrated) in the optical scanning device  100 , so that the optical element  1  swings about the first axis C 1  and the second axis C 2 . The optical scanning device can irradiate the reflecting surface  111  of the plate portion  11  of the optical element  1  with light from a light source (not illustrated) and scan the reflected light in the direction along the first axis C 1  and the direction along the second axis C 2 . 
       FIG.  15    is a cross-sectional view of another example of an optical scanning device  100   a  according to the present disclosure. In the optical scanning device  100   a  illustrated in  FIG.  15   , a first stator core  51   a  and a second stator core  52   a  are different from the first stator core  51  and the second stator core  52  illustrated in  FIG.  4    and the like. More specifically, the first stator core  51   a  has the same configuration as the first stator core  51  except that the end surface  543  is replaced with an end surface  544 . In addition, the second stator core  52   a  has the same configuration as the first stator core  51  except that the end surface  573  is replaced with an end surface  574 . The other portions of the optical scanning device  100   a  have the same configurations as those of the optical scanning device  100 , and the substantially same portions will be denoted by the same reference signs, and detailed descriptions of the same portions will not be omitted. 
     As illustrated in  FIG.  15   , the end surface  574  of the second stator core  52   a  of the optical scanning device  100   a  has an inclination that is away from the central axis Cx as proceeding upward in the direction of the central axis Cx. Further, the end surface  544  has a curved shape whose angle with respect to a plane perpendicular or substantially perpendicular to the central axis Cx increases as proceeding upward in the direction of the central axis Cx. The end surface  544  of the first stator core  51   a  also has the same configuration as the end surface  574 . That is, each of the end surfaces  544  and  574  is a curved surface whose angle with respect to the plane perpendicular or substantially perpendicular to the central axis Cx increases as proceeding upward in the direction of the central axis Cx. 
     With such a configuration, the end surface  574  can be brought closer to the holder  6  when the optical element  1  swings about the first axis C 1 . Similarly, the end surface  544  can be brought closer to the holder  6  when the optical element  1  and the frame portion  2  swing about the second axis C 2 . As a result, the magnetic force between each of the first stator core  51   a  and the second stator core  52   a  and the magnet  13  can be used more effectively. 
     Although the optical element  1  has been described as an example of the swing portion in the above-described example embodiment, the disclosure is not limited thereto. It is also possible to use the actuator for a purpose other than optics, such as optical scanning. At this time, the swing portion has a configuration that is suitable for the purposes. 
     Although the example embodiment of the present disclosure has been described as above, the present disclosure is not limited to this content. In addition, the example embodiment of the present disclosure can be modified in various ways without departing from a gist of the disclosure. 
     The optical scanning device of the present disclosure can be used for a detection device that detects a distance to a surrounding object, a shape of an object, and the like by scanning and irradiating the surroundings with light and acquiring the reflected light. In addition to this, the optical scanning device can be also used as an actuator of a device which is used by being swung about two perpendicular or substantially perpendicular axes. 
     Features of the above-described preferred example embodiments and the modifications thereof may be combined appropriately as long as no conflict arises. 
     While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.