Patent Publication Number: US-2011050006-A1

Title: Actuator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an actuator, and more particularly, to an actuator used in a photograph module. 
     2. Description of the Prior Art 
       FIG. 1A  shows a cross-sectional view of a prior art actuator. The actuator includes a yoke  101 , a pad  102 , a holder  107 , a movable member  105 , an elastic member  106  and a magnetic circuit system. As shown in  FIG. 1B , the magnetic circuit system comprises a magnet  103  and a coil  104 . The coil  104  is electrically driven so that it will interact with the magnetic field of the magnet  103  to generate a force that drives the movable member  105  to move with respect to an axis (Z-axis) when a current is directed therethrough. 
     Though the prior art actuator can cause a movement with respect to an axis, it is not capable of providing an angle of inclination with respect to any axis. Accordingly, the compensation for an angle of inclination cannot be performed. There remains a need in the art for an improved actuator to resolve the aforementioned drawback. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide an improved actuator capable of causing a movement with respect to an axis and, at the same time, providing an angle of inclination with respect to at least one axis to enable the compensation for an angle of inclination. 
     The present invention provides an actuator including a holder having a movable member accommodation space and at least three magnet accommodation spaces, a movable member received by the movable member accommodation space of the holder, and a magnetic circuit system comprising at least three magnets and at least three coils, the magnetic circuit system enabling the movable member to move with respect to an axis and incline at an angle with respect to at least one axis; wherein each of the at least three magnets is received by one of the at least three magnet accommodation spaces and the directions of the top and bottom magnetic poles thereof are perpendicular to the axis with respect to which the movable member moves; and wherein each of the at least three coils corresponds to one of the at least three magnets and is associated with the movable member, and the central axis of each of the at least three coils is perpendicular to the axis with respect to which the movable member moves. 
     In the aforementioned actuator, a power source is used to drive the three coils, enabling the three coils and the corresponding magnets to create a force to drive the movable member. When the currents delivered from the power source are simultaneously directed to the three coils with the same current values, respectively, the movable member can move with respect to an axis; when the currents delivered from the power source having different current values are directed to the three coils, respectively, the movable member can move with respect to an axis and incline at an angle with respect to more than one axis; when only one of the three coils is driven by the current delivered from the power source, the movable member can incline at an angle with respect to an axis; when two of the three coils are driven by the current delivered from the power source, the movable member can incline at an angle with respect to more than one axis. 
     The present invention provides another actuator including: a holder having a movable member accommodation space and at least three coil accommodation spaces; a movable member received by the movable member accommodation space of the holder; and a magnetic circuit system comprising at least three magnets and at least three coils, the magnetic circuit system enabling the movable member to move with respect to an axis and incline at an angle with respect to at least one axis; wherein each of the at least three coils is received by one of the at least three coil accommodation spaces and the central axis thereof is perpendicular to the axis with respect to which the movable member moves; and wherein each of the at least three magnets corresponds to one of the at least three coils and is associated with the movable member, and the directions of the top and bottom magnetic poles thereof are perpendicular to the axis with respect to which the movable member moves. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a schematic cross-sectional view of a prior art actuator. 
         FIG. 1B  shows a schematic top view of the magnetic circuit system of the prior art actuator shown in  FIG. 1A . 
         FIG. 2  shows a schematic perspective view of an actuator in accordance with a first embodiment of the present invention. 
         FIG. 3  shows a schematic perspective view of the magnetic circuit system of the actuator in accordance with the first embodiment of the present invention. 
         FIG. 4  shows a schematic top view of the elastic member of the actuator shown in  FIG. 2  in accordance with the first embodiment of the present invention. 
         FIG. 5  shows a schematic perspective view of an actuator in accordance with a second embodiment of the present invention. 
         FIG. 6  shows a schematic perspective view of the magnetic circuit system of the actuator in accordance with the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of an actuator of the present invention will be described in detail with references to the accompanying drawings. 
       FIG. 2  shows a schematic perspective view of an actuator  300  in accordance with a first embodiment of the present invention. The actuator  300  includes a holder  301  having a moveable member accommodation space and three magnet accommodation spaces, a movable member  302  received by the moveable member accommodation space of the holder  301 , an elastic member  309 , and a magnetic circuit system comprising three magnets  303 ,  304  and  305  and three coils  306 ,  307  and  308  (as shown in  FIG. 3 ), each of the three magnets  303 ,  304  and  305  being received by a corresponding one of the three magnet accommodation spaces of the holder  301 ; wherein the three magnet accommodation spaces of the holder  301  are evenly and symmetrically disposed around the movable member  302 . In the present invention, the movable member  302  may be cylindrical in shape with the magnets  303 ,  304  and  305  and the coils  306 ,  307  and  308  evenly disposed around the circumference thereof. 
       FIG. 3  shows a schematic perspective view of the magnetic circuit system of the actuator  300  shown in  FIG. 2  in accordance with the first embodiment of the present invention. The magnetic circuit system comprises three magnets  303 ,  304  and  305  and three coils  306 ,  307  and  308  so as to form three magnet-coil sets whereby the magnetic circuit system is evenly and symmetrically disposed around the movable member  302 . The magnetic circuit system enables the movable member  302  to move with respect to an axis and incline at an angle with respect to at least one axis. The first magnet-coil set comprises the magnet  303  and the coil  306 ; the second magnet-coil set comprises the magnet  304  and the coil  307 ; the third magnet-coil set comprises the magnet  305  and the coil  308 . Each of the magnets  303 ,  304  and  305  is received by a corresponding one of the three magnet accommodation spaces of the holder  301 . In each magnet-coil set, the directions of the top and bottom magnetic poles of the magnet are opposite and perpendicular to the axis with respect to which the movable member  302  moves, and the central axis of the coil is perpendicular to the axis with respect to which the movable member moves. Take the second magnet-coil set as an example, the directions of the top and bottom magnetic poles of the magnet  304  are in the Y and −Y directions, respectively, and the central axis of the coil  307  is Y-axis. When being directed to the coil  307 , an electric current may, for example but not limited to, flow through the upper portion of the coil  307  in the X direction while passing through the lower portion of the coil  307  in the −X direction, such that either the upper or the lower portion of the coil  307  is acted upon by a force (Lorentz Force) in the Z direction, that is, the coil  307  moves in the Z direction. As the coil  307  is associated with the movable member  302 , the force further drives the movable member  302 . 
     In the aforementioned magnetic circuit system, a power source is used to drive the three coils, enabling the three coils and the corresponding magnets to generate a force to drive the movable member  302 . When the currents delivered from the power source are simultaneously directed to the three coils with the same current values, respectively, the movable member  302  can move with respect to an axis. For example, when the currents delivered from the power source are simultaneously directed to the three coils  305 ,  306  and  307  with the same current values, respectively, each of the three coils  305 ,  306  and  307  is acted upon by a force of the same magnitude in the Z direction, thereby enabling the movable member  302  to move with respect to the Z-axis. When only one of the three coils is driven by the current delivered from the power source, the movable member  302  can incline at an angle with respect to an axis. For example, when the coil  306  is the only one of the three coils driven by the current delivered from the power source, it is acted upon by a force in the Z direction, thereby enabling the movable member  302  to incline at an angle with respect to the X-axis. When two of the three coils are driven by the current delivered from the power source, the movable member  302  can incline at an angle with respect to more than one axis. For example, when the coils  306  and  307  are driven by the current delivered from the power source, each of the coils  306  and  307  is acted upon by a force in the Z direction, thereby enabling the movable member  302  to incline at an angle with respect to the X-axis and the Y-axis at the same time. When the currents delivered from the power source having different current values are directed to the three coils, respectively, the movable member  302  can move with respect to an axis and incline at an angle with respect to more than one axis. For example, when the coils  305 ,  306  and  307  are driven by the power source and the current values of the electric currents flowing through the coils  306  and  307  are greater than that of the electric current passing through the coil  305 , each of the coils  305 ,  306  and  307  is acted upon by a force in the Z direction and the forces applied to the coils  306  and  307  is greater than the force applied to the coil  305 , thereby enabling the movable member  302  to move with respect to the Z-axis and incline at an angle with respect to the X and Y axes at the same time. The movable member  302  can move with respect to an axis and incline at an angle with respect to at least one axis depending on the current values and directions of the electric currents and the selection of the coils to which the electric currents are to be directed. 
     The aforementioned magnetic circuit system is a moving-coil system. Alternatively, the aforementioned magnetic circuit system may be embodied as a moving-magnet system by exchanging the positions of the magnet and the coil in each of the three magnet-coil sets shown in  FIGS. 2 and 3 . For example, the positions of the magnet  303  and the coil  306  in the first magnet-coil set are exchanged, with the magnet  303  associated with the movable member  302  and the coil  306  received by a coil accommodation space (i.e. the aforementioned magnet accommodation space is replaced with the coil accommodation space) of the holder  301 . In the present invention, the holder  301 , which is associated with the moving-coil system or the moving-magnet system, may be made of magnetic conductive material to increase the magnetic efficiency. 
       FIG. 4  shows a schematic top view of the elastic member  309  of the actuator  300  in accordance with the first embodiment of the present invention. The elastic member  309  has a fixed portion  401  coupled to the holder  301 , a movable portion  402  coupled to the movable member  302 , and a bridge portion  403  formed between and in connection with the fixed portion  401  and the movable portion  402 . The magnetic circuit system enables the movable member  302  to move axially or incline at an angle with respect to at least one axis, thereby the movable portion  402  of the elastic member  309  can be driven to cause a linear movement of the bridge portion  403  of the elastic member  309 . The elastic member  309  may be a plate spring or a coil spring with non-pre-compressed, unidirectional pre-compressed or bidirectional pre-compressed function and provides a linear force which is proportional to the amount of deformation of the bridge portion  403  with the motion of the movable member  302 , in other words, the linear force follows the Hooke&#39;s law. 
       FIG. 5  shows a schematic perspective view of an actuator  500  in accordance with a second embodiment of the present invention. The first and second embodiments of the present invention are similar in terms of the components contained and the arrangement thereof. The two embodiments only differ in the design of the magnetic circuit systems. The magnetic circuit system of the second embodiment comprises four magnet-coil sets while the magnetic circuit system of the first embodiment comprises three magnet-coil sets. In the second embodiment of the present invention, the actuator  500  includes a holder  501  having a moveable member accommodation space and four magnet accommodation spaces, a movable member  502  received by the moveable member accommodation space of the holder  501 , an elastic member  511 , and a magnetic circuit system comprising four magnets  503 ,  504 ,  505  and  506  and four coils  507 ,  508 ,  509  and  510  (as shown in  FIG. 6 ), each of the four magnets  503 ,  504 ,  505  and  506  being received by a corresponding one of the four magnet accommodation spaces of the holder  501 ; wherein the four magnet accommodation spaces are evenly and symmetrically disposed around the movable member  502 . In the present invention, the movable member  502  may be cylindrical in shape with the magnets  503 ,  504 ,  505  and  506  and coils  507 ,  508 ,  509  and  510  evenly disposed around the circumference thereof. 
       FIG. 6  shows a schematic perspective view of the magnetic circuit system of the actuator  500  shown in  FIG. 5  in accordance with the second embodiment of the present invention. The magnetic circuit system comprises four magnets  503 ,  504 ,  505  and  506  and four coils  507 ,  508 ,  509  and  510  so as to form four magnet-coil sets whereby the magnetic circuit system is evenly and symmetrically disposed around the movable member  502 . The magnetic circuit system enables the movable member  502  to move with respect to an axis and incline at an angle with respect to at least one axis. The first magnet-coil set comprises the magnet  503  and the coil  507 ; the second magnet-coil set comprises the magnet  504  and the coil  508 ; the third magnet-coil set comprises the magnet  505  and the coil  509 ; the fourth magnet-coil set comprises the magnet  506  and the coil  510 . Each of the magnets  503 ,  504 ,  505  and  506  is received by a corresponding one of the four magnet accommodation spaces of the holder  501 . The operation of this magnetic circuit system is the same as that of the magnetic circuit system of the first embodiment. The aforementioned magnetic circuit system is a moving-coil system. Alternatively, the aforementioned magnetic circuit system may be embodied as a moving-magnet system by exchanging the positions of the magnet and the coil in each of the four magnet-coil sets shown in  FIGS. 5 and 6 . For example, the positions of the magnet  503  and the coil  507  in the first magnet-coil set are exchanged, with the magnet  503  associated with the movable member  502  and the coil  507  received by a corresponding coil accommodation space (i.e. the aforementioned magnet accommodation space is replaced with the coil accommodation space) of the holder  501 . In the present invention, the holder  501 , which is associated with the moving-coil system or the moving-magnet system, may be made of magnetic conductive material to increase the magnetic efficiency. 
     The actuator of the present invention features the following advantages: 
     1. The coils of the actuator can be driven independently. 
     2. The actuator can provide a movement with respect to an axis and an angle of inclination with respect to an axis at the same time. 
     3. The actuator can provide a movement with respect to an axis and an angle of inclination with respect to more than one axis at the same time. 
     4. The actuator can facilitate the compensation of an angle of inclination caused during the module assembly. 
     5. The actuator can provide a movement with respect to an axis and an angle of inclination with respect to one or more than one axis for the entire system. 
     The preferred embodiments described above are exemplary and are not intended to limit the claim scope of the present invention. Various modifications and variations made within the spirit of the invention shall be considered as falling within the scope of the appended claims.