Actuator

Abstract

An actuator includes a casing, a stationary member having a coil member and mounted in the casing and a movable member having a moving element and supported by the casing. The moving element has a shaft and is supported by the casing so as to be moved in an axial direction of the shaft and in a rotational direction having the axial direction of the shaft as its rotational axis and the moving element is moved in the axial direction and in the rotational direction by causing electric current to flow through the coil member. The stationary member includes a first stationary member for imparting to the movable member a force oriented in the axial direction and a second stationary member for imparting to the movable member a force oriented in the rotational direction, while the coil member includes a first coil member for exciting a first magnetic path passing through the first stationary member and a second coil member for exciting a second magnetic path passing through the second stationary member.

1 . An actuator comprising: 
 a casing;    a stationary member which has a coil member and is mounted in the casing; and    a movable member which includes a moving element and is supported by the casing,    wherein the moving element has a shaft and is supported by the casing so as to be moved in an axial direction of the shaft and in a rotational direction having the axial direction of the shaft as its rotational axis;    wherein electric current is caused to flow through the coil member such that the moving element is moved in the axial direction and in the rotational direction;    wherein the stationary member includes a first stationary member that imparts to the movable member a force oriented in the axial direction and a second stationary member that imparts to the movable member a force oriented in the rotational direction;    wherein the first stationary member includes a pair of first stationary elements provided symmetrically with respect to the rotational axis and the second stationary member includes a pair of second stationary elements provided symmetrically with respect to the rotational axis;    wherein the coil member includes a first coil member that excites a first magnetic path passing through the first stationary member and a second coil member that excites a second magnetic path passing through the second stationary member;    wherein the first coil member includes a pair of first coils each provided in each of the first stationary elements and the second coil member includes a pair of second coils each provided in each of the second stationary elements; and    wherein the first coils excite the first stationary elements in an antiphase excitation mode, respectively and the second coils excite the second stationary elements in an antiphase excitation mode, respectively.    
   
   
       2 . The actuator as claimed in  claim 1 , 
 wherein the first stationary member imparts to the moving element the force oriented in the axial direction and the second stationary member imparts to the moving element the force oriented in the rotational direction; and    wherein the moving element includes a magnet member having a magnetization direction substantially orthogonal to the axial direction.    
   
   
       3 . The actuator as claimed in  claim 2 , wherein the magnet member of the moving element is disposed symmetrically with respect to the rotational axis.  
   
   
       4 . An actuator comprising: 
 a casing;    a stationary member which has a coil member and is mounted in the casing;    a movable member which includes a moving element and is supported by the casing; and    an axial resonant spring that effects resonant motion of the moving element in the axial direction, which is provided between the moving element and the casing,    wherein the moving element has a shaft and is supported by the casing so as to be moved in an axial direction of the shaft and in a rotational direction having the axial direction of the shaft as its rotational axis;    wherein electric current is caused to flow through the coil member such that the moving element is moved in the axial direction and in the rotational direction;    wherein the stationary member includes a first stationary member that imparts to the movable member a force oriented in the axial direction and a second stationary member that imparts to the movable member a force oriented in the rotational direction; and    wherein the coil member includes a first coil member that excites a first magnetic path passing through the first stationary member and a second coil member that excites a second magnetic path passing through the second stationary member.    
   
   
       5 . An actuator comprising: 
 a casing;    a stationary member which has a coil member and is mounted in the casing;    a movable member which includes a moving element and is supported by the casing; and    a spring member which includes a first spring provided between the casing and the moving element, a second spring provided between the moving element and the further moving element and a third spring provided between the further moving element and the casing such that the first, second and third springs are deflectable in the axial direction,    wherein the moving element has a shaft and is supported by the casing so as to be moved in an axial direction of the shaft and in a rotational direction having the axial direction of the shaft as its rotational axis;    wherein electric current is caused to flow through the coil member such that the moving element is moved in the axial direction and in the rotational direction;    wherein the stationary member includes a first stationary member that imparts to the movable member a force oriented in the axial direction and a second stationary member that imparts to the movable member a force oriented in the rotational direction;    wherein the coil member includes a first coil member that excites a first magnetic path passing through the first stationary member and a second coil member that excites a second magnetic path passing through the second stationary member; 
 wherein the movable member further includes a further moving element disposed coaxially with the moving element and movable in the axial direction; and  
   wherein the first stationary member and the second stationary member impart to one of the moving element and the further moving element the force oriented in the axial direction and the force oriented in the rotational direction, respectively.    
   
   
       6 . The actuator as claimed in  claim 5 , wherein the first stationary member imparts to one of the moving element and the further moving element the force oriented in the axial direction and the second stationary member imparts to the other of the moving element and the further moving element the force oriented in the rotational direction.  
   
   
       7 . The actuator as claimed in  claim 6 , 
 wherein the one of the moving element and the further moving element includes a magnet member disposed symmetrically with respect to the rotational axis and having a magnetization direction substantially orthogonal to the axial direction;    wherein the first stationary member includes a pair of first stationary elements provided symmetrically with respect to the rotational axis and the second stationary member includes a pair of second stationary elements provided symmetrically with respect to the rotational axis;    wherein the first coil member includes a pair of first coils each provided in each of the first stationary elements and the second coil member includes a pair of second coils each provided in each of the second stationary elements; and    wherein the first coils excite the first stationary elements in an antiphase excitation mode, respectively and the second coils excite the second stationary elements in an antiphase excitation mode, respectively.    
   
   
       8 . The actuator as claimed in  claim 7 , 
 wherein each of the moving element and the further moving element includes a magnet member disposed symmetrically with respect to the rotational axis and having a magnetization direction substantially orthogonal to the axial direction;    wherein the first stationary member includes a pair of first stationary elements provided symmetrically with respect to the rotational axis and the second stationary member includes a pair of second stationary elements provided symmetrically with respect to the rotational axis;    wherein the first coil member includes a pair of first coils each provided in each of the first stationary elements and the second coil member includes a pair of second coils each provided in each of the second stationary elements; and    wherein the first coils excite the first stationary elements in an antiphase excitation mode, respectively and the second coils excite the second stationary elements in an antiphase excitation mode, respectively.