ELECTROMAGNETIC ACTUATOR
An electromagnetic actuator includes an optical element L which is movable with respect to an optical axial direction, an optical-element holder which holds the optical element, a coil which is installed to enclose the optical element L and the optical-element holder, and a coil holder which holds the coil, wherein at least one of the optical-element holder and the coil holder comprises magnetic material which generates a magnetic flux in a radial direction and the optical element L is disposed at an inner side of the magnetic material.
1 . An electromagnetic actuator comprising:
an optical element which is movable with respect to an optical axial direction;
an optical-element holder which holds the optical element;
a coil which is installed to enclose the optical element and the optical-element holder; and
a coil holder which holds the coil, wherein
at least one of the optical-element holder and the coil holder comprises magnetic material which generates a magnetic flux in a radial direction,
the optical element is disposed at an inner side of the magnetic material.
2 . The electromagnetic actuator according to claim 1 , wherein at least one of the optical-element holder and the coil holder serves also a function of the magnetic flux generator.
3 . The electromagnetic actuator according to claim 1 , wherein the magnetic flux generator is a permanent magnet.
4 . The electromagnetic actuator according to claim 3 , wherein the magnetic flux generator has a plurality of permanent magnets disposed therein.
5 . The electromagnetic actuator according to claim 4 , wherein the plurality of permanent magnets is disposed asymmetrically with respect to an optical axis.
6 . The electromagnetic actuator according to claim 1 , wherein the coil is longer than the optical-element holder in an optical axial direction.
7 . The electromagnetic actuator according to claim 1 , wherein the coil holder is longer than the optical-element holder in the optical axial direction.
8 . The electromagnetic actuator according to claim 1 , further comprising a restraining structure which regulates an amount of movement of at least one of the optical element and the optical-element holder.
9 . The electromagnetic actuator according to claim 4 , wherein the permanent magnet is rectangular parallelepiped.
10 . The electromagnetic actuator according to claim 4 , wherein the permanent magnet is tile-shaped.
11 . The electromagnetic actuator according to claim 3 , wherein the permanent magnet is curve-shaped.
12 . The electromagnetic actuator according to claim 1 , wherein an intermediate member is interposed between the optical-element holder and the coil.
13 . The electromagnetic actuator according to claim 12 , wherein the intermediate member is a nonmagnetic body.
14 . The electromagnetic actuator according to claim 12 , wherein the intermediate member improves sliding with the optical-element holder, and reduces a coefficient of friction.
15 . The electromagnetic actuator according to claim 12 , wherein the intermediate member is parallel with respect to the optical axis.
16 . The electromagnetic actuator according to claim 11 , wherein the intermediate member has a circular cylindrical shape.
17 . The electromagnetic actuator according to claim 12 , wherein the intermediate member seals the optical element tight.
18 . The electromagnetic actuator according to claim 1 , wherein at least one of the optical-element holder and the coil holder includes a magnetic material.