Voice coil type actuator

An actuator for displacing a movable lens in a lens system of a camera, comprising:

• a lens tube defining respective adjacent inner spaces for said actuator and for said lens system, said lens system including said movable lens movable along an optical axis in said tube, an inner surface of said inner space for said actuator defining a recess extending substantially coaxially with said optical axis for arranging the actuator, an inner surface of said inner space also defining means for arranging a guide portion including an auxiliary guide shaft for said movable lens, said actuator comprising:
• a guide shaft formed of a material, at least a portion in a radial direction in a cross-section of which is permeable, said guide shaft extending substantially coaxially with said optical axis;
• an auxiliary guide shaft supported in said lens tube at a position which is substantially coaxial with said optical axis;
• a movable member substantially located in said actuator inner space of said casing and supported slidably on said guide shaft of the actuator and the auxiliary guide shaft in a fore and aft directions, said movable member being displaced by the actuator between opposed positions in said inner space;
• a moveable coil supported on the movable member;
• a generally tubular yoke surrounding the movable coil and covering a range of movement of the movable coil;
• a magnet for generating a magnetic field, said magnet being arranged to surround the movable coil through the range of movement of the movable coil;
• an axially extending cutout formed in the yoke;
• and
• a portion of said movable member which supports said movable lens projecting through the cutout from the actuator portion of the inner space to the lens portion of the inner space of said casing.