Patent ID: 7150447

Claim:
An electromagnetic driving apparatus comprising: a slider; a cylindrical member made of non-magnetic material, the cylindrical member covering an outer surface of the slider to reciprocatably support the slider; a stator generating a magnetic circuit in cooperation with the slider, the stator including an attracting portion which attracts the slider in one direction of the reciprocating motion of the slider; and a coil disposed outside of the cylindrical member, the coil generating a magnetic attracting force between the slider and the attracting portion when energized; wherein the cylindrical member has a small diameter portion reciprocatably supporting the slider, and a large diameter portion having a larger diameter than that of the small diameter portion, the large diameter portion continuously formed with the small diameter portion at one side of a reciprocating direction, at least one part of the attracting portion is disposed on an outer side of the large diameter portion so that an inner surface of the attracting portion faces an outer surface of the large diameter portion, and a boundary portion between the small diameter portion and the large diameter portion is located at a position that is on an opposite side of an attracting end surface of the slider with respect to the attracting portion when no electric current is supplied to the coil.