Patent ID: 7345438

Claim:
An electromagnetic driver, comprising: two electromagnetic units each having a coil unit which induces in one direction magnetic fluxes formed by supplying a direct current to an exciting coil with a yoke core and a magnet unit in which a permanent magnet is so arranged as to interfere with the magnetic field of the coil unit, wherein either the coil unit or the magnet unit is made movable by the supply of the direct current to the exciting coil; a shaft which is capable of reciprocating in the axial direction, having the electromagnetic units arranged in the axial direction, and is firmly stuck to the movable coil unit or the magnet unit; and a power supply change-over device which, when a direct current is supplied to the exciting coil, is capable of so changing over alternately the current polarity of the exciting coil that, when an attractive magnetic field is formed between the coil unit and the magnetic unit of one of the electromagnetic units, a repulsive magnetic field is formed between the coil unit and the magnetic unit of the other of the electromagnetic units and, when an attractive magnetic field is formed between the coil unit and the magnetic unit of the other of the electromagnetic units, a repulsive magnetic field is formed between the coil unit and the magnetic unit of the one of the electromagnetic units.