Patent ID: 7443061

Claim:
A driving device comprising: a magnet ( 1 ) that has a hollow cylindrical shape and is magnetized so as to have alternately different poles in a circumferential direction thereof; a first coil ( 2 ) and a second coil ( 3 ) that are arranged concentric with said magnet ( 1 ) and disposed on axially opposite sides of said magnet ( 1 ), respectively; first outer magnetic pole parts ( 8 A, 8 B, 8 C, and 8 D) that each have a tooth shape and are arranged in opposed relation to said magnet ( 1 ) to extend from a side close to one axial end face of said magnet ( 1 ) along an outer peripheral surface of said magnet ( 1 ), for being magnetized by said first coil ( 2 ); second outer magnetic pole parts ( 9 A, 9 B, 9 C, and 9 D) that each have a tooth shape and are arranged in opposed relation to said magnet ( 1 ) to extend from a side close to another axial end face of said magnet ( 1 ) along the outer peripheral surface of said magnet ( 1 ), for being magnetized by said second coil ( 3 ); and a rotary shaft ( 10 ) that is fixed to an inner periphery of said magnet ( 1 ), and said rotary shaft has an inner magnetic pole part ( 10 A) disposed in opposed relation to at least either of said first outer magnetic pole parts ( 8 A, 8 B, 8 C, and 8 D) and said second outer magnetic pole parts ( 9 A, 9 B, 9 C, and 9 D), for being magnetized by at least one of said first coil ( 2 ) and said second coil ( 3 ), wherein said first outer magnetic pole parts ( 8 A, 8 B, 8 C, and 8 D) and said second outer magnetic pole parts ( 9 A, 9 B, 9 C, and 9 D) are each formed into a spiral shape.