Patent ID: 7304408

Claim:
A driving apparatus comprising: a magnet that is cylindrical and is magnetized to two poles in a circumferential direction and fixed to a rotor axis of which an inner circumferential surface is formed with a soft magnetic material; first and second coils arranged on a same side as said magnet with respect to an axial direction of said magnet and arranged adjacent to an end surface of said magnet in the axial direction; a first outer magnetic pole portion excited by energizing said first coil; a second outer magnetic pole portion excited to a pole opposite to said first outer magnetic pole portion by energizing said second coil; and a yoke portion formed with a soft magnetic material for supporting said first and second outer magnetic pole portions, wherein said first outer magnetic pole portion includes, in the axial direction of said magnet, a first coil insertion portion that is inserted to an internal diameter portion of said first coil, and a first magnet facing portion that is arranged to face a magnetized outer circumferential portion of said magnet with a predetermined gap at a predetermined angle, with the first coil insertion portion and the first magnet facing portion being integratedly formed adjacent to the axial direction of the rotor axis and extending in parallel with the axial direction of the rotor axis, said second outer magnetic pole portion includes a second coil insertion portion that is inserted to an internal diameter portion of said second coil, and a second magnet facing portion that is arranged to face a magnetized outer circumferential portion of said magnet with a predetermined gap at a predetermined angle, with the second coil insertion portion and the second magnet facing portion being integratedly formed adjacent to the axial direction of the rotor axis and extending in parallel with the axial direction of the rotor axis, and said rotor axis is arranged adjacent to outer circumferential portions of said first and second coils and forms a first inner magnetic pole portion and a second inner magnetic pole portion, with said first inner magnetic pole portion excited by energizing said first coil and said second inner magnetic pole portion excited by energizing said second coil, with said rotor axis further comprising first and second cylinder portions in the axial direction, with the first cylinder portion facing with the first and second magnet facing portions through an intermediary of a stationary magnet, and the second cylinder portion being adjacent to the outer circumferential portions of said first and second coils, and wherein a facing angle of said first magnet facing portion that faces said magnet is larger than a facing angle of said first coil insertion portion that faces the rotor axis, and a facing angle of said second magnet facing portion that faces said magnets is larger than a facing angle of said second coil insertion portion that faces the rotor axis.