Motor and driving device having integrally formed magnetic-pole portions

A motor comprising:

• a cylindrical magnet whose outer periphery has a plurality of magnetized segments;
• a cylindrical yoke having an inner periphery that is disposed facing the magnet;
• a coil that excites the yoke;
• a first magnetic-pole portion that is formed in the inner periphery of the yoke, and is excited by the coil;
• and
• a second magnetic-pole portion that is formed in the inner periphery of the yoke, and is excited by the coil to a pole that is different from that of the first magnetic-pole portion,
• wherein a first thin-wall portion is formed connecting the first magnetic-pole portion and the second magnetic-pole portion in the inner periphery of the yoke, a thickness of the first thin-wall portion is smaller in a radial direction of the yoke as compared to thicknesses of the first magnetic-pole portion and the second magnetic-pole portion in the radial direction, the first thin-wall portion extends at a first predetermined angle with respect to a circumferential direction of the inner periphery,
• wherein a second thin-wall portion is formed connecting the first magnetic-pole portion and the second magnetic-pole portion in the inner periphery of the yoke, a thickness of the second thin-wall portion is smaller in the radial direction of the yoke as compared to thicknesses of the first magnetic-pole portion and the second magnetic-pole portion in the radial direction, the second thin-wall portion extends at a second predetermined angle with respect to the circumferential direction of the inner periphery, and
• wherein the first predetermined angle and the second predetermined angle are different from each other.