Stepping motor

Abstract

A stepping motor is disclosed which is capable of obtaining desired driving torque without sacrificing magnetic properties of a magnet with respect to a stator, reducing inertia mass of a rotor by decreasing a use amount of a magnet material, and thereby, can enhance driving performance including control responsiveness. In a stepping motor in which a plurality of stators (20A, 20B) around which coils (21) are wound are placed in an axial direction of a motor shaft (31), a rotor (30) is rotatably provided with a space at inner periphery sides of these stators (20A, 20B), the motor shaft (31) is placed in a center of the rotor (30), and the rotor (30) includes a rotor body (33) placed at an outer periphery of the motor shaft and a cylindrical magnet (32) integrally provided on an outer periphery of the rotor body and magnetized to form multipoles in a circumferential direction, the stepping motor is characterized in that the cylindrical magnet (32) has at least its inner peripheral surface bulged inward in a diameter direction so that a portion corresponding to a central portion in the above described axial direction of each of the coils (21) becomes thicker than the other portions.

Dependencies are inferred from the claim text.