Jeco Co., Ltd.

Toru Iwasa

Akio Ito

Noboru Watanabe

Yoshiyuki Ariki

Katsumi Yokota

Syouichi Mitsugi

In a stepping motor, each of four integrally molded annular stators constituting two pairs has an annular plate having a central hole in which a magnet rotor is to be inserted, and pole teeth that form magnetic pole portions separated from the magnet rotor at a predetermined gap. The pole teeth of one annular stator of a given pair extend from the annular plate to be perpendicular to the other of the given pair, and are equidistantly arranged around the central hole to be shifted from the pole teeth of the other annular stator by a half pitch. Mounting holes are formed in each annular plate at predetermined spaces in the circumferential direction, and the mounting holes formed in the annular plates of given annular stators of different pairs that are arranged back to back are located at the same positions. Molded insulating films are formed on surfaces, which do not oppose the magnet rotor, of all the annular stators. The insulating films are coupled to each other through the mounting holes formed in the annular plates of the given annular stators. Excitation coils are wound on all the annular stators through the insulating films. A plate-like yoke has a major portion inserted between opposing surfaces of the annular plates adjacent to the outer circumferential surfaces of all the annular stators.

Stepping motor having improved construction to reduce parts and

A stepping motor for a timepiece is constituted by a rotatable rotor magnet on an outer surface of which magnetic poles having different polarities are alternately formed, and two stator assemblies, each including a pair of stators opposing around the rotor magnet to have a gap and having stator magnetic pole portions, and an excitation coil for exciting the pair of stators, for supplying currents to the excitation coils to rotate the rotor magnet. The two stator assemblies are disposed to be separated by a predetermined distance in an axial direction of the rotor magnet, so that stator gap central lines of the two stator assemblies cross each other at an angle of 90.degree. when viewed from the axial direction.

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Saitama, Japan

Toru Iwasa