| 摘要 |
PROBLEM TO BE SOLVED: To provide a drive unit for an indicator instrument with a magnetic gap lessened between a magnetic pole and a rotor by keeping high positioning accuracy of the magnetic pole of a yoke relative to the rotor. SOLUTION: This drive unit is equipped with a front-side unit 100 fixed on the front side of a wiring board 10 with a stator S mounted therein, and a back-side unit 200 fixed on the back side of the wiring board with the rotor 500 and a gear train G mounted therein. The back-side unit is provided with a rotor housing projection part 250 with the rotor housed therewithin. The front-side unit is provided with fit cylindrical walls 120 and 150 with the projection part close fitted on an inner circumference thereof. The yoke 300 is disposed around the cylindrical walls. The magnetic pole 302 of the yoke projects out of openings 123 of the cylindrical walls toward a rotor magnet 525. A recessed part 252 with the magnetic pole fitted thereinto is provided on an outer surface of a peripheral wall of the projection part. An end of the magnetic pole confronts the rotor magnet with a thin-walled bottom wall of the recessed part interposed between them. COPYRIGHT: (C)2009,JPO&INPIT
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