To suppress the decreased amount of grease to a small amount, after the height of a motor has been suppressed by only providing an inner shield plate on the inside of a ball bearing in the axial direction and forming an outer shield plate, positioned on the outside of the ball bearing in the axial direction by extending a part of a member which constitutes a rotor inward.
In a ball bearing 3, an inner shield plate 12 is provided inside the bearing 3 in the axial direction. In addition, a nearly annular first outer shield plate 14 is provided by extending a part of the inner peripheral surface of an expanded section 11. In another ball bearing 4, a second outer shield plate 27 is formed by extending part of a bush 23 which constitutes a part of a rotor 5 inward. In the ball bearing 4, an inner shield plate 35 is provided inside the bearing in the axial direction. Therefore, the decrease of grease in the bearings 3 and 4 can be reduced and a spindle motor can be rotated stably for a long period, because the splashing out of the grease can be effectively prevented by the inner shield plates 12 and 35 and outer shield plates 14 and 27.
NISHIMURA HIDEKI
SHIMIZU TOSHIAKI
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