| 摘要 |
PURPOSE:To increase the recording density of a recording medium by setting the outer diameter of one bearing, on the side of a load to be coupled with the shaft, larger than that of the other bearing thereby preventing vibration of a motor. CONSTITUTION:The micromotor comprises a tubular bearing bush 22 mounted on a board 21, a shaft 25 supported on the inside thereof through a pair of sleeve bearings 23, 24, a rotor 26 secured to the upper part of the shaft 25, an annular rotor magnet 28 fixed to the inner peripheral surface at the peripheral wall part of the rotor 26, and a stator 27 disposed oppositely to the outside of the bearing bush 22. The sleeve bearing 23 on the upper side of the shaft 25 subjected to a load has outer diameter being set larger than that of the other sleeve bearing 24. The sleeve 23 having larger diameter abuts on a step part 22a provided at the inner peripheral part of the bearing bush 22 and secures the shaft in place. This structure prevents radial vibration of the shaft thus realizing high density recording on a recording medium. |
