To provide a means for preventing wear resulting from contact sliding movement of a thrust dynamic pressure bearing surface at the time a spindle motor starts.
There are provided a column 4 of a radial dynamic pressure bearing having a radial dynamic pressure generating groove in an outer peripheral surface of an upper limit on an axial center of a stator core 2 equipped with a stator 2a wound with a motor coil 7; and a disc 3 of the thrust dynamic pressure bearing having the radial dynamic pressure generating groove in an upper surface. A hub 5 as a rotary member has a cylinder 6 with a smooth internal surface opposed to the column 4 of the radial dynamic pressure bearing and a rotor magnet 8 opposed to the motor coil 7. Radial directional load is supported by the radial dynamic pressure bearing and thrust directional load is supported by using simultaneously a magnetic bearing and the thrust dynamic pressure bearing that are composed of the stator 2a and the rotor magnet 8.
TAKEUCHI HISAO
OTSUKI MAKOTO
MURABE KAORU
