SHAFT SUPPORTING METHOD IN SPINDLE MOTOR

摘要

PROBLEM TO BE SOLVED: To provide a shaft supporting method preventing generation of negative pressure in the vicinity of a thrust plate and capable of stably supporting a shaft and capable of reducing costs of a spindle motor and a loss. SOLUTION: In the spindle motor using a hydrodynamic bearing with a fulfilling structure in which oil is a working fluid, hydrodynamic pressure is only induced by a herringbone groove formed on at least one face between an outer peripheral face of the shaft and an inner peripheral face of a sleeve and having an unbalanced shape to an axial direction, and a spiral groove formed at least one face between one face of the thrust plate and an end face of the sleeve. Floating force of the shaft and thrust plate is generated by using inner pressure of oil boosted by the herringbone groove.