Patent ID: 7911092

Claim:
A spindle motor comprising: a base in contact with a bearing housing; a bearing installed in the bearing housing; a rotational shaft rotatably supported by the bearing; a stator disposed around the bearing housing and having a coil; a rotor comprising: a rotor yoke fixed on the rotational shaft, wherein the rotor yoke is provided with a groove opened upward, the groove being opened upward within a first upwardly directed inner sidewall and a second upwardly directed inner sidewall facing the first upwardly directed inner sidewall, and a magnet fixed on the rotor yoke; a turntable for a loaded disk provided above the rotor yoke and capable of rotating together with the rotational shaft, wherein the turntable is provided with a groove opened downward; and a plurality of balls provided in a space defined by the groove provided on the rotor yoke and the groove provided on the turntable, wherein the first upwardly directed inner sidewall is disposed at a first distance from the rotational shaft in a radial direction, and wherein the second upwardly directed inner sidewall is disposed at a second distance larger than the first distance in the radial direction.