Spindle motor and clamping apparatus

A clamping apparatus comprising:

• a case having a side surface on which a plurality of arm holes are formed;
• an arm, which moves inside and outside the case through one of the arm holes while being restricted by the case;
• and
• an elastic member installed inside the case to elastically support the arm,
• wherein, when the arm moves, an upper surface of the arm is slid while making contact with the case at a first distance from a center of the case and a lower surface of the arm is slid while making contact with the case at a second distance longer than the first distance,
• wherein the arm comprises:
• a body, which has a first end disposed at an outside of the case and a second end disposed at an inside of the case,
• a guide rail, which is formed at both sides of the body such that a motion of a lower part of the guide rail is guided by the case at the second distance, and
• an anti-separation rail, which is formed at the both sides of the body such that a motion of an upper part of the anti-separation rail is guided by the case at the first distance.

A spindle motor comprising:

• a base;
• a bearing housing installed on the base;
• a bearing press-fitted into an inner circumference of the bearing housing;
• a rotary shaft, which is supported by the bearing and rotatably installed on the bearing;
• a stator including a core disposed around the bearing housing and a coil wound around the core;
• a rotor including a rotor yoke which is coupled to the rotary shaft and a magnet which is coupled to the rotor yoke to face the coil;
• and
• a clamping apparatus installed on the rotor yoke,
• wherein the clamping apparatus comprises:
• a case having a side surface on which a plurality of arm holes are formed;
• an arm which moves inside and outside the case through one of the arm holes by being restricted by the case and has an upper part and a lower part that are guided by the case;
• and
• an elastic member installed inside the case to elastically support the arm.