An automatic balancing apparatus which includes a support shaft which is rotated by a drive; a case body which is fixed to the support shaft and which rotates together with the support shaft; a ring magnet which is placed at the inside corner, in the radial direction, of an inner space of the case body; and a balancing member. The balancing member further includes a plurality of magnetic bodies which are movable in the inner space of the case body and which can be drawn up by the magnetic field of the ring magnet. When the rotational frequency of a rotor, which rotates together with the case body, exceeds the resonant frequency, the automatic balancing apparatus reduces vibrations of the rotor; and the outer circumference of the ring magnet has a flat portion.
The present invention relates to a spindle motor employed for a disk player. The spindle motor comprises: a deck plate; a shaft rotatably disposed on the deck plate; a stator having a core wound with coils which is disposed on the outer peripheral surface of the shaft and generates a magnetic force; a magnet which is provided at the upper part of the stator and generates a magnetic force; a cap type rotor which is coupled to the upper end of the shaft integrally with the shaft so as to be located at the upper part of the pulling magnet and the stator and is provided on the upper part with a track having a different height from another; a magnet which is disposed on the inner peripheral surface of the rotor so that it can be opposed to the core of the stator with an air gap therebetween; and a turntable which is disposed on the upper surface of the rotor integrally with the rotor and mounts a disk.
A disc clamp assembly and method for balancing a spindle hub assembly within a disc drive utilizes a base piece, a balance ring retainer piece and a balance ring. The disc clamp base piece is positioned on the top surface of the rotatable spindle hub to secure a disc stack to the spindle hub. The balance ring retainer piece is attached to the top surface of the base piece and defines a peripheral rim for accepting a balance ring. The balance ring has a predetermined mass to modify the center of gravity of the spindle hub assembly toward the central axis of rotation for the spindle hub.
A speaker vibrating plate having a voice coil secured thereto is provided in a frame, a rotor having poles is rotatably supported in the frame, and a stator having poles is provided in the frame. A permanent magnet is provided in the rotor for forming a magnetic circuit passing through the rotor and the stator, and a stator coil is provided in the stator. A driving circuit is provided for energizing the stator coil for rotating the rotor.
