Originally, this meant a type of linear actuator that drives the coils of a speaker, but the motor for driving the head of a hard disk (HDD) has also been recently called such. A VCM for HDDs usually has a structure in which a coil is disposed between two magnet plates, and the suspension arm is driven by a force generated by a current flowing through the coil and a magnetic field. The suspension arm is equipped with a detection head. All VCMs for hard disks use one or two Nd rare earth magnets. Recent miniaturization of hard disk drives has led to miniaturization of VCMs, and rare earth magnets are also required to be smaller and more powerful.
Company:Shin-Etsu Chemical Co., Ltd.
Department:Electronics Materials Division, Magnet Dept.