Voice coil - Definition and Overview

Voice coil originally described the coil of copper wire mounted to the moving paper cone of a loudspeaker. By applying a voltage to the voice coil, a magnetic field was produced. This magnetic field would be cause the voice coil to be attracted to or repelled from a magnet fixed to the speaker's frame, thereby moving the paper cone of the speaker. By applying an audio waveform to the voice coil, the paper cone could be caused to reproduce the original sound pressure waves, reproducing the original voice, music, etc.

Nowadays, the term has been generalized and refers to any coiled wire that is used to move an object back-and-forth within a magnetic field. In particular, it is commonly used to refer to the coil of wire that moves the read-write disk heads in a moving-head disk drive. In this application, a very light weight coil of wires is mounted within a very strong magnetic field produced by rare earth permanent magnets. By means of a servo system driving the voice coil, the heads of the disk drive can be positioned very quickly and accurately.