The voice coil is an electromagnetic actuator in its simplest
form. Voice coil actuators come in two forms; rotary and
linear. A linear voice coil will move in a back and forth
motion and the rotary voice coil moves in an arc.
Voice coil actuators are ideal when a inertial mass needs to be
accelerated quickly or positioned accurately. The control
circuit to drive a voice coil is not complicated as a voice coil
does not require commutation.
A voice coil is a two-element device. There will be a coil
assembly and a permanent magnet assembly. The coil assembly
is inserted into the permanent magnet field. When current
passes through the coil a magnetic flux field a force is produced
at a right angle to the direction of the current. This
produces the back and forth motion of a voice coil.