A "voice coil" is a generalized term that refers to any galvanometer-like mechanism that uses a solenoid 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 heads in a moving-head disk drive. In this application, a very lightweight coil of wires is mounted within a strong magnetic field produced by permanent rare-earth magnets. The voice coil is the motor part of the servo system that positions the heads: an electric control signal drives the voice coil and the resulting force quickly and accurately positions the heads.
How Voice Coil Actuators Work
Voice coil actuators, or non-commutated DC linear actuators, consist of a permanent magnetic field assembly (permanent magnets and ferrous steel) and a coil assembly. The current flowing through the coil assembly interacts with the permanent magnetic field and generates a force vector perpendicular to the direction of the current. The force vector can be reversed by changing the polarity of current flowing through the coil.
The force generated by the voice coil is proportional to the cross product of the current flowing through the coil and the magnetic flux in the permanent magnetic field, as dictated by Lorentz’ force equation. Either the coil assembly or permanent magnetic field assembly can be used as the moving member in a voice coil actuator. The force generated by a voice coil motor or actuator is relatively constant throughout the stroke of the actuator, with minor dips at the beginning and end of the travel length.
Voice coil actuators are typically used in focusing applications, oscillatory systems, mirror tilting, and miniature position control.
Voice Coil Motors from Akribis Systems feature:
- Direct drive, zero cogging, and zero backlash
- Low coil mass with very fast response and bandwidth
- No contact between coil and core movement (no wear and tear)
- Cylindrical or rectangular shape
- A variety of Voice Coil Motors and Voice Coil Modules (Position Actuators)
- Smooth motion at low speeds with limitless resolution (depends on feedback device)