Analog Devices, Inc.
Position sensor for a voice coil

Abstract:

A position sensor may include a resonator attachable to a first object, and an antenna attachable to a second object and driven at a resonant frequency of the resonator. A change in a position of the first object relative to the second object may be sensed as a change in a power of the antenna when the antenna is driven at the resonant frequency of the resonator. The first object may be a former of a speaker, and a voice coil of the speaker may be positioned on the former together with the position sensor. In operation, the antenna may output a position signal to an external system of electronics, indicating a position of the voice coil. The external system of electronics may perform feedback processing to compensate for nonlinearities in the voice coil's position when the voice coil is used to drive a diaphragm of the speaker.