INDUCTANCE-BASED POSITION SENSING IN A DIGITAL CAMERA ACTUATOR

摘要

Inductance-based sensing in a digital camera in which actuation of at least one electromagnetic (EM) actuator that includes at least one stationary ferromagnetic member associated with a large air gap causes a moving ferromagnetic member mechanically coupled to an optical element to by-pass or bridge the large air gap through at least one smaller air gap. The stationary member includes at least one ferromagnetic core surrounded at least partially by a coil. An inductance value correlated with a position of the optical element may be measured using the same coil as the one used for the actuation. In some embodiments, a single EM actuator includes two coils and the actuator is driven using both coils, while a regular or a mutual inductance is measured. In some camera embodiments that include two opposite EM actuators, one actuator is used to move the optical element while the other actuator is used to measure the inductance value.