Under actuation detection in a micro electromechanical device

摘要

A method of detecting an under actuation condition within a micro electro-mechanical device in the form of an ink ejection nozzle having an actuating arm that moves an ink displacing paddle when heat inducing electric current is passed through the actuating arm and having a movement sensor associated with the actuating arm. The method comprises the steps of passing at least one current pulse having a predetermined duration through the actuating arm and detecting for a predetermined level of movement of the actuating arm. A fault is detected to exist by comparing the detected movement with the movement for desired operation, and where a fault is present, at least one further current pulse having an energy level greater than the fault detecting pulse may be passed through the actuating arm in an attempt to clear the fault.