Method of detecting a fault condition in a micro-electromechanical device

1. A method of detecting a fault condition in a micro-electromechanical device, the method comprising the steps of:

applying at least one current pulse to an actuator of the device such that the actuator is cyclically displaced at least once;

determining an extent of displacement of the actuator;

calibrating the device by determining a relationship between an operational parameter and said displacement; and

testing the device by applying said parameter to the device, such that an error is detectable where said relationship is not achieved;

wherein the step of determining the extent of displacement of the actuator includes the step of generating an electrical signal when the actuator is displaced to said extent; and wherein the step of generating the electrical signal includes the step of establishing a switch that is operable upon displacement of the actuator to direct the current from the actuator to processing circuitry upon displacement of the actuator to said extent, such that a switch contact is positioned to correspond with said extent of displacement.

2. A method as claimed in claim 1 , in which the step of a applying at least one current pulse to the actuator comprises the step of applying a series of current pulses to the actuator.

3. A method as claimed in claim 1 , in which the step of calibrating the device includes the step of applying the series of current pulses to be of increasing duration until such time as the switch closes and a series of the electrical signals are generated such that a current pulse of a particular duration corresponds with said extent of displacement.

4. A method as claimed in claim 3 , in which the step of testing the device includes the step of applying a series of current pulses of said particular duration and determining whether or not said series of electrical signals are generated.