Patent ID: 7554243

Claim:
An apparatus comprising: a first output to drive a piezo-element, a driving unit configured to provide a driving voltage to said first output, an input configured to receive a position signal, a first signal processing unit configured to determine one or more values, each of said one or more values being dependent on a rate of chance of said position signal, a second signal processing unit configured to determine an optimum driving frequency based on said one or more values such that a noise level generated by said piezo-element when driven at said optimum driving frequency is reduced when compared with a noise level associated with a maximum obtainable velocity of said movable object, and an adjustment unit configured to adjust the driving frequency of said driving voltage to be substantially equal to said optimum driving frequency, wherein said apparatus further comprises a temperature sensor interface unit configured to receive a temperature signal, and wherein the adjustment unit is further configured to tune said driving frequency based on said temperature signal.