An active power factor correction circuit and its controlling method are provided. The drive unit comprises a piezoelectric element, a rod provided at an end of the piezoelectric element, a movable object frictionally engaged with the rod, and drive pulse generating means that apply drive signals to the piezoelectric element. The capacitor bank is arranged on the first path, and includes capacitor cells. Window inserts can be removed and replaced using adapters and removable brackets. One configuration includes a lip member attached to the back of the communications device and a channel contained within the back of the housing for engaging the lip member.