A portable electronic device (MS) has a user interface (DPL1) that is protected by a motorized slide (SL1). The device has a first slide (SL1) which is moveable between positions in which it protects and exposes the user interface (DPL1). The slide is driven by an epicyclical gear which is, in turn, driven by an electrical motor. The epicyclical gear gears down a rotational speed provided by the motor into a rotational speed that is suitable for driving the slide.