Abstract: Paper feed rollers are in a paper supply path before a printing unit. A paper detector is between the printing unit and the paper feed rollers for sensing the presence of paper in the path. A control of the paper transport is facilitated in the paper supply direction by a movement detector before the paper feed rollers, which is driven by the transported paper and produces a number of pulses proportional to the passage length of the paper. The paper detector comprises a magnet on a rotatable lever and a fixed unipolar Hall element. The movement detector comprises a rotatable wheel having multipole magnets on its periphery and a bipolar Hall element secured to respond to the rotating magnetic poles of the wheel.