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.

Abstract: A lever projects into the space between two guide plates for a sheet data carrier and is journalled so as to upwardly pivotable in the transport direction of the carrier against the force of a spring. A Hall-element sensor is secured adjacent to a magnet secured to the journalled end of the lever so that the sensor is activated by translation or rotation of the lever effected by engagement of the lever with the feeding of the data carrier. The lever is arranged to initially translate to activate the sensor and rotated after the translation so that when the lever is returned to its position prior to translation, only rotation of the lever switches the state of the sensor to indicate the position of the trailing edge of the carrier.