Abstract: A control device for a matrix printer in which the mechanical printing elements of the matrix printer are selectively triggered by the control device a certain time before they reach the desired printing spot on the information carrier in order to compensate for the fact that the printing head will move further over a certain distance between the triggering moment and the moment that the printing element actually hits the information carrier. This distance depends on the speed of the printing element. If the print signal, however, is always generated a constant distance before the printing element reaches the desired printing spot, this signal must be delayed as a function of the speed of the printing element if the printing head is to print accurately also during its run-up and slow-down. To this end, a delay device is provided which delays the print signal for the relevant printing element by a time interval which depends on the printing head speed.

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.