Abstract: A method of measuring of backlash arising in a drive mechanism comprising a screw and a nut device co-operating with the screw, the nut device being connected to a movable unit which is displaceable in opposite directions along the screw. The drive mechanism comprises a pulse generating system of which the number of pulses emitted for each displacement corresponds to the distance traveled in accordance with the method the movable unit is operated to move away from an end position adjacent one end of the screw, and when a predetermined position has been reached the pulse counter is reset while the movement continues. The movement is maintained a distance beyond the position in which the pulse counter was reset, the distance being greater than the possible maximum backlash. The drive mechanism is then stopped and operated to move the movable unit back to the end position, during which movement the pulse counter is counting backwards.

Abstract: A drive mechanism comprising a power driven screw (16) and a nut means (17) co-operating with the screw includes a device for the correction of backlash prevailing between the screw and the nut means. The correction takes place electronically by modification of two pulse trains (A, B) which are generated by a pulse generator (19) which is synchronized with the movement of the screw. From the two pulse trains information as to position and direction of movement is derived for a movable unit (11), which is connected to the nut means and which, for instance, can be a printing unit in a printer or a typewriter. A measured or estimated value of the backlash is digitally stored with a resolution of one quarter of the period of the pulse trains. This resolution is four times the smallest distance through which the movable unit can be moved.

Abstract: The disclosure relates to a method and device for reading data in the form of data pulses in a pulse train. The pulse train is obtained by the sensing of a flexible disc and contains, conventionally, a sequence of clock pulses which, in at least a portion of the pulse train, define mutually subsequent bit cells. These contain at most one of the data pulses. A bistable circuit is switched to its one state by the clock pulses and switched to its other state by the data pulses. The time which has elapsed after each switching of the bistable circuit is measured by means of a time circuit and the bistable circuit is switched if the elapsed time exceeds a value which is settable for each switching. A combinational circuit is provided for setting the above-mentioned level in dependence of the contents of at least the preceding bit cell.