Abstract: The present invention relates to an assembly of electromagnetic actuators for the hammers of an impact printer arranged side by side and extending along a line. Each actuator comprises a first stator part formed with at least one pole piece, a second stator part formed with at least one pole piece and positioned relative to the first stator part so that the pole pieces are spaced apart so as to form a gap therebetween. A single coil is associated with one of the stator parts. Each actuator also includes an armature member formed with a body of non-magnetizable material, at least one armature element of magnetizable material and a hammer head. The armature member is supported between the stator parts so that the armature element is located adjacent to the gap. Energization of the coil causes the generation of a flux which passes across the gap and through the armature element tending to move the armature element into the gap and to cause the hammer head to move into a print position.

Abstract: This invention relates to a mechanism for positioning an output member of a mechanical system and in particular a mechanical system that has backlash present. The mechanism has a step motor, regulated by control means, connected to the output member by a mechanical transmission. The control means delivers units of electrical energy to the step motor in response to a number of steps specified to be moved. The control means also has means for detecting whether the step to be performed by the step motor is a single remaining step or single step only. The control means responds to detection of the single remaining step or detection of the single step only by applying a unit of energy to the step motor at a rate that is substantially slower than the rate that would be applied for the other steps.