Abstract: A plunger armature printing system incorporates an opto-electronic sensor for sensing the movement of a vane fixed to the armature of the print mechanism. The output signal generated by the sensor is employed to define periods for measurement of the speed of movement of the armature. A microprocessor is employed for supplying accelerating and decelerating pulses to the armature magnet for causing the armature to achieve a preselected printing force, in response to the time intervals between similar signals produced by said sensor, and to return said armature to its rest position rapidly without rebound.

Abstract: An impact printing device having a plunger-type magnet system has an armature consisting of two joined portions which are a cylindrical principal portion and a guide portion which serves as the printing hammer. The principal portion of the armature consists of material of high magnetic permeability and carries a cylindrical peg thereon which mates with a corresponding receptacle in the printing hammer, which is comprised of non-magnetic material. The principal portion and the peg thereon terminate at sharp edges which cause the magnetic lines of force to converge at those edges thereby increasing the kinetic energy available for moving the armature during a printing stroke. A position sensor is connected to a drive circuit for the magnet system for controlling acceleration of the armature on its way to the striking point and deceleration of the armature during a return after a printing stroke in accordance with the speed of the returning armature.

Abstract: A damping device for a printing hammer which is driven by an electromagnetically actuated pivotable armature has a circuit associated therewith for operating the electromagnetic coils which generates a high excitation current for rapid acceleration of the armature and printing hammer which is followed by a switch over to a considerably lower holding current which maintains the armature in a position to abut the printing hammer during its return stroke. The armature also actuates a rotatable angle lever into engagement with the printing hammer for frictional braking thereof so that the hammer is rapidly damped to a rest position and is ready for a subsequent printing stroke.

Abstract: A device is disclosed for index and exponent impression printing in typewriters. An exponent or index switching key has associated with it an edge detector, and parallel thereto, a state detector. A time function element which triggers a gate circuit for the triggering of the drive motor for the roller is connected behind the edge detector. A rotational direction reversal switching device is connected behind the state detector. The device is useful in office typewriters, data printers or telex machines not equipped with their own exponent or index printing symbols.