Abstract: In a drive circuit for an electromagnetic printing element of an impact printer, a drive pulse drives the printing element from a backstop toward a record medium to print indicia. A voltage comparator senses the change in the induced voltage in the printing element when it impacts on the backstop for triggering a single shot circuit to apply to the printing element a damping pulse of a polarity such as to oppose its rebound from the backstop. A latch circuit is responsive to the damping pulse to disable the single shot circuit until the end of the next drive pulse. The drive and damping pulses are applied to the printing element through a bidirectional current source.

Abstract: In a drive circuit for an electromagnetic printing element of a matrix impact printer, a drive pulse drives the printing element from the backstop toward a record medium to print indicia, and a damping pulse, applied to the printing element after its return to the backstop, urges it toward the backstop to limit rebound therefrom. Logical control circuitry is responsive to overlap of a drive pulse with a preceding damping pulse for terminating the damping pulse and for decreasing the width of the drive pulse in proportion to the amount of overlap. Blanking means are provided to prevent application of a damping pulse to the printing element until after the completion of a preceding drive pulse and after impact of the printing element with the record medium and with the backstop.

Abstract: A printhead for a dot matrix impact printer comprises a stack of thin printing blades each including a flat spiral coil mounted in a rim which is in turn connected by flexible mounting arms to a mounting portion. Each blade has an arcuate printing arm extending from one side of the rim thereof and carrying a stylus, with the printing arms of adjacent blades being curved in opposite directions with the concave sides thereof facing each other so as to provide therebetween a large separation area to prevent wicking of ink from the styli to the coils of the blades. Each print arm carries a stabilizing member extending from the concave side thereof, with the stabilizing members of adjacent blades overlapping for cooperation to divide the separation area between said blades into inner and outer regions, the outer region serving to block particulate debris and isolate it from the inner regions thereby to prevent interference with the anti-wicking function of the inner regions.

Abstract: The object of the invention is to provide an effective means of circulating inked ribbon by means of friction rollers into and out of a cartridge where it has been stored as a compact mass of ribbon folds. Means must be provided to prevent this mass of ribbon from being damaged or jammed when it leaves the rollers.This has been accomplished by introducing a movable stripper which does not frictionally engage the ribbon during its passage through friction rollers but which frictionally engages the ribbon after such passage to move the ribbon away from the friction rollers and thereby minimize scuffing and rubbing action between ribbon and friction rollers.

Abstract: A drive circuit is responsive to input pulses to supply drive energy pulses to the printing head of a matrix printer so as to produce constant impact forces and constant print intensity over a wide range of print rates by decreasing the energy of the drive pulses as a function of the time interval between successive input pulses as said interval diminishes below a predetermined value. In one embodiment the amplitude of the drive pulses is reduced as the frequency of the input pulses exceeds the predetermined value. In a second embodiment the duration of the drive pulses is reduced as the frequency of the input pulses exceeds the predetermined value.

Abstract: The object of the invention is to provide a means of circulating inked ribbon into and out of a cartridge where it has been stored as a compact mass of ribbon folds. Means must be provided to prevent this mass of ribbon from jamming the exit port and forming clumps which result in excessive ribbon tension at the exit.This has been accomplished by introducing a plurality of restrictors in the cartridge ahead of the exit port. In one embodiment, the first of these restrictors consists of a single dam positioned such that the mass of folded, compressed ribbon is restrained by this dam. Tension of withdrawal causes a small quantity of ribbon length to separate from the ribbon mass and cross the restrictor in small clumps or folds. The second restrictor which in one embodiment consists of two aligned dams, one above and one below, causes the ribbon to be restrained to the degree that it exits after passage as a single, unfolded ribbon under slight tension.