International Business Machines Corporation

Han C Wang

Alfred J Landon

Jerome J Cuomo

Paul S Chang

William B Pennebaker

Keith S Pennington

Eric Gung-Hwa Lean

Samuel C-c Tseng

Joseph E Wallace

An impact printer is described which includes a shock wave generator means, a print hammer, and a solid wave guide interposed between the shock wave generator and print hammer. The solid wave guide acts to transmit a shock wave from the shock wave generator to the print hammer to cause its movement towards a substrate upon which printing is to occur. In a preferred embodiment, the shock wave generator comprises a piezoelectric or electrostrictive actuator, which actuator is held in compression by a frame that prevents any substantial longitudinal movement thereof. In a further preferred embodiment, circuitry is connected to the actuator for detecting, after an actuation, the return of the hammer into contact with the solid wave guide. In response to that detection, the circuitry provides a signal which enables operation of the shock wave generator.

Printer actuated by piezoelectrically generated shock wave

A two-lever electromagnetic print actuator having a pivoted bellcrank armature and an end-pivoted print hammer is urged to free-flight by energy transfer at an energy transfer contact surface. The armature pivot, print hammer pivot and energy transfer surface are aligned in sequence and substantially coplanar. This converts input energy to optimum print velocity with minimum wear. In operation, energizing a coil attracts the armature to the stator, imparting energy to an energy transfer surface on an energy transfer armature leg. The energy transfer surface moves in an arc, delivering energy to a related energy transfer surface on the print hammer. The print hammer goes into pivoted free-flight when the armature strikes a stop pad. There is mimimum sliding, and thus minimum wear, between the energy transfer surfaces of the print hammer and armature as they both move in arcs of similarly convex circles which remain tangent at their contact point. The two-lever print actuator provides a low mass print hammer with a short contact time; the hammer moves at a substantially higher velocity than the armature at the pole face due to the optimized lever length ratios.

Two lever print actuator with aligned pivots and energy transfer surfaces

The present invention relates to a dot matrix printer which makes use of multiple dot patterns distributed on the cylinder, belt, hand or drum of a line printer to provide an improved printing throughput for an all addressable line printer. In a dot-helix matrix printer, different arrangements of the dots are used which can be varied in position and spacing to increase printing speed. On a belt, band or drum line printer, multiple dot patterns are given a predetermined distribution. More specifically, arrangements of dots are used which provide enhanced performance due to the fact that they are determined by an analysis of the statistical occurrence of a particular dot pattern in a character set. The higher statistical probability dot patterns are used more often on the belt, band or drum.

Dot matrix printer

An electrostatic clutch operable by the Johnsen-Rahbek effect, which may be used to operate, e.g., a print hammer device, is described, said clutch comprising a rotatable drum and a band engagable therewith, wherein the engagable surface of the drum is a semiconductive surface prepared by sputtering or vapor depositing a layer of substantially pure silicon carbide onto a conductive substrate.

Electrostatic clutch

An impact printing mechanism is disclosed having an electrostatic clutch assembly, including a rotatively mounted semiconductive coated drum and a conductive band wrapped around the circumference thereof. The printing mechanism includes a printing hammer and a print spring for actuating the printing hammer. When a print command is issued, a voltage is applied to the band to create a field between the band and the drum coating. An electrostatic force is therefore generated when the drum is rotating slowly or synchronous with the drum step motion. That motion will pull the band and compress the print spring. The potential energy stored in the spring is then ready to fire the hammer. A hammer firing command turns off the voltage pulse and discharges the field, releasing the electrostatic holding force instantaneously and firing the hammer by the compressed spring.

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Chappaqua, NY, United States of America

Han C Wang