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Rebound Suppression for Print Hammer Actuators

IP.com Disclosure Number: IPCOM000043040D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Evans, DR: AUTHOR [+2]

Abstract

Rebound suppression in moving armature or moving hammer printing actuators is a well-known problem addressed by the present article. Rebound absorption by the principle of multiple oblique impacts between the moving member and a fixed backstop is presented as a solution to poorly damped or undamped rebound for wire matrix print hammers, armatures, solenoids, or the like. Fig. 1 illustrates a schematic of the principle employed. A moving mass M represents the mass of a print hammer or wire matrix armature-actuating member. The mass M is moving with a velocity V1 in a direction generally toward the rebound energy absorption surface S. An indentation is formed for the mass to impact against. In the present instance, Fig. 1 illustrates a sloped pair of sidewalls and the mass is oriented to strike one of the sidewalls first.

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Rebound Suppression for Print Hammer Actuators

Rebound suppression in moving armature or moving hammer printing actuators is a well-known problem addressed by the present article. Rebound absorption by the principle of multiple oblique impacts between the moving member and a fixed backstop is presented as a solution to poorly damped or undamped rebound for wire matrix print hammers, armatures, solenoids, or the like. Fig. 1 illustrates a schematic of the principle employed. A moving mass M represents the mass of a print hammer or wire matrix armature-actuating member. The mass M is moving with a velocity V1 in a direction generally toward the rebound energy absorption surface S. An indentation is formed for the mass to impact against. In the present instance, Fig. 1 illustrates a sloped pair of sidewalls and the mass is oriented to strike one of the sidewalls first. This will result in a rebound which does not reverse the direction of the velocity V1 but directs it toward the opposite sidewall of the indentation where yet another impact occurs. The process continues with multiple impact and rebounds until the mass is firmly seated in the indentation. A very great improvement in rebound reduction and the time to fully damped rest position results. Fig. 2 illustrates graphically the difference between a flat undamped planar impact and the oblique multiple impact rebound absorption of the present article. In Fig. 2, displacement of a hammer actuator, solenoid or armature is depicted on the vertical scale and the time is depicted on the horizontal scale. In curve A, a hammer armature, for example, is deflected to an initial twenty-five thousandths of an inch and allowed to return to impact a fixed flat surface. Curve A in the time interval between 2 and 5 milliseconds shows the rebound of such an element after impacting a flat backstop of damping material. It will be observed that the total energization of the hammer occupied approximately 1 millisecond, but damping of the rebound may take 2, 3, or even more m...