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Actuator Magnetic Gap Adjustment in Wire Matrix Print Heads

IP.com Disclosure Number: IPCOM000059669D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Rieland, RA: AUTHOR

Abstract

A technique is described whereby the magnetic gaps in ballistic-type actuators, as used in wire matrix print heads, are adjusted using a current/time-based orientation rather than a measurement of distance. A simple modified drive pulse is used to provide accurate measurements, thereby increasing the efficiency of the magnetic actuator. In prior art, actuators were adjusted by setting the static stroke of the lever arm of the actuator. Variations due to friction, pole face alignment, arm inertia and material properties caused significant differences in operational performance. The technique described herein utilizes a time-oriented adjustment which measures the "Seal Time" value of the actuator. The "Seal Time" is the amount of time required to close the armature from a rest position utilizing a specified drive current pulse.

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Actuator Magnetic Gap Adjustment in Wire Matrix Print Heads

A technique is described whereby the magnetic gaps in ballistic-type actuators, as used in wire matrix print heads, are adjusted using a current/time-based orientation rather than a measurement of distance. A simple modified drive pulse is used to provide accurate measurements, thereby increasing the efficiency of the magnetic actuator. In prior art, actuators were adjusted by setting the static stroke of the lever arm of the actuator. Variations due to friction, pole face alignment, arm inertia and material properties caused significant differences in operational performance. The technique described herein utilizes a time-oriented adjustment which measures the "Seal Time" value of the actuator. The "Seal Time" is the amount of time required to close the armature from a rest position utilizing a specified drive current pulse. This current pulse causes an exponential rise in the inductance/permeance circuit value as the armature reaches the seal position. This results in an inflection point in the current trace, as observed on the oscilloscope. Since the armature-to-stator location tolerances and the relative alignment of the armature can cause this inflection point to become indistinguishable, the drive pulse must be extended so as to accurately measure the "Seal Time". To accomplish this, an alternate drive pulse is used to correlate the "Seal Time" value. The alternate drive pulse is superimposed on th...