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Performance Stabilization of Magnetic Actuators

IP.com Disclosure Number: IPCOM000078416D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Mills, SH: AUTHOR [+2]

Abstract

Magnetic actuators are extremely sensitive to input drive and output load variations. The sensitivity creates a problem in applications requiring multiple print energies from a single actuator.

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Performance Stabilization of Magnetic Actuators

Magnetic actuators are extremely sensitive to input drive and output load variations. The sensitivity creates a problem in applications requiring multiple print energies from a single actuator.

The magnetic actuator shown includes a hammer 1 travelling between pole pieces 2 and 3, which are extensions of permanent magnet 5. Detection coil 4 is wound on pole pieces 2 and 3 to sense a change in flux due to change in hammer velocity.

As the hammer velocity increases, the change in magnetic flux increases resulting in an increase in output voltage from the detection coil. The output of the detection coil is compared with a threshold value, where the threshold level is adjustable to allow the hammer to achieve any desired velocity. When a compare is obtained between the detection coil output and the threshold level, the hammer coil driver is turned off. Due to the coil inductance and inertia of the hammer, the hammer will continue to impact the desired surface. It has been observed that the largest change in kinetic energy occurs in the final portion of the hammer flight. Therefore, the free-flight portion of hammer travel should be relatively short to prevent any significant change in hammer velocity.

An alternate method of achieving the same result, would be to sense displacement of the hammer just prior to impact. In this situation, the displacement may be sensed by a photodetector or some equivalent device. The resul...