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Linearization of an Edge Wound Voice Coil Motor

IP.com Disclosure Number: IPCOM000087773D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Bastianelli, CD: AUTHOR [+2]

Abstract

Fig. 1 shows part of a linear voice coil motor in which an edge-wound rectangular section coil is employed in a long coil-short gap configuration. Such a motor may be used, for example, to position magnetic heads in a disk file. Because of differences in flux density between the fringing fields and the gap itself, the force output of the motor is coil-position dependent.

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Linearization of an Edge Wound Voice Coil Motor

Fig. 1 shows part of a linear voice coil motor in which an edge-wound rectangular section coil is employed in a long coil-short gap configuration. Such a motor may be used, for example, to position magnetic heads in a disk file. Because of differences in flux density between the fringing fields and the gap itself, the force output of the motor is coil-position dependent.

To obtain a linear response to applied current, one or more dummy turns or spacers are included in the coil, as shown in Fig. 2, so as to vary the number of effective turns per unit length over the length of the coil. Each individual spacer is slotted, as shown, so that eddy currents capable of producing a back e.m.f. opposing the motion are not generated. The slots are also necessary to allow the coil winding to pass through the spacers.

An alternative method of linearization is to machine a uniform edge-wound coil so that some turns are shorted together, e.g., by a milling operation. Again, eddy current paths have to be broken, for example, by electrical discharge machining.

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