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Magnet Field Bias

IP.com Disclosure Number: IPCOM000080281D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Boler, VH: AUTHOR

Abstract

A rotating emitter wheel 10, polarized alternately north and south produces a magnetic field such as in Fig. 1. As it rotates from north to south pole, the magnetic field goes from a more positive to a more negative level. This magnetic field is used with a Hall effect switch 12, to sense rotary motion.

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Magnet Field Bias

A rotating emitter wheel 10, polarized alternately north and south produces a magnetic field such as in Fig. 1. As it rotates from north to south pole, the magnetic field goes from a more positive to a more negative level. This magnetic field is used with a Hall effect switch 12, to sense rotary motion.

At times it would be beneficial to increase the level in the north portion of the field to allow a larger airgap between the Hall effect switch 12 and emitter wheel 10, or just to increase the field enough to make the Hall effect switch operate. This can be done by placing a bias magnet 14, behind the Hall effect switch 10, polarized such that it will add to the magnetic field in the direction wanted and decrease the field where the flux is not needed, Fig. 2. By putting the south pole of bias magnet 14 behind Hall effect switch 12, it causes the output of the emitter wheel 10 to shift into a more usable range, Fig. 3.

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