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Differential reactance permanent magnet position transducer

  • US 5,444,368 A
  • Filed: 01/10/1994
  • Issued: 08/22/1995
  • Est. Priority Date: 01/10/1994
  • Status: Expired due to Fees
First Claim
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1. A differential reactance permanent magnet transducer comprising a stator and an armature, said stator having a first section with at least two pole elements thereon of ferromagnetic material, each stator pole element having an electrically conductive coil wound thereabout, and said armature having a first magnet section with at least one permanent magnet pole element thereon, said pole elements being so disposed as to cause said magnet pole element to register sequentially with said pole elements of said first section of said stator as said armature moves relative to said stator, and being so disposed that the flux density variation produced in one of said stator pole elements by movement of said magnet pole element relative thereto varies in an out-of-phase relationship to the flux density variation produced in the other of said stator pole elements by such magnet pole element movement, said coils being comprised of effectively equal numbers of turns and being connected in series to provide at least one circuit having terminals to enable the application of voltages thereacross and to enable measurement of voltage values at a junction between said coils thereof, each coil comprising a leg of said one circuit, whereby said first stator section, said first magnet section, and said coils provide a first sensor section, and whereby the values of voltages applied across said circuit will be so modulated by such relative movement of said armature as to enable the generation of signals from said first sensor section that vary sinusoidally as a function of armature position and reactance variation in said coils, the electrical and mechanical features of said transducer being such that no net back-EMF value is inductively generated from said coils as a result of such relative movement.

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