US 12,228,431 B2
Rotary position sensing apparatus and method
David Witts, Cambridge (GB); Timothy Biggs, Cambridge (GB); Paul Smith, Cambridge (GB); and Peter Constantinou, Cambridge (GB)
Assigned to Kyocera AVX Components (Werne) GMBH, Werne (DE)
Filed by Kyocera AVX Components (Werne) GmbH, Werne (DE)
Filed on Jul. 10, 2023, as Appl. No. 18/349,556.
Application 18/349,556 is a continuation of application No. 17/048,149, granted, now 11,698,275, previously published as PCT/GB2018/051453, filed on May 29, 2018.
Prior Publication US 2024/0011800 A1, Jan. 11, 2024
Int. Cl. G01D 5/22 (2006.01)
CPC G01D 5/225 (2013.01) [G01D 5/22 (2013.01); G01D 5/2258 (2013.01); G01D 5/2275 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A rotary position sensor comprising a first member and a second member, the first member having a transmit aerial and a receive aerial and the second member having an intermediate coupling element,
the transmit aerial comprising at least one conductive winding arranged to form a first loop aligned with a first minor arc of a circle centered on the axis of rotation and a second loop diametrically opposed to the first loop and aligned with a second minor arc of the circle centered on the axis of rotation, wherein current flows through the first loop and the second loop in opposing rotational senses so that alternating current flowing in the at least one conductive winding generates a transmit alternating magnetic field,
the receive aerial comprising at least one conductive winding arranged to form a first set of current loops and a second set of current loops arranged so that current flowing in the conductive winding flows in a first rotational sense in the first set of current loops and in a second rotation sense opposing the first rotational sense in the second set of current loops, and
the intermediate coupling element comprising regions of conductive material and regions of ferromagnetic material arranged in a pattern such that the current induced in the conductive winding of the receive aerial by the magnetic field generated by the transmit aerial varies in dependence on the relative rotary position of the first and second members;
wherein the regions of ferromagnetic material comprises a thin layer of ferromagnetic material, the thin layer of ferromagnetic material having a thinness such that an alternating background magnetic field will pass through the intermediate coupling element;
wherein the pattern of the intermediate coupling element is arranged such that any electromotive force induced in the first set of current loops by the background alternating magnetic field is substantially balanced by electromotive force induced in the second set of current loops by the background alternating magnetic field.