Patent ID: 7239130

Claim:
A pitch-compensated induced current position transducer, comprising: a first member including a plurality of scale elements arranged periodically along a scale track according to a scale wavelength, the scale track aligned with a measuring axis direction; a second member positioned adjacent to the first member, and at least one of the first and second members movable relative to the other along the measuring axis direction; at least one magnetic field generator positioned on the second member for generating a changing magnetic flux; and at least one magnetic flux sensor positioned on the second member to couple to the changing magnetic flux of the at least one magnetic field generator, the coupling to the changing magnetic flux influenced by the scale elements arranged periodically along the scale track, and the magnetic flux sensor comprising a plurality of windings overlapping one another and aligned along the scale track, each winding comprising: a first set of loops including loops of plus polarity and loops of minus polarity, the first set of loops arranged to correspond to a plurality of hypothetical basic polarity zones that alternate in polarity periodically along the measuring axis at the scale wavelength; a second set of loops including loops of plus polarity and loops of minus polarity, the second set of loops arranged to correspond to a plurality of hypothetical offset polarity zones that alternate in polarity periodically along the measuring axis at the scale wavelength; wherein: the offset polarity zones are offset from the basic polarity zones along the measuring axis direction by an offset dimension that is less than half the scale wavelength; respective hypothetical offset zones are defined along the entire length of each respective winding at positions along the measuring axis direction where a basic polarity zone overlaps with an offset polarity zone having the opposite polarity, and a conductive portion of the winding that forms the first set of loops is connected to a conductive portion of the winding that forms the second set of loops by a series connection; wherein: each of the plurality of windings includes at least one offset zone wherein a net coupling area within that offset zone is an unbalanced net coupling area, and a total coupling area within that offset zone is less than the largest of any portion of a single loop area that is included in any offset zone of that winding; and the plurality of windings is configured such that the phase error of each respective winding of the plurality of windings is approximately the same.