Inductive position detection configuration for indicating a measurement device stylus position

A scanning probe for a coordinate measuring machine, the scanning probe comprising:

• a stylus suspension portion that is coupled to a frame of the scanning probe, comprising:
• a stylus coupling portion that is configured to be rigidly coupled to a stylus;
• and
• a stylus motion mechanism that is configured to enable axial motion of the stylus coupling portion along an axial direction, and rotary motion of the stylus coupling portion about a rotation center;
• and
• a stylus position detection portion arranged along a central axis that is parallel to the axial direction and nominally aligned with the rotation center, comprising:
• a receiver coil portion comprising a planar top coil substrate including N top rotary sensing coils and a top axial sensing coil configuration and a planar bottom coil substrate including N bottom rotary sensing coils and a bottom axial sensing coil configuration, wherein N is an integer that is at least 3, and the top and bottom coil substrates are mounted in a fixed relationship to the frame of the scanning probe with the bottom coil substrate closer to the stylus suspension portion, and the top and bottom coil substrates are nominally parallel to one another and nominally orthogonal to the central axis, and are spaced apart along the central axis with a disruptor motion volume located therebetween;
• a disruptor configuration comprising a disruptor element that comprises a conductive plate or conductive loop that provides a disruptor area, wherein the disruptor element is located along the central axis in the disruptor motion volume between the top and bottom coil substrates and is coupled to the stylus suspension portion by a coupling configuration, wherein the disruptor element moves in the disruptor motion volume relative to an undeflected position in response to a deflection of the stylus suspension portion, the disruptor element moving over an operating motion range +/−Rz along the axial direction in response to the axial motion, and over respective operating motion ranges +/−Rx and +/−Ry along orthogonal X and Y directions that are orthogonal to the axial direction in response to the rotary motion;
• a field generating coil configuration comprising at least a first field generating coil that is located proximate to the disruptor motion volume and that is nominally planar and orthogonal to the central axis, wherein a projection of a coil area of the first field generating coil along the axial direction encompasses the conductive plate or loop that provides the disruptor area and a coil area of all the rotary and axial sensing coils located on the top and bottom coil substrates, the field generating coil configuration generating a changing magnetic flux generally along the axial direction in the disruptor motion volume in response to a coil drive signal;
• and
• signal processing and control circuitry that is operably connected to the coils of the stylus position detection portion to provide the coil drive signal and configured to input signals from the receiver coil portion comprising respective signal components provided by the respective rotary and axial sensing coils located on the top and bottom coil substrates, and output signals indicative of an axial position and a rotary position of at least one of the disruptor element or the stylus relative to the frame of the scanning probe,
• wherein:
• a projection of the disruptor element along the axial direction through an interior coil area of the top axial sensing coil configuration defines a top axial sensing overlap area TASOA, a projection of the disruptor element along the axial direction through an interior coil area of the bottom axial sensing coil configuration defines a bottom axial sensing overlap area BASOA, a projection of the disruptor element along the axial direction through an interior coil area of any respective top rotary sensing coil TRSCi defines a respective top rotary coil sensing overlap area TRSCOAi, and a projection of the disruptor element along the axial direction through an interior coil area of any respective bottom rotary sensing coil BRSCi defines a respective bottom rotary coil sensing overlap area BRSCOAi, where i is an individual coil identification index in a range 1 to N;
• the receiver coil portion and the disruptor element are configured to provide the top axial sensing overlap area TASOA and the bottom axial sensing overlap area BASOA wherein an amount of each of the overlap areas TASOA and BASOA is unchanged or independent of a position of the disruptor element within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, and
• the receiver coil portion and the disruptor element are configured to provide N complementary pairs of rotary sensing coils CPi that each comprise a top rotary sensing coil TRSCi and a bottom rotary sensing coil BRSCi, wherein for any complementary pair CPi for any disruptor element displacement increment within the operating motion ranges +/−Rz, +/−Rx, and +/−Ry, a magnitude of a change in overlap areas TRSCOAi and BRSCOAi associated with the disruptor element displacement increment is nominally the same in that complementary pair.