Capacitive incremental position measurement and motion control
First Claim
1. A capacitive position-sensing system of the type comprisinga plurality of conducting elements lying essentially in a configuration defining a smooth surface;
- at least some of said elements being spaced apart in said smooth surface in a first direction in which motion is to be sensed;
means for providing capacitive effects with respect to said elements, includingmeans for forming a capacitive reference surface for said elements; and
means for sensing differences of capacitances between the reference surface and respective ones of said elements;
the means for providing capacitive effects with respect to said elements includingmeans for establishing a spatially modulated repetitive capacitive pattern between said reference surface and said conducting elements;
said system being characterized in thatthe forming means forms a conductively monolithic capacitive reference surface;
the spaced apart elements are subdivided into at least three groups; and
the sensing means simultaneously senses at least two capacitive difference signals.
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Accused Products
Abstract
A capacitance based, high resolution, incrementally encoding, position measuring system employs an array of identical replicated electrodes that are driven in unison from an RF source and mounted in proximity to a patterned monolithic reference ground plane of arbitrary size. Motion of such position-sensing arrays is monitored by measuring both the sums and the differences of the electrode displacement currents in such a way as to provide incrementally encoding position signals in both one and two dimensions together with a continuous measurement of the height of the sensor array above the patterned ground plane. In various modifications, the system and methods are applied both to one dimensional linear, as well as to two dimensional planar and two dimensional cylindrical motion measurement and control. Various techniques for eliminating the effects of spurious capacitances are also disclosed.
92 Citations
29 Claims
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1. A capacitive position-sensing system of the type comprising
a plurality of conducting elements lying essentially in a configuration defining a smooth surface; -
at least some of said elements being spaced apart in said smooth surface in a first direction in which motion is to be sensed; means for providing capacitive effects with respect to said elements, including means for forming a capacitive reference surface for said elements; and means for sensing differences of capacitances between the reference surface and respective ones of said elements; the means for providing capacitive effects with respect to said elements including means for establishing a spatially modulated repetitive capacitive pattern between said reference surface and said conducting elements; said system being characterized in that the forming means forms a conductively monolithic capacitive reference surface; the spaced apart elements are subdivided into at least three groups; and the sensing means simultaneously senses at least two capacitive difference signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A system of the type comprising
a plurality of conducting elements lying essentially in a configuration defining a smooth surface; -
at least some of said elements being spaced apart in said smooth surface in a first direction; means for providing capacitive effects with respect to said elements, including means for forming a capacitive reference surface for said elements; and means for sensing differences of capacitances between the reference surface and respective ones of said elements; the means for providing capacitive effects with respect to said elements including means for establishing a spatially modulated repetitive capacitive pattern between said reference surface and said conducting elements;
said system being characterized in thatthe forming means forms a conductively monolithic capacitive reference surface; the spaced apart elements are subdivided into at least three groups and the sensing means simultaneously senses at least two capacitive difference signals. - View Dependent Claims (27, 28, 29)
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Specification