System for sensing spatial coordinates
First Claim
1. An apparatus for determining the spatial position of a probe with respect to a conductive surface comprising:
- conductive surface means having first and second pairs of regions;
drive means for alternately providing current to the first pair of regions of said conductive surface means and to the second pair of regions of said conductive surface means;
reference position shift means for alternately clamping first and second locations on said conductive surface means to a reference potential, said reference position shift means alternately clamping the first and second locations to the reference potential while said drive means provides current in succession to each of the first and second pairs of regions per each referene position;
probe means for providing a potential signal related to the potential on said conductive surface means at a point nearest to said probe means, said probe means providing a first potential signal when the first location on said conductive surface means is clamped to the reference potential by said reference position shift means and a second potential signal when the second location on said conductive surface means is clamped to the reference potential by said reference position shift means; and
processor means for determining a first coordinate position of said probe means with respect to said conductive surface means from a relationship between said first and second potential signals and values of said first and second potential signals during the time said drive means is providing current to the first pair of regions of said conductive surface means, and for determining a second coordinate position of said probe means with respect to said conductive surface means from the relationship between said first and second potential signals and the values of said first and second potential signals during the time said drive means is providing current to the second pair of regions of said conductive surface means.
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Abstract
A system for sensing the spatial position of a moveable object with respect to an energized conductive surface whereby the spatial coordinates of the object are determined. The system provides a means of accurately measuring the coordinates of the object with respect to a two-dimensional coordinate system independent of the third orthogonal dimension, thereby avoiding significant measurement errors due to variations of the object'"'"'s position in the third orthogonal dimension. The system also ascertains the coordinate position of the object in this third dimension, which can then be utilized as an independent control variable in the system. Further, the system can accommodate a number of energized conductive surfaces over which the object may be positioned and can determine the spatial coordinates of the object with respect to any such surface. In general, the system of the present invention can ascertain the generalized n-tuple position vector of the object with respect to each of a plurality of generalized, energized conductive surfaces. In any of the foregoing forms, the energized conductive surfaces can be transparent.
97 Citations
36 Claims
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1. An apparatus for determining the spatial position of a probe with respect to a conductive surface comprising:
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conductive surface means having first and second pairs of regions; drive means for alternately providing current to the first pair of regions of said conductive surface means and to the second pair of regions of said conductive surface means; reference position shift means for alternately clamping first and second locations on said conductive surface means to a reference potential, said reference position shift means alternately clamping the first and second locations to the reference potential while said drive means provides current in succession to each of the first and second pairs of regions per each referene position; probe means for providing a potential signal related to the potential on said conductive surface means at a point nearest to said probe means, said probe means providing a first potential signal when the first location on said conductive surface means is clamped to the reference potential by said reference position shift means and a second potential signal when the second location on said conductive surface means is clamped to the reference potential by said reference position shift means; and processor means for determining a first coordinate position of said probe means with respect to said conductive surface means from a relationship between said first and second potential signals and values of said first and second potential signals during the time said drive means is providing current to the first pair of regions of said conductive surface means, and for determining a second coordinate position of said probe means with respect to said conductive surface means from the relationship between said first and second potential signals and the values of said first and second potential signals during the time said drive means is providing current to the second pair of regions of said conductive surface means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An apparatus for determining at least three spatial coordinates of an object with respect to a surface, the apparatus comprising:
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conductive surface means, energizing means for energizing said conductive surface means; a plurality of reference means; distinguishng means for distinguishing each of said reference means; probe means for providing a signal corresponding to the reference means distinguished by said distinguishing means and to the location of said probe means in relationship to said conductive surface means; and signal processing means responsive to the signal provided by said probe means and to said energizing means for producing an output signal uniquely representative of the location of said probe means with respect to said conductive surface means. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A process for determining at least two spatial coordinates of an object with respect to a surface, which comprises:
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energizing a conductive surface along a first axis thereby creating a field in the vicinity of said conductive surface and along the first axis; sensing a first field potential difference between the location of the object and a first reference location; sensing a second field potential difference between the location of the object and a second reference location; summing the first and second sensed potential differences; scaling the first and second potential differences by a first scale variable to cause the sum to equal a constant; determining a first coordinate from the scaled first potential difference; energizing the conductive surface along a second axis substantially orthogonal to the first axis thereby creating a field in the vicinity of said conductive surface and along the second axis; sensing a third field potential difference between the location of the object and the first reference location; sensing a fourth field potential difference between the location of the object and the second reference location; summing the third and fourth sensed potential differences; scaling the third and fourth sensed potential differences by a second scale variable to cause the sum to equal a constant; and determining a second coordinate from the scaled third potential difference. - View Dependent Claims (27, 28)
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29. An apparatus for determining spatial coordinates of an object with respect to at least two surfaces comprising:
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first conductive surface means for carrying signals corresponding to at least two dimensional positional coordinates of the object with respect to said surface means; second conductive surface means for carrying signals corresponding to at least two dimensional positional coordinates of the object with respect to said surface means; energizing means for energizing said first and second conductive surface means; probe means for providing a probe signal corresponding to the signals carried by said first and second conductive surface means; and signal processing means responsive to the probe signal for producing output data uniquely representative of the location of said probe means with respect to at least a selected one of said first and second conductive surface means. - View Dependent Claims (33, 34, 35, 36)
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30. An apparatus for determining the spatial coordinates of an object with respect to a surface, the apparatus comprising:
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a plurality of conductive surface means, each carrying signals corresponding to at least two dimensional position coordinates of the object with respect to that particular surface means; energizing means for energizing each of said conductive surface means at an energizing frequency different from the energizing frequencies at which the other of said conductive surfaces are energized; a plurality of reference means on each of said conductive surface means; selecting means for selecting each of said reference means; probe means responsive to the energizing of at least one of said conductive surface means for providing a probe signal corresponding to the reference means selected, to the signals carried by the at least one of said conductive surface means and to the energizing frequency of the at least one of said conductive surface means; decoder means responsive to the probe signal for detecting the energizing frequency of the at least one of said conductive surface means and thereby determining which of said conductive surface means the probe signal is responsive to; and signal processing means responsive to the probe signal and to said energizing means for producing an output signal uniquely representative of the location of said probe means with respect to each of said conductive surface means to which the probe signal is responsive.
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31. An apparatus for determining the spatial position of a probe with respect to a conductive surface, comprising:
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conductive surface means having first and second pairs of regions; drive means for providing alternating current at a first frequency to the first pair of regions of said conductive means and for providing alternating current at a second frequency to the second pair of regions of said conductive means; reference position shift means for alternately clamping first and second locations on said conductive surface means to a reference potential, said reference position shift means alternately clamping the first and second locations to the reference potential while said drive means provides current in succession to each of the first and second pairs of regions per each reference position; probe means for providing a potential signal related to the potential on said conductive surface means at a point on said conductive surface means nearest to said probe means, said probe means providing a first potential signal when the first location on said conductive surface means is clamped to the reference potential by said reference position shift means and a second potential signal when the second location on said conductive surface means is clamped to the reference potential by said reference position shift means; and processor means for determining a first coordinate position of said probe means with respect to said conductive surface means from a relationship between said first and second potential signals and values of said first and second potential signals derived from the alternating current at said first frequency provided to the first pair of regions of said conductive surface means, and for determining a second coordinate position of said probe means with respect to said conductive surface means from the relationship between said first and second potential signals and the values of said first and second potential signals derived from the alternating current at said second frequency provided to the second pair of regions of said conductive surface means.
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32. An apparatus for determining the spatial position of a probe with respect to a conductive surface, comprising:
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conductive surface means having first and second pairs of regions; drive means for providing current to said first and second pairs of regions in quadrature, whereby the current is provided to said first and second pairs of regions with a phase difference of one-fourth of one period. reference position shift means for alternately clamping first and second locations on said conductive surface means to a reference potential, said reference position shift means alternately clamping the first and second locations to the reference potential while said drive means provides current in succession to each of the first and second pairs of regions per each reference position; probe means for providing a potential signal related to the potential on said conductive surface means at a point on said conductive surface means nearest to said probe means, said probe means providing a first potential signal when the first location on said conductive surface means is clamped to the reference potential by said reference position shift means and a second potential signal when the second location on said conductive surface means is clamped to the reference potential by said reference position shift means; and processor means for determining a first coordinate position of said probe means with respect to said conductive surface means from a relationship between the first and second potential signals and values of said first and second potential signals derived from the current provided at the first of two said phases one-fourth of one period apart to the first pair of regions of said conductive surface means, and for determining a second coordinate position of said probe means with respect to said conductive surface means from the relationship between said first and second potential signals and the values of said first and second potential signals derived from the current provided at the second of two said phases one-fourth of one period apart to the second pair of regions of said conductive surface means.
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Specification