Digitizer for position sensing

Claim 1

A method for determining the positional coordinates of a pointer movable relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method comprising the steps of: (a) storing information functionally related to the characteristic shape of said response curve; (b) measuring said responses produced when said pointer is at an unknown positional coordinate relative to said planar pad; and (c) mathematically fitting said measured responses to a functional expression which represents said characteristics shape of said response curve to determine said positional coordinates of said pointer.

Claim 2

A method for determining the positional coordinates of a pointer movable relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method comprising the steps of: (a) storing information functionally related to the characteristic shape of said response curve; (b) measuring said responses produced when said pointer is at an unknown positional coordinate relative to said planar pad; and (c) mathematically fitting said measured responses to a functional expression which represents said characteristics shape of said response curve to determine said positional coordinates of said pointer.

Claim 6

A method for determining the positional coordinates of a pointer movable relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method, for each axis comprising the steps of: (a) measuring said responses at a plurality of predetermined positional coordinates to obtain a plurality of calibration values; (b) mathematically fitting said plurality of calibration values to a polynomial to obtain therefrom a plurality of polynomial coefficients for said polynomial which define a polynomial response function representing said characteristic shape of said response curve; (c) measuring responses produced when said pointer is at an unknown positional coordinate relative to said planar pad; and (d) mathematically fitting said measured responses to said polynomial response function to determine therefrom said unknown positional coordinate of said pointer.

Claim 7

A method for determining the positional coordinates of a pointer movable relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method, for each axis comprising the steps of: (a) measuring said responses at a plurality of predetermined positional coordinates to obtain a plurality of calibration values; (b) mathematically fitting said plurality of calibration values to a polynomial to obtain therefrom a plurality of polynomial coefficients for said polynomial which define a polynomial response function representing said characteristic shape of said response curve; (c) measuring responses produced when said pointer is at an unknown positional coordinate relative to said planar pad; and (d) mathematically fitting said measured responses to said polynomial response function to determine therefrom said unknown positional coordinate of said pointer.

Claim 15

A method for making an initial coarse determination of the position of a pointer relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method, for each axis, comprising the steps of: (a) selecting a group of said spaced conductors located at one edge of said grid; (b) measuring the responses for each conductor of said group; (c) mathematically fitting the measured responses to a functional expression of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2 )+C.sub.3 which represents the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 is the distance along said planar pad from said pointer to the nearest of said spaced conductors, and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine the values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group; (d) storing the value of C 1 and the location of said group of conductors; (e) successively selecting next groups of conductors each spatially offset from the previously selected group of conductors by one conductor spacing and determining and storing for each of said next groups the value of C 1 and the location of said group in accordance with the above steps (b), (c) and (d), for each of said successively selected groups of conductors comparing the value of C 1 to the previously stored value of C 1 , retaining the greater of the two values of C 1 and the corresponding location of said group of conductors associated with said greater value until all the conductors along said axis have been so selected to determine therefrom which of said group of conductors corresponds to a maximum value of C 1 ; and (f) determining the coordinate of said conductor nearest said pointer from the location of said group of conductors corresponding to said maximum value of C 1 , which coordinate defines the coarse location of said pointer along each of said axes.

Claim 16

A method for making an initial coarse determination of the position of a pointer relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method, for each axis, comprising the steps of: (a) selecting a group of said spaced conductors located at one edge of said grid; (b) measuring the responses for each conductor of said group; (c) mathematically fitting the measured responses to a functional expression of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2 )+C.sub.3 which represents the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 is the distance along said planar pad from said pointer to the nearest of said spaced conductors, and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine the values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group; (d) storing the value of C 1 and the location of said group of conductors; (e) successively selecting next groups of conductors each spatially offset from the previously selected group of conductors by one conductor spacing and determining and storing for each of said next groups the value of C 1 and the location of said group in accordance with the above steps (b), (c) and (d), for each of said successively selected groups of conductors comparing the value of C 1 to the previously stored value of C 1 , retaining the greater of the two values of C 1 and the corresponding location of said group of conductors associated with said greater value until all the conductors along said axis have been so selected to determine therefrom which of said group of conductors corresponds to a maximum value of C 1 ; and (f) determining the coordinate of said conductor nearest said pointer from the location of said group of conductors corresponding to said maximum value of C 1 , which coordinate defines the coarse location of said pointer along each of said axes.

Claim 17

A method for determining the fine position of a pointer movable relative to a planar pad having sets of spaced conductors arranged along orthogonal axes thereof, said fine position being the distance along said planar pad of said pointer from a conductor previously determined to be nearest said pointer, said spaced conductor and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method, for each axis, comprising the steps of: (a) selecting a group of said spaced conductors including said conductor nearest said pointer; (b) measuring the responses for each conductor of said group; (c) mathematically fitting the measured responses to a function of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2)+C.sub.3 which represents the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 is said fine position, and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group, said value of C 2 determined therefrom corresponding to the fine position of said pointer along each of said axes.

Claim 18

A method for determining the fine position of a pointer movable relative to a planar pad having sets of spaced conductors arranged along orthogonal axes thereof, said fine position being the distance along said planar pad of said pointer from a conductor previously determined to be nearest said pointer, said spaced conductor and pointer being energized to produce responses which form a response curve dependent upon the distance between said pointer and said energized spaced conductors, said method, for each axis, comprising the steps of: (a) selecting a group of said spaced conductors including said conductor nearest said pointer; (b) measuring the responses for each conductor of said group; (c) mathematically fitting the measured responses to a function of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2)+C.sub.3 which represents the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 is said fine position, and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group, said value of C 2 determined therefrom corresponding to the fine position of said pointer along each of said axes.

Claim 22

An apparatus comprising: (a) a planner pad having spaced conductors arranged along orthogonal axes thereof to form a grid; (b) a pointer capable of being moved along said planar pad; (c) energizing means to produce responses dependent upon the distance between said pointer and said energized spaced conductors which form a response curve; and (d) a control system including a microprocessor having means for controlling said energizing means and means for determining the positional coordinates of said pointer along each axis as it is moved relative to said planar pad, by the steps of: (i) storing information functionally related to the characteristic shape of said response curve; (ii) measuring the responses produced when said pointer is at unknown positional coordinate; and (iii) mathematically fitting said measured response to a functional expression which represents said characteristic shape of said response curve to determine therefrom said unknown positional coordinate of said pointer.

Claim 23

An apparatus comprising: (a) a planner pad having spaced conductors arranged along orthogonal axes thereof to form a grid; (b) a pointer capable of being moved along said planar pad; (c) energizing means to produce responses dependent upon the distance between said pointer and said energized spaced conductors which form a response curve; and (d) a control system including a microprocessor having means for controlling said energizing means and means for determining the positional coordinates of said pointer along each axis as it is moved relative to said planar pad, by the steps of: (i) storing information functionally related to the characteristic shape of said response curve; (ii) measuring the responses produced when said pointer is at unknown positional coordinate; and (iii) mathematically fitting said measured response to a functional expression which represents said characteristic shape of said response curve to determine therefrom said unknown positional coordinate of said pointer.

Claim 27

An apparatus comprising: (a) a planner pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer capable of being moved relative to said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means, and means for determining positional coordinates of said pointer along each axis as it is moved relative to said planar pad by the steps of: (i) measuring said responses at a plurality of predetermined positional coordinates to obtain a plurality of calibration values which are stored therein; (ii) mathematically fitting said plurality of calibration values to a polynomial to obtain therefrom a plurality of polynomial coefficients which are stored therein to define the characteristic shape of said response curve; (iii) measuring said responses corresponding to an unknown positional coordinate of said pointer along said axis; and (iv) mathematically fitting said measured responses to said polynomial to obtain therefrom said positional coordinate of said pointer along said axis.

Claim 28

An apparatus comprising: (a) a planner pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer capable of being moved relative to said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means, and means for determining positional coordinates of said pointer along each axis as it is moved relative to said planar pad by the steps of: (i) measuring said responses at a plurality of predetermined positional coordinates to obtain a plurality of calibration values which are stored therein; (ii) mathematically fitting said plurality of calibration values to a polynomial to obtain therefrom a plurality of polynomial coefficients which are stored therein to define the characteristic shape of said response curve; (iii) measuring said responses corresponding to an unknown positional coordinate of said pointer along said axis; and (iv) mathematically fitting said measured responses to said polynomial to obtain therefrom said positional coordinate of said pointer along said axis.

Claim 36

An apparatus comprising (a) a planner pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer capable of being moved relative to said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means and means for determining an initial coarse position along each axis when said pointer if first placed onto said planar pad by the steps of: (i) selecting a group of said spaced conductors located at one edge of said grid; (ii) measuring the responses for each conductor of said group; (iii) fitting the measured responses to a function of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2)+C.sub.3 representing the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 the distance along said planar pad from said pointer to the nearest of said spaced conductors, and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine the values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group; (iv) storing the value of C 1 and the location of said group of conductors; (v) successively selecting next groups of conductors each spatially offset from the previously selected group of conductors by one conductor spacing and determining and storing for each of said next groups the value of C 1 and the location of the group in accordance with the above steps (ii) (iii), and (iv) for each of said successively selected groups of conductors comparing the value of C 1 to the previously stored value of C 1 , retaining the greater of these two values of C 1 and the corresponding location of said group of conductors associated with said greater value until all the conductors along said axis have been so selected to determine therefrom which of said group of conductors corresponds to a maximum value of C 1 ; (vi) determining the coordinate of said conductor nearest said pointer from the location of said group of conductors corresponding to said maximum value of C 1 , which coordinate defines the coarse location of said pointer.

Claim 37

An apparatus comprising (a) a planner pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer capable of being moved relative to said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means and means for determining an initial coarse position along each axis when said pointer if first placed onto said planar pad by the steps of: (i) selecting a group of said spaced conductors located at one edge of said grid; (ii) measuring the responses for each conductor of said group; (iii) fitting the measured responses to a function of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2)+C.sub.3 representing the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 the distance along said planar pad from said pointer to the nearest of said spaced conductors, and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine the values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group; (iv) storing the value of C 1 and the location of said group of conductors; (v) successively selecting next groups of conductors each spatially offset from the previously selected group of conductors by one conductor spacing and determining and storing for each of said next groups the value of C 1 and the location of the group in accordance with the above steps (ii) (iii), and (iv) for each of said successively selected groups of conductors comparing the value of C 1 to the previously stored value of C 1 , retaining the greater of these two values of C 1 and the corresponding location of said group of conductors associated with said greater value until all the conductors along said axis have been so selected to determine therefrom which of said group of conductors corresponds to a maximum value of C 1 ; (vi) determining the coordinate of said conductor nearest said pointer from the location of said group of conductors corresponding to said maximum value of C 1 , which coordinate defines the coarse location of said pointer.

Claim 38

An apparatus comprising: (a) a planar pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer capable of being moved along said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means and means for determining the distance of said pointer from a conductor previously determined to be nearest said pointer by performing, for each axis, the steps of: (i) selecting a group of said spaced conductors including said conductor nearest said pointer; (ii) measuring the responses for each conductor of said group; (iii) mathematically fitting the measured responses to a function of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2)+C.sub.3 which represents the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term for said pointer having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 is the distance from said pointer to said nearest of said spaced conductors and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group, said value of C 2 determined thereby corresponding to the distance of said pointer from said nearest conductor.

Claim 39

An apparatus comprising: (a) a planar pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer capable of being moved along said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means and means for determining the distance of said pointer from a conductor previously determined to be nearest said pointer by performing, for each axis, the steps of: (i) selecting a group of said spaced conductors including said conductor nearest said pointer; (ii) measuring the responses for each conductor of said group; (iii) mathematically fitting the measured responses to a function of the form Y.sub.i =C.sub.1 f(x.sub.i +C.sub.2)+C.sub.4 g(x.sub.i +C.sub.2)+C.sub.3 which represents the response Y i for a conductor at coordinate x i , where f(x) is an amplitude term for said pointer having a gain coefficient C 1 , g(x) is a tilt term having a tilt coefficient C 4 , C 2 is the distance from said pointer to said nearest of said spaced conductors and C 3 represents an offset term, said fitting being performed by a least-squares technique to determine values of C 1 , C 2 , C 3 and C 4 which fit said measured responses for said group, said value of C 2 determined thereby corresponding to the distance of said pointer from said nearest conductor.

Claim 43

A method for determining the tilt angle of a pointer positioned on and movable over a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the tilt angle and distance between said pointer and said energized spaced conductors, said method comprising the steps of: (a) storing information functionally related to the characteristic shape of said response curve; (b) measuring responses produced when said pointer is at an unknown position and tilt angle relative to said planar pad; and (c) mathematically fitting said measured responses to a functional expression which represents said characteristic shape of said response curve to determine therefrom said tilt angle and position of said pointer.

Claim 44

A method for determining the tilt angle of a pointer positioned on and movable over a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the tilt angle and distance between said pointer and said energized spaced conductors, said method comprising the steps of: (a) storing information functionally related to the characteristic shape of said response curve; (b) measuring responses produced when said pointer is at an unknown position and tilt angle relative to said planar pad; and (c) mathematically fitting said measured responses to a functional expression which represents said characteristic shape of said response curve to determine therefrom said tilt angle and position of said pointer.

Claim 48

A method for determining the positional coordinate and tilt angle of a pointer movable relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the tilt angle and distance between said pointer and said energized spaced conductors, said method comprising the steps of: (a) storing information functionally related to the characteristic shape of said response curve; (b) measuring responses produced when said pointer is at an unknown positional coordinate and tilt angle relative to said planar pad; (c) mathematically fitting said measured responses to a functional expression which includes parameters representing said positional coordinate and tilt angle to determine therefrom values for said parameters.

Claim 49

A method for determining the positional coordinate and tilt angle of a pointer movable relative to a planar pad having spaced conductors arranged along orthogonal axes thereof, said spaced conductors and pointer being energized to produce responses which form a response curve dependent upon the tilt angle and distance between said pointer and said energized spaced conductors, said method comprising the steps of: (a) storing information functionally related to the characteristic shape of said response curve; (b) measuring responses produced when said pointer is at an unknown positional coordinate and tilt angle relative to said planar pad; (c) mathematically fitting said measured responses to a functional expression which includes parameters representing said positional coordinate and tilt angle to determine therefrom values for said parameters.

Claim 50

An apparatus comprising: (a) a planar pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer movable relative to said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the tilt angle and distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means, and means for determining said positional coordinate and tilt angle of said pointer, for each axis as it is moved along said planar pad, by the steps of: (i) storing information functionally related to the characteristic shape of said response curve; (ii) measuring responses produced when said pointer is at an unknown positional coordinate and tilt angle relative to said planar pad; (iii) mathematically fitting said measured responses to a functional expression which includes parameters representing said positional coordinate and tilt angle to determine therefrom values for said parameters.

Claim 51

An apparatus comprising: (a) a planar pad having spaced conductors arranged along orthogonal axes thereof; (b) a pointer movable relative to said planar pad; (c) energizing means to produce responses which form a response curve dependent upon the tilt angle and distance between said pointer and said spaced conductors; and (d) a control system including a microprocessor having means for controlling said energizing means, and means for determining said positional coordinate and tilt angle of said pointer, for each axis as it is moved along said planar pad, by the steps of: (i) storing information functionally related to the characteristic shape of said response curve; (ii) measuring responses produced when said pointer is at an unknown positional coordinate and tilt angle relative to said planar pad; (iii) mathematically fitting said measured responses to a functional expression which includes parameters representing said positional coordinate and tilt angle to determine therefrom values for said parameters.