Position determination device
First Claim
1. An automatic coordinate determining device comprising:
- a tablet having a grid of parallel spaced electrical conductors;
a longitudinal magnetostrictive element with an axis transverse to said conductors;
a device movable over the surface of said tablet and including a flux producing element inductively coupled to at least one of said parallel conductors;
means for energizing said flux producing element to induce an electrical current in said one conductor, said current in turn inducing a first strain wave in said magnetostrictive element at a region adjacent said one conductor, said strain wave being propagated along the axis of said magnetostrictive element; and
sensing means comprising a delay line for producing an output in response to said strain wave, said delay line including a plurality of serially connected inductive coils inductively coupled to said magnetostrictive element, a capacitor coupling each of said plurality of inductive coils to a common reference potential, and terminating impedance connecting the last of said plurality of inductive coils to said common ground.
1 Assignment
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Accused Products
Abstract
A position determining device has two perpendicular longitudinal magnetostrictive elements. A grid of a plurality of closed loop conductors has two parallel straight legs which form the grid. A flux producing element inductively coupled to at least one of said grid conductors causes an electrical current in that conductor. In turn that current induces a strain wave in the magnetostrictive element. Near the end of the magnetostrictive element is a sensing means to detect the strain wave comprising a lumped inductive capacitive delay line substantially having a plurality of evenly spaced inductive coils aligned with the magnetostrictive elements.
The lumped delay line is defined by the formulas ##EQU1## where w is the overall length of the delay line; L is the total inductance, C is the total capacitance, Z is the terminating impedance, c is capacitance of the capacitance associated with each coil, and n is the number of coils.
42 Citations
15 Claims
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1. An automatic coordinate determining device comprising:
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a tablet having a grid of parallel spaced electrical conductors; a longitudinal magnetostrictive element with an axis transverse to said conductors; a device movable over the surface of said tablet and including a flux producing element inductively coupled to at least one of said parallel conductors; means for energizing said flux producing element to induce an electrical current in said one conductor, said current in turn inducing a first strain wave in said magnetostrictive element at a region adjacent said one conductor, said strain wave being propagated along the axis of said magnetostrictive element; and sensing means comprising a delay line for producing an output in response to said strain wave, said delay line including a plurality of serially connected inductive coils inductively coupled to said magnetostrictive element, a capacitor coupling each of said plurality of inductive coils to a common reference potential, and terminating impedance connecting the last of said plurality of inductive coils to said common ground. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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5. An automatic coordinate determining device as in claim 1 including initializing means.
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6. An automatic coordinate determining device as in claim 5 wherein said initializing means includes means to produce a uniform magnetic field in the near neighborhood of said magnetostrictive element.
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7. An automatic coordinate determining device as in claim 6 wherein said means to produce a uniform magnetic field includes a wire coil.
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8. An automatic coordinate determining device as in claim 7 wherein said magneostrictive element is substantially coincident with the axis of said wire coil.
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9. An automatic coordinate determining device as in claim 1 including a fiducial coil to calibrate the device including a wire having a plurality of turns around said magnetostrictive element and means to induce a pulse in said wire.
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10. An automatic coordinate determining device as in claim 1 wherein each of said spaced electrical conductors is a portion of a closed loop having one section thereof in parallel to said magnetostrictive element.
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11. An automatic coordinate determining device comprising:
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an elongated magnetostrictive element; a tablet having an array of a plurality of conductors including two parallel straight conductors joined by a wire, said wire being perpendicular to said two parallel conductors and parallel to and inductively coupled to said magnetostrictive element; a device movable over the surface of said tablet and including a flux producing element inductively coupled to at least one of said conductors; means for energizing said flux producing element to produce an electrical current in said one conductor, said current in turn inducing a first strain wave in said magnetostrictive element at a region adjacent said wire joining said two conductors;
said strain wave being propagated along said magnetostrictive element;a sensing means comprising a lumped inductive-capacitive delay line inductively coupled to and substantially aligned with said magnetostrictive delay line for producing an output in response to said strain wave, where the transversal time of said delay line is substantially represented by w v, where w is the overall length of the lumped delay line, v is the velocity of sound in the magnetostrictive element, and wherein the total capacitance C is determined by ##EQU15## wherein L is the total inductance of the lumped delay line C is the capacitance of the lumped delay line, and a terminating impedance substantially represented by ##EQU16## where Z is the terminating impedance. - View Dependent Claims (12, 13)
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13. A coordinate determining device as in claim 12 including a permanent magnet aligned with said coils.
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14. An automatic coordinate determining device comprising:
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a tablet having a first plurality of parallel spaced electrical first conductors and a second plurality of parallel spaced electrical second conductors, the first and second conductors being normal to each other; first and second longitudinal magnetostrictive elements having axes transverse of said first and second conductors; a device movable over the surface of said tablet and including a flux producing element inductively coupled to at least one of said first and one of said second parallel conductors; means for energizing said flux producing element to induce an electric current in said one first and said one second conductor, said current in turn inducing first and second strain waves in said first and second magnetostrictive elements respectively at a region adjacent said one conductor of said first and second pluralities of conductors respectively, said strain waves being propagated along the axes of said first and second magnetostrictive elements, respectively; and first and second sensing means each comprising a delay line for producing an output in response to the strain wave of the respective first and second magnetostrictive elements, said delay lines including a plurality of serially connected inductive coils inductively coupled to the respective said magnetostrictive element, a capacitor coupling each of plurality of inductive coils to a common reference potential, and a terminating impedance connecting the last of the plurality of respective inductive coils to said common ground. - View Dependent Claims (15)
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Specification