Array sensors based on the magnetrostrictive delay line technique
First Claim
1. A sensor array comprising:
- a plurality of parallel stress-current annealed sensing magnetostrictive delay lines made of a magnetostrictive material,a plurality of parallel pulsed current conductors located at right angles to each one of said magnetostrictive delay lines, the crossing point of each one of said pulsed current conductors and each one of said magnetostrictive delay lines defining an acoustic stress point of origin of the sensor array,means for generating current pulses in said plurality of parallel pulsed current conductors, each one of said current pulses causing an acoustic stress at each one of said acoustic stress points of origin propagating along each one of said magnetostrictive delay lines,a plurality of magnetoresistive devices, each one of said magnetoresistive devices being located at a receiving point of each one of said magnetostrictive delay lines, each one of said magnetostrictive delay lines and each one of said pulsed current conductors and each one of said magnetoresistive devices defining a magnetic circuit of the sensor array, a change of magnetic flux being induced at each one of said plurality of magnetoresistive devices, as a result of each one of said plurality of acoustic stresses propagating along each one of said magnetostrictive delay lines, said change of magnetic flux producing a pulsed voltage output at the two ends of each one of said plurality of magnetoresistive devices,a plurality of means for inducing a change in said magnetic circuit and in one of said pulsed voltage outputs, each one of said means for inducing a change in said magnetic circuit being located at any point of each one of said magnetostrictive delay lines, said point being a sensing point of the sensor array,a plurality of small field magnets close to each one of said receiving points of said magnetostrictive delay lines to maximise each one of said pulsed voltage outputs,means for measuring the value of pulse width T of each one of said pulsed voltage outputs, said means being connected at said two ends of each one of said plurality of magnetoresistive devices and obtaining said pulsed voltage outputs therefrom, including a voltage threshold comparator to monitor said value of pulse width T of each one of said pulsed voltage outputs, said value being normalized by means of multiplying it with a weight factor, said weight factor being selected to be the inverse maximum pulse width of the corresponding said pulsed voltage output, said weight factor being retrieved from a previously electronically stored weight factor table.
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Abstract
Array sensors are described which are based on the magnetostrictive delay line technique, where sensing is based on the modification of the magnetic circuit along the magnetostrictive delay line. The proposed array sensors can perform a quantitative measurement of signals instead of the merely sensing activity performed by sensors of the prior art. Further advantageous characteristics of the proposed array sensors is that magnetoresistive devices and alternatively a detecting magnetostrictive delay line with two detecting coils at the ends thereof are used at the output of the sensor array, and that the detected pulsed width T is monitored instead of the peak voltage, this offering an improved response of the proposed array sensors. The above improvements are used in various applications and specifically are proposed novel digitizers and displacement sensors as well as a magnetic field distribution sensor.
24 Citations
23 Claims
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1. A sensor array comprising:
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a plurality of parallel stress-current annealed sensing magnetostrictive delay lines made of a magnetostrictive material, a plurality of parallel pulsed current conductors located at right angles to each one of said magnetostrictive delay lines, the crossing point of each one of said pulsed current conductors and each one of said magnetostrictive delay lines defining an acoustic stress point of origin of the sensor array, means for generating current pulses in said plurality of parallel pulsed current conductors, each one of said current pulses causing an acoustic stress at each one of said acoustic stress points of origin propagating along each one of said magnetostrictive delay lines, a plurality of magnetoresistive devices, each one of said magnetoresistive devices being located at a receiving point of each one of said magnetostrictive delay lines, each one of said magnetostrictive delay lines and each one of said pulsed current conductors and each one of said magnetoresistive devices defining a magnetic circuit of the sensor array, a change of magnetic flux being induced at each one of said plurality of magnetoresistive devices, as a result of each one of said plurality of acoustic stresses propagating along each one of said magnetostrictive delay lines, said change of magnetic flux producing a pulsed voltage output at the two ends of each one of said plurality of magnetoresistive devices, a plurality of means for inducing a change in said magnetic circuit and in one of said pulsed voltage outputs, each one of said means for inducing a change in said magnetic circuit being located at any point of each one of said magnetostrictive delay lines, said point being a sensing point of the sensor array, a plurality of small field magnets close to each one of said receiving points of said magnetostrictive delay lines to maximise each one of said pulsed voltage outputs, means for measuring the value of pulse width T of each one of said pulsed voltage outputs, said means being connected at said two ends of each one of said plurality of magnetoresistive devices and obtaining said pulsed voltage outputs therefrom, including a voltage threshold comparator to monitor said value of pulse width T of each one of said pulsed voltage outputs, said value being normalized by means of multiplying it with a weight factor, said weight factor being selected to be the inverse maximum pulse width of the corresponding said pulsed voltage output, said weight factor being retrieved from a previously electronically stored weight factor table. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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2. A sensor array adapted to work as a digitiser, comprising:
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a plurality of parallel stress-current annealed sensing magnetostrictive delay lines made of a magnetostrictive material, a first plurality of parallel pulsed current conductors located at right angles to said magnetostrictive delay lines, means for generating current pulses in each one of said plurality of pulsed current conductors, a cordless pen creating at least one acoustic stress propagating along at least one of said plurality of magnetostrictive delay lines when brought at any point above said plurality of magnetostrictive delay lines and said first plurality of pulsed current conductors, said point being a sensing point of the digitiser, a small field magnet close to said sensing point of the digitiser to maximize said acoustic stress propagating along at least one of said plurality of magnetostrictive delay lines, a detecting magnetostrictive delay line with two detecting coils at two ends thereof, said detecting magnetostrictive delay line being disposed at an angle of 45 degrees with respect to said plurality of sensing magnetostrictive delay lines, said acoustic stress propagating along at least one of said plurality of magnetostrictive delay lines resulting in a magnetic coupling between said at least one of said plurality of magnetostrictive delay lines and said detecting magnetostrictive delay line, said magnetic coupling inducing a pulsed voltage output at said detecting coils on either side of said magnetostrictive delay line, a small field magnet close to each one of said two detecting coils at the ends of said detecting magnetostrictive delay line to maximize said pulsed voltage output, and means for measuring the value of pulse width T of said pulsed voltage output, said means being connected at said two detecting coils at the two ends of said detecting magnetostrictive delay line and obtaining said pulsed voltage output therefrom, said means including a voltage threshold comparator to monitor said value of the output pulse width T, said value being normalized by means of multiplying it with a weight factor, said weight factor being selected to be the inverse maximum pulse width of the corresponding said pulsed voltage output, said weight factor being retrieved from a previously electronically stored weight factor table. - View Dependent Claims (12, 13)
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Specification