Remotely readable data storage devices and apparatus
AssigneeScientific Generics Limited
InventorsAndrew N. Dames, Peter J. Hyde
Life of this patent
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Abstract
A magnetostrictive element, which may be of rectangular shape, is positioned next to a hard magnetic biasing element field with patterns recorded therein which bias the magnetostrictive element to resonate at selected frequencies, particularly harmonics of the fundamental frequency, in response to an alternating interrogating magnetic field at the same frequencies. Data may thus be encoded by selecting the frequencies at which the element will resonate. In addition to resonance at different harmonics, resonance in different modes, particularly longitudinal, transverse or flexural modes may be produced. The device may be applied to article identity systems, such as security systems but also has many other applications.
Claims39
A data storage device comprising:
- a piece of magnetostrictive material, and
- a magnetic bias field producing means for biasing said piece to resonate at a predetermined frequency in response to an applied interrogating alternating magnetic field at said predetermined frequency,
- said magnetic bias field producing means producing a magnetic field pattern relative to said piece which causes resonance in said piece at a plurality of different predetermined natural frequencies in response to an applied interrogating alternating magnetic field at said predetermined frequencies.
A data storage device comprising:
- a piece of magnetostrictive material, and
- a magnetic field producing means, said magnetic field producing means being arranged for producing in said piece a field pattern for causing said piece to resonate at a predetermined frequency in response to an applied interrogating alternating field at said predetermined frequency, said field pattern having a strength which varies as a smoothly curved function over said piece.
A data storage device comprising:
- a piece of magnetostrictive material, and
- a magnetic field producing means for producing in said piece a biasing field pattern which is such that said piece will resonate in a non-longitudinal mode in response to an applied interrogating magnetic field of a predetermined frequency.
A magnetically detectable magnetostrictive device which comprises:
- a piece of magnetostrictive material adapted to respond to an interrogating alternating magnetic field, means for providing a magnetic bias field pattern relative to said piece, and
- flux concentrating means separate from and adjacent to said piece, the flux concentrating means being shaped for concentrating the flux of the interrogating field in the region containing the piece.
A data storage device comprising:
- a piece of magnetostrictive material, and
- a magnetic field producing means, said magnetic field producing means being arranged for producing in said piece a field pattern such that said piece will resonate at a predetermined frequency higher than its natural frequency in response to an applied interrogating alternating field at said predetermined frequency.
Dependencies are inferred from the claim text.