Magnetic field detection device
First Claim
1. A magnetic field detection device comprising:
- a magneto-impedance element whose impedance changes according to an external magnetic field, a detector coil that converts changes in impedance detected by said magneto-impedance element into electric signals, a negative feedback coil that controls the internal magnetic field of said magneto-impedance element, and a frequency characteristic affording means provided in a negative feedback circuit which connects an output terminal thereof with said negative feedback coil and for affording a frequency characteristics on negative feedback signals of said negative feedback circuit.
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Abstract
The present invention is a magnetic field detection device that makes use of a frequency characteristic affording circuit in order to selectively detect magnetic signals from a frequency domain accurately at a high level of sensitivity. The present invention has a magneto-impedance element, a detector coil and a negative feedback coil which is wound around the magneto-impedance element, and a frequency characteristic affording circuit which affords a frequency characteristics on the negative feedback signal of a negative feedback connecting an output terminal thereof with the negative feedback coil. Using filters as the frequency characteristic affording circuit, the following are possible uses of this magnetic field detection device: a geomagnet detection device for earthquake prediction (using a high-pass filter), a bill validation apparatus for vending machines, etc. (using a low-pass filter), and a magnetic oscillation detection device for a magnetic gate system (using a band-reject filter).
16 Citations
22 Claims
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1. A magnetic field detection device comprising:
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a magneto-impedance element whose impedance changes according to an external magnetic field, a detector coil that converts changes in impedance detected by said magneto-impedance element into electric signals, a negative feedback coil that controls the internal magnetic field of said magneto-impedance element, and a frequency characteristic affording means provided in a negative feedback circuit which connects an output terminal thereof with said negative feedback coil and for affording a frequency characteristics on negative feedback signals of said negative feedback circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification