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US 2015/0316622 A1Published application
Magnetism detection device
AssigneesIndependent Administrative Institution National Traffic Safety and Environment Laboratory, Hano Manufacturing Co., Ltd.
InventorsTakeshi Mizuma, Shinjiro Takeuchi
Life of this patent
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Abstract
An apparatus for detecting magnetism includes a self-exciting fluxgate type magnetic oscillation sensor in each of three axes perpendicular to one another, the magnetic oscillation sensor includin a magnetism sensor including a core-coil including a core made of a magnetic material and a coil wound around the core, and an operational amplifier circuit causing an AC excitation current to run through the coil to generate an output in accordance with a strength of an external magnetic field applied to the core. An air core coil not wound around a core is arranged in the vicinity of and in parallel with the core-coil of each of the magnetic oscillation sensors arranged in each of the axes.
Claims3
An apparatus for detecting magnetism, including comprising:
- a self-exciting fluxgate type magnetic oscillation sensor in each of three axes perpendicular to one another, the magnetic oscillation sensor including comprising:
- a magnetism sensor comprised of a core-coil including a core made of a magnetic material, and a coil wound around the core;
- and
- an operational amplifier circuit causing an AC excitation current to run through the coil to generate an output in accordance with a strength of an external magnetic field applied to the core,
- wherein an air core coil not wound around a core is arranged in the vicinity of and in parallel with the core-coil of each of the magnetic oscillation sensors arranged in each of the axes,
- wherein a node through which a non-earthed terminal of the core-coil in each of the axes and one of terminals of the air core coil is electrically connected is electrically connected to a non-inverted input terminal of the operational amplifier circuit,
- wherein the other terminal of the air core coil and an output terminal of the operational amplifier circuit are electrically connected to each other through a passive element,
- wherein when the core-coil of the magnetism sensor is excited with an excitation current, the operational amplifier circuit generates a current by which a magnetic field having the same strength as that of the leakage magnetic field and having a direction opposite to a direction of the leakage magnetic field is generated, and supplies the current to the air core coil,
- wherein an output terminal of the operational amplifier circuit included in the magnetic oscillation sensor in each of the axes and a terminal of the air core coil in the subsequent axis are electrically connected to each other through an electrical connector to thereby construct a loop-type oscillation-synchronization signal circuit network for unifying oscillation frequencies of the magnetic oscillation sensors in each of the axes, in order to avoid beat phenomenon caused by a difference among oscillation frequencies of the magnetic oscillation sensors in the axes, and
- wherein a core of the magnetism sensor is compulsorily excited by a unified magnetic oscillation frequency by virtue of an excitation current comprised of a combination of an oscillation-synchronization signal running through the oscillation-synchronization signal circuit network, and an excitation current output from the operational amplifier circuit.
7 more elements
An apparatus for detecting magnetism, comprising:
- a self-exciting fluxgate type magnetic oscillation sensor in each of three axes perpendicular to one another,
- the magnetic oscillation sensor comprising:
- a magnetism sensor comprised of a core-coil including a core made of a magnetic material, and
- a coil wound around the core;
- and
- an operational amplifier circuit causing an AC excitation current to run through the coil to generate an output in accordance with a strength of an external magnetic field applied to the core,
- wherein an air core coil not wound around a core is arranged in the vicinity of and in parallel with the core-coil of each of the magnetic oscillation sensors arranged in each of the axes,
- wherein a node through which a non-earthed terminal of the core-coil in each of the axes and one of terminals of the air core coil is electrically connected is electrically connected to a non-inverted input terminal of the operational amplifier circuit,
- wherein the other terminal of the air core coil and an output terminal of the operational amplifier circuit are electrically connected to each other through a passive element,
- wherein when the core-coil of the magnetism sensor is excited with an excitation current, the operational amplifier circuit generates a current by which a magnetic field having the same strength as that of the leakage magnetic field and having a direction opposite to a direction of the leakage magnetic field is generated, and supplies the current to the air core coil,
- wherein a terminal of the air core coil in each of the axes and a common terminal are electrically connected to each other through an electrical connector to thereby construct a star-type oscillation-synchronization signal circuit network for unifying oscillation frequencies of the magnetic oscillation sensors in each of the axes, in order to avoid beat phenomenon caused by a difference among oscillation frequencies of the magnetic oscillation sensors in the axes, and
- wherein a core of the magnetism sensor is compulsorily excited by a unified magnetic oscillation frequency by virtue of an excitation current comprised of a combination of an oscillation-synchronization signal running through the oscillation-synchronization signal circuit network, and an excitation current output from the operational amplifier circuit.
9 more elements
Dependencies are inferred from the claim text.