Aichi Steel Corporation

Akihiro Shimode

Norihiko Hamada

Michiharu Yamamoto

Yoshinobu Honkura

Shunichi Tatematsu

Masayuki Kato

A magneto-sensitive wire for a magnetic sensor with both measurement range expansion and environment resistance performance improvement, includes a Co-based alloy containing more Fe than a reference composition that is amorphous overall and exhibits zero magnetostriction. The Co-based alloy may have an Fe ratio (Fe/(Co+Fe+Ni)) of 6.1% to 9.5%. The Fe ratio is an atomic fraction of the Fe amount with respect to the total amount of a magnetic element group consisting of Co, Fe, and Ni. By heating an amorphous wire of a Co-based alloy at a temperate at least equal to a crystallization start temperature and lower than a crystallization end temperature, allows the magneto-sensitive wire to have a composite structure in which crystal grains are dispersed in the amorphous phase. The magneto-sensitive wire's anisotropy field is, for example, 5 to 70 Oe and the stress sensitivity, indicative of magnetostriction, is −30 to 30 mOe/MPa.

Magneto-sensitive wire and manufacturing method therefor

An object is to provide a magneto-sensitive wire that exhibits a stable anisotropic magnetic field even under a high-temperature environment and can achieve expansion of the measurement range of an MI sensor, etc. The present invention provides a magneto-sensitive wire for magnetic sensors that comprises a Co-based alloy having a composite structure in which crystal grains are dispersed in an amorphous phase. The Co-based alloy contains 0.05 to 0.80 at %, preferably 0.10 to 0.60 at %, of Cu with respect to 100 at % of the Co-based alloy as a whole. The Co-based alloy may further contain 65 to 90 at % of the group of magnetic elements consisting of Co, Fe, and Ni as the total, 15 to 27 at % of Si and/or B as the total, and 0.5 to 2.5 at % of Mo. Such a magneto-sensitive wire is excellent in the heat resistance and exhibits a stable anisotropic magnetic field even under a high-temperature environment. By using the magneto-sensitive wire of the present invention, it is possible, for example, to efficiently produce an MI sensor with an expanded measurement range.

Magneto-sensitive wire for magnetic sensors and production method therefor

A magneto-sensitive wire (magneto-sensitive body) made of a Co-based alloy having a composite structure in which crystal grains are dispersed in an amorphous phase. The Co-based alloy is, for example, a Co&#x2014;Fe&#x2014;Si&#x2014;B-based alloy, and the total amount of Si and B is preferably 20 to 25 at % with respect to the Co-based alloy as a whole. Preferably, the average diameter of the crystal grains is 70 nm or less and the area ratio of the crystal grains is 10% or less to the composite structure as a whole. The magneto-sensitive wire has a circular cross section and the wire diameter is about 1 to 100 &#x3bc;m. Such a magneto-sensitive wire can be obtained, for example, through a heat treatment step of heating an amorphous wire composed of a Co-based alloy at a temperature equal to or higher than a crystallization start temperature and lower than a crystallization end temperature.

Magneto-sensitive wire for magnetic sensor and production method therefor

A magneto-sensitive wire for a magnetic impedance sensor and a method of manufacturing the same are provided which can prevent generation of abnormal noise in an output voltage and deterioration in hysteresis characteristics and enable higher-accuracy measurement than conventional magneto-sensitive wires. The magneto-sensitive wire () comprises an amorphous wire for detecting magnetism. The magnetic impedance sensor () has the magneto-sensitive wire () and a detection coil () around the magneto-sensitive wire (). The magnetic impedance sensor () is configured to apply a pulse current to the magneto-sensitive wire () and detect a voltage generated in the detection coil () thereby capable of measuring strength of a magnetic field. The voltage has magnitude in response to strength of an external magnetic field. The magneto-sensitive wire () is a Co-based amorphous wire manufactured using an in-rotating liquid spinning method and finished by wire drawing. The magneto-sensitive wire () is subjected to removal treatment for a process-affected residual layer generated at a surface and near the surface due to finishing by the wire drawing.

Magneto-sensitive wire for magnetic impedance sensor capable of high-accuracy measurement and method of manufacturing same

Apparatus for heat treating magnetic wire includes a wire supply unit, a wire property measuring unit, a wire tensile force measuring unit, a heat treatment unit, and a wire winding unit. The wire supply unit includes a supply bobbin, a supply rotary part, a wire reel, and a tension roller. The wire property measuring unit includes a size measuring device, an after measurement capstan, and a wire reel and measures a size of the wire prior to the heat treatment. The wire tensile force measuring unit includes a tensile force measuring device, a tension roller, and a wire reel. The wire heat treatment unit includes a heat treatment furnace, a temperature measuring device, an after heat treatment capstan, and a wire reel. The wire winding unit includes a winding bobbin, a winding rotary part that rotates the winding bobbin, a tension roller, and a wire reel.

Apparatus for treating magnetic wire and method for treating the same

Method for heat treating magnetic wire includes a wire supply unit, a wire property measuring unit, a wire tensile force measuring unit, a heat treatment unit, and a wire winding unit. The wire supply unit includes a supply bobbin, a supply rotary part, a wire reel, and a tension roller. The wire property measuring unit includes a size measuring device, an after measurement capstan, and a wire reel and measures a size of the wire prior to the heat treatment. The wire tensile force measuring unit includes a tensile force measuring device, a tension roller, and a wire reel. The wire heat treatment unit includes a heat treatment furnace, a temperature measuring device, an after heat treatment capstan, and a wire reel. The wire winding unit includes a winding bobbin, a winding rotary part that rotates the winding bobbin, a tension roller, and a wire reel.

The magneto-sensitive wire of the invention has a vortex-spin structure and hence includes no magnetic domain walls, so that the magneto-sensitive wire of the invention has an excellent hysteresis characteristic exhibiting nearly zero hysteresis. Therefore, the linearity related to the output voltage characteristic for the applied magnetic field in the determination range of an MI sensor is significantly improved as compared to MI sensors using the conventional magneto-sensitive wires. Using the magneto-sensitive wire of the invention makes it possible to provide a magneto-impedance (MI) element exhibiting a higher precision than the conventional ones and further provide a sensor using such an MI element.

Magneto-sensitive wire, magneto-impedance element and magneto-impedance sensor

Provided is a magnetoimpedance (MI) sensor having a high magnetic sensor sensitivity and a wide measurement range. The MI sensor comprises an MI element, an electric current supply unit and a signal processing circuit. The MI element comprises a magnetosensitive wire formed of an amorphous soft magnetic alloy having zero magnetostriction, and a detection coil provided around the magnetosensitive wire with an electric insulator disposed therebetween, thereby detecting voltage generated at the detection coil and corresponding to an external magnetic field upon application of a high frequency electric current to the magnetosensitive wire. The electric current supply unit supplies the high frequency electric current to the MI element. The signal processing circuit processes an output signal from the detection coil. In this MI sensor, the magnetosensitive wire has at least a surface layer in which spins are aligned in a circumferential direction of the wire, and the high frequency electric current has a frequency in the range of 0.3 to 1.0 GHz inclusive.

Ultra-sensitive magnetoimpedance sensor

A magnetic detection device of the present invention includes at least one pair of first magnetosensitive bodies each comprising a soft magnetic material extending in a first axis direction and being sensitive to an external magnetic field oriented in the first axis direction; and a magnetic field direction changer comprising a soft magnetic material and changing an external magnetic field oriented in a different axis direction from the first axis direction into a measurement magnetic field having a component in the first axis direction which can be detected by the at least one pair of first magnetosensitive bodies. With this magnetic detection device, the external magnetic field oriented in the different axis direction can be detected by way of the first magnetosensitive bodies. As a result, while attaining magnetic detection with high accuracy, the magnetic detection device can be reduced in size or thickness by omitting a magnetosensitive body extending long in the different axis direction.

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Aichi, Japan

Akihiro Shimode