A current sensor includes, a bus bar through which a current flows, a magnetic detection element detecting a magnetic field intensity generated by the current, first and second shielding plates arranged so as to sandwich the bus bar between the first and second shielding plates, a first conductive plate made of a conductive nonmagnetic material, arranged between the bus bar and the first shielding plate, and a second conductive plate made of the conductive nonmagnetic material, arranged between the bus bar and the second shielding plate, wherein the magnetic detection element is arranged at a first conductive plate-side. A distance between the first conductive plate and the bus bar is longer than a distance between the second conductive plate and the bus bar. The first conductive plate includes a slit formed in the first conductive plate at an overlapping position, and the slit pierces the first conductive plate.

A sensing system is provided for contactless sensing of current. The system includes a conductor for generating a magnetic field as electric current flows through the conductor, the conductor having a predetermined width and comprising a hole with a predetermined hole width passing through the whole thickness of the conductor, and a magnetic sensor for measuring at least one component of the magnetic field generated by the conductor. The magnetic sensor overlaps the hole. The current sensing is done based on the measured magnetic field. The sensor is positioned at a predetermined distance over a top surface of the conductor. The width of the hole is at least 0.15 times the width of the conductor.

A magnetic sensor includes a magnetoresistive effect element having a sensitivity axis in a specific direction. The magnetoresistive effect element has on a substrate, a laminate structure in which a fixed magnetic layer and a free magnetic layer are laminated with a nonmagnetic material layer interposed therebetween and includes at a side of the free magnetic layer apart from the nonmagnetic material layer, a first antiferromagnetic layer which generates an exchange coupling bias with the free magnetic layer and aligns a magnetization direction thereof in a predetermined direction in a magnetization changeable state. The free magnetic layer includes a first ferromagnetic layer in contact with the first antiferromagnetic layer to be exchange-coupled therewith and a magnetic adjustment layer at a side of the first ferromagnetic layer apart from the first antiferromagnetic layer. The magnetic adjustment layer contains at least one iron group element and at least one platinum group element.

A magnetic sensor device includes a first detection circuit that generates a first detection signal, a coil through which a feedback current is passed to generate a cancellation magnetic field, a second detection circuit that generates a second detection signal having a correspondence with a value of the feedback current, and a control circuit that controls the feedback current. In a closed-loop operation, the control circuit controls the feedback current so that the first detection signal has a constant value. In an open-loop operation, the control circuit maintains the feedback current at a constant value.

According to one embodiment, a sensor includes a nonmagnetic layer and a plurality of magnetic field sensors. The nonmagnetic layer has a first surface and a second surface. The magnetic field sensors are arranged along the second surface. The second surface is between the first surface and the magnetic field sensors. Each of the magnetic field sensors includes a first magnetic layer, a second magnetic layer provided between the first magnetic layer and the nonmagnetic layer, and an intermediate layer provided between the first magnetic layer and the second magnetic layer. The intermediate layer is nonmagnetic. A distance between the first surface and the second magnetic layer is not more than a pitch of the magnetic field sensors.

A current leakage detector for detecting current leakage between a power source and a load including a first sensing coil and a second sensing coil positioned opposite the first sensing coil. The current leakage detector further includes a magnetic field sensor proximate the first sensing coil and the second sensing coil and the magnetic field sensor has a response range. The current leakage detector also includes a bias circuit configured to adjust the response range of the magnetic field sensor. A method for detecting current leakage includes providing a first sensing coil and a second sensing coil. The method continues with the steps of providing a magnetic field sensor in proximity to the first and second sensing coils and providing a bias circuit. The method continues with the step of utilizing the bias circuit to place the response of the magnetic field sensor within a preferred response range.

A current detection circuit includes a coil that is constituted by a metal wiring formed on a semiconductor substrate, a resistor that is provided in a position near the coil on the semiconductor substrate, constituted by a metal wiring formed on the semiconductor substrate, which is made of a metal material being same as that of the coil, and arranged so as to prevent any magnetic field from being generated due to a current flowing in the resistor, an output circuit that outputs currents in accordance with a resistance ratio between the coil and the resistor to the coil and the resistor correspondingly through a common terminal, and a detection circuit that detects the current flowing in the resistor to thereby detect the current flowing in the coil.

Each of three magnetic sensors is positioned on a first virtual line that passes the centers of two magnetic shields in the width direction and is perpendicular to a virtual plane, so a value detected by the magnetic sensor is less likely to be influenced by an external magnetic field. The first virtual line and the center of a conductor intersecting the first virtual line are separated from each other by a certain distance. Therefore, even if a distance from the center of the conductor in the width direction to the magnetic sensor is short, it is possible to improve, on a high-frequency side, frequency characteristics in the detection sensitivity of the magnetic sensor for the frequency of the current under measurement.

Magnetoresistive sensors are used to measure a load current of a switch. In some implementations, additionally a further current sensor may be used. In other implementations, more than one magnetoresistive sensor may be provided.

A current sensor includes a plurality of individual sensors and a wiring case. Each of the individual sensors includes an electrical-conduction member through which a measurement current to be measured flows, a magnetoelectric converter and an insulating sensor housing. The magnetoelectric converter converts a measurement magnetic field caused by a flow of the measurement current into an electric signal. The sensor housing accommodates the electrical-conduction member and the magnetoelectric converter therein. The wiring case is larger than the sensor housing. The wiring case includes an insulating integrated housing in which the plurality of individual sensors is fixed, and an input/output wiring disposed in the integrated housing and electrically connected to the megnetoelectric converter of each of the plurality of individual sensors.