Alps Green Devices Co., Ltd.

Alps Green Devices., Ltd.

Tatsuya Kogure

Akira Takahashi

Masamichi Saito

Yosuke Ide

Yoshihiro Nishiyama

Hidekazu Kobayashi

Kenji Ichinohe

Masahiro Iizuka

Naoki Sakatsume

Tsuyoshi Nojima

Shigenobu Miyajima

Nobuhiro Hayashi

Hideharu Matsuo

A current measurement apparatus includes multiple GMR elements and a calculation unit. The multiple GMR elements each include a pinned magnetic layer having a pinned magnetization direction, and a free magnetic layer having a magnetization direction to be changed by an external magnetic field. The calculation unit obtains the magnitude of a current to be detected, from outputs of the multiple GMR elements. The multiple GMR elements are disposed in ring shape around a conductor through which the current to be detected flows, and are electrically connected so as to form a series variable resistor by using the multiple GMR elements. The magnetization directions of the pinned magnetic layers are pinned in the same direction when viewed from an extension direction of the conductor at each of the positions of the elements.

Current measurement apparatus having a series of magnetoresistive effect elements disposed in a ring shape

A magnetic balance type current sensor includes a magnetoresistance effect element whose resistance value changes owing to the application of an induction magnetic field from a current to be measured; a feedback coil disposed in the vicinity of the magnetoresistance effect element and generating a cancelling magnetic field cancelling out the induction magnetic field; a magnetic field detection bridge circuit including two outputs causing a voltage difference corresponding to the induction magnetic field to occur; and a magnetic shield attenuating the induction magnetic field and enhancing the cancelling magnetic field, wherein, on the basis of the current flowing through the feedback coil at the time of an equilibrium state in which the induction magnetic field and the cancelling magnetic field are cancelled out, the current to be measured is measured, wherein the feedback coil, the magnetic shield, and the magnetic field detection bridge circuit are formed on a same substrate.

Magnetic balance type current sensor

A magnetic-balance-system current sensor includes: a magnetoresistive element, a resistance value of the magnetoresistive element being changed by applying an induction magnetic field generated by a measurement target current; magnetic cores disposed near the magnetoresistive element; a feedback coil disposed near the magnetoresistive element and configured to generate a cancelling magnetic field that cancels out the induction magnetic field; and a magnetic-field detecting bridge circuit having two outputs. The measurement target current is measured on the basis of a current flowing through the feedback coil when the induction magnetic field and the induction magnetic field and the cancelling magnetic field cancel each other out. The feedback coil, the magnetic cores, and the magnetic-field detecting bridge circuit are formed on a same substrate. The feedback coil is of a spiral type, and the magnetic cores are provided above and below the feedback coil.

Magnetic-balance-system current sensor

A magnetic balance type current sensor measures a measured current which flows in a feedback coil when electrical conduction is provided by a voltage difference according to an induction magnetic field from the measured current and an equilibrium state is reached in which the induction magnetic field and a cancel magnetic field cancel each other. Sensor elements in a pair are arranged at positions with magnetic field from the measured current. The magnetization direction of the pinned magnetic layer in the magnetoresistive effect element of one sensor element is aligned in a forward direction with respect to the magnetic field formed by the measured current. The magnetization direction of the pinned magnetic layer in the magnetoresistive effect element of the other sensor element is aligned in a reverse direction with respect to the magnetic field formed by the measured current.

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Niigata-ken, Japan

Tatsuya Kogure