Hitachi Metals, Ltd.

Yuji Nihei

Yasunori Abe

Tomoki Ono

Shinji Furuichi

Yasuko Furuichi, Legal Representative

To disclose a magnetic encoder being subjected to only small gap variation between a magnetic sensor element and a magnetic medium and readily assembled, and having a smaller number of components, high sliding resistance, and high stability against outside force, such as shock or the like. The magnetic sensor holding mechanism has a swirling spring plate structure having elasticity with respect to rotation around a rotation axis in a reciprocative slide relative movement direction, elasticity with respect to rotation around a rotation axis in a direction perpendicular to the reciprocative relative movement direction and in parallel to the magnetic medium, and elasticity in the direction perpendicular to the sensor element. A load between 50 mN and 80 mN is applied to press onto the magnetic medium.

Magnetic encoder

Disclosed is a small-sized two-axis magnetic field sensor having a function to cause a magnetic field canceling an external offset magnetic field. The two-axis magnetic field sensor contains a plane coil disposed on a plane and four sets of magneto-resistance element pairs on a plane parallel to the plane coil. The plane coil includes at least two pairs of parallel conductors, and two magneto-resistance elements cross only a single conductor of the coil. A current for canceling the external offset magnetic field is determined in advance, and while a DC current that causes total magnetic fields of biasing magnetic fields plus a magnetic field for canceling the external offset magnetic field flows through the coil, intermediate potential outputs from the magneto-resistance element pairs are detected to measure a magnetic field direction, such as geo-magnetism.

Two-axis geo-magnetic field sensor with elimination of eefect of external offset magnetic fields

A magnetic encoder having a magnetic sensor composed of SVGMR elements, in which a signal output with a half of a cycle of magnetic regions on a magnetic medium. The magnetic encoder comprises the magnetic medium, on which first magnetic regions and second magnetic regions are oppositely magnetized along the medium extending and disposed successively and alternately with each other, and the magnetic sensor that has an even number of SVGMR elements and is movable relatively to the medium along the medium extending. Magnetizations of pinned magnetization layers of all the SVGMR elements are directed in a same direction along the medium extending. Each of the even number of SVGMR elements in the magnetic sensor is apart by a half of the sum of a first magnetic region length plus a second magnetic region length from each other along the medium extending, and the even number of SVGMR elements are connected in series so that a cycle of resistance change of the magnetic sensor is a half of a cycle length of the first and the second magnetic regions on the medium and the signal output with high resolution can be obtained.

A magnetic encoder having a magnetic sensor composed of SVGMR elements, in which a signal output with a cycle equal to or less than a third of a cycle of magnetic patterns on a magnetic medium. The magnetic encoder comprises the magnetic medium, on which first magnetic regions and second magnetic regions are oppositely magnetized along the medium extending and disposed successively and alternately with each other, and the sensor that has three SVGMR elements or more and is movable relatively to the medium along the medium extending. Magnetizations of pinned magnetization layers of all the SVGMR elements are directed in the same direction along the medium extending. The SVGMR elements in the sensor are apart from each other along the medium extending by a length p, defined by 1/(the number N of the SVGMR elements in the sensor) of the sum of a first magnetic region length plus a second magnetic region length, and the SVGMR elements in the sensor are connected in series so that a cycle of resistance change of the sensor is 1/N of a cycle length of magnetic patterns on the medium, and the signal output with high resolution can be obtained.

Growing community of inventors

Mohka, Japan

Yuji Nihei