Application of Sn-doped InSb Single Crystal Thin Film Magneto-resistance Devices to Detecting Gear-rotation Speed

We could accurately detect the rotation angle or speed of the spindle axis of the motors used for industrial purposes by using a combination of an iron gear and a magnetic sensor device with a bias permanent magnet. The relation between the accuracy of detecting the rotation angle and the deviation from the sine curve of the output signal from the magnetic sensors was studied by analyzing the magnetic field. A device made from a bridged pair of magneto-resistance (MR) elements demonstrated the smallest deviation and the best accuracy of three kinds of magnetic sensors, such as a bridged pair of MR-elements, a bridged pair of MR-single element and a fixed resistor, and a Hall element (HE) used as a magnetic sensor. The results were also verified from experiments.