| 摘要 |
PROBLEM TO BE SOLVED: To generate index pulses with stable signal-to-noise ratio and make it possible to cope with thresholds on both sides, by installing a magnetic substance for converging magnetic fields behind a surface mount-type ferromagnetic orthogonal magnetic resistance element placed on a stator board. SOLUTION: A surface mount-type ferromagnetic orthogonal magnetic resistance element (orthogonal MR element) as a magnetic sensor 7, is installed on a stator board 8 opposite to a single-pole index magnet 6 installed outside a rotor. Thus, a rotation signal generator is constituted which detects magnetic fields from the index magnet 6, rotated integrally with the rotor, through the orthogonal MR element and generates rotation signals. A magnetic substance 9 for converging magnetic fields is installed behind the orthogonal MR element placed on the stator board 8. This increases effective magnetic flux detected by the orthogonal MR element to enhance signal-to-noise ratio, and obtains an accurate rotation signal generator suitable for spindle motors for driving magnetic disks. |
