| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve reductions in size, weight and cost of a motion detection device, which counts rotational frequency or the like of a detection body with no power source, without decreasing accuracy of detecting rotational frequency or the like of the detection object. <P>SOLUTION: A motion detection device has: stand-by magnets 15 and 17 as well as an output magnet 16 arranged in a circumferential direction at intervals Da on outer peripheral portion of a movable section 13 which rotates; and magnetic sensors 1, 2 and 3 around the movable section 13 at wider intervals Db than the interval Da. When the stand-by magnets 15 and 17 pass near either of the magnet sensors 1, 2 and 3 while the movable section 13 is rotated in tandem with rotation of a rotational axis 150, the magnet sensor comes into a stand-by state. When the output magnet 16 passes near the magnet sensor which is in the stand-by state, a large Barkhausen effect is produced at a magnetic element 21 of the magnetic sensor and a coil 22 outputs a detection signal. Rotational frequency of the rotational axis 150 is counted based on the detection signal. <P>COPYRIGHT: (C)2013,JPO&INPIT |
