| 摘要 |
PURPOSE: To reduce viscous damping and dust contamination of a sensor by oscillating an oscillatory structure through electromagnetic excitation thereby detecting the oscillation. CONSTITUTION: An oscillation unit 10 comprises an exciter 12 generating a magnetic force (Fm), and a paramagnetic region 14 on an oscillatory structure 16 of a speed sensor 18 wherein the exciter 12 is a permanent magnet having one or more core part 22. The magnetic force Fm is determined by a coil current I and a magnetizing force H0 regardless of the flowing direction of the coil current I. A large oscillation amplitude is obtained through the electromagnetic excitation while avoiding the problems of viscous damping and contamination. A first mode oscillation detected by a pitch off transducer 30 vertical to the unit 10 is then amplified 68 and led to an oscillator 70 thus sustaining the oscillation of an oscillatory structure 32. When the structure 32 turns about Z-axis, Coriolis force couples the first mode oscillation with a second axis arranged with a transducer 60. A detected 60 second mode oscillation is then amplified 72 and passed through a synchronous demodulator 74 thus leading out a signal corresponding to the rotational speed of the sensor. |
