| 摘要 |
PURPOSE:To detect the rotational frequency and rotational direction of a rotary body correctly and without contact therewith, by emitting an incident wave to a reflection surface of the rotary body at an angle having a velocity component to the rotary shaft of the rotary body and by receiving a reflected wave subjected to the frequency change caused by the Doppler effect in accordance with the rotational velocity of the rotary body. CONSTITUTION:The incident wave of light, etc. is made to fall from an oscillator 2-2 at an incident angle theta onto the cylindrical reflection surface of a rotary body 2-1 rotating counterclockwise with a rotational frequency f around a rotary shaft. A reflected wave from the reflection surface, which is subjected to the frequency change caused by the Doppler effect in accordance with the rotational velocity of the rotary body, is received by a receiver 2-3. The frequency of a signal transmitted from the oscillator 2-2 and the frequency of a signal received by the receiver 2-3 are compared with each other by an operator 2-4. That is, the rotational frequency of the rotary body is detected from the frequency of a beat generated through the synthesis of the incident and reflected waves by the operator 2-4, while the rotational direction of the rotary body is detected from a mark obtained from the comparison of the frequency of the incident wave with that of the reflected wave. |
