| 摘要 |
PURPOSE:To directly measure the rotating speed and rotational irregularity of a body of rotation at the same time by adding a means which detects the rotating speed of the body of rotation from periodic level vibration of received light due to the flaw, roughness, etc., of the surface of the body of rotation. CONSTITUTION:Devices 1-3 in a figure are of the same constitution as a rotational irregularity measuring instrument which uses a conventional noncontact optical speed sensor and the rotational irregularity of the body 1 of rotation is found as wow and flutter. Reflected light from the body 1 of rotation varies in level periodically at a period T0 on every turn of the body 1 of rotation owing to the flaw, roughness, etc., of the surface of the body 1 of rotation. The output of a photodetector 6 is amplified by a DC amplifier 15 and the center frequency f0 of a band-pass filter 16 is so adjusted that the indicated value of a level meter 17 is maximum, thereby obtaining a sine wave signal with the period T0 as the output signal. This signal is waveform-shaped by a waveform shaping device 18 and a pulse counter 19 counts pulses or period T0 in time units, thereby measuring the rotating frequency of the body 1 of rotation directly without measuring the radius (r) of rotation.
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