| 摘要 |
PURPOSE:To shorten length of time for measurement and also to improve accuracy, by providing a voltage control oscillator, a light source, a photoelectric converting element, a multiplyer and an integrator, etc., and then, by changing oscillation frequency of the voltage control oscillator synchronously with rotation of a rotary body. CONSTITUTION:The tachometer is composed of the voltage control oscillator (VCO)1, the light source 4 to be driven by output signal of the VCO1, the photoelectric converting element 7, the multiplyer 9 and the integrator 10, etc. In case if timing of rotation of the rotary body 5 has failed to agree with timing of radiation of the light source 4, output current wave of the photoelectric converting element 7 changes, and minus and plus components appear to output of the multiplyer 9. By integrating these minus and plus components, the voltage output, whose absolute value increases with elapse of time, is obtained. Now, by setting in such a manner as to enable oscillation frequency fo of the VCO1 to increase and decrease in compliance with increase and decrease of output signal Si of the integrator 10, timing of rotation becomes automatically synchronized with timing of radiation when they have failed to agree with each other. It is possible, by using this mechanism, to shorten length of time for measurement and also to improve accuracy. |
