ROTATIONAL SPEED DETECTOR

摘要

PURPOSE:To obtain a high responsiveness, by providing a computing means with a kind of differentiation property to ease a phase delay with an improved phase property. CONSTITUTION:A pulse generating means 2 for generating a pulse train with the frequency proportional to a rotational speed is made up of an encoder 201 rotating integral with a rotating shaft of a motor 1 and a photosensor 202. An output pulse of a pulse generating means 3 is measured by a cyclically measuring means 3 and the results of measurement are held by a latch means 4 until the subsequent pulse arrives. A computing means 5 is made up of a multiplier 502 and a subtractor 501 and performs a subtraction with a subtractor 501 according to a value obtained by multiplying an output of a delay means 6 (b) times with a multiplier 502. An output of the computing unit 5 is held by a latch means 7 until the subsequent pulse arrives. An output of the latch means 7 is multiplied (a) times with a multiplier 8 to adjust a detection gain. The results of the multiplier 8 are given as such of detection of a rotational speed.