Method and apparatus for detecting rotational speed of rotary member

摘要

A method of detecting the rotational speed of a rotary member, which comprises the steps of detecting, in sequence, a time period indicative of the interval between successive preceding and following angular positions of the rotary member, memorizing in turn from each of the angular positions of the rotary member a series of the time periods detected during one rotation of the rotary member, substituting the foremost time period memorized during one rotation of the rotary member for the foremost time period memorized during the preceding one rotation of the rotary member, and calculating the sum of the substituted time period and the remaining time periods memorized during the preceding one rotation of the rotary member upon detection of each of the angular positions to detect the actual rotational speed of the rotary member.