Speed detection apparatus and method

Claim 1

A speed detection apparatus for a motor, in which a position detector generates position pulses and an actual speed V of the motor is detected from the position pulses generated by the position detector operatively connected to the motor, and the actual speed is compared with a commanded speed in order to control the motor, said apparatus comprising: means, operatively connected to the position detector to receive the position pulses, for counting a number of the position pulses received within a fixed period To; means, operatively connected to the position detector, for measuring a first interval T1 between a prior position pulse generated just prior to the fixed period To and an instant at which the fixed period begins; means, operatively connected to the position detector, for measuring a second interval T2 between a final position pulse generated in the fixed period To and an instant at which the fixed period ends; means, operatively connected to said counting means, said first interval measuring means and said second interval measuring means, for obtaining a time T required for input of the position pulses within the fixed period by performing an operation T=To+T1-T2; and means, operatively connected to said time obtaining means, for dividing the time T by the number of position pulses, and for detecting the actual speed V by performing an operation V=K·N/T, where K is a proportional constant.

Claim 11

An apparatus for detecting an actual speed of a motor using position pulses generated by a position detector operatively connected to the motor, said apparatus comprising: counting means, operatively connected to the position detector, for counting a number of the position pulses received within a fixed time period having a beginning and an end; time measuring means, operatively connected to the position detector, for measuring a first time interval between a prior position pulse, generated immediately prior to the beginning of the fixed time period, and the beginning of the fixed time period, and a second time interval between a final position pulse, generated immediately prior to the end of the fixed time period, and the end of the fixed time period; and calculating means, operatively connected to said counting means and said time measuring means, for calculating an input time by adding the first time interval to the fixed time period and subtracting the second time interval, and for detecting the actual speed by multiplying the number of the position pulses by a proportional constant and dividing by the input time.

Claim 12

An apparatus for detecting an actual speed of a motor using position pulses generated by a position detector operatively connected to the motor, said apparatus comprising: counting means, operatively connected to the position detector, for counting a number of the position pulses received within a fixed time period having a beginning and an end; time measuring means, operatively connected to the position detector, for measuring a first time interval between a prior position pulse, generated immediately prior to the beginning of the fixed time period, and the beginning of the fixed time period, and a second time interval between a final position pulse, generated immediately prior to the end of the fixed time period, and the end of the fixed time period; and calculating means, operatively connected to said counting means and said time measuring means, for calculating an input time by adding the first time interval to the fixed time period and subtracting the second time interval, and for detecting the actual speed by multiplying the number of the position pulses by a proportional constant and dividing by the input time.