ANGLE MEASURING METHOD AND SPEED MEASURING APPARATUS

PURPOSE:To enable accurate measurement of speed regardless of non-coincidence in a positional relationship of a mark for detecting a rotational speed by performing a mean computation for a data pertaining to a plurality of angles obtained with rotations for calibration applied several times. CONSTITUTION:A sensor 5 is provided to detect a change in shape and pattern of a rotating part of a rotor 10 as a passing time range and an angle is measured for calibration corresponding to each passing, time range from a ratio of each passing time range as determined when a rotation for calibration is applied to the rotor 10 and time of one rotation. An averaging computation is performed for a data related to a plurality of angles obtained with rotations for calibration applied several times. The position of the sensor 5 in the direction of the rotor 10 rotates is shifted to repeat a calculation for calibration of an angle for each sensor position and a data obtained is calculated into the averaging computation. A speed measuring apparatus measures a speed of an object desired to measure a speed thereof from a ratio between a data pertaining to each passing time range determined and a data pertaining to a corresponding angle as read out of a memory mean.