INSPECTION APPARATUS FOR SCALE

摘要

PROBLEM TO BE SOLVED: To enable more accurate inspection and measurement by making as little as possible a time difference between the time when a reading of a master scale assumes a predetermined value and the time when the read value of a detection head of a scale to be inspected is obtained. SOLUTION: A trigger signal is outputted when zero is reached after counting down from a predetermined value by means of counting pulses outputted from the detection head of the master scale. The count data of the scale to be inspected are held by the trigger signal whereby the count value of the scale to be inspected can be obtained with a minimal time difference after a drive stage has reached a predetermined position. Thus, even if the drive scale on which the master scale and the scale to be inspected are placed is kept moving at constant speed without stopping, inspection and measurement are made possible and inspection time can be reduced.