JPH0619670B

An automatic accurate alignment system for positioning at a required position an object to be worked which has a certain pattern on its surface. The system includes a key pattern memory, a pattern matching device and movement control device. The key pattern memory memorizes a first signal indicative of a key pattern existing in a specified area and its position when the object to be worked is positioned at a predetermined position, and memorizes a second signal indicative of the key pattern existing in the specified area and its position when the object to be worked is rotated through 90 degrees from the predetermined the second signal is determined from the first signal. The pattern matching device performs a first pattern matching on the basis of the first signal and a second pattern matching on the basis of the second signal. The movement control device performs a first positioning of the object to be worked on the basis of the first pattern matching, then, rotates the object to be worked through 90 degrees, and thereafter, performs a second positioning of the object to be worked on the basis of the second pattern matching.