Patent ID: 8717544

Claim:
An alignment method for aligning a photomask with an object to be exposed having a pattern in a matrix with a long side in at least a portion thereof and conveyed in a direction of the long side, the alignment method comprising the steps of: successively processing a plurality of images captured at regular time intervals by imaging device having a plurality of light-receiving elements arranged in a straight line in a direction perpendicular to a conveying direction of the object to be exposed, thereby detecting a position at which brightness changes in an arrangement direction of the light-receiving elements; adding up, in the conveying direction of the object to be exposed, the number of times the brightness changes detected at the same position in the arrangement direction of the light-receiving elements while the object to be exposed moves by a certain distance, thereby obtaining a plurality of edge count data; identifying a plurality of positions of long sides of the patterns parallel to the conveying direction based on a plurality of edge count data exceeding a predetermined threshold value in the plurality of edge count data; selecting a position of a long side close to a target position preset in the imaging device from the identified positions of long sides; calculating an amount of position displacement between the selected position of the long side and the target position of the imaging device; and relatively moving at least the photomask in the direction perpendicular to the conveying direction of the object to be exposed so that the amount of position displacement is a predetermined value, thereby performing alignment between the photomask and the object to be exposed.