| 摘要 |
To increase operating efficiency and prevent operating errors, such as adjustment errors and the like, by automatic computation of the distance between the workpiece alignment marks, according to the invention, workpiece alignment marks located at two locations on a workpiece are subjected to image recording by alignment units, their positions are stored as first positions, then by rotation of the workpiece by a preset very small angle, the workpiece alignment marks located at two locations on the workpiece are determined again, and their positions are stored as second positions. Based on the data of the first and second positions, the distance between the workpiece alignment marks is determined. Then, based on the distance data, the angular offset of the workpiece is determined. After correction of this angular offset, the mask and/or the workpiece is/are moved such that the images of the mask alignment marks and the workpiece alignment marks come to rest on top of one another.
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