| 摘要 |
PURPOSE:To enable the recognition of the position of a pattern for recognizing a position with high accuracy even when HAL processing is executed for a substrate or stain exists on the substrate by providing a scanning means which scans image data obtained by image-pickup to obtain gradation data. CONSTITUTION:An image pattern signal picked up by an image pickup device 2 is converted to the digital signal of plural gradation by an A/D converter 3 and stored in an image memory 5 in an image processor 4. By receiving the instruction of a main control part 6, the scanning circuit 8 sets the respective scanning number of an (x) and a (y) directions based on the image data stored in the memory 5. For example, the scanning number (n) of the (x) direction and the scanning number (n) of the (y) direction are set so that a cross pattern Q is included within the scanning limits. When this setting is finished, the scanning is executed for the (x) and (y) directions in order of 1-n. The result of the scanning is temporarily stored in the memory 5. A pattern extraction part 9 successively reads each gradation data from the memory 5 according to the scanning order and detects two parts where the gradation level is suddenly changed in the gradation data. Then, when the most steep parts (a) and (b) are detected, the width of the cross pattern is judged to exists between a point (Fa) and a point (Fb) in the gradation data (d3). |
