| 摘要 |
For examining defects in sheet material, in particular bank notes, the sheet material is convexly curved and tested in the area of the convex curvature. A detector is disposed tangentially to an apex line of the convex curvature for detecting elevations on the bank note surface due to bank note defects against a light background. A suitable optic is used to image this silhouette onto the detector. The detector is formed as a pixel array, and the number and height of shaded pixels are assessed as measures of defect density and size and nature of defects. |
