| 摘要 |
The surface of a material is inspected for defects by visual examination of a television picture of the surface produced by at least one camera focused on the material and transmitting an image to a screen in the form of a video signal. The connection between screen and camera is made only when a defect is detected on the surface of the material. The video signal is delimited by an upper and a lower signal level which, if exceeded, results in a trigger signal being activated. In addition a trigger mechanism and an image storage facility are provided between the screen and the camera. Appearing on the screen are only pictures of surface areas showing defects; areas without defects are not displayed on the screen.
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