| 摘要 |
Measuring and regulating a height of a melt surface (5) in a device for drawing crystals from a melt in a circular cross-section, where the transition between a drawn crystal and the melt is visible as a bright ring on the melt surface, comprises: providing a target level for the melt surface and a position of a central axis of the crystal in a level of the target level; determining image coordinates of at least three pixels of the ring to determine the ring diameter and the position of its center; adjusting an input value to control a lifting device; and adjusting height of a crucible. Measuring and regulating a height of a melt surface (5) in a device for drawing crystals from a melt in a circular cross-section, where the transition between a drawn crystal and the melt is visible as a bright ring on the melt surface, and the device comprises a camera (9) facing the melt surface and the ring, where the camera exhibits an image evaluation device for its image information, a height-adjustable crucible (1) receiving the melt, and a lifting device (7) for adjusting the height of the crucible, where the image information delivered by the camera in the image evaluation device adjusts an input value for a control device (8), which controls the lifting device in such a manner that the height of the melt surface remains constant with respect to the device, comprises: providing a target level for the melt surface and a position of a central axis of the crystal in a level of the target level; determining image coordinates of at least three pixels of the ring; determining the diameter of the ring and the position of its center in the target level from the image coordinates of these pixels; adjusting the input value for controlling the lifting device from the deviation of the position of the determined center of the ring from the position of the central axis of the crystal; and adjusting height of the crucible in such a manner that the deviation of the position of the determined center of the ring from the position of the central axis of the crystal becomes zero. An independent claim is also included for the device for drawing crystals from the melt in a circular cross-section, comprising the camera, the height-adjustable crucible and the lifting device, where the image evaluation device and the control device are arranged in such a manner that the target level for the melt surface and the position of the central axis of the crystal are stored in the level of the target level, and the image coordinates of the three pixels of the ring are determined, and then the diameter of the ring and the position of its center in the target level are calculated from the image coordinates of these pixels.
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