| 摘要 |
PURPOSE:To detect a molten liquid level directly by capturing a reference point determined on a radiation screen and a reflection image of the reference surface for the molten liquid surface by a linear sensor, and finding the isolation dimension between the reference point and reflection image on the sensor. CONSTITUTION:A camera 11 is arranged outside facing the observation window 1b of a chamber 1. The linear sensor 2 of the camera 11 is directed crossing the tangent to the curved edge part of the lower edge 5c of the tapered part 5b of the radiation screen 5 and captures an image Na of the lower edge 5c and a reflection image Nb of the edge 5 for the molten liquid surface. Then electric signals corresponding to the images Na and Nb captured by respective photodetecting elements are outputted. An arithmetic control part 13 detects the positions of the images Na and Nb according to the signal level from the sensor 12 and computes the isolation dimension (h) between the lower edge 5c and reflection image from those positions. Therefore, the distance lfrom the lower edge 5c to the molten liquid surface is h/2. A control part 13 compares the distance l with a predetermined reference level value and outputs a control signal to a motor M2 for a crucible 2 so as to eliminate the difference, thereby adjusting the position of the crucible 2. |
