| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the effect of disturbance light, by providing a colored wire extending in the longitudinal direction of a glass tube on one side of the glass tube communicated in a bath, and detecting the surface of liquid from the colored wire in the image of a camera observing the glass tube from the opposite side of the colored wire. SOLUTION: A cylindrical glass gage 2, which is communicated in a bath 1 at the upper part and the lower part of the bath 1, is provided at the outside of the bath 1 containing oil. On one side of the glass gage 2, a colored wire 22 is provided so that the wire is observed when the glass gage 2 is observed at the part separated from the bath 1. On the side, where the colored wire 22 is observed through the glass gage 2, a camera 6 is provided. An operating part 8 detects the bounary, where the thickness is changed as the liquid surface from the image of the camera 6. When the colored wire 22 is visually observed, the colored wire 22 is observed at the thickness along the entire inner body of the glass gage 2 in a liquid phase 4. The wire is hardly observed in the gaseous phase. Therefore, the boundary of the part, where the colored wire 22 appears, and the part, where the wire is not appreared, can be judged as the liquid surface. |
