| 摘要 |
PURPOSE:To reduce measuring errors along a highly sensitive measurement by arranging a detection coil, a detection circuit for driving the detection coil and detecting impedance and a temperature compensating circuit for compensating for variation in the impedance on the same substrate. CONSTITUTION:A molten steel 12 is injected into a mold 10 through a nozzle 11 and withdrawn continuously with a roll 13 from a outlet. A detection unit 20 is arranged at the position facing opposite to the surface of the molten steel in the mold 10. The unit 20 has a detection coil 22, a detection circuit 25 comprising an oscillation circuit section 23 for exciting and driving the coil 22 and a detection/ amplification circuit section 24 for detecting changes in the impedance of the coil 22 and a temperature compensation circuit 26 for compensating for temperature changes in the impedance of the coil 22 using a transistor temperature sensor on a substrate 21. The coil 22, which is a thin film coil, is connected to circuits 25 and 26 with a printed circuit pattern 27. Thus, as the surface of the molten steel in the mold 10 changes, the distance from the coil 22 varies thereby enabling a highly accurate measurement with a high speed.
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