| 摘要 |
PURPOSE:To execute a simple and stable measurement, by subtracting a signal which adjust voltage and phase of an energizing current applied to an energizing winding, from an output signal of an output winding corresponding to a variation of magnetic permeability. CONSTITUTION:A detecting part 6 is energized by an output current which amplifies an output signal of a sine wave oscillator 2, and a magnetic line of force by this energizing winding 4 penetrates a material to be inspected 1. In this state, when internal stress of the material to be inspected 1 is varied, magnetic permeability of the material to be inspected 1 is varied. This variation of magnetic permeability becomes a voltage variation of an output signal of an output winding 5 of the detecting part 6. The output signal of the output winding 5 is amplified by an amplifier 9 through a subtracter 8, and a detecting output is obtained. |
