| 摘要 |
PURPOSE:To improve the uniformity of a current distribution in a measurement area and to monitor the progressive state of a surface defect with high accuracy by forming plural couples of feed terminals so that they can be displaced, and providing a terminal position control part which displaces and positions the terminal couples according to the current distribution inside the terminal couples. CONSTITUTION:The plural feed terminal couples 3 are displaceable and displaced by the terminal position control part 6. When a current is supplied to the terminal couples 3 under the command of a computer 7 through a constant current source 9 and a polarity converting device 8, the current distribution is generated inside. The current distribution is measured through a potential difference measurement terminal 4, a scanner 10, and a voltmeter 11 and inputted to and processed by the computer 7. The terminal couples 3 are moved with a control signal from the control part 6 according to the result to uniform the current distribution in the measurement area. In such a state, signals from terminals 4 are processed by the computer 7 to detect whether or not there is a surface defect and its shape.
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