| 摘要 |
PROBLEM TO BE SOLVED: To detect a defect smaller than a magnetic head size and a recorded bit length, and a defective point which is magnetically changeable as thermal fluctuation, etc., and causes medium noise. SOLUTION: A defective part which is prone to magnetic inversion is detected by DC-magnetizing a surface of a magnetic recording medium 1 in a single direction by the saturation magnetization from a magnetic head 2, measuring noise with a head current varied beforehand when DC-degaussing it with the magnetic field in the opposite direction afterwards, DC-degaussing it in the opposite direction such a write current as generates 5-50% noise of the maximum noise, further, scanning the track with a magnetic force microscope head 3, and detecting leakage flux caused by the magnetization inversion.
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