| 摘要 |
PROBLEM TO BE SOLVED: To determine the cause of a reading error when the reading error occurs. SOLUTION: In an amplitude comparator 40, the amplitudes of data read by reading heads 10-1 to 10-n and amplified by preamplifiers 20-1 to 20-n are compared with one another, in an error determination circuit 50, reductions in reading levels in the reading heads 10-1 to 10-n are detected based on the result of the comparison made in the amplitude comparator 40 and, when a reading error is detected by a signal processing part 60, reference is made to the result of the detection made by the error determination circuit 50 and, if the reading head of the detected reading level reduction exists, it is determined that the cause of the reading error is a reading means. If no reading head of the detected reading level reduction exists, then it is determined that the cause of the reading error is other than the reading heads 10-1 to 10-n.
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