Patent ID: 6175459
Filing Date: 2001-01-16
Classification: G11B

Abstract:
A magnetic disk drive capable of detecting a defect of a medium from a read signal read out of a head, comprising:sampling means for sampling said read signal;calculation means for calculating by using the current sample value and the preceding sample value, said calculation means includes adder means for calculating the sum of the current sample value and the preceding sample value, wherein the calculation result is capable of being a positive value or a negative value;comparator means for comparing the calculation results obtained by said calculation means with predetermined reference values, whereby said comparator means compares the sum of the current sample value and the preceding sample value with a lower reference value representing a preset lower limit and an upper reference value representing a present upper limit; anddefect detection signal generating means for detecting a type of defect in accordance with the comparison results obtained by said comparator means, whereby said defect detection signal generating means detects a portion where the sum of said sample values is lower than said lower reference value and a portion where the sum of said sample values is higher than said upper reference value as a medium defect due to a thermal asperity and generating a defect detection signal.