MAGNETIC DISK DEFECT TEST METHOD, PROTRUSION TEST DEVICE AND GLIDE TESTER

摘要

Acceptability of a disk is determined by passing a detection signal from a head through a low-pass filter to obtain a detection signal component corresponding to side runout of the disk due to rotation of the disk and by comparing the maximum level of the signal with a predetermined reference value. Thus, it is possible to extract unacceptable disk which causes erroneous write and/or read or clash due to surface undulation of disk, even when the disk has no protrusion having bad influence upon the disk.