Patent ID: 6172953
Filing Date: 2001-01-09
Classification: G11B

Abstract:
A defect detector for detecting a defect in a detection signal obtained by detecting information, the defect having a level lower than a predetermined level of the detection signal, the detector comprising:an upper envelop signal generating unit for detecting an upper envelop of the detection signal to generate an upper envelop signal corresponding to the detected upper envelop;a lower envelop signal generating unit for detecting a lower envelop of the detection signal to generate a lower envelop signal corresponding to the detected lower envelop;a slice signal generating unit for dividing a voltage difference of the upper envelop signal and the lower envelop signal using a predetermined division ratio to generate a slice signal;an averaging unit for averaging the slice signal to produce an average signal; anda defect detecting unit for comparing the average signal and the upper envelop signal to produce a defect detection signal indicating the period in which the voltage of the upper envelop signal is lower than the voltage of the average signal.