Magnetic disk defect inspecting device

Abstract

Abstract PURPOSE:To rectify a reproduced signal with good linearity even when a recording frequency increases and to detect normally a reference level for detection of a defect, by replacing the rectifying part of a conventional inspecting device with a phase-locked loop which synchronizes with the recording frequency, a multiplier, and a low-pass filter. CONSTITUTION:The part of the rectifying circuit 11 of a circuit system for setting the reference level is replaced with the multiplier 16, phase-locked loop 17, and low-pass filter 18 in combination. Rectifying operation is not carried out and a signal synchronizing with the recording frequency is multiplied by the reproduced signal; the multiplication output is passed through the low-pass filter 18 to detect the signal amplitude of the recording frequency, whose signal is an envelope. The envelope signal is integrated by an integrating circuit 19, whose output is inputted to a reference level storage circuit 13; and following processes are performed as usual. Thus, the multiplication frequency of the multiplier is possible up to 30MHz and an error during high-frequency recording is inspected sufficiently.

Inventors

• 👤 Hideo Tanaka
• 👤 英男 田中

Bibliographic Details