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This letter considers a method of the detecting wear of CoCr perpendicular flexible disk media by acoustic emission (AE). The AE signal generated by the disk rubbing against the head varies according to the progress of media wear. The pass number at which the AE signal level increases steeply, increases with a decrease in the initial friction coefficient.
Kenji MOCHIZUKI Isamu SATO Takefumi HAYASHI
This letter describes the comparison of the impulse force detection method for a head slider and a disk medium using a small piezoelectric transducer (PZT) stuck on the head slider, with the method using visible laser interferometry. The experimental results for the signal level of the PZT agree very well with the acceleration measured from laser interferometry method. There is also good agreement between the spectrum of signal output of the PZT and laser interferometry, when the head slider flies over a rectangular bump made on a glass disk.
The relationship between peak shift and local media noise with regard to each pulse bit has been studied. Local media noise in each bit region was measured using an unsaturated dc erasure method that makes it possible to observe the noise component contained in the pulse peak of signal. A distinct relationship has been found to exist between the peak shift and method noise.
Kenji MOCHIZUKI Isamu SATO Ryoichi ARAI
This letter describes a highly sensitive method for detecting contact between a head slider and disk medium. It is shown to provide 10 dB or greater improvement in the signal to noise ratio (SNR) from the small piezoelectric transducer attached to the head slider by using a new frequency mixer circuit.