Detection of mechanical defects in a disc drive using injected t

Details Detection of mechanical defects in a disc drive using injected t Detection of mechanical defects in a disc drive using injected t

1995-07-07

1997-08-05

Psitos, Aristotelis

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the head

360 31, 360 7704, 360 7809, 324210, 395500, G11B 2102

Patent

active

056548419

ABSTRACT:
A method and apparatus for testing for mechanical defects in a disc drive during manufacturing test is disclosed. Resonances in the disc drive are excited by injecting a sinusoidal test signal of known magnitude and frequency into an incoming servo position error (SPE) signal in the servo loop to provide a modified SPE. While the test signal is injected, the modified SPE is sampled and filtered to characterize the test frequency in the modified SPE which is compared to a resultant frequency characterized in the incoming SPE. The presence of resonances in the disc drive structure will result in an increase in the gain of the loop as indicated by the characterized resonant frequencies from the incoming and modified SPE. When the gain exceeds predetermined criteria, an error flag is set indicative of a failure condition for the disc drive, enabling the disc drive to be removed from test for subsequent remedial actions.

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patent: 5339206 (1994-08-01), Takahashi
patent: 5397971 (1995-03-01), McAllister et al.
patent: 5465183 (1995-11-01), Hattori

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