Seagate Technology Incorporated

Kok Hiang Cheong

KianKeong Ooi

MingZhong Ding

Kian Keong Ooi

Ricky Wei Watt Yeo

Jack Ming Teng

Wing Kong Chiang

An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. A region of the disc stack is identified as a parking band, and when power is not provided to the disc drive, the actuator assembly is held in a parked position within the parking band by a magnetic latch. The magnetic latch is overcome during a powerup process by a voice coil motor coupled to the actuator. Other regions of the disc stack are associated with various functions performed by the voice coil motor as the actuator passes over such regions.

AC unlatch using grey code detection with zone partitioning

The present invention provides a method to screen tracks on a magnetic disc in a disc drive for harmonic resonance. There are several algorithms in the method performing different functions at various stages of the method. At any point in time, only one track is subjected to test by the method. The first stage of the method has one algorithm performing the function of obtaining a summation of all the absolute Position Error Signal (PES) velocities on a single track. Another algorithm performs the function of obtaining the average PES velocity with the summation of the absolute PES velocities. At the subsequent stage, another algorithm performs the function of obtaining the average PES velocity of a number of revolutions. An algorithm at the final stage performs the function of comparing the average PES velocity to a preset standard criterion, which is determined empirically in a separate algorithm. The track would be failed if the average PES velocity exceeds the preset standard criterion value.

Method for screening oscillatory PES with 1.7 kHz harmonic resonance

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Kok Hiang Cheong