In the start up of the magnetic disk apparatus, the phase relation between servo information numbers recorded on the magnetic disk 15 in advance and the eccentricity of the magnetic disk is learned. In the positioning of the magnetic head, a signal generated by multiplying, by a weight coefficient, a sine wave or a cosine wave the phase the revolution frequency of the magnetic disk is fed forward as an eccentricity control amount, whereby the eccentricity is compensated.

 
Web www.patentalert.com

< Exposure dose control of rotating electron beam recorder

< Disk drive with capacitance sensing of disk vibration and feedforward control for removal of read/write head track misregistration

> Recording and reproducing device

> Disk drive and methods that calibrate micro actuator positioning before seek operations
~ 00245