Continuous-plus embedded data position control method for magnetic disk device

Claim 1

A method for use in a magnetic disk drive incor­porating a disk assembly (10) having a dedicated servo surface having circular tracks containing dedicated servo signals and at least one data surface having circular data tracks containing sectors each of which includes a data field (256) and a servo field (254) containing embedded servo signals, a dedicated servo signal detector (172) for detecting servo signals on said dedicated surface, an embedded signal detector (36) for detecting embedded servo signals on a data surface and a head positioning system for positioning a read/write head (22-26) over a selected data track, said method comprising the following steps to maintain said read/write head over the centerline of said selec­ted data track : a. generating a first error position signal from said dedicated servo signals representing the position of said read/write head over a selected circu­lar track on said dedicated servo surface ; b. generating a second error position signal from said embedded servo signals representing the position of said read/write head over the centerline of a circular data track on said data surface ; said method being characterized in that it further comprises the steeps of c. filtering said first error position signal through a high-pass filter ; d. summing said first error signal after said filtering with said second error signal to generate a composite track error signal ; and e. positioning said read/write head over the centerline of said selected data track in response to said composite track error signal.