Abstract: A disc drive with an information portion previously written on a rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing a reference mark to the rotatable disc surface in substantial time alignment and phase and frequency coherent with the information portion previously written to the rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing the reference mark, a pulse detector circuit for creating logic level signals from the reference mark, a pattern generator for generating reference mark write signals from the logic level signals, a memory buffer for storing radial position correction tables and values for writing the reference mark, and a self-servo control and sequencing circuit synchronizing timing signals for writing the reference mark to rotatable disc surface of disc drive.

Abstract: Many parallel tracks on a storage surface of a data handling device are arranged in a longitudinal direction. Each track has a track center comprising reference points for fine lateral positioning. Each successive pair of track centers has a succession of lateral offset distance having an average. Because there are many successive pairs of tracks, there are many average lateral offset distances defining a statistical distribution having a variance.

Abstract: The present invention proposes a new servo track writing technique called Extended Copying with Head Offset (“ECHO”). The read and write elements of the read/write head are offset from each other. A servo writer writes a guide pattern on the magnetic media disc. ZAP correction factors are added to the guide pattern. The head disc assembly is then connected to an electrical control system for self-propagating servo writing. The actuator arm is displaced until the read head is aligned over the guide pattern. A new servo track is written by the write element. ZAP correction factors are added to the newly written servo track. The actuator arm is displaced until the read element is aligned with the newly written servo track. A new servo track is written. ZAP correction factors are added to the newly written servo track. The process is repeated until a desired number of servo tracks are written.

Abstract: An apparatus and method for correcting static track spacing errors in a data storage device having a plurality of concentric servo tracks. The data storage device includes a disc having a plurality of concentric servo tracks, an actuator assembly including a head adjacent the disc, and a controller operable for controlling the position of the head relative to the disc and operable to determine a correction factor indicative of a static track spacing error between servo tracks. The correction factor is used during operation of the data storage device to generate a corrected position signal for use by the data storage device in positioning the head with respect to the disc.

Abstract: The invention eliminates relative and absolute track shape errors by writing zero acceleration path (ZAP) correction factors into the servo sectors during track propagation. A servo track guide zone is written to the disc. ZAP correction factors are written to the guide zone and self-propagating servo writing commences. The ZAP correction factors are determined in only two disc revolutions per track. The read element follows track k, a previously written track, and the write element writes servo marks for track k+1 during a write revolution. The position signal is monitored and recorded in order to estimate the shape of track k+1 according to the inverse transformation method during a correction revolution.