Abstract: In a disk drive, a modified adaptive runout compensation algorithm is employed to measure non-coherent repeatable runout (RRO) of a track. The adaptive runout compensation algorithm is used to control the transducer head to follow the average RRO of adjacent tracks during the process of computing correction factors for non-coherent RRO for a given track. The adaptive runout compensation algorithm does not completely adapt to both the coherent and non-coherent RRO of a particular track because the transducer head is positioned over any one particular track for only a limited number of revolutions.

Abstract: Certifying a media while servowriting the media by formatting a full compliment of servo data in storage tracks of the media in a minimum number of passes per storage track while simultaneously performing a 100% media certification of the storage tracks during the minimum number of passes per storage track.

Abstract: Certifying a storage media while servowriting the media by formatting a full compliment of servo data in storage tracks of the media in a minimum number of passes per storage track while simultaneously performing a 100% media certification of the storage tracks during the minimum number of passes per storage track.

Abstract: Certifying a media while servowriting the media by formatting a full compliment of servo data in storage tracks of the media in a minimum number of passes per storage track while simultaneously performing a 100% media certification of the storage tracks during the minimum number of passes per storage track.

Abstract: A compensation element (317) in a feedforward line in a dual stage control system for a data storage system compensates for the undesired transient motion of a first positioning element (i.e., a coarse actuator). The compensation element is a transfer function that is applied from the first positioning element's control signal (Uv) to a second positioning elements's (306) (i.e., microactuator's) input. The transfer function is defined as formula (I) where ^Vnom (z) is a transfer function model of the nominial portion of the first positioning element, ^Vres (z) is a transfer function model of the resonance portion of the first positioning element, and ^M(z) is a transfer function model of the dynamics of the second positioning element. This feedforward transfer function effectively cancels the resonances of the first positioning element without requiring the inversion of the resonance transfer function.

Abstract: The present invention offers a time efficient means to determine and eliminate dynamic track squeeze error. The present invention can be used to correct imperfections in tracks written by a conventional servowriter or using self-propagating servo writing. The dynamic track squeeze is determined within a single disc revolution. The read head is positioned half way between two servo tracks. Positioning information for track following is obtained from either track as one disc revolution is completed. During the disc revolution, position measurement is simultaneously collected from both tracks. The difference between the position measurements from each track, which represents the dynamic track squeeze between the two tracks, is determined. An appropriate ZAP correction factor is determined and written to the servo sector of the desired track. The ZAP correction factor is input to the disc drive servo controller and eliminates the dynamic track squeeze.

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: A propagating method is provided in which timing and servo sector information is propagated throughout a data storage media that initially contains only a guide pattern. The method uses an offset between the write element and the read element in a read/write head to position and propagate the timing information. In addition, a method for circumferentially aligning timing and servo sector information is disclosed that utilizes a time delay to position the propagated timing and servo sector information. Another method for attenuating timing errors during timing and servo sector propagation to a data storage media is disclosed. Timing errors are attenuated through the use of phase locked loop circuit and measurement of the phase error detected between different tracks on the data storage media. Apparatuses implementing the methods including a storage device readable by a computer system that implements the methods are provided.

Abstract: Radial correction factors are calculated for each ruler on a patterned media in a data storage system. A ruler is a position-sensing pattern that defines the radial position of a recording head. Rulers are patterned onto each disk before the disks are assembled into a storage system. The radial correction factors are then added to the measured position information during read and/or write operations of the data storage system. The radial correction factors correct for any radial misalignment created by disturbances in the data storage system. Circumferential correction factors are calculated for each patterned media in the data storage system. A corrected sector number is then determined by redefining the original sector numbers using the circumferential correction factors.

Abstract: A method for self-servo writing begins by calibrating at least one ruler formed on at least one storage disk. A ruler is a position-sensing pattern that defines the radial position of a recording head. The calibration process determines at least one correction factor for the at least one ruler on the disk. A servo system is then activated and the correction factors are used when writing the final servo pattern. During the process of writing the final servo patterns, the correction factors are modified to account for variations in any repeatable disturbances and for errors caused by any non-repeatable disturbances.

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. The device includes a laterally movable transducer head and a longitudinally movable data surface. A signal is received from the transducer head while the data surface moves past the head. Many values each indicative of a lateral offset distance between a corresponding pair of lateral reference points are derived from the received signal. These offset-indicative values are used to shift at least some of the latitudinal reference points laterally so as to reduce this variance.

Abstract: A controller generates a control signal that is input into a voice coil motor and causes an actuator to move to a particular position on a storage disk. An actuator model of the actuator is also coupled to the output, of the controller. The actuator model is used to estimate the response of the actuator when a signal is input into the voice coil motor. If some voltage is induced in the voice coil motor by an external vibration or resonance of the actuator, then the voltage output by the actuator will not be equal to the estimated voltage output by the actuator model. The difference of the estimated voltage and the actual voltage output the actuator is input into a resonance controller. The resonance controller then generates a compensation signal that is combined with the control signal to compensate for any actuator resonances.

Abstract: The present invention maintains the low frequency run-out at a desired level during self-servo track writing. Included in the present invention is a method that keeps the low frequency track shape errors (the first few harmonics of the spindle rotational frequency) at a desired level during self-servo track writing. To that end, the present invention generates a correction signal. The correction signal is injected into the servo loop and modifies the path of the actuator while writing the next servo track, and thus modifies the shape of the next servo track. One embodiment injects the correction signal in the servo loop prior to the servo controller and combines it with the position error signal. Another embodiment injects the correction signal after the controller, and directly modifies the actuator input signal. The method does not require any extra disc revolutions, and therefore, it does not increase the time required for the self-servo writing process.

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.

Abstract: A compensation element (317) in a feedforward line in a dual stage control system for a data storage system compensates for the undesired transient motion of a first positioning element (i.e., a coarse actuator). The compensation element is a transfer function that is applied from the first positioning element's control signal (Uv) to a second positioning elements's (306) (i.e., microactuator's) input. The transfer function is defined as formula (I) where Vnom (z) is a transfer function model of the nominial portion of the first positioning element, Vres (z) is a transfer function model of the resonance portion of the first positioning element, and M(z) is a transfer function model of the dynamics of the second positioning element. This feedforward transfer function effectively cancels the resonances of the first positioning element without requiring the inversion of the resonance transfer function.

Abstract: A propagating method is provided in which timing and servo sector information is propagated throughout a data storage media that initially contains only a guide pattern. The method uses an offset between the write element and the read element in a read/write head to position and propagate the timing information. In addition, a method for circumferentially aligning timing and servo sector information is disclosed that utilizes a time delay to position the propagated timing and servo sector information. Another method for attenuating timing errors during timing and servo sector propagation to a data storage media is disclosed. Timing errors are attenuated through the use of phase locked loop circuit and measurement of the phase error detected between different tracks on the data storage media. Apparatuses implementing the methods including a storage device readable by a computer system that implements the methods are provided.

Abstract: A method of correcting track misregistration in a servo system for a disc drive including one or more discs includes positioning a head over a track located on a disc and maintaining the head centered over the track. The process for maintaining the head centered may include measuring the radial position of the head relative to the disc and determining correction factors for a zero acceleration path. Correction factors are determined by modeling an actuator transfer function to produce an estimated position signal. Subsequently, an estimated disturbance signal is determined by subtracting the measured position and the estimated position signal and filtering it with an adaptation filter. Thereafter, the estimated disturbance signal is subtracted from the measured radial position to produce a modified position measurement signal. The head is repositioned in accordance with the modified position measurement signal.

Abstract: The present invention offers a time efficient means to determine and eliminate dynamic track squeeze error. The present invention can be used to correct imperfections in tracks written by a conventional servowriter or using self-propagating servo writing. The dynamic track squeeze is determined within a single disc revolution. The read head is positioned half way between two servo tracks. Positioning information for track following is obtained from either track as one disc revolution is completed. During the disc revolution, position measurement is simultaneously collected from both tracks. The difference between the position measurements from each track, which represents the dynamic track squeeze between the two tracks, is determined. An appropriate ZAP correction factor is determined and written to the servo sector of the desired track. The ZAP correction factor is input to the disc drive servo controller and eliminates the dynamic track squeeze.