Abstract: A reference spiral is written on a recording surface of a magnetic storage disk that is free of position or timing information. The reference spirals are written on the recording surface with a substantially uniform slope by using open loop control of the position of a read/write head in conjunction with an iterative learning control scheme. A voltage profile applied to a voice coil motor is adapted over multiple iterations of moving the read/write head across the recording surface to closely approximate a target voltage profile, and the reference spiral is written using the adapted voltage profile. In addition, ramp contact detection based on actuator current profile may be employed to achieve full utilization of available actuator stroke.

Abstract: A write head is positioned over a disk surface of a hard disk drive during a self-servo write process. A virtual window mode is employed for positioning the write head, in which the read channel of the hard disk drive continuously searches for servo spirals, but spiral detection is disabled except during specific time intervals, or “virtual windows.” Each virtual window is associated with one specific servo spiral on the disk surface, and has a predetermined duration. The duration and timing of these virtual windows may be selected to ensure that spiral detection is enabled while a read head of the hard disk drive passes over the associated servo spiral, even when servo spiral placement is not ideal.

Abstract: A write head is positioned over a disk surface of a hard disk drive during a self-servo write process. A virtual window mode is employed for positioning the write head, in which the read channel of the hard disk drive continuously searches for servo spirals, but spiral detection is disabled except during specific time intervals, or “virtual windows.” Each virtual window is associated with one specific servo spiral on the disk surface, and has a predetermined duration. The duration and timing of these virtual windows may be selected to ensure that spiral detection is enabled while a read head of the hard disk drive passes over the associated servo spiral, even when servo spiral placement is not ideal.

Abstract: A magnetic write head is positioned based on position signals generated by a read head as the read head crosses a plurality of reference spirals. The spiral gate for monitoring a particular reference spiral is timed to begin at a time based on the radial position of the magnetic head when crossing the preceding reference spiral. In this way, the spiral crossing time for the particular reference spiral can be estimated with sufficient accuracy that the spiral gate coincides with the magnetic head crossing the particular reference spiral. Consequently, spiral detection is assured, even in the presence of large non-repeatable runout.

Abstract: A magnetic write head is positioned based on position signals generated by a read head as the read head crosses a plurality of reference spirals. The spiral gate for monitoring a particular reference spiral is timed to begin at a time based on the radial position of the magnetic head when crossing the preceding reference spiral. In this way, the spiral crossing time for the particular reference spiral can be estimated with sufficient accuracy that the spiral gate coincides with the magnetic head crossing the particular reference spiral. Consequently, spiral detection is assured, even in the presence of large non-repeatable runout.

Abstract: During a self-servo write process, servo sectors that have uniform radial spacing are written on a disk surface. As part of the in-drive writing of the servo sectors, a radial offset between a reader element and a writer element of a magnetic head is measured. The measured radial offset, or micro-jog, is compared to a known nominal micro-jog value for the current radial position of the magnetic head. When the measured micro-jog value does not match the nominal micro-jog value, an appropriate correction to the self-servo write step size is applied to the radial spacing between the servo sectors being written. Variations from ideal servo spiral slope that are inherent in some servo spirals can be compensated for, thereby improving the uniformity of radial spacing of data tracks associated with the servo sectors.

Abstract: A reference spiral is written on a recording surface of a hard disk drive. By launching writing of fine guide spirals from a launch point that is disposed on a pre-existing coarse guide spiral, writing of the fine guide spiral can be launched in response to a write head crossing the pre-existing coarse guide spiral, rather than in response to a precisely timed event. To enable launch points being disposed on pre-existing coarse guide spirals, launch points are not all located at the same radial position on the recording surface.

Abstract: A reference spiral is written on a recording surface of a magnetic storage disk that is free of position or timing information. The reference spirals are written on the recording surface with a substantially uniform slope by using open loop control of the position of a read/write head in conjunction with an iterative learning control scheme. A voltage profile applied to a voice coil motor is adapted over multiple iterations of moving the read/write head across the recording surface to closely approximate a target voltage profile, and the reference spiral is written using the adapted voltage profile. In addition, ramp contact detection based on actuator current profile may be employed to achieve full utilization of available actuator stroke.

Abstract: In an in-drive erase process for erasing disk surfaces of a hard disk drive, erase spirals are written on multiple disk surfaces and at a different write frequency than that of other data patterns on the disk surfaces. The erase spirals written on a first disk surface can be used to control an erase process on a portion of the remaining disk surfaces. Erase spirals are then written on a different disk surface and can then be used to erase all data on the first disk surface. Consequently, even when every disk surface includes previously written data patterns that can potentially interfere with control of the erase process, the erase spirals so written can control the erase process with sufficient precision to thoroughly erase each disk surface.

Abstract: The location of a load/unload ramp in a disk drive is calibrated by monitoring servo spirals that are crossed by a magnetic read/write head during an unload process. Monitoring the number servo spirals crossed allows an accurate velocity of the read/write head to be determined. Based on this unload velocity and the time elapsed during the unload operation, a distance between an ID crash stop position and the load/unload ramp can be calculated quickly and accurately.

Abstract: The location of a load/unload ramp in a disk drive is calibrated by monitoring servo spirals that are crossed by a magnetic read/write head during an unload process. Monitoring the number servo spirals crossed allows an accurate velocity of the read/write head to be determined. Based on this unload velocity and the time elapsed during the unload operation, a distance between an ID crash stop position and the load/unload ramp can be calculated quickly and accurately.

Abstract: Preamble fields are written on a storage disk in a hard disk drive in a way that reduces track squeeze. Preamble fields for a particular data storage track on the storage disk are written over multiple revolutions of the storage disk to eliminate low-frequency variations of the preamble stitch line from an ideal position of the preamble stitch line. By writing the preamble fields for one data storage track over multiple revolutions, and by writing the preamble fields in each revolution to non-consecutive servo wedges, low-frequency variations of the preamble stitch line from its ideal position can be converted to high-frequency variations of the preamble stitch line that do not produce low-frequency track squeeze.

Abstract: Preamble fields are written on a storage disk in a hard disk drive in a way that reduces track squeeze. Preamble fields for a particular data storage track on the storage disk are written over multiple revolutions of the storage disk to eliminate low-frequency variations of the preamble stitch line from an ideal position of the preamble stitch line.

Abstract: Producing a servo pattern on a media involves rotating a master, and during a first revolution of the master, forming a first transition at a first radial position on the master, and forming a first transition at a second radial position. During a second revolution of the master, a second transition at the first radial position is formed, and a second transition at the second radial position is formed. By exposing individual servo burst transitions located at the first and second radial positions, in separate disk revolutions, only one of the magnetic transitions will inherit a particular deflection from a nominal radial position. If there are any mechanical disturbances, each magnetic transition will be randomly displaced from its nominal position, reducing the written-in run-out by ?n, where n is the number of magnetic transitions in a particular servo burst.

Abstract: Producing a servo pattern on a media involves rotating a master, and during a first revolution of the master, forming a first transition at a first radial position on the master, and forming a first transition at a second radial position. During a second revolution of the master, a second transition at the first radial position is formed, and a second transition at the second radial position is formed. By exposing individual servo burst transitions located at the first and second radial positions, in separate disk revolutions, only one of the magnetic transitions will inherit a particular deflection from a nominal radial position. If there are any mechanical disturbances, each magnetic transition will be randomly displaced from its nominal position, reducing the written-in run-out by ?n, where n is the number of magnetic transitions in a particular servo burst.

Abstract: In a disk drive, a method for servo burst-decoding demodulation that accommodates track pitch variation. Depending on the distance a read head is displaced from a read head target position, a target-based blending scheme, a position-based blending scheme, or a weighted combination of both is used to determine the position of the transducer head. When the transducer head is relatively close to the target position, the target-based blending scheme is used to decode servo bursts and calculate the exact head position. When the transducer head is relatively far from the target position, the position-based blending scheme is used to decode servo bursts and calculate head position. When the transducer head is an intermediate distance from the target position, a weighted combination of the target-based and position-based blending schemes is used.

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: 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: A servo wedge on a recording medium for a disk drive includes a gray-code field that stores a micro-jog correction factor for a data track. The micro-jog correction factor compensates for the effect of accumulated track pitch variations. In one embodiment, the radial wedge formed by gray-code fields for adjacent data tracks is a continuous radial wedge similar to the gray-code field used for encoding track numbers.

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.