Abstract:
Various embodiments of the present invention provide systems and methods for determining changes in fly-height. For example, various embodiments of the present invention provide storage devices that include a storage medium having servo data thereon. A read/write head assembly is disposed in relation to the storage medium. A servo based fly-height adjustment circuit receives the servo data via the read/write head assembly, and calculates a first harmonics ratio based on the received data and compares the first harmonics ratio with a second harmonics ratio to determine an error in the distance between the read/write head assembly and the storage medium.
Abstract:
A magnetic recording head comprises a transducer, a heater, a writer and a laser. The transducer is configured to write to a magnetic recording medium during a write operation. The heater, writer and laser are configured to affect a protrusion of the transducer. The heater is calibrated to produce a pre -write heater power to obtain a target pre -write clearance for a write operation through use of a clearance-heater power curve. The curve is generated by measuring a clearance between the transducer and the medium as the heater is cycled from zero to a contact power.
Abstract:
A disk (106) attached to a spindle motor (304) is accelerated to an operating rotational velocity. The head is positioned over a portion of the disc non-accessible to customer data and a data pattern of selected frequency is written. A magnetoresistive element of the head is biased and the data pattern is read while the disc is decelerated to a predetermined rotational velocity threshold. Occurrence of a read signal landing signature (308) comprising relatively low frequency, peak to peak readback signal amplitude modulation prior to reaching the predetermined rotational velocity threshold enables a control circuit (306) to identify the head as a low-flying head.
Abstract:
A method of detecting a contact between a transducing head and a storage medium is provided. The method applies an input signal, having a select power level and known frequency, to an actuator for actuating the head. An output signal is obtained in response to the input signal. At least one signal component is extracted from the output signal at the same or a harmonic of the same known frequency as the input signal applied to the actuator. Whether the at least one extracted signal component indicates a contact between the head and the medium is determined. The power level of the applied wave pattern is increased incrementally until the extracted signal component indicates a contact between the head and the storage medium.
Abstract:
A method for detecting a change in fly-height comprises measuring a baseline position error signal, measuring a position error signal at later time, and comparing the measured change in PES to a predetermined value. If the measured change in PES is greater than the predetermined value, it is determined that a decrease in fly-height has occurred. Depending on whether the disk drive has a head cleaner or whether the PES signal changes occur only at the certain diameter of the disk, a head cleaning is initiated to correct the fly-height change. If no head cleaning is necessary, a general error signal may be generated to indicate potential drive failure.
Abstract:
A method for detecting a change in fly-height comprises measuring a baseline position error signal, measuring a position error signal at later time, and comparing the measured change in PES to a predetermined value. If the measured change in PES is greater than the predetermined value, it is determined that a decrease in fly-height has occurred. Depending on whether the disk drive has a head cleaner or whether the PES signal changes occur only at the certain diameter of the disk, a head cleaning is initiated to correct the fly-height change. If no head cleaning is necessary, a general error signal may be generated to indicate potential drive failure.
Abstract:
A system for determining whether the flying height of a read/write head above a disk (14) in a disk drive (10) is within an acceptable range, in substantially real time. The system relies on variations in read signal resolution with flying height to make the determination. In one embodiment, read signal resolution is measured and compared to a predetermined threshold value to determine whether the present flying height is in the desired range. In another embodiment, the number of peaks in a read signal that are detected (and/or not detected) by a detector is used to determine whether the head is in the proper flying height range. Because of read signal resolution effects, the number of detected peaks will decrease as the flying height of the head is decreased. The system also provides for postponing a transfer of data to/from the disk (14) when it is determined that the head is not within the acceptable range.
Abstract:
Various embodiments of the present invention provide systems and methods for determining fly height. For example, a system for fly height determination is disclosed that includes a head assembly disposed in relation to a storage medium, a write channel, and a read circuit. The read circuit is operable to receive information from both the head assembly and the write channel. A frequency determination circuit is included that is operable to receive a first signal from the read circuit corresponding to information received from the write channel and to provide a first fundamental frequency and a first higher order frequency based on the first signal, and the frequency determination circuit is operable to receive a second signal from the read circuit corresponding to information received from the head assembly channel and to provide a second fundamental frequency and a second higher order frequency based on the second signal. A compensation variable calculation module is included that is operable to divide the first fundamental frequency by the first higher order harmonic to yield a compensation variable. A fly height calculation module is included that is operable to divide the second fundamental frequency by the second higher order harmonic and the compensation variable to yield an indication of a distance between the head assembly and the storage medium.