Maxtor Corporation

Storage Technology Corporation Partners Ii

Harlan P Mathews

Michael McNeil

James A Valent

Michael A Blatchley

Roger G Bailey

Paul M Romano

David W Rickert

Charlie M Monroe, Jr

Robert P McIntosh

Alexander M Muckle

Jerry Walker

Patrick L Adcock

Craig Cambier

Robert E Gercken

The present invention relates to circuitry for processing an analog read signal, such as a signal produced by a magnetoresistive head, in a magnetic data storage system. The circuitry processes the analog signal before the signal reaches the detector which converts the analog signal into a digital signal representative of the data originally stored on the magnetic medium. In one embodiment, the invention comprises circuitry for equalizing the amplitudes of the positive and negative pulses in the analog read signal. In another embodiment, the invention comprises circuitry for reducing the baseline shift of the analog read signal. The invention may be used in magnetic data storage systems using any conventional data detection method.

Mr head read signal preconditioning circuitry

A method for fabricating a dual element head is disclosed. One embodiment includes first depositing a first head element upon a substrate and second depositing a second head element upon the first head element. Each of the depositing steps includes a tolerance that is independent of the other. In the second depositing step, the functional width of the second head element (i.e., the write width if the second head element is a write element) is made wider than a desired functional width for the second head element. The second head element is then trimmed to substantially achieve the desired functional width while using a portion of the first head element as a reference to reduce errors associated with the independent nature of the first and second tolerances. For instance, the portion of the first head element used as a reference can be an edge of a magnetoresistive (MR) read element that defines the read width of the read element. Preferably, the trimming step includes creating erase notches on a portion of the write element that are capable of erasing data from a recording medium. Thereafter, second notches that are deeper than the erase notches and hence less capable of erasing data than the erase notches are created next to the erase notches to adjust the width of the erase notches. It is also preferred that the first head element and the second head element include an air bearing surface that resides substantially in the x-z plane, and that the second head element is trimmed by a focussed ion beam from a direction that includes a y-component to adjust the width of the second head element in the z-direction.

Method for fabricating a dual element head

A head positioning system accurately positions a read/write head along a selected track of a rotating magnetic disk. In one aspect, servo information is embedded along the track with the centerline of the servo information offset a radial distance from the centerline of data stored or written along the track. The head positioning system micro-jogs the read/write head a first and a second radial distance from the centerline of servo information for a read operation and a write operation.

Positioning system for accurately positioning a read/write head over a

MR head differential micro-jog

MR head read signal preconditioning circuitry for reducing pulse

A dual element head is provided that includes a read element and a separate write element, wherein the read width of the read element is greater than the write width of the write element. The head also includes an erase notch for creating an erase strip along the edge of data written by the write element during a write operation. The width of the erase strip is optimized so that undesired data on the track, that could otherwise be read by the wider read element during a subsequent read operation, is removed during the write operation.

Disk drive head having a read wide/write narrow architecture

A vertical recording head structure combines a tri-pad shaped slider body with a uniquely shaped thin-film recording element disposed along a trailing edge of the slider body. The recording element, or transducer, includes a narrow probe tip for writing data to a rotating magnetic disk. The recording element also includes a wide permalloy area to distribute the magnetic field returning from the disk. The wide area spreads the magnetic field lines such that the returning flux is kept from unintentional writing or reading information. The size and orientation of the air-bearing surfaces on the tri-pad slider body causes the slider to assume a flying attitude wherein the leading edge is lifted above the rotating magnetic disk, and the trailing edge is in substantial contact with the disk, during data transfer operations.

Vertical recording using a tri-pad head

A resonant frequency control circuit communicates with a head of a disk drive and the preamplifier of a read channel. The resonant frequency control circuit is useful in achieving peaking of a readback signal generated by reading data from a magnetic disk. The read channel also includes an equalizer circuit for enhancing equalization of the readback signal. A controller communicates with the read channel and the resonant frequency control circuit for, in one embodiment, selectively adding capacitance to that capacitance which is present in the read element of the head and the preamplifier. By controlling the resonant frequency, this desired signal peaking can be achieved, which is related to the frequencies of the coded data on the disk.

Adaptive preamplifier for resonance tuning useful in a disk drive

A magnetic head that vertically records information on a disk and which creates erase bands between the disk tracks. The head has a single pole that has a pair of erase band segments which extend from a center pole section. When the head is writing information, the erase band segments create erase bands at the outer edges of the track by not fully magnetizing the disk and/or increasing the azimuth angle of the magnetized outer edges. The azimuth angle can be increased by constructing the outer segments of the pole to extend at an angle from the center pole section. The reduction in field strength in the outer track edges can be accomplished by making the outer pole segments thinner to cause a saturation of the outer magnetic field. The weaker, angled outer track portions do not generate a significant magnetic field in a head located on an adjacent track, thereby in effect creating erase bands in the disk.

Erase bands for vertical recording

A pulse detection sensing system which provides an output signal only when a maximum voltage peak is detected. The system has a comparator which generates a comparator output signal when an output signal generated by the transducer of the system is equal to or greater than a threshold signal. The comparator is coupled to a peak follower and a sample/hold circuit which increases the voltage of the threshold signal to the level of the head output signal when the output signal attains a zero slope and has equaled or exceeded the set threshold value.

Method of tracking thresholds on a read signal

A differentiating qualifier channel in a hard disk drive. The analog signal read off a magnetic disk by the transducer is amplified and filtered, then immediately differentiated. This differentiated waveform is used to both qualify and to detect the peaks of the analog read signal. Data pulses are qualified by noting that the differentiated waveform always changes polarity after the zero-crossing of a valid peak. Positive and negative peak signals are generated whenever the differentiated waveform exceeds established positive and negative thresholds. From this, a polarity signal is constructed. The pulses indicating where the polarity signal changes states are used to enable a latch. The latch is clocked by a zero-crossings signal which has been delayed such that the zero-crossings occur after the change in polarity. The output from this latch gives the valid qualified data pulses.

Channel qualifier for a hard disk drive which differentiates a raw data

Many of the data read errors encountered in an optical disk system are due to reading off track. These errors are the result of bit shift, which is the shifting of the data transition relative to the center of the detection timing window. This bit shift is the result of the rounded edges of the data marks on the recording medium. A normal data signal is read off the recording medium while the read apparatus is centeed on the data storage track of the recording medium. If the read beam of the read apparatus moves off track radially to either side of the center of the data storage track, the detected data transitions move toward each other due to the rounded edges of the recorded data on the data storage track. This makes the data mark appear shorter and results in bit shift and increased error rate. The off-track bit shift compensation apparatus compensates for this misalignment and the resultant bit shift by dynamically adjusting the analog detection threshold of the read apparatus. The modification of the detection threshold makes the data bit written on the data storage track appear longer. Thus, if the detection threshold is lowered slightly, the detected data transitions will be shifted back to the zero position associated with the read apparatus being centered on the data storage track of the optical disk. This allows the use of both edges of the recorded mark to contain information, thereby doubling the capacity over systems which use the entire mark as a data transition.

Off-track bit shift compensation apparatus

A system and method for maintaining a prescribed track pitch in an optical storage system wherein a second radiation beam is aligned a desired distance from a first radiation beam, the first radiation beam being controllably steered to follow a previously written data track on a record carrier used within the optical storage system. A write alignment servo aligns the second radiation beam the prescribed distance from the first radiation beam in response to an offset signal. The offset signal is generated by optically measuring the distance between a pair of calibration tracks that have previously been placed on the disk so as to have the desired track pitch therebetween. The effect of variations or drift occurring in the optical or electrical components of either the write alignment servo or the optical track pitch measurement system is significantly reduced by regularly calibrating against the fixed track pitch of the calibration tracks.

Track pitch calibration system for use in optical storage devices

A system and method for optically measuring and maintaining track pitch in an optical storage system. A set of at least four calibration tracks, each having a prescribed track pitch or distance therebetween, are precisely placed on a record carrier of the optical storage system during the manufacture thereof. When this record carrier is subsequently inserted into the optical storage system, the track pitch of a select pair of the calibration tracks is optically measured, and an offset signal is generated in response to this measurement. This offset signal is used within the optical storage system for controllably positioning a second radiation beam with respect to a first radiation beam, the first radiation beam being directed to follow a previously written data track on the record carrier. The offset signal may be stored so that it need only be generated during an initialization or calibration mode of the optical storage system, and thereafter be readily available for positioning the second radiation beam relative to the first radiation beam. The select pair of calibration tracks may be an inner pair, having additional tracks adjacent both sides thereof, or an outer pair, having an additional track adjacent only one side thereof; thereby having included in the offset signal the optical effects of having additional data tracks adjacent or not adjacent the respective sides of the pair of calibration tracks whose track pitch is being measured.

Track pitch calibration error reduction

A system and method for optically measuring and maintaining track pitch in an optical storage system. A set of at least four calibration tracks, each having a prescribed track pitch or distance therebetween, are precisely placed on a recording medium of the optical storage system during the manufacture thereof. When this recording medium is subsequently inserted into the optical storage system, the track pitch of a select pair of the calibration tracks is optically measured by maximizing the amplitude of a data read radiation beam, and an offset signal is generated in response to this measurement. This offset signal is used within the optical storage system for controllably positioning a second radiation beam with respect to a first radiation beam, the first radiation beam being directed to follow a previously written data track on the recording medium. The offset signal may be stored so that it need only be generated during an initialization or calibration mode of the optical storage system, and thereafter be readily available for positioning the second radiation beam relative to the first radiation beam. The select pair of calibration tracks may be an inner pair, having additional tracks adjacent both sides thereof, or an outer pair, having an additional track adjacent only one side thereof; thereby having included in the offset signal the optical effects of having additional data tracks adjacent or not adjacent the respective sides of the pair of calibration tracks whose track pitch is being measured.

Growing community of inventors

Boulder, CO, United States of America

Harlan P Mathews