Western Digital Technologies, Inc.

Dennis W Hogg

Phillip Scott Haralson

Galvin Chia

Huanxiang Ruan

Prakash Balasubramaniam

Bernhard E Knigge

Jian J Xu

Matthew R Gibbons

Housan Dakroub

Jonas Andrew Goode

Wentao Yan

Enrico Mammei

Lisha Wang

Pradeep K Thayamballi

Michele Bartolini

Ali Hosseinzadeh

Shufun Ho

Alex Y Tsay

Enrico Sentieri

Paolo Pulici

Matteo Tonelli

Tuyen V Trinh

Chee Shu Tay

Amy R Lundberg

A system for determining a fly height includes a first head of a disk drive, a second head of the disk drive, a capacitive sensor circuit coupled to the first head and the second head, and a logic device coupled to the capacitive sensor circuit. The capacitive sensor circuit is configured to measure a first capacitance between the first head and the first disk, remove noise from the first capacitance using a second capacitance between the second head and the second disk, and based thereon determine a corrected first capacitance. The logic device is configured to determine the fly height between the first head and the first disk using the corrected first capacitance.

System and method for disk drive fly height measurement

A data storage device is disclosed comprising a first head actuated over a first disk surface, wherein the first head comprises a laser configured to heat the first disk surface while writing data to the first disk surface. A write power is applied to the laser and a first write operation is executed to write first data to the first disk surface during a first revolution of the first disk surface. A first transient decrease in an output power of the laser is detected during the first write operation, and when the first transient decrease in the output power of the laser is detected during the first write operation, a write-verify of the first data is executed during a second revolution of the first disk surface.

Data storage device modifying write operation when a laser mode hop is detected

A data storage device is disclosed comprising a first head actuated over a first disk surface, wherein the first head comprises a laser configured to heat the first disk surface while writing data to the first disk surface. A write power is applied to the laser when executing a first write operation, and the first write operation is paused when a transient increase in the output power of the laser is detected. In another embodiment, a write-verify of the written data is executed when a transient decrease in the output power of the laser is detected.

A data storage device is disclosed comprising a head actuated over a disk. A first control circuit comprises a pattern detector configured to detect at least one pattern in write data and generate a corresponding multi-state signal, and a transmitter configured to transmit a first differential signal representing the write data and a second differential signal representing the multi-state signal. A second control circuit comprises a receiver configured to receive the first differential signal and the second differential signal, and a write driver configured to generate a write current applied to the head based on the first differential signal and configured to adjust at least one property of the write current based on the second differential signal.

Data storage device employing differential write data signal and differential write pattern signal

A disk drive slider is disclosed comprising a first read element for generating a first read signal, and a first sense amplifier comprising a first input terminal coupled to the first read element, a first output terminal coupled to a first output line, and a first supply terminal coupled to a supply line. The first sense amplifier is for amplifying the first read signal to generate a first amplified read signal, the first output line is for transmitting the first amplified read signal to a preamp, and the supply line is for coupling to the preamp in order to supply power to the first sense amplifier and supply a first bias to the first read element.

Disk drive slider with sense amplifier for coupling to a preamp through a supply/bias line and a read signal line

A method of manufacturing a flex circuit is disclosed for a disk drive comprising a disk, a head actuated radially over the disk, and control circuitry. The flex circuit is for electrically coupling the head to the control circuitry and comprises a substrate. An electrical coating applied to a first side of the substrate is etched to form a first electrical lead. The first side of the substrate is irradiated with radiation such that the first electrical lead masks the radiation from passing through the substrate to prevent curing of a photoresist applied to the second side of the substrate to form an uncured photoresist and a cured photoresist on the second side of the substrate. The uncured photoresist is removed from the second side of the substrate to form a groove, and the groove is filled with electrically conductive material to form the second electrical lead.

Method of manufacturing a double sided flex circuit for a disk drive wherein a first side lead provides an etching mask for a second side lead

A disk drive is disclosed comprising a head actuated over a disk, and a fly height transducer operable to generate a fly height signal for the head. The disk drive further comprises control circuitry comprising a current sensor operable to detect a current flowing through the fly height transducer. The current sensor comprises a differential amplifier operable to amplify the current flowing through the fly height transducer over a first range using a first gain, and amplify the current flowing through the fly height transducer over a second range using a second gain less than the first gain, wherein at least part of the second range is different than the first range.

Disk drive comprising extended range head proximity sensor

A disk drive is disclosed comprising a disk, and a slider comprising a head, where the head comprises a write component electrically insulated from the slider. A bias voltage is applied to the write component, and a current flowing between the write component and the disk is measured, wherein the current is indicative of a fly height of the head.

Disk drive measuring fly height by applying a bias voltage to an electrically insulated write component of a head

A disk drive is disclosed comprising a head actuated over a disk, the head comprising a touchdown sensor. A bias signal is applied at a first bias value to the touchdown sensor and a corresponding first resistance of the touchdown sensor is measured. The bias signal is applied at a second bias value to the touchdown sensor and a corresponding second resistance of the touchdown sensor is measured. A reference resistance of the touchdown sensor is estimated based on the first and second bias values and the first and second resistances. An operating bias value is generated for the bias signal based on a predetermined operating temperature of the touchdown sensor, the reference resistance, and a thermal coefficient of resistance (TCR) of the touchdown sensor, wherein the TCR specifies a change in temperature of the touchdown sensor relative to a change in the resistance of the touchdown sensor.

Disk drive calibrating touchdown sensor

A current sensor is disclosed comprising a differential amplifier including a first node, a second node, and an output. The current sensor further comprises a first resistor having a first end coupled to the first node and a second end for coupling to a transducer, and a second resistor having a first end coupled to the second node and a second end. When the second end of the second resistor is unconnected and the differential amplifier is driven with a supply voltage, the first node is biased by a first leakage current and the second node is biased by a second leakage current such that the output represents a current flowing through the transducer.

Current sensor comprising differential amplifier biased by leakage current

A disk drive is disclosed wherein during a write operation a write fly height actuator is configured with a pre-heat value and a read fly height actuator is configured with a read value. When the head is over a target data sector, the write fly height actuator is configured with a first write value and the read fly height actuator is configured with a second write value, and data is written to the target data sector. When the head transitions from writing data to the target data sector to reading a servo sector, the write fly height actuator is configured with the pre-heat value and the read fly height actuator is configured with a read value. After reading the servo sector, the write fly height actuator is configured with the first write value and the read fly height actuator is configured with the second write value.

Disk drive configuring dual fly height actuators during write operation

A disk drive is disclosed comprising a disk comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A head is actuated over the disk, wherein the head comprises a laser operable to heat the disk while writing data to the disk. When a write command is received to write data to a target data sector of a target data track, the head is positioned over the target data track. When the head reaches the target data sector, a power applied to the laser is increased to above a steady state value to compensate for a high fly height of the head. The power applied to the laser is decreased toward the steady state value while writing at least part of the data to the target data sector.

Disk drive increasing laser power at beginning of write in heat assisted magnetic recording

A disk drive is disclosed. The disk drive comprises a disk, a head configured to write data to and read data from the disk, and an actuator configured to position the head relative to the disk. The disk drive also comprises a die including internal circuitry electrically coupled to the head and a bypass trace electrically coupled to the actuator, wherein the internal circuitry comprises one or more preamplifiers and the bypass trace is electrically isolated from the internal circuitry.

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Laguna Hills, CA, United States of America

Dennis W Hogg