Seagate Technology Incorporated

Kian Keong Ooi

Qiang Bi

Ming Zhong Ding

MingZhong Ding

Wing Kong Chiang

Xiong Liu

Beng Wee Quak

Ricky Wei Watt Yeo

Jack Ming Teng

Xiang Lu

Louis Seng Hong Pang

YangQuan Chen

June Christian Ang

WenJun Cao

Shuang Quan Min

Chiap Heok Ang

Robert Warren

ChoonKiat Lim

Choon Kiat Lim

Choon Wei Ng

ShuangQuan Min

Brent Jay Harmer

Utt Heng Kan

GuoQing Zhang

WeiSung Lee

Christopher M Woldemar

Tze Ming Jimmy Pang

Lee Ling Tan

Lucas KongYaw Lee

Soon Wah Leow

Ricky WeiWatt Yeo

Kok Hiang Cheong

Chi Sern Tan

Lai Kein Chang

ShihMing Lau

Wei Wei Sun

Siok Yin Tan

Chee Meng Leong

Poh Guat Bay

Wei Kin Wan

Brian Nollinger Nollinger

Yang Quan Chen

A data storage drive includes a servo loop for positioning a head over a disc. The servo loop includes a sensor, located in the head, that senses servo information located on the disc and produces a servo signal therefrom. The servo signal is combined with a reference signal to produce a raw position error signal (PES). The servo loop further also at least one phase-matching disturbance attenuation (PMDA) filter that receives the raw PES as an input and responsively outputs a vibration-cancellation signal, which, when combined with the raw PES, cancels vibration-induced disturbance from the raw PES, thereby producing a refined PES. A servo controller receives the refined PES and responsively produces a servo control signal. An actuator moves the head in response to receiving the servo control signal.

Attenuation of vibration-induced disturbances in a data storage device

The disclosed technology provides a system and method that improves interlaced magnetic recording (IMR) data throughput in vibration in storage systems. In one implementation, a method includes determining whether there are write retry operations in the IMR storage device, determining whether bottom track caching space is available responsive to determining whether there are write retry operations in the IMR storage device, performing a vibration detection scheme to identify vibration events responsive to determining whether bottom track caching space is available, determining if a number of vibration events is above a predetermined threshold, and writing data to available bottom track caching space responsive to determining if the number of vibration events is above a predetermined threshold.

Interlaced magnetic recording storage system

Apparatus and method for managing data transfers in a data storage device with rotational media that can be rotated at different speeds. In some embodiments, a non-volatile main memory is formed on a rotatable medium accessed by a moveable data transducer. A media cache provides a non-volatile data storage area. A control circuit directs writes to the main memory as the medium is rotated at a first speed and directs reads from the main memory as the medium is rotated at a higher, second speed. Writes during the rotation of the medium at the second speed are directed to the media cache instead of to the main memory so that no data are written to the main memory at the second speed. The media cache may also be located on the medium or may be formed from solid-state semiconductor memory.

Multi-speed data storage device with media cache for high speed writes

An apparatus includes a disk locked clock system and a feedforward microactuator compensator. The disk locked clock system is configured to estimate a timing error and generate a timing error signal. The feedforward microactuator compensator is configured to generate a microactuator compensation signal, without use of a vibration sensor signal, in response to the timing error signal.

Vibration compensation using disk locked clock error

Systems and methods for compensating for magnetoresistive (MR) jog offset direct current (DC) drift in a disc drive are described. In one embodiment, a method may include determining an occurrence of NOS, for example, by monitoring disc slip, to determine when the method should proceed. An MR jog offset DC drift amount is determined for each head of the disc drive. One of several approaches may be employed for determining the MR jog offset DC drift amount. By determining an MR jog offset DC drift amount for each head, a compensation profile is determined for the drive. The determined compensation profile may then be used during operation of the disc drive to compensate for the DC drift. One of several approaches may be employed for compensating based on the compensation profile.

Direct current magnetoresistive jog offset compensation

In accordance with one embodiment of the described technology, a retract controller capacitor is charged using a back electromagnetic force voltage to produce a backup power source voltage, the retract controller capacitor is discharged to power a retract controller circuit, and an actuator arm of a storage drive is driven toward a desired location concurrently with the discharging operation.

Discontinuous charge/discharge power source for retract application

An interface controller of a storage device configured to manage a write cache of the storage device responsive to changes in a voltage supply provided to the storage device. In one implementation, the interface controller reduces the size of the write cache responsive to the voltage supply dropping at or below a first threshold. The interface controller further disables write permissions to the write cache responsive the voltage supply dropping at or below a second threshold, wherein the second threshold is lower in magnitude that the first threshold. The interface controller periodically receives the voltage supply responsive to transmitting sequential requests to a servo firmware of the storage device.

Dynamic cache reduction utilizing voltage warning mechanism

A power management circuit is provided for a data storage device that is adapted for communicating with a host via an interface circuit. The power management circuit is responsive to a utilization of a control circuit of the data storage device, determined independently of the communication between the data storage device and the host, in providing a supply power to the data storage device. A method is provided comprising connecting a data storage device with a host via an interface circuit; sending data transfer commands from the host to the interface circuit; and monitoring the utilization of a control circuit of the data storage device in terms of the rate at which commands are processed by the control circuit for use in selectively providing a supply power to the data storage device.

Power management in data storage device determining utilization of a control circuit by its rate of command processing

A method of handling resonance effects on disc drives includes the steps of monitoring a position error signal (PES) for an actuator arm of a disc drive, generating a feedforward compensation signal from the PES using a bandpass filter, and applying the compensation signal to a servo control signal. The bandpass filter has a center frequency set to a known resonance frequency. A disc drive includes an actuator assembly including an arm for carrying a head in a transducing relation with respect to a disc in response to a control signal, and a controller that monitors a PES for the arm and generates the control signal. The controller includes a servo controller that generates a servo control signal from the PES, and a feedforward compensation element which bandpass filters the PES to generate a compensation signal which is combined with the servo control signal to generate the control signal.

Method and apparatus for handling resonance effects in disc drives using active damping

An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. A region of the disc stack is identified as a parking band, and when power is not provided to the disc drive, the actuator assembly is held in a parked position within the parking band by an actuator latch. The actuator latch and actuator assembly have different resonant frequencies based on several environmental elements near the actuator assembly, including the temperature of the environment in the disc enclosure. The actuator assembly is unlatched by measuring the environmental element near the actuator assembly and applying an alternating current to a voice coil coupled to the actuator. The frequency of the alternating current applied to the actuator assembly during the unlatching procedure is near the resonant frequency of the actuator assembly in the measured environment.

Adaptive temperature compensated AC unlatch algorithm

A method for writing servo information to a disc rotatably mounted to a spindle motor. A measured cage frequency is obtained from a written reference track, from which an actual cage frequency is predicted. The predicted cage frequency is then used to derive compensated position commands. During a servo write interval, the compensated position commands are used to control the head such that the head follows the disc movements caused by the cage frequency.

Prediction and cancellation of cage frequency in a disc drive

The present invention provides a method to screen tracks on a magnetic disc in a disc drive for harmonic resonance. There are several algorithms in the method performing different functions at various stages of the method. At any point in time, only one track is subjected to test by the method. The first stage of the method has one algorithm performing the function of obtaining a summation of all the absolute Position Error Signal (PES) velocities on a single track. Another algorithm performs the function of obtaining the average PES velocity with the summation of the absolute PES velocities. At the subsequent stage, another algorithm performs the function of obtaining the average PES velocity of a number of revolutions. An algorithm at the final stage performs the function of comparing the average PES velocity to a preset standard criterion, which is determined empirically in a separate algorithm. The track would be failed if the average PES velocity exceeds the preset standard criterion value.

Method for screening oscillatory PES with 1.7 kHz harmonic resonance

A method of producing a modified control signal to an actuator arm assembly of a disc drive to reduce RRO includes the step of generating a correction signal corresponding to a position error signal of a current track. Then to determine a high pass filter transfer function of a high pass filter to decrease a gain of an unwanted frequency generated when increasing a learning gain of the correction signal to achieve a faster convergence without any loss of performance in the disc drive. Then to determine filter parameters from the high pass filter transfer function, and to filter the correction signal by passing the correction signal through the high pass filter to generate a modified control signal to the actuator arm assembly of the disc drive using the filtered correction signal to remove the RRO on a next track.

Enhanced adaptive feedforward control to cancel once-per-revolution disturbance by shaping the internal mode

Growing community of inventors

Singapore, Singapore

Kian Keong Ooi