Maxtor Corporation

Texas Instruments Corporation

Seagate Technology Incorporated

Larry G Hutsell

Curt Bruner

Jeff Reh

Lance R Carlson

Robert L Metz

Keith W Malang

Paul Ray Tomlinson

Terence Joseph Murphy

Glenn Douglas Albert

Farhad Navid

Dave Finamore

Mark Birtzer

Doug Martin

Disturbances to actuator control caused by external vibrations are corrected using feed-forward techniques that are selectively enabled or disabled based on signal values within a track follow loop. An increase in data integrity and reliability may be achieved by reducing off-track reads and writes caused by physical disturbances to disk drives during operation. Accelerometers detect external forces imparted on a disk and an acceleration feed-forward (AFF) signal is generated to compensate for disturbances to the location of a head caused by such external forces. Application of the AFF signal to an actuator may be based on whether signal values along the track follow loop exceed a certain threshold.

Acceleration feed-forward correction enabled or disabled based on track follow loop signals

Control of micro actuator movement is calibrated in response to a sinusoidal input signal. A response of the micro actuator to the sinusoidal input signal is measured, for example, based on measurement of a change in radial location of a transducer connected to the micro actuator responsive to the sinusoidal input signal. Control of the movement of the micro actuator is calibrated based on the measured response of the micro actuator to the sinusoidal input signal. For example, a gain of a micro actuator control loop that controls movement of the micro actuator may be regulated based on the measured change in radial location of the transducer. Related circuits and devices are also discussed.

Micro actuator gain calibration based on a sinusoidal input signal

A method and apparatus are disclosed which are operable to determine a capacitance associated with at least one piezoelectric element in an dual actuator disk drive. The capacitance information is used to adjust a driver used to drive the piezoelectric element. Capacitance is determined by supplying a predetermined current into the piezoelectric element(s) for a predetermined time period. A voltage associated with the piezoelectric element(s) is measured following the predetermined time period. The capacitance of the piezoelectric element(s) is then calculated based on the measured voltage, the current supplied, and the predetermined time period.

Method and apparatus for calibrating piezoelectric driver in dual actuator disk drive

A piezo actuator drive circuit ( ) adapted to operate in both a charge mode and a voltage mode. A low frequency compensation loop ( ) is formed from a piezo actuator output (OUT6XP) of a driver ( ) to the input thereof. The resulting closed loop system produces charge mode operation within a bandpass that can be tuned for desired operation. Below the bandpass turn on frequency (F ) the closed loop system restores the piezo output (OUT6XP) to a defined DC voltage and compensates for any wandering effects, such as DC current mismatches in the closed loop configuration, such that the piezo output is centered around the desired DC operating point. The circuit is further provided with a DC restore feature in combination with the feedback which allows for a low frequency DC coupled path and thus allows for the DC positioning of the piezo in the charge mode to be changed. The DC restoring amplifier is used to compensate for offsets in the amplifier chain. The DC restore amplifier ensures the overall circuit is balanced and that the charge mode operation is maintained. The circuit is particularly adapted to drive a varying number of multiple piezo actuators.

Closed loop charge mode drive for piezo actuators using a DC restore amplifier

The present invention relates to a disk drive seek control system which is capable of rapidly moving a transducer from an initial position to a target position above a data storage medium. The system applies control to an actuator motor means based on projected transducer velocity at a future servo sample time rather than velocity at a previous servo sample time. This allows the system to significantly reduce transducer velocity errors relative to a desired velocity profile. In addition, the system utilizes dynamically adapted feed forward deceleration current during a deceleration portion of the seek cycle to further reduce velocity errors during this period. By reducing velocity error during the seek cycle, the system significantly reduces the length of time required for settling the transducer on the target track of the disk after the seek cycle has ended.

Disk drive seek control system utilizing predicted motion parameter and

An electronic architecture that provides a portable hard disk drive that can meet the type II PCMCIA specification and which can efficiently operate with a 3.3 V power supply. The architecture includes a digital signal processor with a first internal bus for transferring instructions and a second internal bus for transferring data. The digital signal processor performs fetching, decoding, reading and execution routines in parallel while simultaneously receiving data.

System architecture for hard disk drive

A disk drive system comprising a shock evaluator is disclosed. The shock evaluator includes a shock evaluation circuit and threshold logic and firmware that is capable of evaluating the level of physical shocks to the disk drive system. The shock evaluation circuit is capable of comparing the level of a physical shock to threshold shock values. The threshold logic and firmware is capable of periodically resetting the threshold shock values to account for the change in operating conditions experienced by the disk drive system. When the shock evaluator determines that a physical shock is present, communication between the read/write transducer and the disk is interrupted to prevent corruption of data stored on the disk.

Disk drive with shock evaluator

A disk drive system comprising a shock sensing circuit is disclosed. The shock sensing circuit includes a shock evaluation circuit and threshold logic and firmware that is capable of evaluating the level of physical shocks to the disk drive system. The shock evaluation circuit is capable of comparing the level of a physical shock to threshold shock values. The threshold logic and firmware is capable of periodically resetting the threshold shock values to account for the change in operating conditions experienced by the disk drive system. When the shock sensing circuit determines that a physical shock is present, communication between the read/write transducer and the disk is interrupted to prevent corruption of data stored on the disk.

Integrated shock sensing device

An electronic architecture that provides a portable hard disk drive that can meet the type II PCMCIA specification and which can efficiently operate with a 3.3 V power supply.

System architecture for HDD

A servo system for controlling the position of a read/write head over a rotating data disk is disclosed. The servo system includes the addition of a compensation scheme to the feedback loop that causes the open loop gain of the servo to increase only in a very narrow spectrum of its operating bandwidth. In a preferred embodiment, the compensation takes the form of a second order digital filter combined with a proportional-integral-differential phase compensation filter in the feedback loop of an embedded servo system for a digital data disk drive.

Servo system with once per revolution rejection

Dual internal bus system architecture for hard disk drive

An integrated servo circuit that controls the spin motor and voice coil motor of a hard disk drive in response to digital commands that are generated by a microprocessor based controller chip. The servo chip contains a spin motor control circuit and a voice coil control circuit that control the speed of the spin motor and the position of the actuator arm, respectively. The spin motor and voice coil motor control circuits are coupled to a digital to analog converter which converts the digital commands from the controller chip into analog control signals which are utilized to control the spin motor and voice coil motor. Additionally, the servo chip has an analog to digital converter to convert analog signals, such as the servo burst signals, to digital bit strings that relayed to the controller chip. The controller chip and servo chip communicate through a 16 bit synchronous serial port.

TUT servo IC architecture

A method for starting spin-up of a spindle motor in a hard disk drive. When power is initially applied to the spindle motor, the spindle motor is set to a first commutation state. The spindle motor is maintained in this first commutation state for a pre-determined period of time to allow the spindle motor to reach a known null point. Thereupon, the spindle motor is advanced to a second commutation state. The spindle motor is then maintained at this second commutation state for another pre-determined period of time. Finally, the spindle motor is advanced two successive commutation states to a peak torque curve. Once the spindle motor has started spinning, the commutation process is controlled according to the sensed back EMF voltage being generated in the off-phase.

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Longmont, CO, United States of America

Larry G Hutsell