Seagate Technology Incorporated

Prysm, Inc.

Other

Mark A Pajdowski

Duc T Phan

Roger A Hajjar

Alan Claude Burroughs

David L Kent

John Julian Uebbing

Phillip H Malyak

Ich V Pham

Donald Krall

Steven Wayne Burge

Alan SunTzi Shih

Ho Seong Lee

Scanning beam display systems using fluorescent screens and various servo feedback control mechanisms to control display imaging qualities.

Servo-assisted scanning beam display systems using fluorescent screens

Methods and systems for improving imaging quality and power efficiency of scanning beam display systems using fluorescent screens are disclosed. In various embodiments, beam shaping mechanisms for maximizing overlap between the beam cross-section and the florescent element corresponding to each color sub-pixel of the screen, as well as pulse width and timing adjustments, are introduced to reduce imaging noise and improve power efficiency of the display system.

Scanning beam display systems using fluorescent screens and various servo feedback control mechanisms to control display imaging qualities, including techniques and mechanism for measuring and correcting pyramidal errors of a polygon scanner.

Correcting pyramidal error of polygon scanner in scanning beam display systems

A data recording disk file includes rotatable disks with concentric data tracks thereon. The data disk file includes servo information recorded on at least one of the disks, at least one head for reading the servo information during rotation of the disk, and a voice coil motor (VCM) attached to the head for positioning the head relative to the data tracks. A servo is driven by signals read from the head to control the VCM. The servo includes a processor employing an estimator model for estimating the parameters of the VCM and for generating, from the estimated parameters and the servo information, a digital control signal. The digital control signal is converted to an analog control signal. The control signal is applied to a power amplifier which generates an input current for use by the VCM. The processor provides solely a single estimator model which operates in both saturated mode and linear mode depending on the magnitude of the digital PES. In the processor, a discrete model is formed by using a linear continuous model in which the effect of the back electromotive force (emf) is implicitly added into the model, and the current rise time in the VCM is ignored. The processor employs an adaptive estimator model which adjusts its calculations based on both calibrated overall servo gain and the VCM torque constant. The processor also employs a technique used during calibration to identify the average VCM torque constant. The processor employs a technique used during calibration to identify head offsets. The servo includes a short seek and head switch technique which adaptively adjusts the estimator position, the feed forward durations and magnitude based on the identified head offsets.

Disk file head positioning servo system incorporating adaptive saturated

An adaptive feedforward method of canceling and calibrating harmonic disturbances in a magnetic disk drive storage system includes expressing harmonic disturbances to the system as d(t) and expressing an output of the system as y(t). A control signal u(t) is used to cancel the harmonic disturbance d(t), where u(t) is the estimated value of d(t) such that u(t) is an estimated value of d(t). Estimated coefficients a.sub.i and b.sub.i of u(t) are updated using the derivatives of the estimated coefficients and a constant adaptation gain g.sub.i for the ith frequency component of the disturbance. The values of estimated coefficients are implemented in real time. The control signal u(t) is combined with the system output signal y(t) to cancel u(t) from y(t). The functions representing d(t), y(t), and u(t) are included in drive code for the system. A sine function is implemented by a polynomial curve fitting method and the sine function is approximated as a polynomial function for a quarter cycle of the sine function using only four data points. Corrections for phase shift are obtained by modifying estimation equations for the coefficients of d(t) using a d-step delay in a position error signal (PES) measurement for the system. Calibration of the control signal u(t) is initiated in several ways. The coefficient function G.sub.p (s) for y(t) can be a simple plant transfer function or a plant transfer function with a feedback controller which stabilizes the open-loop plant and satisfies a desired specifications, including track-following.

Cancellation and calibration procedures of harmonic disturbances in

A method for carrying out seeks of a transducer between tracks of a disc drive to limit acoustic noise arising from changes in the acceleration of the actuator which supports the transducer. The rate of change of the acceleration is limited utilizing three techniques: limitation of changes in the control signal outputted to an actuator driver that supplies an electrical current to the actuator that gives rise to a torque on the actuator to a preselected slew rate limit, averaging the control signal in successive repetitions of the generation of the control signal and outputting the averaged control signal during an initial portion of the time for the repetition while outputting the control signal determined in the repetition for the remainder of the time for the repetition, and determining a component of the control signal in relation to the difference between the radial velocity of the transducer and a profile velocity determined in relation to the smaller of the distance remaining in the seek and a deceleration distance determined by multiplying the length of the seek by a predetermined factor selected to cause the transducer to coast at substantially constant speed between acceleration and subsequent deceleration of the transducer.

Method for carrying out seeks in a hard disc drive to limit the

A method for carrying out seeks of a transducer between tracks of a disc drive to limit acoustic noise arising from changes in the acceleration of the actuator which supports the tansducer. The rate of change of the acceleration is limited utilizing three techniques; limitation of changes in the control signal outputted to an actuator driver that supplies an electrical current to the actuator that gives rise to a torque on the actuator to a preselected slew rate limit, averaging the control signal in successive repetitions of the generation of the control signal and outputting the averaged control signal during an initial portion of the time for the repetition while outputting the control signal determined in the repetition for the remainder of the time for the repetition, and determining a component of the control signal in relation to the difference between the radial velocity of the tansducer and a profile velocity determined in relation to the smaller of the distance remaining in the seek and a deceleration distance determined by multiplying the length of the seek by a predetermined factor selected to cause the tansducer to coast at substantially constant speed between acceleration and subsequent deceleration of the transducer.

Growing community of inventors

Los Gatos, CA, United States of America

Mark A Pajdowski