David Shen Tien

US Patent:

6972540, Dec 6, 2005

Filed:

Nov 19, 2004

Appl. No.:

10/993077

Inventors:

Zhi Wang - San Jose CA, US
Jenghung Chen - Cupertino CA, US
David Dung Tien Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

H02P005/00
G11B021/02

US Classification:

318650, 318560, 318561, 318254, 318268, 360 75, 360 7708, 360 7812

Abstract:

A disk drive is disclosed wherein a BEMF speed error is measured during a BEMF spindle speed control mode, and a spindle control current is updated in response to the BEMF speed error to drive the disk at an operating speed. A reference time period (RTP) is calibrated, and a sinusoidal error in a wedge time period (WTP) due to eccentricity in the disk rotating is estimated to generate an eccentricity compensation value. After switching to a wedge spindle speed control mode, an actual WTP is detected and a wedge speed error is generated in response to the RTP, the detected actual WTP, and the eccentricity compensation value. The disk is then maintained at the operating speed by updating the spindle control current in response to the wedge speed error.

US Patent:

6995941, Feb 7, 2006

Filed:

Jan 7, 2005

Appl. No.:

11/031616

Inventors:

Masao Miyamura - Diamond Bar CA, US
David Dung Tien Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 21/02

US Classification:

360 75

Abstract:

A method is disclosed for improving head position determination in a disk drive having a transducer head and a rotating disk with a plurality of embedded servo wedges for defining a plurality of concentric data tracks. Each servo wedge has a plurality of servo bursts for providing radial track position information. In the method, the servo bursts within a servo wedge are read and a burst amplitude is determined for each servo burst. The burst amplitudes are compared to determine a radial servo position zone. A fine radial head position within the radial servo position zone is determined based on a ratio having a numerator consisting of an algebraic sum and difference of the burst amplitudes and a denominator consisting of an algebraic difference between a largest burst amplitude and a smallest burst amplitude.

US Patent:

7068451, Jun 27, 2006

Filed:

Nov 16, 2004

Appl. No.:

10/989674

Inventors:

Zhi Wang - San Jose CA, US
Jenghung Chen - Cupertino CA, US
David Dung Tien Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 5/09

US Classification:

360 51, 360 25

Abstract:

A disk drive and method for estimating a sinusoidal error in a wedge time period is disclosed. An estimated WTP is calculated according to:EST_WTP=RTP+*cos(2π)+*sin(2π)wherein RTP is a reference time period corresponding to a nominal WTP, k is an index representing a servo wedge, and {â,{circumflex over (b)}} are adjustable coefficients. A wedge time error e(k) is estimated as the difference between the estimated WTP and a detected actual WTP. The coefficients {â,{circumflex over (b)}} for generating the estimated WTP are adjusted according to:(+1)=()−()*cos(2π){circumflex over (b)}(k+1)={circumflex over (b)}(k)−G*e(k)*sin(2πk/N)wherein G is a predetermined gain.

US Patent:

7110214, Sep 19, 2006

Filed:

Jan 18, 2005

Appl. No.:

11/039401

Inventors:

Kuang-Yang Tu - Irvine CA, US
David Dung Tien Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 5/596

US Classification:

360 7806

Abstract:

Disclosed is a disk drive including an actuator having a coil, a head attached to the actuator, and a disk including at least a first track and a second track, and a processor for controlling operations in the disk drive including a seek operation from the first track to the second track in which the head is moved between the first track and the second track by the movement of the actuator. The processor under the control of a program generates a deceleration velocity profile for the seek operation that is determined based upon a deceleration velocity profile function that includes a back electromagnetic force (BEMF) model to take into account back electromagnetic forces (BEMFs) associated with the coil of the actuator such that the BEMFs are mathematically modeled. The head is commanded to seek to the second track utilizing the deceleration velocity profile function that includes the BEMF model.

US Patent:

7251098, Jul 31, 2007

Filed:

Nov 19, 2004

Appl. No.:

10/992930

Inventors:

Zhi Wang - San Jose CA, US
Jenghung Chen - Cupertino CA, US
David Dung Tien Nguyen - Fountain Valley CA, US

Assignee:

Western Digital Technologies, Inc. - Lake Forest CA

International Classification:

G11B 5/596
G11B 5/09

US Classification:

360 7704, 360 51

Abstract:

A disk drive is disclosed that estimates a sinusoidal error in a wedge time period due to eccentricity in the disk rotating to generate eccentricity compensation values. During a write operation a head is positioned over a target data sector within a target track, a write clock frequency is set using an eccentricity compensation value corresponding to the target data sector, and data is written to the target data sector using the write clock frequency. In this manner, the eccentricity compensation value adjusts the write clock frequency to better optimize the linear bit density from the inner to outer diameter tracks.

US Patent:

20060242313, Oct 26, 2006

Filed:

Jun 7, 2006

Appl. No.:

11/449058

Inventors:

Chinh Le - San Jose CA, US
David Tien - San Jose CA, US
Thanh Truong - San Jose CA, US

Assignee:

LeWiz Communications - San Jose CA

International Classification:

G06F 15/16

US Classification:

709230000

Abstract:

Packets received over a network are routed using a packet engine of the invention based on information contained in layer 4 or above. The information for switching is contained in the header information of the packet. Based on this higher level information, the packet engine may drop the packet, redirect the packet, load balance the packet, perform bandwidth provisioning (e.g., limit the speed of a connection), or adjust quality of service (e.g., change priority or rearrange a queue of packets to be handled), or combinations of these.

US Patent:

20120022679, Jan 26, 2012

Filed:

Jun 9, 2011

Appl. No.:

13/156865

Inventors:

DongSub Choi - Sungnam City, KR
Amir Widmann - Sunnyvale CA, US
Daniel Kandel - Aseret, IL
David Tien - Santa Clara CA, US

Assignee:

KLA-TENCOR CORPORATION - Milpitas CA

International Classification:

G06F 19/00

US Classification:

700108

Abstract:

A method for automatic process control (APC) performance monitoring may include, but is not limited to: computing one or more APC performance indicators for one or more production lots of semiconductor devices; and displaying a mapping of the one or more APC performance indicators to the one or more production lots of semiconductor devices.

US Patent:

20130060354, Mar 7, 2013

Filed:

Aug 29, 2012

Appl. No.:

13/597944

Inventors:

Dongsub Choi - Yongin City, KR
David Tien - Santa Clara CA, US

Assignee:

KLA-TENCOR CORPORATION - Milpitas CA

International Classification:

G05B 13/02

US Classification:

700 51

Abstract:

The invention may be embodied in a system and method for monitoring and controlling feedback control in a manufacturing process, such as an integrated circuit fabrication process. The process control parameters may include translation, rotation, magnification, dose and focus applied by a photolithographic scanner or stepper operating on silicon wafers. Overlay errors are used to compute measured parameters used in the feedback control process. Statistical parameters are computed, normalized and graphed on a common set of axes for at-a-glance comparison of measured parameters and process control parameters to facilitate the detection of problematic parameters. Parameter trends and context relaxation scenarios are also compared graphically. Feedback control parameters, such as EWMA lambdas, may be determined and used as feedback parameters for refining the APC model that computes adjustments to the process control parameters based on the measured parameters.