Min J Chen

7440225, Oct 21, 2008

Aug 21, 2006

11/507234

Min Chen - San Rafael CA, US
Zhi Wang - Irvine CA, US

Western Digital Technologies, Inc. - Lake Forest CA

G11B 5/596

360 7804, 360 7809

A disk drive is disclosed including a disk having a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors forming N servo wedges, and a wedge time period (WTP) occurs between each servo wedge. A VCM control signal is generated by generating an estimated WTP by detecting the servo sectors, estimating a pivot velocity in response to the estimated WTP, the pivot velocity representing a velocity of an actuator arm about a pivot, generating a pivot friction compensation in response to the estimated pivot velocity, and generating the VCM control signal in response to the pivot friction compensation.

7589593, Sep 15, 2009

Jan 30, 2008

12/022159

Jie-Wei Lai - Taipei, TW
Min Chen - Fremont CA, US

Mediatek Inc. - Hsin-Chu

H03F 3/04
H03F 1/22

330295, 330311

An amplifier circuit for amplifying an input signal to generate an output signal is provided. The amplifier circuit has a stacked main amplifier, a parallel sub-amplifier, and a signal combiner. The stacked main amplifier includes a first amplifier unit for outputting a first amplified signal generated from processing the input signal; and a second amplifier unit for outputting a second amplified signal generated from processing the first amplified signal. The first amplifier unit and the second amplifier unit share bias current. The parallel sub-amplifier is coupled to the stacked main amplifier according to a parallel connection fashion, and outputs a third amplified signal generated from processing the input signal. The signal combiner combines the second amplified signal and the third amplified signal to generate the output signal.

7595954, Sep 29, 2009

Apr 18, 2006

11/406089

Min Chen - San Jose CA, US
Li Yi - Berkeley CA, US

Western Digital Technologies, Inc. - Lake Forest CA

G11B 5/596

360 7708, 360 7704

Disclosed is a method of estimating repeatable runout (RRO) for a disk drive. The method includes: determining a plurality of position error signal (PES) values for a plurality of servo wedges of a track of a disk; and estimating repeatable runout (RRO) in the PES values for the servo wedges of the track by averaging determined PES values over a pre-determined number of revolutions of the disk of the disk drive and scaling the averaged PES values by a pre-determined ratio of the variance of non-repeatable runout (NRRO) to the variance of an optimal estimation of the RRO for the disk drive.

7616399, Nov 10, 2009

Dec 7, 2006

11/635904

Min Chen - San Rafael CA, US
Zhi Wang - Irvine CA, US
Duc T. Phan - Saratoga CA, US

Western Digital Technologies, Inc. - Lake Forest CA

G11B 5/596

360 7708

A disk drive comprising a moveable head, a disk, and a servo controller that implements servo control techniques to preserve PES continuity during track following operations is disclosed. The disk includes a plurality of tracks in which a substantial majority of the tracks include a plurality of servo sectors having a plurality of servo bursts that are utilized in track following operations. The servo controller controls track following operations with the moveable head and implements operations to preserve PES continuity during track following. These operations include: dividing tracks of the disk into a plurality of zones wherein each zone includes zone boundaries; and utilizing a PES equation for each zone to generate a PES value based upon read servo bursts wherein each zone PES equation includes a normalizing factor to account for boundary conditions associated with zone boundaries to preserve PES value continuity between zones.

7675707, Mar 9, 2010

Nov 21, 2008

12/275989

Min Chen - San Leandro CA, US

Western Digital Technologies, Inc. - Lake Forest CA

G11B 21/02

360 75

A disk drive is disclosed comprising a disk, a head actuated over the disk, and control circuitry operable to generate a fly height control signal. A fly height of the head is measured, and the measured fly height is combined with a target fly height and a feedforward signal, wherein the feedforward signal is generated according to:acos(2πnk/N)+bsin(2πnk/N)where aand bare coefficients and 2πnk/N represents a frequency of a repeatable disturbance in the fly height of the head.

7688538, Mar 30, 2010

Nov 16, 2007

11/941467

Min Chen - San Leandro CA, US
Duc T. Phan - Saratoga CA, US

Western Digital Technologies, Inc. - Lake Forest CA

G11B 21/02

360 75

A disk drive is disclosed comprising a disk surface having a plurality of servo sectors for defining a plurality of servo tracks, and a head actuated radially over the disk surface. A first servo sector defines a first servo track comprising a first track address having a first width, and a second servo sector defines a second servo track comprising a second track address having a second width substantially less than the first width. In one embodiment the servo sectors are written using an external servo writer or media writer, and in another embodiment the servo sectors are self-servo written by the disk drive.

7961422, Jun 14, 2011

Feb 19, 2009

12/388644

Min Chen - San Leandro CA, US
Li Yi - Mountain View CA, US
Duc T. Phan - Saratoga CA, US

Western Digital Technologies, Inc. - Irvine CA

G11B 5/596

360 7704, 360 7708

A disk drive is disclosed comprising a disk having a plurality of servo tracks that define a plurality of data tracks, and a head actuated over the disk by a voice coil motor (VCM), wherein the head comprises a read element offset radially from a write element. The read element is positioned over a first servo track and the write element is positioned over a second servo track, and a first repeatable runout (RRO) of the first servo track is measured. The read element is positioned over the second servo track, and a second RRO of the second servo track is measured. A data center off-track is computed in response to the first RRO and the second RRO.

8001733, Aug 23, 2011

Dec 4, 2009

12/592844

Min Chen - Fremont CA, US

B66F 3/08
E21D 15/00

521264, 254 98, 254 92, 254 93 A, 254100, 521266, 52632, 2483543, 405290

A post adjustable in length as required. The post can be adjusted at any time during and after construction. The post can be used as an extension of a column which requires adjustment in length. The post can be used as a jack. The post is capable of withstanding compression, tension, and dynamic loading. The post can be used to provide support to beams and girders in a house frame.