Data Storage Institute

National University of Singapore

Other

Teck Seng Low

Shixin Chen

Qide Zhang

Zhejie Liu

Yuen Ann Mah

Yong Feng Lu

Yaolong Lou

Daniel S Chan

Zhimin He

Tong Heng Lee

Shuzhi Ge

Mohammed Abdul Jabbar

Ma Jabbar

Qinghua Li

Huai Lin

Bo Liu

Yaolong Zhu

Chun-Hung Tony Huang

Friction existing between any two surfaces having relative motion is nonlinear, multiform, and is difficult to model. Nonlinear friction in the actuator pivot of a hard disk drive (HDD) limits the low frequency gain, which prevents the system positioning accuracy from further improvement. This problem is much more pronounced for the severe nonlinearity at the micrometer level. The conventional two-mode proximate time optimal servomechanism (PTOS) is inadequate for immediate future hard disk drives because of the existence of restrictions in the particular design approach. A triple-mode control scheme, and its variations, as presented herein, include (a) a proximate time-optimal controller (PTOC) having a relatively large output is used for track seeking, (b) a robust compensator having a relatively small output is used for track following to compensate for friction and other nonlinearities, and (c) a bridging (connection) control to guarantee the continuity of the control signals. Because of the introduction of an extra mode, additional freedoms for controler design are made available for improved performance. The robust compensator is non-model based in the sense that it does not depend on the models of friction and other nonlinearities. This makes the invention simpler and more practical than conventional systems.

Robust triple-mode compensator for hard disk drives with dynamic friction

A spindle motor ( ) including a stator component ( ), a rotor component ( ), including a hub ( ) for supporting one or more discs, and a bearing assembly between tHe components, formed of a journal bearing ( ) and a thrust bearing ( ), wherein the journal bearing ( ) is an aerodynamic bearing and the thrust bearing is adapted to function in a bi-directional manner and includes an annular member ( ) projecting radially from one of the components into an associated recess ( ) formed in the other of the components. Preferably, the annular member has two opposed bearing faces ( ) arranged adjacent corresponding bearing surfaces of the recess, and a hydrodynamic bearing is formed between the respective bearing faces and surfaces.

Spindle motor with an aerodynamic and hydrodynamic bearing assembly

An actuator assembly for positioning read/write heads above a data storage media comprises a pivotally mounted carriage arm assembly with a voice coil and a magnetic device having a plurality of poles for generating a magnetic field. The voice coil is positioned with its effective portions crossing through the magnetic field to generate at least one pair of driving forces in a direction substantially orthogonal to a seeking direction of the read/write heads. The carriage arm driven by said pair of forces has substantially no reacting force generated onto the pivot so that the servo bandwidth of the head positioning assembly can be improved and achieves a high degree of head positioning accuracy.

Actuator assembly with orthogonal force generation

A method and apparatus for measuring the flying height of a slider above a disk surface and in-situ monitoring the slider disk interface comprising the steps of: providing a beam of light; providing a slider disk interface comprising a disk having a substantially transparent substrate and a thin film layer, a slider for carrying a read/write element, the slider having a reflective surface; and an air bearing having a thickness d for supporting the slider above the disk; directing the beam of light to the slider disk interface through the disk, the thin film layer, the air bearing and then to the reflective surface of the slider; and measuring one of the intensity and phase information of the light reflected from the slider disk interface to provide an indication of the thickness d of the air bearing and/or of the thin film layer.

Method and apparatus for measuring flying height of the slider and in-situ monitoring a slider-disk interface

An electric spindle motor has a base assembly (19) and a hollow notatable hub (16) housing a motor. The hub (16) is mounted for rotation about an axis and a stator (12) is mounted on the base assembly (19) inside the hub (16). A liquid filled journal bearing (11, 21) acts between the base assembly (19) and the hub (16) to provide radial support of the hub (16). A gas filled thrust bearing (26, 27, 35) also acts between the hub (16) and base assembly (19) to provide at least axial support of the hub (16).

Electric spindle motor

An electric spindle motor has a base assembly (19) and a hollow notatable hub (16) housing a motor. The hub (16) is mounted for rotation about an axis and a stator (12) is mounted on the base assembly (19) inside the hub (16). A liquid filled journal bearing (11,21) acts between the base assembly (19) and the hub (16) to provide radial support of the hub (16). A gas filled thrust bearing (26, 27, 35) also acts between the hub (16) and base assembly (19) to provide at least axial support of the hub (16).

A dry process to remove mold flash on integrated circuit packages (IC packages) by using pulse, short wavelength laser irradiation. The mold remnants on the surface or in holes of the lead frame can be removed by pulse laser irradiation, with the effect of thermal expansion of lead frame metals and momentum transferring from the laser beam to the mold remnants. Compared with conventional water jet or etching processes, the new technique has high productivity and does not degrade the reliability of the IC packages, due to the fact that there is no water or chemical solutions involved in the process.

Growing community of inventors

Singapore, Singapore

Teck Seng Low