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Piezoelectric micro-actuators for conventional disk drives

By Lauren Torres,2014-11-26 10:21
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Piezoelectric micro-actuators for conventional disk drives

    MEMS for high-density data storage

    Xiaoyu Yang

    Thin Films and Nanosynthesis Laboratory,

    Department of Mechanical and Aerospace Engineering,

    State University of New York at Buffalo, Buffalo, NY 14260

     Abstract MEMs for high-density data storage usage are studied under three main classifications. First of all, several approaches have been utilized to modify conventional data storage system, to achieve positioning more precisely and faster. Different type of design and techniques are employed or introduced to manufacture such MEMs. Secondly, scanning probe microscopy (SPM) method is studied for even higher density data storage. MEMs are critical in this new technique for achieving read and write data, miniaturizing and integrating the whole systems. Thirdly, MEMs mirror for 3D holographic data storage is also analyzed. Finally, in MEMs point of view, some new considerations towards high-density data storage are reviewed in this study.

I. MEMs for conventional data storage system.

    Conventional dual-stage servo architecture for data storage system is shown in the Fig.1.

    Fig.1 The servo positioning mechanism of a conventional magnetic disk drives.

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    Read and write elements, which transfer data to and from the disk, are affixed to a ceramic slider, which is bonded to a gimbal at the end of the stainless steel suspension.

    An electromagnetic voice-coil motor (VCM) attached to the opposite end of the

    suspension is used to move the slider radially across the disk. Increased tracking accuracy can be provided by a dual-stage control system, using the VCM for coarse positioning

    and a micro-actuator mounted between the slider and suspension for fine positioning.

(1) Piezoelectric micro-actuators for conventional disk drives (actuated suspension)

    Increasing the track density revealed many kinds of disturbance. One of them is the nonlinear response of actuator’s ball-bearing friction. One of the answers is to introduce a piezoelectric micro-actuator into the conventional micro-actuator. A planar-type piezoelectric micro-actuator is placed on the bottom of head suspension, which need lower driving voltage and has higher resonance frequency. In this approach, conventional assembly and machining techniques are used to integrate an electromagnetic or piezoelectric actuator into a conventional steel suspension.

    A planar piezoelectric micro-actuator on a head-arm assembly is shown in Fig.2. The micro-actuators are built into the stainless steel head-mounting block and placed between the head suspension and the arm. The integrated micro-actuator is only 300m thick and

    185mg in weight. This micro-actuator has four piezoelectric elements to generate displacement. Each piezoelectric element is 90m thick and 5.3mm in length.

    Fig.2 Head-arm assembly with piezoelectric micro-actuator.

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