• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.3 s.96
• /
• pp.334-340
• /
• 2005

A disk-type 3-DOF actuator which has new principle and very simple structure is proposed. Also it utilizes the relation of bias and control fluxes produced by permanent magnets and coils, respectively, like other conventional electromagnetic actuators, but its main feature is that both the coils and permanent magnets are fixed in the stator, which makes it easy to design the shape of moving part. Operating principle is that a moving disk is driven by reaction force of Lorentz force acting on the fixed equivalent coil. Simple analytic approach and FEM analysis are performed to determine the design parameters so as to increase the driving force and distance. And some experimental results show the feasibility of the proposed actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.577-580
• /
• 2005

This paper reports the high sensitivity actuator for flexible disk. The air stabilized flexible optical disk has very small axial runout. Therefore, It is proper to develop an actuator which has high sensitivity in tracking direction rather than in focusing direction. In order to maximize driving force in radial direction, we present an efficient design of magnetic circuit with simple multi-polarized magnets and auxiliary magnets. Designed magnetic circuit has big force in tracking direction. And we shift 2$^{nd}$ resonance frequency of moving parts Into high frequency band, not causing increase of mass and discord between force and mass centers to secure high sensitivities and sufficient control bandwidth. Finally, experimental results show that designed actuator has superior sensitivity in tracking direction.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.1
• /
• pp.82-88
• /
• 2001

The demands of high data transfer rate and high recording density in optical disk memory device are being increased. In this paper, 4 design parameters for next generation optical disk are investigated. As for the high data transfer rate, two design parameters such as driving acceleration and transmissibility are introduced. As the high recording density is concerned, the minimum linearity and the tilt of the actuator are introduced. Two kinds of pickup actuator are used to evaluate the validity of the parameters through the simulation and the experiment. The 4-wire actuator has good linearity but bad stability and tilt characteristics, while the rotary and axis actuator has good stability for the external vibration but bad linearity. It is demonstrated that the newly proposed design parameters are available to design and evaluate quantitatively the performance of the actuator for the next generation optical disk.

• 정보저장시스템학회:학술대회논문집
• /
• 2005.10a
• /
• pp.248-253
• /
• 2005

The recording density of a hard disk drive is increasing so rapidly that the storage capacity of a commercial HDD in PC reaches several hundred giga bytes recently. Many technologies related to the HDD, such as servo, media, actuator dynamics, thermo and fluid dynamics, etc. must be developed together to realize high recording density. Especially, researches in the airflow inside the HDD cavity become important as the rotational speed of a disk increases. Typical problem due to the airflow is the vibration of an actuator as the airflow collides with an I-block, suspensions and sliders, that is, FIV(Flow Induced Vibration). This problem is one of the significant sources of increasing TMR so that it must be resolved. In this research, a disk damper shape has been modified to minimize the effects of airflow on the actuator. Modified disk dampers which change flow field inside HDD cavity show good effects not only on the disk (tufter but also on the vibration of an actuator. Vibrations of E- block and slider have been measured with LDV and the airflow field inside the HDD cavity has been analyzed using a commercial package to verify these effects.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.660-665
• /
• 2006

This paper presents a finite element method to analyze the free and forced vibration of a hard disk drive (HDD) considering the flexibility of a spinning disk-spindle with fluid dynamic bearings (FDBs), an actuator with pivot bearings, an air bearing between head-disk interface and the base with complicated geometry. Finite element equation of each component is consistently derived with the satisfaction of the geometric compatibility of the internal boundary between each component. The spinning disk, hub and FDBs are modeled by annular sector elements, beam elements and stiffness and damping elements, respectively. The actuator am, E-block, suspension and base plate are modeled by tetrahedral elements. The pivot bearing in the actuator and the air bearing between head-disk interfaces are modeled by the stiffness element with five degrees of freedom and the axial stiffness, respectively. A global matrix equation obtained by assembling the finite element equations of each substructure is transformed to a state-space matrix-vector equation, and both damped natural frequencies and modal damping ratios are calculated by solving the associated eigenvalue problem with the restarted Arnoldi iteration method. Modal and shock testing are performed to show that the proposed method well predicts the vibration characteristics of a HDD.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.1072-1075
• /
• 1997

To enhance the effective data transfer rate the multi-beam optical disk drive is presented. The Beam rotating actuator is necessary for putting multi-beam on more than one track. Ray tracing was also executed for real system set-up. The Beam Rotating Actuator is made up of piezoelectric material, high stiffness wire hinge and dove prism. The actuator has about 1kHz natural frequency and suitable and suitable operational range. The dynamic equation for the actuator is derived for the control of real system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.12
• /
• pp.1207-1222
• /
• 2004

In this paper, the explicit equations on the power consumption and sensitivity ratio of VCM-type actuator for disk drive are proposed. The power consumption and sensitivity ratio is derived in frequency domain. The power consumption during the track following of the actuator can be described well in frequency domain and it can be used to calculate the total power dissipation of the actuator which is needed to compensate the tracking and focusing errors. Also, the sensitivity ratio of an actuator is derived by using the reference servo of a disk drive and will be used to optimally obtain the performances of the actuator. This sensitivity ratio can persuasively explain the basis of the target performances of the actuator in the considerations of the reference servo. The usefulness of the proposed equations for the sensitivity ratio and power consumption of an actuator is shown by a lot of simulations. In the near future, we will verify the simulation results by experiments.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.14 no.5
• /
• pp.598-603
• /
• 2004

An optical head actuator of an optical disk drive consists of two servo mechanisms for the focusing and the tracking to acquire data from disk. As the rotational speed of the disk grows, the utilized lag-lead-lead compensator has known to be above its ability for precisely controlling the optical head actuator. To overcome the difficulty, this paper propose a new controller design method for optical head actuator based fuzzy proportional-integral-derivative (PID) control and the genetic algorithm(GA). It employs a two-stage control structure with a fuzzy PI and a fuzzy PD control and is optimized by the GA to yield the suboptimal fuzzy PID control performance. It is shown the feasibility of the proposed method through a numerical tracking actuator simulation.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.670-675
• /
• 2003

With the increase in recording density and higher rotation speeds, the aerodynamic aspect of hard disk drives (HDDs) is now quite significant. To achieve high TPI (tracks per inch) for hard disk drives, the actuator must induce less air turbulence. Also, alternative cross sections for the actuator arms are proposed for the reduction of air turbulence. In this study, off-track vibration of actuator arms used in of 3.5" hard disk drives with different cross sections have been measured by using Laser Doppler Vibrometer (LDV). It has been found that the vibration of the actuator arms with modified cross sections is lower than the conventional one.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.266-271
• /
• 1996

Optimal design of disk shaped piezoelectric actuator and sensor mounted on the plate structure is studied for the control of noise radiated fro the structure. The sensor signal is returned to the actuator through negative gain. Finite element modelling is used for the plate structure and the disk shaped piezoelectric sensor and actuator. The objective function is the total radiated sound power and the design variables are the locations and sizes of the piezoelectric actuator and sensor. The optimal is performed at the resonance and the off resonance frequency and the results show good noise reduction.