• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.977-982
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• 2001

In this paper, we deal with the analysis and optimum design of a disc drive feeding system. Using this proposed design method, we can determine an optimal step motor and lead-screw for the shorter seek time and required seek resolution. Simulation results show that this method can be potentially implemented in the design of a feeding system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.1010-1014
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• 2002

A new type actuator has been designed and investigated to overcome thermal problems in slim optical disc drive which is adopted in mobile storage devices. Recently, in optical storage device technical trends, the size of optical disc drives is slimmer to adopt notebook computer and the spindle rotate velocity is faster to achieve high transfer rate and the power of actuator is higher to perform tilting, etc. However, these trends of optical disc drives tend to raise the environment temperature of drives, actuator power and parts temperature. Moreover, it is more difficult to remove the heat inside a drive and the temperature of an actuator increases and drive slims. As a result, increase of surface temperature of actuator body caused that second resonance of an actuator moves down to a lower frequency band and the performance of optical parts also deteriorates. Especially objective lens, coil and magnet of the actuator parts are easily damaged. To manage these thermal problems, in this paper an actuator with a hybrid blade, which is composed of vectra which has low thermal conductivity and magnesium which has high thermal conductivity, has been suggested and verified. Despite the high temperature environment, the proposed actuator showed good dynamic performance.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2266-2268
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• 2000

본 논문에서는 스캐닝 미러의 일종으로, 광저장 장치의 픽업헤드용으로 미세회전을 하면서 레이저 빔을 편향시키는 용도로 사용되는 미러를 제작하고 구동실험을 하였다. 제작된 미러의 크기는 $2400{\times}2400{\times}64{\mu}m^3$이고, 빔 스프링은 $500{\times}9.6{\times}64{\mu}m^3$이다. 니켈 전해 도금으로 29${\mu}m$ 높이의 구동 전극을 제작하였고(세가지 모델: 공기통로가 없는 전극, 공기통로와 간격이 각각 200${\mu}m$인 전극, 공기통로와 간격이 각각 100${\mu}m$인 전극), 미러판과 전극을 조립하여(미러판과 전극 사이의 간격은 각각 29${\mu}m$, 26${\mu}m$, 26${\mu}m$) 구동실험을 하였다. 공진 주파수의 계산간은 576Hz, 측정값은 3개의 미러에서 모두 568Hz이었다. 전극과 미러판의 간격이 최대 접근거리 18${\mu}m$가 되도록 미세 회전을 시켰을 때, 공기통로가 없는 전극에서는 공진 주파수가 524Hz, 공기통로가 200${\mu}m$인 전극에서는 544Hz로 각각 감쇠되었고, 공기통로가 100${\mu}m$인 전극에서는 그대로 568Hz이었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.5
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• pp.819-827
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• 1997

In this paper, a new modeling of a fine actuator for an optical pick-up has been proposed and multiobjective optimization of the actuator has been performed. The fine actuator is constituted of the bobbin which is supported by wire suspension, the coils which wind around the bobbin, and the magnets which cause the magnetic flux. If current flows in the coils, magnetic force is so produced as to be balanced with spring force of wire, so the bobbin is pisitioned. In this model the transfer function from input voltage to output displacementof bobbin has been obtained so that we can describe this integrated system with electromagnetic and mechanical parts. Wire suspension is regarded as a continuous Euler beam, damper as distributed viscous damping, and bobbin as a rigid body which can move up- and down- ward motion only. According to the model, the high frequency dynamic characteristics of the fine actuator can be known and the effect of damping can be investigated while the conventional second order model cannot. In multiobjective optimization, two objective functions have been chosen to maximize the fundamental frequency and the sensitivity with respect to the input voltage of the actuator so that Pareto's optimal solutions have been obtained using .epsilon.-constraint method. These objective functions will satisfy the trends which will enhance the access speed and reduce the tracking error in the optical pick-up technology of next generation. In the result of optimization, we obtain the designs of the optical pick-up fine actuator which has high speed, high sensitivity and low resonant peak. Furthermore, we offer the relation between two object functions so that the designer can make easy choice.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1147-1152
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• 2004

The objective of this work is to develop a new design method to find optimal coils, especially the optimal coil configuration of an optical pickup actuator. In designing actuator coils, the developed Lorenz force in the coils along the desired direction should be made as large as possible while forces and torques in other directions should be made as small as possible. The design methodology we are developing is a systematic approach that can generate optimal coil configurations for given permanent magnet configurations. To consider the best coil configuration among all feasible coil configurations, we formulate the design problem as a topology optimization of a coil. The present formulation for coil design is noble in the sense that the existing topology optimization is mainly concerned with the design of yokes and permanent magnets and that the optimization of actuator coils is so far limited within shape or size optimization. Though the present design methodology applies to any problem, the specific design example considered is the design of fine-pattern tracking and focusing coils.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.115-120
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• 2005

As a popularity of a portable digital device such as a cellular phone, a digital camera and a MP3 player is spreading, the demand of the mobile storage device increases rapidly. A bluray technology using 405nm laser diode and objective lens having high NA(Numerical Aperture), 0.85, satisfies a miniaturization and a high capacity which are the requirements of the portable device. To develop SFFOP(small form factor optical pickup), it is prerequisite to minimize the number of optical components and establish evaluation and assembly method of micro optical pickup system as well as mass production method of micro optical component. To minimize optical elements of optical pickup, there have been many researches to use P-HOE(Polarized Holographic Optical Element) due to its extremely small size and versatile function. However, P-HOE is handled and assembled very accurately in SFFOP. In this paper, static error signal detection method is developed for an alignment of P-HOE in SFFOP. Using developed static error signal detection method, P-HOE can be aligned very accurately with real time result of static error signals of pickup such as FES(focusing error signal) and TES(Tracking Error Signal). The developed static error signal detection method is verified by the evaluation of commercialized DVD Pickup. And finally. developed static error signal detection method is applied for the assembly of P-HOE in SFFOP system satisfies specification of BD(Blu-ray Disk).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.454-457
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• 1995

In optical disc system, tracking actuator is consisted of coarse actuator and fine tracking actuator. This, two-stage actuator, requires many devices and two servos for large stroke and precisional displacement. These complicate configuration increases moving mass. So dynamic characteristics become bad, that is, sensitivity of high frequency gain decrease. In this paper, frequency performance is willing to be better as so one dimensional tracking actuator is designed. In order to investigate the performance of the proposed tracking actuator, the Bode diagram is plotted with Dynamic analyzer and friction characteristic is explained. Finally, tracking error performance is ins investigated into 0.1 .mu.m resolution with MATLAB simulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.12
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• pp.1261-1267
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• 2004

As the optical disk drives are designed for portable and hostile environment, they have a possibility to miss the track and not to read the data. The shock response of optical disk drives must be analyzed. This research shows the shock response analysis of the optical disk drive. The optical disk drive is modeled as the lumped parameter system in consideration of the pickup and the disk. The lumped parameter model is compared with finite element model in order to verify results. Finally, shock responses are compared with the change of the shock magnitude and the duration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.397-400
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• 2000

The demands of high data transfer rate and high recording density in optical disk memory device are being increased. In order to achieve high performance, lever actuator for optical disk is proposed. Firstly, the role of lever and structure are discussed and the flexure hinge is introduced to enhance the precise movement. Next is to present the magnetic circuit structure and concept design for the lever actuator. Finally, the dynamic modeling of the lever actuator is found and the analysis results are shown. Consequently, the lever actuator shows the possibility as a pickup actuator for the next generation optical disk.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.300-301
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• 2000

DVD는 CD사이즈의 광디스크에 고화질기 MPEG2 디지털 압축동화를 두 시간이상 수록할 수 있는 기록 및 재생기기로써 최초의 규격서가 1996년 8월에 발행되었다. 650nm의 적색반도체레이저와 개구수 0.6의 대물렌즈를 채용한 광픽업으로 직경 12cm의 단면디스크에 CD-ROM의 약 7배인 4.7GB에서 17GB까지의 용량저장이 가능하다. 변조방식은, DC성분을 억제할 수 있고, 또한 DR(Density Ratio)이 큰 EFM-Plus 변조를 채용하고, 에러정정방식은 32kB를 하나의 블록으로 하는 Reed Solomon Product code이다. File system은, 음성, 화상데이터와 컴퓨터 데이터를 통합할 수 있도록 계층구조로 하고, ISO9669 파일시스템과 UDF파일시스템을 함께 사용하고 있다. (중략)