• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.407-412
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• 2004

본 연구에서는 PMN-PT bimorph actuator를 이용하여 초소형 광디스크 드라이브용 광픽업 구동기를 제작하였다. 최근에 휴대용 기기에서의 고용량 정보 저장기기에 대한 필요성이 대두됨에 따라 착탈식이 가능한 수 기가급 초소형 광디스크 드라이브가 개발중에 있다. PMN-PT는 약 1.5kV/cm 이하의 전기장에서는 PZT같은 압전 소자와 마찬가지로 입력 전압에 대한 변형률이 선형성을 나타내는데, 사용된 PMN-PT는 PZT의 약 3배 가까운 압전 상수값을 나타내었다. 보 끝단에 외부 힘이 작용할 때 PMN-PT bimorph 구동기가 낼 수 있는 수직 방향의 힘과 변위에 대해서 일반적인 적층 형태로 이론적인 해석을 수행 하였다. 그리고 이 bimorph로 구동될 Cymbal 형태의 변위 확대 기구의 변위에 대한 이론적인 모델을 제시하고, 이를 이용하여 2개의 bimorph로 2축을 동시에 구동하는 픽업 구동기를 제작하였다. 3개의 제작된 prototype으로 실험을 수행하여 예상 변위량과 잘 일치함을 보였다. 또한, 상용 해석 프로그램인 Matlab과 Ansys를 이용하여 Cymbal 확대 기구의 여러 파라미터에 따른 구동 성능의 민감도를 확인해 보았다.

• Journal of KSNVE
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• v.8 no.2
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• pp.346-352
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• 1998

This paper presents actuating characteristics of an asymmetric high-speed optical pick-up fine actuator that can be installed in a small area such as a notebook personal computer. In the asymmetric actuator four points (mass center, actuation center, supporting point of wire suspension on a bobbin, and optical axis) are not coincident so that the proposed actuator suspension reveals undesirable suspension resonance in the pitch and yaw direction. Lumped parameter dynamic model in each direction is used to investigate the driving characteristics with respect to relative location of the four points. Some of desired design directions toward reducing resonance peaks are suggested by using sensitivity information. In order to avoid undesirable resonance, at least supporting point on the obbin must be located in the middle of the mass and actuation center of the asymmetric pick-up actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.762-769
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• 2003

본 연구에서는 적층형 압전소자를 이용하여 초소형 및 슬림형 광디스크 드라이브용 광픽업 구동기를 개발하였다. 최근에 휴대용 정보기기의 급격한 발달로 인해 다양한 형태의 초소형 정보저장기기가 사용되고 있으며 착탈식 형태의 초소형 광디스크를 사용하는 ODD가 개발 중에 있다. 적층 형태의 압전소자와 유연 힌지 형태의 변위 확대기구를 사용하여 구동기의 출력 힘과 허용 변위를 증가시키도록 설계하였다. 압전형 구동기의 동특성을 고려한 모델링과 이론적 해석을 통해 목표 변위와 성능을 만족하도록 설계 변수를 최적화하였고 이를 ANSYS를 이용한 해석과 비교하였다. 상용화된 적층형 압전소자를 이용한 prototype 올 제작하여 실험을 수행하였으며 이론적인 예상 값과 잘 일치함을 보였다. 이와 같은 이론적 해석과 실험 결과를 토대로 높이가 2.5mm이며 15V 에서 $\pm$400$\mu\textrm{m}$의 변위를 갖는 슬림형 및 초소형 ODD에 적합한 압전형 구동기를 설계하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.786-790
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• 2001

In this paper, we propose an optimum design method for optical pick-up actuators. Using this method, we can design an optimal pick-up actuator having the required tracking/focusing performances. Also, the designed actuator has the small mass, force constant for small size of magnetic circuit and large resistance for reduction of heat generation. Simulation results show that this method can be potentially implemented in all the pick-up actuators.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.368-372
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• 2002

Since rolling (Radial AC Tilt) motion in Optical Pickup Actuator causes RF signal degradation, many researches have been done to find out how to reduce rolling degree. This paper aims to introduce two methods of reducing rolling degree with their theoretical concepts and experimental results. First method rearranges magnetic circuit and the other one adjusts the proportion of the distances among mass center, actuating center and supporting center.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.684-687
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• 2002

In optical disk drive(ODD), pickup actuator, which comprises a key part of an optical disk drive equipment. must be thin. compact, and high sensitive. Low tilt is also an important requirement for the actuator, since optical disks are to high density. This tilt occurs from around the axis parallel to the tangential and radial direction of the disk. The main reason of the moment is the coupling effect between focus driving system and tracking driving system. This paper analyzed tut quantity due to focusing and tracking force through coupled fields analysts with electromagnetic analysis and structural analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.618-621
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• 2001

The proposed lever actuator has no friction and mass balance characteristics in motion, which are adapt to high-speed and high-density optical disk system. This paper discussed about the theoretical analysis of the lever structure. The modeling of the lever actuator is found. Using the Newton's method, the motion of equation is deduced through the constraint equations and equilibrium equations in three directions (focusing, tracking and tilting). From the above analysis, we know that the shape of the hinge is the very important parameter on determining the performance of the lever actuator, and the actuator has the 2nd order system characteristics. And the first resonant frequency in transmissibility is dependent to the rigidity of the lever while the first transmissibility resonance of conventional actuators is dependent to the first natural resonance of those actuators. This means that the lever actuator is more stable to the external vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.378.1-378
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• 2002

DVD, HD(High Density)-DVD등의 고밀도 광 디스크의 광 기록재생장치는 고 개구율(Numerical Aperature)의 대물렌즈로 집광 빔의 크기를 소형화하여 기록용량을 증대시키고 있다. 이 경우 광축과 광 디스크의 기록면에 대한 경사는 광학적인 수차가 발생되어 신호 레벨의 저하나 기록시의 피트(pit) 형성의 오류, Crosstalk등의 문제가 발생한다. 이를 극복하기 위해 직접 디스크의 경사에 따라 제어할 수 있는 픽업 구동기가 제안되어 왔지만 주로 Half Height(12.7mm)에 사용되는 틸트 구동기였으며 Slim(6.3mm)형 틸트 구동기는 제안되지 못하였다. (중략)

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.41-50
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• 2002

Optical disk system aiming at fast data transfer rate and high-density recording requires the improvement in performance of the pickup head. Especially, the pickup actuator needs better linearity and stability. So, a lever actuator for optical disk is proposed. In this paper, the role of lever and its structure are discussed and the flexure hinge is introduced to enhance the precise movement. Using the Newoton's method, the motion of equation for the lever actuator is obtained. The results are compared with the analysis results by the FEM (Finite Element Method) for the vibration and the magnetic field. Consequently, the lever actuator has the 2"d system characteristics in 3-axis moving directions and superior stability for the external vibration.tion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.346-350
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• 1996

In optical disk drives, one of commonly used pickup actuator is a Sliding and rotary type of pickup actuator which is cheaper than other pickup actuators and has simple assembly. However, it reported that non-linearity due to friction between a shaft and a sleeve had to be considerably analyzed in design and servo system in employing this type of pickup actuator. In this paper, this friction is modeled as a Coulomb's friction and the effect of friction is examined in the simulation. A digital servo system is applied to pickup actuator with friction in order to have good focusing servo. To enhance focusing servo performance using digital servo merit, frist PD-controller is applied to have fast response performance, second lead-lag compensator is applied to have stable focusing performance.