• Title/Summary/Keyword: Tangential Tilt

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Development of a 4-axis optical pickup actuator (4 축 광픽업 액추에이터의 개발)

  • Kim, Jae-Eun;Lee, Kyung-Taek;Hong, Sam-Nyol;Ko, Eui-Seok;Seo, Jeong-Kyo;Choi, In-Ho;Min, Byung-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.856-860
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    • 2008
  • Wire-suspensions in the conventional actuators mechanically support the moving part and guarantee the accuracy of the actuator without tangential tilt actuation. However, such a suspension configuration has considerable stiffness in the tangential tilt direction with two additional wire beams for the tangential tilt. Thus, we performed a design sensitivity analysis for the wire-suspension stiffness of 4-axis actuator and controlled the main parameters such as distance among wire-suspensions and wire-suspension length to allow tangential tilt flexibility. The elasticity of frame PCB that supports the moving part by wire-suspensions was also exploited to improve the flexibility of wire-suspension in the tangential tilt direction. A novel suspension structure was devised by establishing eight wire-suspensions at both sides of the moving part for electrical connection to coils. The magnetic circuit according to the proposed 4-axis actuator using multi-polar magnet and coils was also suggested for the generation of electromagnetic forces in the focusing, tracking, radial and tangential tilt directions.

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Design of 2-axis compensation servo system for angle multiplexing Holographic Data Storage (각 다중화 방식의 홀로그래픽 정보저장기기의 양방향틸트 보상시스템 설계)

  • Lim, Sung-Yong;Kim, Nak-Yeong;Han, Cho-Lok;Park, Kyoung-Su;Park, No-Cheol;Yang, Hyun-Seok;Park, Young-Pil
    • Transactions of the Society of Information Storage Systems
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    • v.7 no.1
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    • pp.19-24
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    • 2011
  • Holographic Data Storage System, one of the next generation data storage devices, is a 2-dimensional page oriented memory system using volume holograms in writing and retrieving process. Recently photopolymer with disc type substrate was selected as a media for the Holographic Data Storage System. The disc tilt occurs when the media rotates and the external disturbance applies. The disc tilt causes the change of the angle between the reference beam and the media, the data cannot be retrieved with the right angle or other data page is retrieved. The tilt is generated in a 2-axis direction (tangential, radial). The tangential tilt direction is the same with the multiplexing plane, while the radial tilt direction is a perpendicular to the multiplexing plane. In this research we propose 2-axis tilt angle servo system. The tilt errors are measured by using external photo detector and the additional red laser. Then the tangential direction tilt is compensated by using the galvano mirror. Also the radial direction tilt is compensated by the rotating prism between the relay lens in the reference field. Finally we confirm the compensation results through the Signal to Noise Ratio(SNR) and Bit Error Rate(BER).

PRML Detection for Asymmetric High-density Optical Storage System (고밀도 비선형 광 저장장치를 위한 새로운 부분응답 최대유사도 신호 검출 기술)

  • Lee, Kyu-Suk;Lee, Jae-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.10C
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    • pp.927-932
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    • 2006
  • We Propose a partial response maximum likelihood(PRML) detection method that improves the performance of the high-density optical storage system. It concurrently adjusts the coefficient of equalizer and reference values of branches in Viterbi detector. For the estimation of asymmetric channel characteristics by the tangential tilt, we exploit sync patterns in each data frame. The simulation result shows it improves the Performance up to 4dB at 10-6 BER compared to conventional adaptive PRML.

Study on Tilt of 4-Wire Actuator in Optical Disc (광디스크용 4와이어 구동기의 경사에 관한 연구)

  • 한창수;서현석;이정현;원종화;김수현;곽윤근
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.7
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    • pp.52-60
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    • 1998
  • In optical disc system, 4-wire actuator has undesired tilt which degenerates the performance of RF signal. This tilt occurs from moment around the axis parallel to the tangential direction of the disk. The main reason of the moment is the coupling effect between focus driving system and tracking driving system. This paper constructed tilt mechanism and analyzed tilt quantity due to the moment based on structural analysis and magnetic field analysis. And the experiment about tilt was executed. The results were compared and discussed about the difference. Then, the design method for reducing tilt angle was suggested.

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2-axis deck mechanism for gap servo NFR system (근접장 시스템의 2 축 deck mechanism)

  • Jeong, Mi-Hyeon;Park, Hong-Soo;Lee, Seong-Hun;Seo, Jeong-Kyo;Choi, In-Ho;Min, Byung-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1031-1032
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    • 2007
  • Gap servo NF (Near Field) system is one of technologies to reduce beam spot size by increasing NA (Numerical Aperture) of lens. To achieve higher NA, SIL (Solid Immersion Lens) is used. In the case of using a blue LD (405 nm) as the light source the gap distance should be controlled under 100 nm with much tighter margin. Because of very small gap distance between SIL bottom and the surface of media, relative tilt tolerance is limited. In this paper, we presented 2-axis tilt mechanism for skew adjustment within small tilt margin.

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Tilt analysis of optical pickup actuator using coupled fields analysis (연성해석을 이용한 광픽업 구동기 경사 해석)

  • 신창훈;김철진;이경택;박노철;박영필
    • 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.

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Novel mechanism of Compact size Holographic Data Storage (소형 홀로그래픽 고밀도 저장장치에서의 메카니즘 구성)

  • Ha, Sang-Woo;Park, Hong-Soo;Song, In-Sang;Seo, Jeong-Kyo;Choi, In-Ho;Min, Byung-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1333-1334
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    • 2007
  • Page-oriented angle multiplexing Holographic data storage system is the one of promising techniques for high capacity and data transfer rate, but its size and narrow tilt margin is pointed as a demerit. To overcome this weak point, in this paper, 2-axis deck mechanism for compensation of disc is employed to Compact size Holographic Data Storage (CHDS) which consists of minimized optical components and small 2-axis actuator moving linear & angle direction. Compensation of radial/tangential disc tilt with 2-axis deck mechanism is demonstrated.

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Analysis of coupled effect for 4-wire actuator of optical disc (광디스크용 4-wire 액츄에이터의 연성효과에 관한 해석)

  • 한창수;서현석;이정현;원종화;김수현;곽윤근
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.351-355
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    • 1996
  • In optical disc system, lens actuator of 4-wire has unwanted moment which occurs tilt. The moment around the axis pallet to the tangential direction of the disk occurs to the moving part. when the moving part is moved in tracking direction and focus driving force is applied. This paper analyzed coupled effect due to the moment based on structural analysis and magnetic field analysis, both using finite element method.

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Implementation of a PRML Detection for Asymmetric High-density Optical Storage System (고밀도 비선형 광 저장장치를 위한 새로운 부분응답 최대유사도 신호 검출기 구현)

  • Lee, Kyu-Suk;Lee, Jae-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.11C
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    • pp.1052-1057
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    • 2006
  • The implement the adaptive partial response maximum likelihood (PRML) detector with tilt analyzer for asymmetric high-density optical storage system. For the estimation of disc tilt, we exploit spc patterns in each data frame. Because of using the ROM table to renew the coefficients of equalizer and reference values of branches, the complexity of the hardware is reduced. The proposed PRML has been designed and verified by VerilogHDL and synthesized by the Synopsys Design Compiler with Hynix $0.35{\mu}m$ STD cell library. In the result, the total gate count is 35K, and the maximum operating frequency is 140MHz.

5-Tap Adaptive PRML Architecture for High-Density Optical Disc Channel

  • Choi, Goang-Seog
    • Journal of Korea Multimedia Society
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    • v.10 no.12
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    • pp.1585-1590
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    • 2007
  • This paper introduces adaptive PRML (Partial Response Maximum Likelihood) architecture with PR (a,b,c,d,e) channel type for the improved readability of high-density optical discs with capacity greater than 30GB. The proposed PRML architecture consists of an adaptive equalizer, a Viterbi detector and a channel identifier. Detailed description for each component is included. The architecture is implemented in chip and also confirmed its performance on the test board mounting the chip. Test results show that the proposed 5-tap PRML architecture is well operated, and less than $2{\times}10^{-4}$ of BER (Bit Error Rate) is achieved with radial and tangential tilt margin of ${\pm}0.6^{\circ}$ on self-made 30GB BD at 1x speed.

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