Browsing by Author "Fang, Jen-Yu"

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A multiple power-level approach for wireless sensor network positioning
(2008-11-13)
Fang, Jen-Yu
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Chu, Hung-Chi
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Jan, Rong-Hong
;
Yang, Wuu
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資訊工程學系
Wireless sensor networks enhance our ability to monitor the physical world. Many recent researches on wireless sensor networks have focused on aspects such as routing, node cooperation, and energy consumption. In addition to these topics, the positioning service is also an important function in sensor networks. This paper presents a multiple power-level positioning algorithm, discusses its capabilities, and evaluates its performance in various environments. The simulation results show that the proposed algorithm exhibits better accuracy than do traditional single power-level methods. In critical situations such as reference node failure, unstable radio transmission range and beacon collision, the proposed algorithm still performs well. Finally, the positioning method is implemented on a sensor network test bed, and the actual measurements show that, the average estimation error is 2.5 m when three power-levels are used and adjacent reference nodes are 12 m apart in an outdoor environment. (C) 2008 Elsevier B.V. All rights reserved.
A novel patterned diffuser for high uniform and high bright LCD backlights
(2007)
Lo, Yu-Chun
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Fang, Jen-Yu
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Huang, Yi-Pai
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Shieh, Han-Ping D.
;
Yu, Gu-Sheng
A novel patterned diffuser of which the diffusivity can be optimized spatially for the non-uniform luminance distribution backlights. was designed and realized. An 11% improvement in the brightness uniformity was successfully demonstrated in a 7-in side-edge backlight without sacrificing the brightness.
Dual-probe near-field fiber head with gap servo control for data storage applications
(2007-10-29)
Fang, Jen-Yu
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Tien, Chung-Hao
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Shieh, Han-Ping D.
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光電工程學系
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Department of Photonics
We present a novel fiber-based near-field optical head consisting of a straw-shaped writing probe and a flat gap sensing probe. The straw-shaped probe with a C-aperture on the end face exhibits enhanced transmission by a factor of 3 orders of magnitude over a conventional fiber probe due to a hybrid effect that excites both propagation modes and surface plasmon waves. In the gap sensing probe, the spacing between the probe and the disk surface functions as an external cavity. The high sensitivity of the output power to the change in the gap width is used as a feedback control signal. We characterize and design the straw-shaped writing probe and the flat gap sensing probe. The dual-probe system is installed on a conventional biaxial actuator to demonstrate the capability of flying over a disk surface with nanometer position precision. (C) 2007 Optical Society of America.
Hybrid-effect transmission enhancement induced by oblique illumination in nano-ridge waveguide
(2007-09-03)
Fang, Jen-Yu
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Tien, Chung-Hao
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Shieh, Han-Ping D.
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光電工程學系
;
顯示科技研究所
In a nano-ridge waveguide under oblique illumination, we demonstrated transmission enhancement resulting from a hybrid effect between propagation modes and surface plasmon wave. The measured near-field intensity with 44-degree illumination was 1.6 times higher than that illuminated with normal incident light. Consequently, a wedge-shaped fiber probe was proposed to serve as a compact near-field light source. (c) 2007 Optical Society of America.
Laser diode active height control system for data storage applications
(2006-01-01)
Fang, Jen-Yu
;
Herget, Philipp
;
Bain, James A.
;
Schlesinger, T. E.
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光電工程學系
We describe and characterize an active height control system for near-field data storage applications using a commercial laser diode as a direct position sensor. The self-mixing interference signal was experimentally characterized and the effective spot size of the laser sensor was also measured. A control system utilizing interference in the laser as feedback signal was constructed to drive a conventional DVD pickup with the laser sensor mounted. The residual position error is +/- 9nm when the rotation speed of a glass disk was 1500rpm and the vertical runout was 16 mu m. The approach limit was estimated to be 25nm when the laser size is reduced to 100 mu m.
Laser diode feedback sensor characterization experiments for data storage applications
(2006)
Herget, Philipp
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Fang, Jen-Yu
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Bain, James A.
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Schlesinger, T. E.
;
光電工程學系
An experiment used to measure the effective spot size of a laser diode distance sensor is described. Experimental results indicate that the effective spot size is approximately 1 mu m and is independent of distance.
Multi-performance film (MPF) for highly efficient LCD backlights
(2008)
Hsieh, Jen-Chieh
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Huang, Yi-Pai
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Chen, Chun-Ho
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Lo, Yu-Chun
;
Fang, Jen-Yu
A multi-performance film (MPF) which has concave-parabolic cylinder micro prism structures was proposed to improve light coupling efficiency and to reduce lamp-Mura defect. A MPF combined light diffusion and light collecting performance as a multiple functional film. By applying the MPF wider FWHM angle, higher light output coupling efficiency, and slighter lamp-Mura were demonstrated on a 32-inch direct-type backlight.
Optical feedback height control system using laser diode sensor for near-field data storage applications
(2007-12-01)
Fang, Jen-Yu
;
Tien, Chung-Hao
;
Shieh, Han-Ping D.
;
Herget, Philipp
;
Bain, James A.
We demonstrated a laser diode position sensor for a near-field height control system. The feedback signal of the laser diode sensor that resulted from self-mixing interferometry was characterized and modeled by a simplified method. Due to the fine spatial resolution of the laser sensor, an active, height control system with nanoscale position precision was designed and realized under a spinning disk for near-field applications.