• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.339-340
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• 2006

Recently, many researches have been done to improve optical performance of LCD-BLU(Back Light Unit). One of the most important parts in LCD-BLU is LGP(Light Guiding Plate). Micro-patterned LGP is known to have different optical characteristics depending on their shape, pattern density and size, etc. In the present study, a micro-optical patterned LGP mold was fabricated using LiGA process. The difference in the optical characteristics between positive and negative patterned LGP's was investigated by fixing the density, location and size of each pattern. It was found that the negative patterned LGP showed better optical characteristics than positive one.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.75-76
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• 2006

LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of kernel parts of LCD unit and it consists of several optical sheets(such as prism, diffuser and protector sheets), LCP (Light Guide Plate), light source (CCFL or LED) and mold frame. The LGP of LCD-BLU is usually manufactured by forming numerous dots with $50{\sim}200{\mu}m$ in diameter on it by erosion method. But the surface of the erosion dots of LGP is very rough due to the characteristics of the erosion process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. In order to overcome the limit of current dot patterned LGP, optical pattern design with $50{\mu}m$ micro-lens was applied in the present study. Especially, the negative and positive micro-lens pattern fabricated by modified LiGA with thermal reflow process was applied to the optical design of LGP. The attention was paid to the effects of different pattern conditions to the brightness distribution of BLU with micro-lens patterned LGP. Finally, negative micro-lens patterned LGP showed superior results to the one made by positive in average luminance.

• Design & Manufacturing
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• v.2 no.6
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• pp.1-6
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• 2008

Recently, many researches have been done to improve optical performance of LCD-BLU(Back Light Unit). One of the most important parts in LCD-BLU is LGP(Light Guiding Plate). Micro-patterned LGP is known to have different optical characteristics depending on their shape, pattern density and size, etc. In the present study, a micro-optical patterned LGP mold was fabricated using LiGA process. The difference in the optical characteristics between positive and negative patterned LGP's was investigated by fixing the density, location and size of each pattern. It was found that the negative patterned LGP showed better optical characteristics than positive one.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.193-197
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• 2003

As one of the core technologies in the field of the optical communication with WDM, the optical cross connector with movements of micro mirrors is getting important day by day. The packaging structure of 2-dimensional NxN MOEMS switch should be determined by the harmonization of the following items such as the geometrical compatability between optical and structural components, the characteristics of optical input and output parts with device, and the electrical performance for the operation of micro mirrors. Therefore, the packaging process could be defined as the integrated technology completed by the optical and electrical science and the material science for the understanding of its thermo-mechanical properties with packaging materials. In the present study, the harmonization between the optical and structural components as well as the optical characteristics of lens system used will be investigated.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.293-295
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• 2004

PLS(Plasma Light System) is one of the electrodeless lamp discharged by micro wave. In this new lamp has high efficacy and CRI(Color Rendering Index). It is mainly composed of microwave part and optical part. Microwave parts consist of magnetron, wave-guide and cavity-mesh, while optical parts consist of bulb, mirror and reflector. In this paper, we studied experimentally the heat-resistance and temperature distribution characteristics of bulb in PLS.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.129-132
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• 1996

There is a tendency nowadays to produce increasingly miniaturized electronic equipment which incorporate parts that have to be precisely positioned, like lenses, heads and CCD's in scanners, printers, copiers, VCR's, optical fiber modules, etc. In contrast to the production process of precision parts, which is currently being carried out automatically, the assemblage process is still being performed by specially skilled technicians. The assemblage process comprises normally the following steps: firstly, the parts are roughly positioned and partially fixed, secondly, the parts are manually nudged towards the target position and finally glued, screwed or welded. This paper presents a system that uses six piezo Impact Drive Mechanisms for accurate micro positioning within three degrees of freedom (lateral and longitudinal translation and rotation). The system is designed to positioning a printed circuit board with an accuracy better than 3 .mu.m (for translations), 5 mrad (for rotation).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.12
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• pp.1217-1222
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• 2012

A wall flow sensor has been used for feedback flow control and wall shear stress measurement. In this study, we developed a new wall flow sensor by combining the PIV algorithm and the micro image sensor used in an optical mouse. The feasibility of the wall flow sensor was investigated by using simulated fluid flow experiments. Compared with the quadrature signal from imaging devices, the accuracy of the wall flow velocity measurement was improved and the dynamic range increased. In addition, the depth information of particles was also measured by using the defocusing imaging technique.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.77-83
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• 2007

The study on damaged layer is necessary for machinability improvement in micro machining. The damaged layer in metal cutting is derived from plastic deformation and transformation of metal structure. The damaged layer affects micro mold life and micro machine parts. In this study, the damaged layer of micro machined surface of copper is evaluated according to various machining condition. The damaged layer structure and metallurgical characteristics are measured by optical microscope, and evaluated by cutting forces and surface roughness. The scale of this damaged layer depends on cutting process parameters and machining environments. By experimental results, depth of damaged layer was increased with increasing of cutting depth, also the damaged layer is less occurred in down-milling compared to up-milling during micro endmilling operation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.115-120
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• 1992

Mirror-surface machining is very important machining technology to manufacture optical parts. especially brittle materials. In case of optical plastics, it is produced through both grinding and polishing till now. New machining method which is more efficient and contributed to the protection of the environmental pollution is, therefore, studied. In this , experimental results and an analysis of surface roughness in ultrasonic vibration cutting of optical plastic (CR-39) which is used for optical lens is presented. In results, a comparison of the micro-structure of machined surfaces produced by cutting with ultrasonic vibration and conventional turning is presented by analyzing S.E.M. photograph. Also, wavelength spectrum analysis is performed to investigate the surface-characteristics machined by ultrasonic vibration cutting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1493-1496
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• 2005

In this paper, we describe a simple, precise and low cost method of fabricating PDMS stamp for UV embossing. It is important to improve the replication quality of stamp because the accuracy of fabricated structure is related to that of the stamp in UV embossing. The PDMS stamp has been fabricated by the replica molding technology with ultrasonic vibration to eliminate micro-air bubbles during the fabrication process of PDMS stamp. Also, this fabrication to use ultrasonic vibration promotes PDMS solution to fill into micro channel and edge parts. We report the fabrication of an optical core using UV embossing with fabricated PDMS stamp. This fabricated core is $7\;\mu{m}\;at\;depth,\;6\;\mu{m}\;at\;width.\;This\;measured\;value\;has\;the\;difference\;below\;1\;\mu{m}$compared to the original stamp. The surface roughness of core is about 14 nm root mean square. This is satisfactory value to use low-loss optical waveguide. Our successful demonstration of precise replica technology presents an alternative approach for the stamp of UV embossing.