• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.163-170
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• 2004

In order to produce high-quality optical components, aspheric lenses have been widely applied in recent years. An aspheric lens consists of aspheric surfaces instead of spherical ones, which causes difficulty in the design process as well as the manufacturing procedure. Although injection molding is widely used to fabricate optical lenses owing to its high productivity, there remains lots of difficulty to determine appropriate mold design factors and injection molding parameters. In the injection molding fields, computer simulation has been effectively applied to analyze processes based on the shell analysis so far. Considering the geometry of optical lenses, however, numerical analysis based on solid elements has been reported as more reliable approach than shell -based one. The present work covers three-dimensional injection molding simulation using MP1/Flow3D and relevant deformation analysis of an injection molded plastic lens based on solid elements. Numerical analysis has been applied to the injection molding processes of an aspheric lens for a photo pick-up device. The reliability of the proposed approach has been verified in comparison with the experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.427-427
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• 2007

The global applications of aspherics surfaces will expand rapidly on the electronics, optical components, communications, aerospace, defense, and medical optics devices etc. Especially, Asymmetric aspheric prism lens is one of the important parts in HMD(Head Mounted Display) because it affects dominantly on the optical performance of HMD. The mold core is the most important device to produce the plastic lenses by injection molding method. In this study, the mold cores for asymmetric aspheric prism lens were processed using fly-cutting method which is kind of the ultra precision processing and form accuracy and surface roughness of the cores were measured.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.784-787
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• 2003

The present work covers three-dimensional flow simulation and deformation analysis of injection molded plastic lenses using solid elements. A numerical scheme to evaluate part deformation has been proposed from the results of injection molding analysis. Proposed scheme has been applied to the injection molding processes of optical plastic lenses: a spherical lens and an aspheric lens for a photo pick-up device. Through the simulation processes. residual stress is estimated and the final deformed patters are obtained for both products. The reliability of the proposed approach has also been verified in comparison with the results of real experiments.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.4
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• pp.41-45
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• 2006

In recent years, the demands of the aspheric glass lenses increase since it is difficult to obtain the desirable performance in the plastic lens. Glass lens is manufactured by the forming with high precision mold core. This paper presents the analysis of optimal grinding condition of tungsten carbide(WC, Co 0.5%) using design of experiments(DOE). The process parameters are turbin spindle, work spindle, feedrate and depth of cut. The experiments results are evaluated by MINITAB software.

• Design & Manufacturing
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• v.6 no.1
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• pp.12-17
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• 2012

In order to produce high-quality optical components, aspheric lenses have been widely applied in recent years. An aspheric lens consists of aspheric surfaces instead of spherical ones, which causes difficulty in the design process as well as the manufacturing procedure. Although injection molding is widely used to fabricate optical lenses owing to its high productivity, there remains lots of difficulty to determine appropriate mold design factors and injection molding parameters. In the injection molding fields, computer simulation has been effectively applied to analyze processes based on the shell analysis so far. Considering the geometry of optical lenses, a full-3d simulation based on solid elements has been reported as a reliable approach. The present work covers three-dimensional injection molding simulation and relevant deformation analysis of an injection molded plastic lens based on 3d solid elements. Numerical analyses have been applied to the injection molding processes of three aspheric lenses for an image sensing module of a mobile phone. The reliability of the proposed approach has been verified in comparison with the experimental results.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.143-148
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• 2008

In order to produce high-quality optical components, aspheric lenses have been widely applied in recent years. An aspheric lens consists of aspheric surfaces instead of spherical ones, which causes difficulty in the design process as well as the manufacturing procedure. Although injection molding is widely used to fabricate optical lenses owing to its high productivity, there remains lots of difficulty to determine appropriate mold design factors and injection molding parameters. In the injection molding fields, computer simulation has been effectively applied to analyze processes based on the shell analysis so far. Considering the geometry of optical lenses, a full-3d simulation based on solid elements has been reported as a reliable approach. The present work covers three-dimensional injection molding simulation and relevant deformation analysis of an injection molded plastic lens based on 3d solid elements. Numerical analyses have been applied to the injection molding processes of three aspheric lenses for an image sensing module of a mobile phone. The reliability of the proposed approach has been verified in comparison with the experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.45-50
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• 2007

The aspheric lens has become the most popular optical component used in various optical devices such as digital cameras, pick-up lenses, printers, copiers etc. Using aspheric lenses not only miniaturizes and reduces the weight of products, but also lower prices and higher field angles can be realized. Additionally, plastic lenses are being changed to glass lenses more recently because of low accuracy, low acid-resistance and low thermal-resistance in the plastic lenses. Currently, one fabrication method of glass lenses is using a glass-mold method with a high precision mold core for mass production. In this paper, DOE (Design Of Experiments) and compensation machining were adopted to improve the surface roughness and the form accuracy of the mold core. The DOE has been done in order to discover the optimal grinding conditions which minimize the surface roughness with factors such as work spindle revolution, turbine spindle revolution, federate and cutting depth. And the compensation machining is used to generate high form accuracy of the mold core. From various experiments and analyses, we could obtain the best surface roughness 5 nm in Ra, form accuracy $0.167\;{\mu}m$ in PV.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.893-898
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• 2016

Plastic array lens are cheap to manufacture; however, plastic is not resistant to high temperatures and moisture. Optical glass represents a better solution but is a more-expensive alternative. Glass array lens can be produced using lithography or precision-molding techniques. The lithography process is commonly used, for instance, in the semiconductor industry; however, the manufacturing costs are high, the processing time is quite long, and spherical aberration is a problem. To obtain high-order aspherical shapes, mold-core manufacturing is conducted through ultra-precision grinding machining. In this paper, a $4{\times}1$ mold core was manufactured using an ultra-precision machine with a jig for the injection molding of an aspherical array lens. The machined mold core was measured using the Form TalySurf PGI 2+ contact-stylus profilometer. The measurement data of the mold core are suitable for the design criterion of below 0.5 um.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.51-56
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• 2009

Recently, with the increasing lightness and miniaturization of high resolution camera phones, the demand for aspheric glass lens has increased because plastic and spherical lens are unable to satisfy the required performance. An aspheric glass lens is fabricated by the high temperature and pressure molding using a tungsten carbide molding core, so precision grinding and coating technology for the molding core surface are required. This study investigates the effect of diamond-like carbon (DLC) and rhenium-iridium (Re-Ir) coating For aspheric molding core surface. The grinding conditions of the tungsten carbide molding core were obtained by design of experiments (DOE) for application in the ultra precision grinding process of the tungsten carbide molding core of the aspheric glass lens used in 5 megapixel, $4{\times}$ zoom camera phone modules. A tungsten carbide molding core was fabricated under this grinding condition and coated with the DLC and Re-Ir coating. By measurements, the effect of DLC and Re-Ir coating on the form accuracy and surface roughness of molding coer was evaluated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.39-46
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• 2013

This study aims to develop a plastic aspheric lens for a 13-megapixel mobile phone camera by injection-compression molding. A mold for injection-compression molding experiments was fabricated with a movable upper plate and four springs. During cavity filling for an aspheric lens with a thickness ratio of 2, a weldline was formed under conventional injection molding, whereas no weldline was formed under injection-compression molding with a compression stroke of 0.3 mm. The flow patterns were in good agreement with the simulation results. The birefringence decreased as the compression stroke increased, and the birefringence produced by injection-compression molding was very low and more uniform compared with that produced by injection molding. In addition, the bulk birefringence of an assembly composed of four plastic lenses was significantly affected by the orientation of the lenses to be mounted.