• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1737-1740
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• 2005

As the various manufacturing technology of optical glass is developed, the aspherical lenses are applied to many fields. However, It is still very difficult to manufacture glass lens because of the high cost and the short life of core. In recent years, the demands of the aspherical glass lenses increase since it is difficult to obtain the desirable performance in the plastic lens. In the glass mold lens, it has merits of high productivity and reproductivity since lens is manufactured by the only forming with high precision mold. The fabricating conditions for glass mold lens are glass surface that does not cause fusion, viscosity of 108-1013 poise for the $0.2{\mu}m$ accuracy, and viscoelasticity for the roughness less than 100 angstrom. In this thesis, ultra-precision grinding characteristics of tungsten carbide for forming the aspherical glass lens core were studied and the result of it is applied to manufacture the tungsten carbide-base core of the glass lens used to the laser scanning unit and the camera phone.

• 한국시뮬레이션학회논문지
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• 제22권4호
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• pp.83-92
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• 2013

휴대폰 시장의 확산으로 인하여 휴대폰에 장착되는 카메라 렌즈모듈의 수요도 급증하고 있다. 렌즈모듈 부품의 경우 해상도의 증가에 따른 사출공정의 품질보증과 원가절감이라는 두 가지 목표를 달성해야 한다. 따라서 본 논문에서는 더블카세트 방식의 금형구조를 이용하여 경통과 쉴드 두 종류의 제품을 개발하기 위해 시뮬레이션을 활용한 사례를 소개한다. 개발과정에서 두 종류의 시뮬레이션 기술을 활용하였는데, 첫 번째는 금형 설계단계에서 사출품의 성형성을 분석하기 위한 시뮬레이션(일명 Computer Aided Engineering)을 Mold Flow$^{TM}$를 사용하여 수행하였고, 두 번째는 사출기에 금형을 장착한 후 제품이 사출되어 취출하는 동작을 분석하기 위한 동작 시뮬레이션을 DPM Assembly$^{TM}$를 이용하여 수행하였다. 개발 결과 기존 방식에 비해 제품의 생산성이 300% 이상 증가하는 효과를 얻었다.

• 한국광학회지
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• 제20권1호
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• pp.6-15
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• 2009

2매의 비구면 렌즈로 구성된 카메라 폰 렌즈를 설계하고 상면에서 미광의 분포를 분석하였다. 미광분석에서는 렌즈 경통의 내면과 스페이서에서 대부분의 입사광은 흡수하고 일부만 균일하게 산란하는 것으로 가정하였으며, 경통과 스페이서에서 10%가 산란된다고 가정할 때, 미광의 최대치는 이상적인 상의 강도의 7.1%였다. 이 분석을 통하여 대부분의 미광은 렌즈 리브에서의 내부반사에 의하여 발생하며, 경통과 스페이서에 의한 산란의 기여는 상대적으로 작음을 알 수 있었다. 내부반사를 줄이기 위하여 렌즈사이에 얇은 흡광판을 삽입하고 스페이서의 모양을 수정하였으며, 경통의 재설계 후에는 산란광의 최대치가 이상적인 상의 강도의 1.1%로 감소하였다.

• 한국컴퓨터정보학회논문지
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• 제28권2호
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• pp.19-25
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• 2023

이 논문에서는 image signal processing 을 고려하여 저조도에서 촬영된 저품질의 raw 이미지를 딥러닝에 기반하여 개선하는 방법을 제안한다. 스마트폰 카메라의 경우 DSLR 카메라에 비해 렌즈나 센서의 확장에 제약이 있어 저조도 상황에서 이미지에 노이즈가 증가되고 품질이 저하되는 문제점을 보인다. 기존 딥러닝 기반 저조도 이미지 처리 방식은 image signal processing의 주요 요소인 렌즈 쉐이딩 효과와 화이트 밸런스를 고려하지 못하여 부자연스러운 이미지를 생성하기도 한다. 본 논문에서는 렌즈 쉐이딩 효과와 화이트 밸런스를 딥러닝 모델에 적용하기 위해 중심거리와 채널 평균을 활용한다. 스마트폰으로 촬영된 저조도 이미지를 통한 실험에서 제안하는 방법이 기존 방법에 비해 더 높은 peak signal to noise ratio 와 structural similarity index measure를 달성함과 동시에 높은 품질의 저조도 이미지를 생성함을 확인한다.

• Transactions on Electrical and Electronic Materials
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• 제9권6호
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• pp.237-242
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• 2008

The effects of the process parameters in the molding of aspheric glass lenses for camera phone modules have been investigated experimentally. The molding conditions were optimized with respect to the form accuracy (PV) (the response variable) of the molded lens. The experimental conditions were obtained by employing a factorial design method. From the analysis of variance (ANOVA) and P-value (significance level), the slow cooling rate was found to affect the response variable most significantly. The lens molded under the optimum molding condition showed a transcription ratio of 93.4%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.169-172
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• 2005

Tiny camera module using in modern cellular phone requires precise assembly processes. Higher camera resolution and more functions such as zoom lens make the number of camera parts bigger. As market grows rapidly, automatic assembly process is required. However, diverse product line and short life cycle make it difficult. To attack this, a flexible and expandable lens assembly system is proposed. For the fast manufacturing line formation, modular concept is adopted. Also each module is designed to have intelligence to save system formation time. The assembly system is built up on the standard flat-form which provides vibration free base, air and electric supply, controllers, etc. Futhermore, the assembly cell has the capability of handling tiny, thin, or transparent parts which are very difficult to align with vision.

• Journal of the Optical Society of Korea
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• 제13권2호
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• pp.213-217
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• 2009

The transcription characteristics of the mold surface in the molding of aspherical glass lenses for camera phone modules have been investigated experimentally. The surface topographies of both the form and the roughness were compared between the mold and the molded lens. For the form topography, the molded lens showed a transcription ratio of 93.4% against the mold, which is obtained by comparing the form error (PV) values of the mold and the molded lens. The transcription characteristics of the roughness topography were ascertained by bearing ratio analysis.

• 한국전기전자재료학회논문지
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• 제19권11호
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• pp.1050-1054
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• 2006

There have been intensive and continuous efforts in the field of DLC coating process because of their feature, like high hardness, high elasticity, abrasion resistance and chemical stability and have been applied widely the industrial areas. In this research, optimal grinding condition was investigated using Microlens Process Machine for the development of aspheric glass lens which is to be used for mobile phone module with 3 mega pixel and 2.5X optical zoom, and tungsten carbide(WC) mold cote was manufactured using high performance ultra precision machining and the effects of DLC coating on the form accuracy(PV) and surface roughness(Ra) of WC mold core was evaluated.

• 반도체디스플레이기술학회지
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• 제6권3호
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• pp.65-70
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• 2007

A method to focus the object in camera system by applying the Hill climb algorithm from optical lens moving device (VCM; Voice coil motor) is proposed. The focusing algorithm from VCM is focus on the object but in these criteria is a well-known drawback; the focus is good only at same distance objects but the focus is bad (blur image) at different distance objects because of the DOF (Depth of focus) or DOF (Depth of field) at the optical characteristic. Here, the new camera system that describes the Reflector of free curvature systems (or Diffractive Fresnel lens) and the partition of focusing window area is proposed. The method to improve the focus in all areas (different distance objects) is proposed by new optical system (discrete auto in-focus) using the Reflector of free curvature systems (or Diffractive Fresnel lens) and by applying the partition of all areas. The proposal is able to obtain good focus in all areas.

• Journal of the Optical Society of Korea
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• 제19권2호
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• pp.182-187
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• 2015

This paper presents a new graphical method for selecting a pair of optical glasses to simultaneously achromatize and athermalize an imaging lens made of materials in contact. An athermal glass map that plots thermal glass constant versus inverse Abbe number is derived through analysis of optical glasses and plastic materials in visible light. By introducing the equivalent Abbe number and equivalent thermal glass constant, although it is a multi-lens system, we have a simple way to visually identify possible optical materials. Applying this method to design a phone camera lens equipped with quarter inch image sensor having 8-mega pixels, the thermal defocuses over $-20^{\circ}C$ to $+60^{\circ}C$ are reduced to be much less than the depth of focus of the system.