• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.71-72
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• 2006

In this study, automatic assembly and evaluation system fer phone camera module is conceptually designed. The designed core(Auto focus & UV curing, Image Test) equipments adopts a clustering mechanism and compactible structure using index table for minimum tact time. Using a ball screw actuator and absolute encoder in each axis, we can verifies the repeatability and position accuracy of system within ${\pm}3{\mu}m$. In result of simulation test, the proposed system is expected up to 30% in productivity than manual operation.

• 한국정밀공학회지
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• 제27권2호
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• pp.34-39
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• 2010

In order to achieve and maintain dimensional accuracy in laser micro-machining, dominant parameters such as laser power and laser focus position need to be monitored and controlled real time. Also, in order to selectively machine multi-layered materials, the material being presently machined need to be recognized. This paper presents an auto-focusing (AF) module to keep laser focus on a large-area surface; a real-time laser power stabilizing module based on optical attenuation; and a laser-induced breakdown spectroscopy (LIBS) module. With these monitoring modules, position error in laser focus on a 4" silicon wafer was kept below $4{\mu}m$, initially $51{\mu}m$, and laser power stability of a UV laser source was improved from 1.6% to 0.3%. Also, the material transition from polyimide to copper in machining of FCCL (flexible copper clad laminate) was successfully observed.

• 센서학회지
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• 제24권4호
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• pp.228-231
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• 2015

Ultrasonic motors provide high torques and quick responses compared to their magnetic counterparts; therefore, they are widely used in small-scale applications such as mobile phones, microrobots, and auto-focusing modules in digital cameras. To determine the feasibility of lead-free piezoceramics for ultrasonic motor applications, we fabricated a ring-type piezoceramic with a KNN-based lead-free piezoceramic (referred to as CZ5), intended for use in an auto-focusing module of a digital camera. The vibration of the lead-free stator was observed at 45.1 kHz. It is noteworthy that the fully assembled lead-free ultrasonic motor exhibited a revolution speed of 5-7 rpm, even though impedance matching with neighboring components was not considered. This result suggests that the tested KNN-based piezoceramic has great potential for use in ultrasonic motor applications, requiring minimal modifications to existing lead-based systems.

• 한국정밀공학회지
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• 제27권2호
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• pp.70-77
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• 2010

This study proposed an auto focusing method for a multi-focus image in assembling lens modules in digital camera phones. A camera module in a camera phone is composed of a lens barrel, an IR glass, a lens mount, a PCB board and aspheric lenses. Alignment among the components is one of the important factors in product quality. Auto-focus is essential to adjust image quality of an IR glass in a lens holder, but there are two focal points in the captured image due to thickness of IR glass. So, sharpness, probability and a scale factor are defined to find desired focus from a multi-focus image. The sharpness is defined as clarity of an image. Probability and a scale factors are calculated using pattern matching with a registered image. The presented algorithm was applied to a lens assembly machine which has 5 axes, two vacuum chucks and an inspection system. The desired focus can be determined on the local maximum of the sharpness, the probability and the scale factor in the experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.123-126
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• 2006

We propose a new-focusing method for test handlers of compact camera module (CCM), The MMD (max-min difference) method is applied to calculate the focus value quickly considering the noisy output of CCM. Also, the fuzzy search method is applied to find the maximum focus value effectively. We design a fuzzy processor to control the lens position by focus values and brightness values, which improves the focusing performance in the sense of speed and processor memory. The proposed method is implemented by program and installed at the CCM test handler machines. The simulation results are presented to verify the usefulness of the proposed method.

• 정보저장시스템학회논문집
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• 제9권2호
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• pp.56-61
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• 2013

The recent increased use of mobile phone has resulted in a technical focusing on reliability issues related to drop performance. Since mobile phone may be dropped several times during their use, it is required to survive common drop accidents. The plastic injection parts such as base stopper and carrier in the encoder type actuator can be broken easily in the actual reliability test of 1.5m free drop. So, we analyzed the shock resistance characteristics of auto focus actuator with variables in the material properties using finite element method. By applying the new resin materials, we can decrease the breakage of plastic injection parts and improve the reliability of mobile phone.

• 한국정밀공학회지
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• 제27권10호
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• pp.23-28
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• 2010

Resistance trimming and cutting processes of printed circuit board by making use of high power UV laser with nano-second pulse width have been proposed and investigated experimentally. Also laser-based application system with high flexibility and complex has been designed and adopted power controller, auto beam size control, auto-focusing and control program developed for ourselves. The function of each module shows that they can be reliable for industrial equipments. Resistance trimming method used a plunge and double cut process with $20{\mu}m$ spot size beam. Results show that double cut process is more effective to control resistance trimming in precision than plunge cut process.

• 융합신호처리학회논문지
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• 제10권4호
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• pp.233-238
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• 2009

본 논문에서는 얼굴을 자동 초점(Auto-focus) 디지털 카메라의 관심영역(ROI : Region Of Interest)으로 이용하는 시스템에서 요구되는 검출 영역의 안정적인 선택을 위한 방법을 제안한다. 이 방법은 디지털 카메라와 모바일 카메라에 포함되는 ISP(Image Signal Processor)에서 실시간으로 처리되는 프로그레시브 입력 영상에서 얼굴 영역을 관심영역으로 간주하고 자동으로 초점을 맞추는 방법이다. 얼굴 영역 검출을 위하여 사용한 학습 알고리즘은 에이다부스트 알고리즘을 이용하였다. 학습에 포함되지 않은 기울어진 얼굴에 대한 검출방법과 검출 결과에 대한 후처리 방법, 관심영역이 흔들리지 않고 일정한 영역을 유지하도록 하기 위한 안정화 대책을 제안한다. 제안된 ROI 영역 안정화 알고리즘에 대한 성능을 평가하기 위하여 움직임이 있는 얼굴에 대하여 기준 궤적과의 차이를 보이고, 각 궤적의 회귀곡선과의 RMS 오차를 안정화 성능평가의 척도로 이용하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1853-1855
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• 2005

본 논문에서는 카메라폰용 광학줌(Optical zooming)과 자동초점조절장치(Auto Focusing, AF)에 쓰일 초음파모터를 제작하였다. 초음파모터의 제작 및 시뮬레이션은 유한요소해석 프로그램인 ATILA 5.2.1(Magsoft)를 사용하여 디자인설계에 따른 구동특성을 고찰하였고 세자된 초음파모터는 한쪽 면이 없는 사자형의 탄성체를 제작하였으며 탄성체의 양쪽 다리에 각각 압전체를 부착하였다. 또한 압전세라믹의 조성은 $0.9Pb(Zr_{0.51}Ti_{0.49})O_3$-$0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$의 조성으로 설계하였고 시편의 제조는 7-layer로 적층하였다. 제작된 압전세라믹의 치수는 $6*2*0.35mm^3$ (길이*폭*두께)로 제작하였다. 또한 탄성체의 외형치수는 $10*10*2mm^3$ 제작하였으며 두께를 각각 0.3[mm], 0.5[mm], 0.8[mm]으로 변화시키며 제작하였다. 두께가 0.8[mm]인 경우 공진주파수 60.5[kHz]를 나타내었으며 초음파모터의 압전세라믹에 인가전압이 증가함에 따라 회전속도와 모터에 흐르는 전류는 증가하였다. 인가전압이 40[Vpp], 공진주파수는 60.5[kHz]일때 무게추를 달고 그때의 토크 및 효율을 측정하였다. 회전 속도는 토크가 증가함에 따라 거의 선형적으로 감소하였으며 효율은 토크에 따라 증가하다가 토크가 약 20(mNmm)일 때 약 28[%]로 최대치를 나타내었다.