• Title/Summary/Keyword: Light Uniformity

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Reflector Design to Improve the Uniformity of an Irradiated Area Using a Xenon Flash Lamp (제논 플래시 램프 사용 시 조사 영역 균일도 개선을 위한 반사경 설계)

  • Kim, Seo-Young;Lee, Han-Yul;Jun, Won-Kyoun;Kang, Dong-Hwa;Jo, Ye-Ji;Jung, Mee-Suk
    • Korean Journal of Optics and Photonics
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    • v.30 no.5
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    • pp.197-203
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    • 2019
  • In this paper, we studied a reflector design that can improve the illuminance uniformity when using a xenon flash lamp in the photonic sintering process. To achieve complete sintering of substrates in the irradiated area, the light efficiency and illuminance uniformity were set to target performance. Existing elliptical reflectors or parabolic reflectors make it easy to satisfy the target light efficiency, but have difficulty satisfying the illuminance uniformity. In this paper, a twin-concave feature has been added to the center of the parabolic reflector to satisfy the illuminance uniformity. It was confirmed that the illuminance uniformity of the parabolic reflector with a twin-concave feature was improved, compared to that of the traditional reflector.

Laser Marking for Light Guide Panel using Design of Experiment and Web-based Prototyping System (실험계획법과 웹기반 시스템에 의한 도광판의 레이저 마킹)

  • Kang Hyuk-Jin;Kim Hyung-Jung;Chu Won-Sik;Ahn Sung-Hoon
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.4 s.181
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    • pp.91-98
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    • 2006
  • A light guide panel (LGP) is an element of the LCD back light unit, which is used for display devices. In this study, the laser marking process is applied to the fabrication of light guide panels as the new fabrication process. In order to obtain a light guide panel which has high luminance and uniformity, four principal parameters such as power, scanning speed, ratio of line gap, and number of line were selected. A Web-based design tool was developed to generate patterns of light guide panel at any location, and the tool may assist the designer to develop optimized patterns. Topcon-BM7 was used for luminance measurement of each specimen with $100mm{\times}100mm$ area. By Taguchi method optimized levels of each parameters were found, and luminance of $3523cd/cm^2$ and uniformity of 92% were achieved using the laser machined BLU.

Optimization Method for the Design of LCD Back-Light Unit (LCD Back-Light Unit 설계를 위한 최적화 기법)

  • Seo Heekyung;Ryu Yangseon;Choi Joonsoo;Hahn Kwang-Soo;Kim Seongcheol
    • Journal of KIISE:Computer Systems and Theory
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    • v.32 no.3
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    • pp.133-147
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    • 2005
  • Various types of ray-tracing methods are used to predict the quantity measures of radiation illumination, the uniformity of illumination, radiation performance of LCD BLU(Hack-Light Unit). The uniformity of radiation illumination is one of the most important design factor of BLU and is usually controlled by the diffusive-ink pattern printed on the bottom of light-guide panel of BLU. Therefore it is desirable to produce an improved (ideally, the optimal) ink pattern to achieve the best uniformity of radiation illumination. In this paper, we applied the Welder-Mead simplex-search method among various direct search method to compute the optimal ink pattern. Direct search methods are widely used to optimize the functions which are often highly nonlinear, unpredictably discontinuous, and nondifferentiable, The ink-pattern controlling the uniformity of radiation illumination is one type of these functions. In this paper, we found that simplex search methods are well suited to computing the optimal diffusive-ink pattern. In extensive numerical testing, we have found the simplex search method to be reasonably efficient and reliable at computing the optimal diffusive-ink pattern. The result also suggests that optimization can improve the functionality of simulation tools which are used to design LCD BLU.

Uniformity calibration of large area full color light emitted diodes screens

  • Gibour, Veronique;Leroux, Thierry;Boher, Pierre;Bouwens, Luc
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.475-478
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    • 2004
  • In this paper, we describe a powerful solution for efficient LED wall calibration through the use of a quality 2D-luminance meter : the MURATest and a dedicated applicative software. The intended calibration allows adjusting individually the intensity of each LED so as to obtain a good uniformity on the module. Furthermore the intensity of each module can be adjusted one to the others so as to obtain a good uniformity on a complete display and maintain it even after module exchange for display maintenance needs.

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HARDNESS CHANGE OF LIGHT-ACTIVATED GLASS IONMER CEMENT WITH THICKNESS AND TIME (광경화형 글래스아이오노머 시멘트의 두께 및 시간경과에 따른 경도의 변화)

  • Lee, Kyoung-Jin;Oh, Won-Mann;Kim, Sun-Hun
    • Restorative Dentistry and Endodontics
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    • v.20 no.1
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    • pp.303-315
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    • 1995
  • An adequate and homogeneous cure of light-activated restroative material is very important for improvement of marginal adaptation and prevention of marginal leakage, secondary caries and pulpal irritation as well as expressing natural physical property of that material. The purpose of this study was to evaluate the change of surface hardness and cure uniformity of light-activated glass ionomer cements. Restorative(Fuji II LC, Vitremer) and lining(Baseline VLC, Vitrebond) light-activated glass ionomer cements were investigated for this study. The surface hardness of the top and bottom surfaces and cure uniformity of each 1mm, 1.5mm, 2mm, 2.5mm & 3mm in the thickness of specimen were measured immediately, at 1 hour, 24 hours and 1 week after light activation. The surface hardness change and cure uniformity of all the specimens were measured by Knoop hardness tester. The results were as follows. 1. The surface hardness of top and bottom surfaces in all groups increased with time(p<0.01). 2. Both top and bottom surfaces hardness of Vitrebond group measured immediately after light-activation were significantly lower than those of the other groups(p<0.01). 3. The surface hardness of top and bottom surfaces of restorative light -activated glass ionomer cements was higher than those of lining materials at 1 week(p<0.10). 4. Surface hardness of Vitremer group decreased as the specimen thickness increased, except top and bottom surfaces hardness of the specimen at 1 week(p<0.01). There was no significant difference in the surface hardness of Fuji II LC with changes in the thickness except bottom surface hardness of specimen at 24 hours and 1 week (p>0.05). 5. Surface hardness of Vitrebond group significantly decreased as the specimen thickness increased(p<0.01). There was no significant difference in the surface hardness of Baseline VLC group with changes in the thickness except bottom surface hardness of specimen measured immediately after light -activation(p>0.05). 6. The hardness ratio of top against bottom surface in all groups decreased with time(p<0.05). 7. There was no significant difference in the hardness ratio of top against bottom surface with changes of the thickness except Vitrebond group, 24 hours and 1 week of Vitremer group and 1 week of Baseline VLC group (p>0.05). These results suggest that surface hardness of restorative ligh-activated glass ionomer cements were highter than those of lining light-activated materials. In all groups, the surface hardness and cure uniformity continuously increased with time.

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Light Factor Performance of a Room with Light Guide and Blind Systems by Mockup Experiments (혼합형 채광조절장치가 실내공간의 주광조도분포에 미치는 영향에 관한 Mockup 실험평가)

  • Shin, Hwa Young;Kim, Jeong Tai
    • KIEAE Journal
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    • v.7 no.1
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    • pp.23-31
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    • 2007
  • This study aims to evaluate the illuminance performance of sloped light guide with automated venetian blind systems. For the purpose, a mock-up model was constructed as a prototype of Korean office building with $12.0m{\times}7.3m{\times}3.7m$ ($w{\times}d{\times}h$) and south facing side-window mounted between the clerestory window($2.0m^2$) and the view window($5.6m^2$). The light guide of 1.28m deepth and $29^{\circ}$ tilted angle, is covered with 0.6mm galvanized steel sheet and 97% reflective film. To protect the room from low solar angle, a blind systems, 0.15m deepth and $30^{\circ}$ automated slat angle was installed. To assess illuminance performance, the totally 37 measuring points for illuminance were monitored. For the detailed analysis, photometric sensors were installed at work-plane (8 points), wall (7 points), ceiling (3points), and exterior horizontal illuminance (1 point) respectively. The performance was measured under clear sky and is monitored by Agilent data logger, photometric sensor Li-cor and the Radiant Imaging ProMetric 1400. Comparisons of light factor and uniformity are discussed.

Design and Analysis of Illumination Optics for Image Uniformity in Omnidirectional Vision Inspection System for Screw Threads (나사산 전면검사 비전시스템의 영상 균일도 향상을 위한 조명 광학계 설계 및 해석)

  • Lee, Chang Hun;Lim, Yeong Eun;Park, Keun;Ra, Seung Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.3
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    • pp.261-268
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    • 2014
  • Precision screws have a wide range of industrial applications such as electrical and automotive products. To produce screw threads with high precision, not only high precision manufacturing technology but also reliable measurement technology is required. Machine vision systems have been used in the automatic inspection of screw threads based on backlight illumination, which cannot detect defects on the thread surface. Recently, an omnidirectional inspection system for screw threads was developed to obtain $360^{\circ}$ images of screws, based on front light illumination. In this study, the illumination design for the omnidirectional inspection system was modified by adding a light shield to improve the image uniformity. Optical simulation for various shield designs was performed to analyze image uniformity of the obtained images. The simulation results were analyzed statistically using response surface method, from which optical performance of the omnidirectional inspection system could be optimized in terms of image quality and uniformity.

(Development of 100[W] Border Light using Color Mixing Technique by Simple-Inverse Matching Method) (Simple-Inverse Matching 혼색기법을 이용한 100[W] 무대조명 개발)

  • Youn, Jin-Sik;Song, Sang-Bin;Lim, Young-Cheol;Park, Joung-Wook;Hong, Jin-Pyo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.12
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    • pp.38-46
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    • 2010
  • For the development of 100[W] stage lighting, quantitative and uniform color mixing that applied through color adopted Simple-Inverse matching so that color mixing can be possible along Black Body Locus. R,G,B(Red, Green, Blue) LED(Light Emitting Diode) arrangement through LED package character analysis, LED module, and the characteristic of device were considered for uniform color mixing. A distance changeable optical device was built to assure high uniformity and high diffusion of not only the middle of diffusion side but also the border side. Also, we developed the control power circuit that can expand up to 6 channels which are possible for quantitative color mixing, and the high uniformity and high quantified border light for color mixing control and the verification of color mixing characteristics by composing GUI(Graphical user interface) including color mixing simulator. By presenting the experimental results of light color control, we proved the usefulness of our developed border light and the proposed color mixing method.

A Design of an LED Sensor Luminaire for Visual Function Improvement (시각적 기능개선을 위한 LED 센서 등기구 설계)

  • Seo, Jung-Nam;Yu, Yong-Su;Yeo, In-Seon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.1
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    • pp.134-137
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    • 2010
  • An LED sensor luminaire for visual function improvement necessitates the control algorithm for light level adjustment and the appropriate lens design. The control algorithm adapts to surround lighting condition, and thus has the advantages of energy saving and glare reduction. The multi-cell lens design improves color temperature uniformity and spatial light distribution of the luminaire. Experimental and simulated results show that this approach contributes noticeably to energy saving and color temperature uniformity of the LED sensor luminaire.

Fabrication of a stamper and injection molding for micro pattern product (미세 패턴 제품 마스터 제작 및 성형 공정 기술 개발)

  • Yoo Y.E;Seo Y.H;Je T.J.;Choi D.S
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.216-219
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    • 2005
  • In recent, LCD becomes one of the main display devices and expected to have quite good market share during the next couple of years. The demand for low cost and high performance, however, is becoming severe as the competition among other display devices like PDP, OLED increases. To satisfy this demand from market, we need to optimize the parts or modules of the LCD, reduce the number of the assemble and enhance the process for the high brightness and uniformity of the LCD. The LCD consists mainly of LCD panel and Backlight unit(BLU). BLU, which takes big portion of the cost for LCD, consists of light source, light guide panel and many kinds of functional film. Recently light guide panel or film for BLU has micro patterns on its surface and consequently to reduce the number of parts and enhace the brightness and its uniformity. In this study, some methodologies for the fabrication of the master/stamper and molding the light quide panel are introduced for 50um pitch of prizm patterned substrate. Mechanical machining process is adapted and optimized to fabricate micro patterned stamper using the micro cutting tool. Injection molding technology is also developed to obtain uniformly replicated micro patterned products.

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