Characterization, Modeling, and Optimization of Light-Emitting Diode Systems

Total Page:16

File Type:pdf, Size:1020Kb

Characterization, Modeling, and Optimization of Light-Emitting Diode Systems Downloaded from orbit.dtu.dk on: Oct 09, 2021 Characterization, Modeling, and Optimization of Light-Emitting Diode Systems Thorseth, Anders Publication date: 2011 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Thorseth, A. (2011). Characterization, Modeling, and Optimization of Light-Emitting Diode Systems. Technical University of Denmark. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. FACULTY OF SCIENCE UNIVERSITY OF COPENHAGEN Ph.D. thesis Anders Thorseth Characterization, Modeling, and Optimiza- tion of Light-Emitting Diode Systems Principal supervisor: Jan W. Thomsen Co-supervisor: Carsten Dam-Hansen Submitted: 31/03/2011 i \Here forms, here colours, here the character of every part of the universe are concentrated to a point." Leonardo da Vinci, on the eye [156, p. 20] ii Abstract This thesis explores, characterization, modeling, and optimization of light-emitting diodes (LED) for general illumination. An automated setup has been developed for spectral radiometric characterization of LED components with precise control of the settings of forward current and oper- ating temperature. The automated setup has been used to characterize commercial LED components with respect to multiple settings. It is shown that the droop in quan- tum efficiency can be approximated by a simple parabolic function. The investigated models of the spectral power distributions (SPD) from LEDs are the strictly empirical single and double Gaussian functions, and a semi empirical model using quasi Fermi levels and other basic solid state principles. The models are fitted to measured SPDs, using the free parameters. The result show a high correlation between the measured LED SPD and the fitted models. When comparing the chromaticity of the measured SPD with fitted models, the deviation is found to be larger than the lower limit of hu- man color perception. A method has been developed to optimize multicolored cluster LED systems with respect to light quality, using multi objective optimization. The results are simulated SPDs similar to traditional light sources, and with high light quality. As part of this work the techniques have been applied in practical illumina- tion applications. The presented examples are historical artifacts and illumination of plants to increase photosynthesis. iv Resum´e Denne afhandling udforsker karakterisering, modellering og optimering af lysemitte- rende dioder (LED) til generel belysning. En automatiseret forsøgsopstilling er blevet udviklet til spektro-radiometrisk ka- rakterisering af LED komponenter, for forskellige indstillinger af strøm og driftstempe- ratur. Den automatiserede forsøgsopstilling har været brugt til at karakterisere kom- mercielle LED komponenter. Det er vist, at kvante effektivitet kan tilnærmes ved en simpel parabolsk funktion. De undersøgte modeller af spektralfordelinger fra lysdio- der enkelt og dobbelt Gauss-funktioner som er strengt empiriske, og en semi empirisk model baseret p˚akvasi Fermi niveauer og andre basale faststof principper. De frie parametre in modellerne er fittet til de m˚altespektralfordelinger. Resultatet viser en høj korrelation mellem den m˚alteLED spektralfordelinger og modellerne. N˚arman sammenligner kromaticiteten af de m˚altespektralfordelinger med de modellerede spek- tralfordelinger viser afvigelsen sig at være større end den nedre grænse for menneskets opfattelse af farver. En metode er udviklet til at optimere flerfarvede klynge LED sy- stemer med hensyn til lyskvalitet, ved hjælp af flerm˚aletoptimering. Resultaterne er simulerede spektralfordelinger med egenskaber lig traditionelle lyskilder, og med høj lyskvalitet. Som en del af dette projekt er disse teknikker blevet anvendt i praktiske belysningsprojekter. De beskrevne eksempler er belysning af historiske genstande og belysning af planter for at øge fotosyntesen. vi Preface This PhD project was carried out in the period from April 2007 to June 2010 at Department of Optics & Plasma (OPL) at Risø National Laboratory, Roskilde and in the Diode Lasers & LED Systems group at DTU Fotonik at Technical University of Denmark. Academic supervision was provided by the Niels Bohr Institute (NBI), University of Copenhagen. Principle advisor was Jan W. Thomsen from NBI and project advisor was Carsten Dam-Hansen from DTU Fotonik. A period of four months was spent working with Nadarajah Narendran at the Lighting Research Center at Rensselaer Polytechnic Institute, Troy, New York. The project was funded by OPL and was subsequently transferred to DTU Fotonik, following Risø National Laboratory's merger with DTU in 2007. Acknowledgments This work is dedicated to my wonderful wife Katja, and delightful children Balder and Iben. I would like to express my gratitude towards my advisor at DTU Fotonik; Carsten Dam-Hansen, for invaluable suggestions, support, and encouragement during the work. I would also like to thank Jan W. Thomsen and Birgitte Thestrup for their help and assistance. I am thankful for having being able to work with the members of the Diode Lasers & LED Systems group, and would like to thank group leader Paul Michael Petersen for this opportunity. From the group I would especially like to thank Peter Behrensdorff Poulsen, Søren Stentoft Hansen, Dennis Dan Corell, Peter Jensen, and Bjarne Sass, for their effort, work, and many inspirational conversations in the laboratory. I would also like to thank Dr. Narendran of the LRC for providing me with the privilege of working at the center, and Patric Lockhart and Lalith Jayasinghe for the good ideas and collaboration I received during my stay. I would also like to thank Tracy Meyer, Rosa Irizarry, Danny Miller, and Aaron Smith at the LRC for the their generosity towards my family and I during our stay in Troy. I would also like to express my appreciation for the help and patience from my friends, family the residents of Borchs Kollegium. Furthermore, I would like thank Louise Munk for helpful proofreading and Toke Lund Hansen for discussions and constructive criticism. Anders Thorseth, Copenhagen, March 2011 viii Outline First an introduction to the LED lighting opportunities and challenges is given in Chapter 1, with an overview of the historical development of the light-emitting diode and an overview of the developments within the field of multichannel LED lighting. Chapter 2 is a presentation of the theory related to the properties of LED with em- phasis on the spectral characteristics and modeling of LED spectra. Chapter 3 covers the used methods of characterization of light sources with respect to light quality as perceived by human beings. Chapter 4 presents the methods used for spectral radio- metric measurements of the light output from LEDs. Chapter 5 presents the results of the current and temperature characterization of LED light sources. In Chapter 6, a method for optimization of clustered LED light sources is presented. Chapter 7 covers two cases where different aspects of the previously covered work are used. Finally, a conclusion and outlook is given. Contents Abstract iii Resum´e v Preface vii Acknowledgments . vii Outline . viii List of Figures 1 1 Introduction 3 1.1 Development History of the LED . .7 1.2 Solid State Lighting . .8 1.3 Clustered LED Systems . 10 1.4 Summary . 11 2 Light-Emitting Diodes 13 2.1 Theory of Light-Emitting Diodes . 13 2.1.1 Semiconductors . 13 2.1.2 Radiative Recombination . 15 2.1.3 Non-Radiative Recombination . 17 2.1.4 The p-n Junction . 17 2.1.5 Non-Equilibrium Conditions . 19 2.1.6 Temperature Variations . 20 2.2 Empirical Models . 22 2.2.1 Gaussian Models . 22 2.2.2 Light Output . 23 2.3 Summary . 23 3 Light Quality 25 3.1 Basic Photometric Concepts . 26 3.2 Chromaticity . 29 3.2.1 Uniform Color Spaces . 29 x CONTENTS 3.3 Color Mixing . 31 3.4 Correlated Color Temperature . 31 3.5 Chromaticity Difference . 34 3.6 Color Rendering Index . 35 3.6.1 Reference Illuminants . 36 3.6.2 Chromatic Adaptation . 37 3.6.3 CRI Calculation Procedure . 38 3.7 Visual Thresholds . 40 3.8 Summary . 40 4 Measurement Setup 43 4.1 Integrating Spheres . 44 4.2 Calibration . 47 4.2.1 Spectral Calibration . 48 4.2.2 Calorimetric Calibration . 49 4.2.3 Absorption Correction . 51 4.3 Temperature Control . 53 4.4 Automated Setup . 55 4.4.1 Automated Spectrometeric Measurements . 57 4.4.2 Measurement Procedure . 57 4.5 Summary . 58 5 Current and Temperature Characterization 61 5.1 Current-Temperature Plane Characterization . 62 5.2 Spectral Models . 67 5.2.1 Temperature Dependence . 70 5.2.2 Chromaticity Replication . 73 5.3 Thermal Characterization . 73 5.3.1 Forward Voltage vs. Junction Temperature . 74 5.3.2 Experimental Procedure . 75 5.4 Summary . 77 6 Optimization of Light Quality 79 6.1 Optimization Characteristics . 81 6.2 Multi-Objective Optimization . 82 6.2.1 Hill Climber Search . 83 6.2.2 Pareto Optimal Parameters . 84 6.2.3 Implementation . 85 6.2.4 Possible Calculation Improvements . 87 6.3 Results . 88 6.3.1 Gamut Boundary Problem . 91 CONTENTS xi 6.4 Summary . 92 7 Applications 95 7.1 Museum Lighting . 95 7.1.1 Traditional Lighting Solution . 96 7.1.2 LED Solution . 97 7.1.3 Characterization . 99 7.1.4 Summary . 101 7.2 Plant Illumination .
Recommended publications
  • Confidential Ssociates a History of Energy Part I
    Winter 2014 Luthin Confidential ssociates A History of Energy Part I History of Lighting - Part 1 It wasn’t until the late In the early 1800s, gas M el Brooks’ 2000- 1700’s that European light (initially at less than Inside this issue: year old man used oil lamps (at ~0.3 lu- 1 lumen/watt), used coal torches in his cave, but mens/watt) became gas or natural gas from History of Lighting Part 1 1 today’s lighting is a tad widely available and mines or wells, and was more sophisticated, accepted due to im- relatively common in ur- How to Become A Producer 2 having gone through provements in design ban England. Its use ex- half a dozen stages, and the whaling indus- panded rapidly after the Can Spaceballs Be Shot Out 3 each producing more try’s ability to produce development of the incan- of Earth Tubes? light out of less energy sperm oil. That refined descent gas mantle around i.e., efficacy, than its product burned cleanly, 1890. That device more High (Voltage) Anxiety 3 predecessor. didn’t smell too bad, than doubled the efficacy and was relatively (to 2 lumens/watt) of gas On A Personal Note 4 Torches made of moss cheap compared to lighting, using a filament and animal fat, and commercially-made containing thorium and and the power industry adopted crude oil lamps were candles. cerium, which converted it as a standard. During this the mainstay for indoor more of the gas flame’s period, Nikola Tesla, and oth- lighting until the pro- The Industrial Revolu- heat into white light.
    [Show full text]
  • A Guide to Greater Yields, More Harvests and Higher Profits LED GROW LIGHTING 101
    LED GROW LIGHTING 101: A Guide to Greater Yields, More Harvests and Higher Profits LED GROW LIGHTING 101 To maximize profits, indoor growers need to harvest high-revenue items in the shortest time possible. A new generation of LED lighting products can help you accelerate photosynthesis and generate a greater return on leafy greens, herbs, microgreens and cannabis, as well as specialty crops and flowers that have quick production cycles. This guide presents key considerations to explore, pitfalls to avoid and next steps to take when choosing a superior lighting solution for your greenhouse, indoor farm or controlled environment facility. GROWING UP Worldwide, the outlook for controlled environment agriculture On one hand, LEDs can boost revenue by reducing lighting energy (CEA) is bright. In 2017, the global indoor farming market costs by about 50% compared to conventional high-pressure accounted for nearly $107 billion USD and is expected to top sodium (HPS) and fluorescent lamps.4 On the other, having greater $171 billion by 2026.1 Specifically, the vertical farming segment lighting control helps growers accurately predict output, harvest is anticipated to reach $9.96 billion USD by 2025, surging ahead year-round and customize crops in a variety of ways. at a 21.3% CAGR.2 Lighting technology is a critical component of the complete Urban densification, limited cultivation space and increasing growing equation, and as CEA production hits high gear, LEDs demand for high-quality foods are just a few of the factors behind can promote healthier plants and profits. the budding popularity of CEA. Across North America, Europe and Asia especially, growers of all types are aiming to provide ideal conditions for plants to thrive.
    [Show full text]
  • Growing Importance of Color in a World of Displays and Data Color In
    Importance of Color in Displays Growing Importance of Color in a World of Displays and Data Color in displays Standards for color space and their importance The television and monitor display industry, through numerous standards bodies, including the International Telecommunication Union (ITU) and International Commission on Illumination (CIE), collaborate to create standards for interoperability, delivery, and image quality, providing a basis for delivering value to the consumers and businesses that purchase and rely on these displays. In addition to industry-wide standards, proprietary standards developed by commercial entities, such as Adobe RGB and Dolby Vision, drive innovation and customer value. The benefits of standards for color are tangible. They provide the means for: Color information to be device- and application-independent Maintaining color fidelity through the creation, editing, mastering, and broadcasting process Reproducing color accurately and consistently across diverse display devices By defining a uniform color space, encoding system, and broadcast specification relative to an ideal “reference display,” content can be created almost anywhere and transmitted to virtually any device. In order for that content to be shown correctly and in full detail, the display rendering it should be able to reproduce the same color space. While down-conversion to lesser color spaces is possible, the resulting image quality will be reduced. It benefits a consumer, whenever possible and within reasonable spending, to purchase a display with the closest conformance to standards so that they are assured of the best experience in terms of interoperability and image quality. The Color IQ optic that is referenced as Annex 3 of Exemption 39(b) allows displays to meet these standards, and does so at a lower system cost and higher energy efficiency than alternative solutions.
    [Show full text]
  • LED Lighting Systems for Horticulture: Business Growth and Global Distribution
    sustainability Review LED Lighting Systems for Horticulture: Business Growth and Global Distribution Ivan Paucek 1, Elisa Appolloni 1, Giuseppina Pennisi 1,* , Stefania Quaini 2, Giorgio Gianquinto 1 and Francesco Orsini 1 1 DISTAL—Department of Agricultural and Food Sciences and Technologies, Alma Mater Studiorum—University of Bologna, 40127 Bologna, Italy; [email protected] (I.P.); [email protected] (E.A.); [email protected] (G.G.); [email protected] (F.O.) 2 FEEM—Foundation Eni Enrico Mattei, 20123 Milano, Italy; [email protected] * Correspondence: [email protected] Received: 4 August 2020; Accepted: 5 September 2020; Published: 11 September 2020 Abstract: In recent years, research on light emitting diodes (LEDs) has highlighted their great potential as a lighting system for plant growth, development and metabolism control. The suitability of LED devices for plant cultivation has turned the technology into a main component in controlled or closed plant-growing environments, experiencing an extremely fast development of horticulture LED metrics. In this context, the present study aims to provide an insight into the current global horticulture LED industry and the present features and potentialities for LEDs’ applications. An updated review of this industry has been integrated through a database compilation of 301 manufacturers and 1473 LED lighting systems for plant growth. The research identifies Europe (40%) and North America (29%) as the main regions for production. Additionally, the current LED luminaires’ lifespans show 10 and 30% losses of light output after 45,000 and 60,000 working hours on average, respectively, while the 1 vast majority of worldwide LED lighting systems present efficacy values ranging from 2 to 3 µmol J− (70%).
    [Show full text]
  • Those Magnificent Chandeliers We Are
    Those Magnificent Chandeliers We are blessed with a beautiful church, “a model of elegance and good taste” The Mecklenburg Times announced in April 1895 in anticipation of the re-opening of the First Presbyterian Church in Charlotte following an extensive and quite expensive (just over $30,000) rebuilding and remodeling of the church. One of the new and much anticipated features of the 1894-1895 remodeling was the installation of three very large and exquisitely ornate chandeliers. “The First Presbyterian Church is to have the handsomest chandeliers in the State”, revealed the Daily Charlotte Observer in a sneak preview in 1894. Prior to the remodeling, First Presbyterian had been regarded as one the most dimly lit churches in Charlotte, having only 39 lights in total. The Session decided as early as 1888 that new lighting, and lighting with electricity, was highly desirable and some electric lights were added at that time to supplement the gas lights. Electric lighting, though a relatively new technology (it wasn’t until 1883 that the first church in the United States was wired for electricity), was much easier to use and much safer than gas. Electrical lighting was rapidly replacing gas lighting across the country. The chandeliers that were going to adorn First Presbyterian actually had dual fuel capability, thus combining the new technology of electrical lighting with the more proven technology of gas lighting. A fail-safe system seemingly. Each of the chandeliers had 72 lights, 36 electric and 36 gas, for a total potential of 216 lights. Dim lighting at First Presbyterian was going to be a feature of the past.
    [Show full text]
  • Light and Dark.Pdf
    LIGHT AND DARK DAVID GREENE Institute of Physics Publishing Bristol and Philadelphia ­c IOP Publishing Ltd 2003 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publisher. Multiple copying is permitted in accordance with the terms of licences issued by the Copyright Licensing Agency under the terms of its agreement with Universities UK (UUK). British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. ISBN 0 7503 0874 5 Library of Congress Cataloging-in-Publication Data are available Commissioning Editor: Nicki Dennis Production Editor: Simon Laurenson Production Control: Sarah Plenty Cover Design: Fr´ed´erique Swist Marketing: Nicola Newey and Verity Cooke Published by Institute of Physics Publishing, wholly owned by The Institute of Physics, London Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK US Office: Institute of Physics Publishing, The Public Ledger Building, Suite 929, 150 South Independence Mall West, Philadelphia, PA 19106, USA Typeset in LATEX2ε by Text 2 Text, Torquay, Devon Printed in the UK by J W Arrowsmith Ltd, Bristol CONTENTS PREFACE ix 1 ESSENTIAL, USEFUL AND FRIVOLOUS LIGHT 1 1.1 Light for life 1 1.2 Wonder and worship 4 1.3 Artificial illumination 6 1.3.1 Light from combustion 6 1.3.2 Arc lamps and filament lamps 9 1.3.3 Gas discharge lamps
    [Show full text]
  • Using Leds to Grow Bonsai
    CHERYL SYKORA • LED is short for light emitting diode. • Electric current passing through semi-conductor diodes the “die” glows a color depending on its chemical components. The die sits in a reflective cup to direct the light outward through an epoxy lens. An LED grow light consists of many diode emitters, a heat sink to pull heat away, cooling fans, and a driver that provides power to the LEDs similar to ballasts in fluorescent lights. • Grow lights have multiple LEDs with different configurations of light chips to provide many different ways of providing lighting to the plant below. How do we know what is needed? • Promote photosynthesis in the plant. •- light-dependent reactions •- light independent reactions •The light-dependent reactions use light to react with water to create chemicals for the light independent reactions. Carbon dioxide is ultimately converted to sugars in this process. • Purpose similar to hemoglobin in blood – absorb energy from the light photos the plant is exposed to. Chlorophyll absorbs in the red and blue regions of the light spectrum. Early on LED manufacturers produced lights with only these spectrum colors. Found this was not enough. • Chlorophyll is green because plants reflect back some of the “green” light but not all. Green Light is absorbed deep within the tissue by Cartenoid compounds Carotenoids cause plant leaves to thicken, increasing their ability to capture more light. Green light can continue to drive photosynthesis when the plant is over exposed to light. Green light can control some diseases and spider mites. Phytochrome – plant growth regulator that functions in the red end of the visible light spectrum – controls internodal elongation and flowering initiation.
    [Show full text]
  • LIGHT's LABOUR's LOST Policies for Energy-Efficient Lighting
    INTERNATIONAL ENERGY AGENCY LIGHT'S LABOUR'S LOST Policies for Energy-efficient Lighting In support of the G8 Plan of Action Warning: Please note that this PDF is subject to specific restrictions that limit its use and distribution. The terms and conditions are available online at http://www.iea.org/w/ bookshop/pricing.html ENERGY EFFICIENCY POLICY PROFILES 01 - 23 Pages début + 531-537 abbr.qxd 15/06/06 16:55 Page 1 LIGHT'S LABOUR'S LOST Policies for Energy-efficient Lighting In support of the G8 Plan of Action ENERGY EFFICIENCY POLICY PROFILES INTERNATIONAL ENERGY AGENCY The International Energy Agency (IEA) is an autonomous body which was established in November 1974 within the framework of the Organisation for Economic Co-operation and Development (OECD) to implement an international energy programme. It carries out a comprehensive programme of energy co-operation among twenty-six of the OECD’s thirty member countries. The basic aims of the IEA are: • to maintain and improve systems for coping with oil supply disruptions; • to promote rational energy policies in a global context through co-operative relations with non-member countries, industry and international organisations; • to operate a permanent information system on the international oil market; • to improve the world’s energy supply and demand structure by developing alternative energy sources and increasing the efficiency of energy use; • to assist in the integration of environmental and energy policies. The IEA member countries are: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, the Republic of Korea, Luxembourg, the Netherlands, New Zealand, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, the United Kingdom, the United States.
    [Show full text]
  • Energy Efficient Landscape Lighting
    energy efficient landscape lighting OPTIONS FOR COMMERCIAL & RESIDENTIAL SITES June 2008. Casey Gates energy efficient landscape lighting OPTIONS FOR COMMERCIAL & RESIDENTIAL SITES June 2008. A Senior Project Presented to the Faculty of the Landscape Architecture Department University of California, Davis in Partial Fulfillment of the Requirement for the Degree of Bachelors of Science of Landscape Architecture Accepted and Approved by: __________________________ Faculty Committee Member, Byron McCulley _____________________________ Committee Member, Bart van der Zeeuw _____________________________ Committee Member, Jocelyn Brodeur _____________________________ Faculty Senior Project Advisor, Rob Thayer Casey Gates Acknowledgements THANK YOU Committee Members: Byron McCulley, Jocelyn Brodeur, Bart Van der zeeuw, Rob Thayer Thank you for guiding me through this process. You were so helpful in making sense of my ideas and putting it all together. You are great mentors. Family: Mom, Dad, Kelley, Rusty You inspire me every day. One of my LDA projects 2007 One of my LDA projects 2007, Walker Hall The family Acknowledgements Abstract ENERGY EFFICIENT LANDSCAPE LIGHTING IN COMMERCIAL AND LARGE SCALE RESIDENTIAL SITES Summary Landscape lighting in commercial and large scale residential sites is an important component to the landscape architecture industry. It is a concept that is not commonly covered in university courses but has a significant impact on the success of a site. This project examines the concepts of landscape lighting and suggests ideas to improve design standards while maintaining energy efficiency. This project will discuss methods and ideas of landscape lighting to improve energy efficiency. Designers should know lighting techniques and their energy efficient alternatives. This project demonstrates how design does not have to be compromised for the sake of energy efficiency.
    [Show full text]
  • Review Lpr the Global Information Hub for Lighting Technologies March/April 2019 | Issue 72
    www.led-professional.com ISSN 1993-890X Review LpR The Global Information Hub for Lighting Technologies March/April 2019 | Issue 72 Interview: Scott Wade Research: Freeform Microlens Arrays Technologies: Smart Buildings DC Grids www.FutureLightingSolutions.com Applications: Office Lighting Controls May 19 – 23, 2019 2019 LIGHTFAIRVisit Internationalus at our stand! Booth #1349 We look forward to seeing you. FLS_CoverCorner_LED Pro_Lightfair.indd 1 2019-02-21 9:04 AM CATEGORYEDITORIAL 4 Connected Miniaturized Lighting In this issue of the LED professional Review (LpR) we want to catch up on the current topics in the lighting world again and also touch on future development and some of the main trends. One topic that affects lighting technologies is progressing miniaturization. The control electronics, in particular, are still too heavy in relation to the LEDs and determine the form factors. There are two main directions concerning this topic that are dealt with: On the one hand, Micro-LEDs are becoming a rapidly growing segment and optimized optics are required for this purpose. On the other hand, there is the approach of "centralizing" the electronics and supplying the energy via a DC grid. The topics in the automotive sector are also related and offer interesting solutions for miniaturization. The second major area, in addition to miniaturization, is networking and, in a broader sense, Smart/AI controlled systems. This edition also concerns itself with EnOcean technology, a method of transmitting data without energy storage and the DALI standard, an interface that is developed, promoted and supported worldwide by the DiiA organization. The DiiA (Digital Illumination Interface Alliance) will also host the first DALI Summit in Bregenz on September 25th, 2019, which will take place parallel to LpS 2019 and TiL 2019.
    [Show full text]
  • Visor: Hao-Chung Kuo 李柏璁 Po-Tsung Lee
    國立交通大學 顯示科技研究所 碩士論文 應用於 紅,藍,綠 發光二極體色彩穩定之 控制回饋系統設計 Light Output Feedback Control System Design for RGB LED Color Stabilization 研究生:李仕龍 指導教授:郭浩中 教授 李柏璁 教授 中華民國九十七年六月 應用於 紅,藍,綠 發光二極體色彩穩定之 控制回饋系統設計 Light Output Feedback Control System Design for RGB LED Color Stabilization 研 究 生: 李仕龍 Student: Shih-Lung Lee 指導教授: 郭浩中 Advisor: Hao-chung Kuo 李柏璁 Po-Tsung Lee 國立交通大學 顯示科技研究所 碩士論文 A Thesis Submitted to Display Institute College of Electrical and Computer Engineering National Chiao Tung University in Partial Fulfillment of the Requirements for the Degree of Master In Display Institute June 2008 HsinChu, Taiwan, Republic of China. 中華民國九十七年六月 應用於 紅,藍,綠 發光二極體色彩穩定之 控制回饋系統設計 碩士班研究生:李仕龍 指導教授: 郭浩中,李柏璁 國立交通大學 顯示科技研究所 摘要 顯示科技蓬勃發展,液晶顯示器(Liquid Crystal Display)已成為取 代陰極射線管顯示器(Cathode Ray Tube Monitor)最強大的主流產品,由 於液晶顯示器並非主動發光元件,必須仰賴一個外加的光源系統,此即所 謂的背光模組,而背光模組使用冷陰極射線管(Cold Cathode Fluorescent Lamp)充當光源已行之有年;發光二極體(Light Emitting Diode)因較冷 陰極射線管具有壽命長,廣色域、省電、環保、反應快速等多項優點,已 成為液晶顯示器背光源的新選擇。然而,長時間使用下而產生的熱,往往 造成發光二極體的發光顏色偏移,此在顯示器要求高色彩品質的標準下, 是最不樂見的。 本論文提出了使用光二極體感測發光二極體的光輸出訊號,經類比數 位轉換的裝置,套用反覆逼近的程式,設計建立一組μA等級的電流逼近 的發光二極體色彩穩定回饋系統。回饋系統在 13 位元解析下,可將對應 於使用 3250, 3969, 及4462小時的紅色,藍色及綠色發光二極體的色偏 值(Δu'v')維持在內 0.005 (人眼恰可接受的範圍) 內。使用 14 位元 解析下,可將紅,藍及綠色發光二極體的色偏值維持在內 0.004 之內。 I Light Output Feedback Control System Design for RGB LED Color Stabilization Student : Shih-Lung Lee Advisor: Hao-chung Kuo Po-Tsung Lee Display Institute National Chiao-Tung University Abstract LCD (Liquid Crystal Display) is the mainstream product to replace CRT (Cathode Ray Tube). Conventionally, CCFL (Cold Cathode Fluorescent Lamp) is used as a light source of LCD backlight. However, LED (Light Emitting Diode) is regarded as the candidate to replace CCFL (Cold Cathode Fluorescent Lamp) as light source of LCD backlight due to its wide color gamut, low operation voltage, mercuryfree characteristic, and fast switch response.
    [Show full text]
  • Grow Light” Application Primer
    “Grow Light” Application Primer A grow light or plant light is designed to stimulate plant growth by emitting an electromagnetic spectrum appropriate for photosynthesis. Grow lights are used in applications where there is either no naturally occurring light, or where supplemental light is required. For example, in the winter months when the available hours of daylight may be insufficient for the desired plant growth, lights are used to extend the time the plants receive light. If plants do not receive enough light, they will grow long and spindly. Grow lights either attempt to provide a light spectrum similar to that of the sun, or to provide a spectrum that is more tailored to the needs of the plants being cultivated. Outdoor conditions are mimicked with varying color, temperatures and spectral outputs from the grow light, as well as varying the lumen output (intensity) of the lamps. Depending on the type of plant being cultivated, the stage of cultivation (e.g., the germination/vegetative phase or the flowering/fruiting phase), and the photoperiod required by the plants, specific ranges of spectrum, luminous efficacy and color temperature are desirable for use with specific plants and time periods. 1 Page Our LED light engine produces bright and long-lasting grow lights that emit only the wavelengths of light corresponding to the absorption peaks of a plant’s typical photochemical processes. Compared to other types of grow lights, LEDs for indoor plants are attractive because they require significantly less energy to run and produce considerably less heat than incandescent lights. These Grow Modules usually run at around 45-60 degrees Celsius.
    [Show full text]