Rozprawy doktorskie na temat „COLOR RENDERING INDEX (CRI)”

Recent advances in solid state lighting (SSL) technology have encouraged its utilization in versatile applications. SSL technology based on phosphor converted light emitting diodes (pc-LEDs) are acting potentially as a substitute for traditional incandescent and fluorescent lamps on an account of their unprecedented luminous efficiency, low energy consumption, less emission of harmful gases, high brightness, compact design, fast switching and long working lifetimes. The pc-LEDs utilize phosphors coated on the LED chip capable of emitting light in desirable spectral regions upon an appropriate excitation. In the light of the above mentioned advantages, pc-LEDs are believed to be the next generation SSL technology and will bring a revolutionary changes in the lighting industry. For example, the white pc-LEDs have been the most preferred lighting devices for general illumination due to effective energy utilization, long lifetime, safety and so on. Moreover, pc-LEDs can be harnessed for indoor agricultural lighting owing to their excellence in controlling the spectral composition and lighting intensity to mimic the changes of sunlight during the day. Therefore, all the above mentioned fascinating features like effective energy saving and desirable light emission have enabled pc-LEDs to become economically feasible choice for general illumination and large scale indoor agricultural lighting applications around the corners of the world. The phosphor based w-LEDs can be developed by (i) coating of appropriate mixture of red, green and blue (RGB) phosphors excited with UV LED chip (ii) single yellow phosphor by a blue LED chip. However, reabsorption of blue color by RG phosphors in the former approach and lack of red component in later approach may lead to shortcomings like low color saturation, deteriorated color rendering index (CRI) and low color temperature stability. To overcome the above mentioned shortcomings, it is necessary to develop single phase phosphor doped with appropriate combination of rare earth ions (such as Dy3+/Eu3+, Tb3+/Eu3+ , Tb3+/Sm3+, Dy3+/Sm3+ etc.) providing white light emission via energy transfer or new red vii phosphor for the improvement of performance factors like luminous efficiency, CRI and correlated color temperature (CCT). Further, for plant growth under controlled environment fitted with smart pc-LEDs, it is necessary to conduct a widespread research for deep-red, far- red and blue light emitting phosphors that can be utilised to best drive photosynthetic metabolism and photo-morphogenesis as per the literature survey. Therefore, the ascending demand of energetically efficient lighting devices for general illumination and plant growth applications has led to a significant interest in the development of novel high quality phosphors with superior brightness, multiple emission color and excellent color purity. Besides lighting, the phosphors facilitate their utilization in diverse applications such as solar cells, bio-sensing and other optoelectronic devices due to their versatile physical, chemical and luminescent properties. In general, phosphor consisting of a host matrix (crystalline host) and an activator (luminescent center) have been pondered as a technologically significant components for the development of w-LEDs and agricultural lighting systems. In the past few decades, inorganic phosphors activated with rare earth (RE) ions have remained the prevalent protocol for fabricating pc-LEDs due to unique luminescence properties of RE ions. In such phosphors, the intermixing of oxygen atomic orbitals of host with orbitals of RE ion creates a specific crystal field environment around it such that transitions between incompletely filled 4f energy levels of RE ions deliver distinctive luminescence features. Also, the efficient energy transfer from the host crystal to the RE activators have been investigated to comprehend interesting optical phenomena. Among all the various inorganic oxides, vanadates have attracted acquiescent utilization in the wide-spread of luminescent device applications due to their wide-range of excitation wavelengths with abundant luminous colour, good physical and chemical stability. In addition, the vanadate materials are cost-effective and their preparation methods are energy efficient. The vanadate based phosphors give a broadband emission originating from inherent [VO4] 3- group. The broadband emission in the visible range by vanadate hosts can bring viii improvement in CRI and CCT values. Recent investigations have been established the possibility of achieving tunable visible emissions in RE activated vanadate phosphors via controlling [VO4] 3- to RE ions energy transfer. To harness the above mentioned precedencies, an investigation on a new ternary vanadate (CaBiVO5) phosphor doped with RE ions has been done for general and agricultural lighting applications. By incorporating suitable RE ions, the present host (CaBiVO5) can be tuned to emit different colors in the visible region suitable for pc-LEDs used in general illumination and agricultural lighting applications. Based on the extensive structural, morphological and photoluminescence characterizations, the outcome of the research work for accomplishing the research objectives has been organized in seven chapters. The brief summary of each chapter is as follows: Chapter 1 highlights the brief history, motivation, an outlook on the recent developments, potential challenges and great opportunities in white light generation and agricultural lighting. This chapter explains the basic concepts related to luminescence, spectroscopic features of RE ions, theoretical models implemented for examining the observed spectral data, and possible energy transfer processes. This chapter also present a brief viewpoint on the various characteristics and indices such as chromaticity coordinates, color purity, CCT and activation energy describing the color quality, thermal stability and performance of pc-LEDs. The importance of the present work and selected vanadate host have been discussed briefly in this chapter. At the last, the objectives of the thesis based on literature review have been included. Chapter 2 makes a thorough discussion about the different synthesis methods opted for the synthesis of single phase calcium bismuth vanadate (CaBiVO5: CBV) phosphors activated with different RE ions (Eu3+, Sm3+, Pr3+ and Dy3+). It also explicates the basic principle and working of experimental techniques employed to explore structural, morphological, optical and luminescent properties of CBV phosphors. The thermal and structural properties are studied by thermogravimetric analysis (TGA) and X-ray Diffraction (XRD) method, respectively. The ix scanning electron microscopy (SEM) reveals the morphology of the as synthesized phosphors. The optical properties are determined from diffuse-reflectance (DR) spectral measurements, while photoluminescence properties, thermal stability and decay kinetics of the CBV phosphors doped with different RE ions were investigated using spectrofluorophotometer. All these characterization techniques have been discussed in this chapter. Chapter 3 describes about the synthesis of single phase Eu3+ activated calcium bismuth vanadate (CaBiVO5) phosphors using solid state reaction method. X-ray diffraction (XRD) analysis confirms the pure phase formation and scanning electron microscope (SEM) micrographs exhibit inhomogeneous particle formation with irregular morphology of Eu3+ doped CaBiVO5 (CBV) phosphor. The photoluminescence excitation (PLE) spectrum indicates significant absorption in the ultraviolet (UV) and near ultraviolet (n-UV) spectral regions for un-doped CBV sample, whereas Eu 3+ doped CBV phosphors reveal various sharp absorption bands in n-UV and blue region along with host absorption bands. Trivalent europium activated CBV phosphors under 342 nm excitation exhibit dominant red emission peak at 613 nm wavelength accompanied by weak broadband originating from VO4 groups, whereas the phosphors under 464 nm excitation, exhibit similar emission profile with most intense one centered at 613 nm by excluding host emission bands. The energy transfer mechanism and the probable cause for concentration quenching beyond 4.0 mol% of Eu3+ ions concentration have been discussed in detail. The CIE chromaticity coordinates for the optimized phosphor, (0.551, 0.398) and (0.639, 0.358), situated in the reddish-orange and red region under 342 and 464 nm excitations, respectively. The CIE coordinates calculated based on the emission spectra measured under 464 nm excitation are close to the commercial phosphor Y2O2S: Eu3+ (0.622, 0.351). All the above mentioned results support the utilization of Eu3+ doped CBV phosphor as a potential red emitting component for luminescent devices. x The research work described in this chapter has been published in “Ceramics International 45 (2019) 15385-15393” (Impact factor =4.527) Chapter 4 describes the optimization of synthesis procedure for Sm3+ doped CaBiVO5 phosphor by preparing through it via three different synthesis methods, solid-state reaction (SR), combustion (CB) and citrate sol-gel (SG) method to enhance the luminescent properties. The pure phase formation of CBV: Sm3+ phosphors via diverse routes (SR, CB and SG) is confirmed as diffraction peaks for all prepared phosphors correspond to the standard data (JCPDS card no: 81-1775). The SEM results reveal that CBV: Sm3+ phosphors are synthesized with improved homogeneity and shape regularity at lower reaction temperature via SG method. The excitation spectra measured by monitoring the emission at 649 nm for CBV: Sm3+ phosphors reveal significant absorption in ultraviolet (UV), near (n)-UV and blue spectral regions. The comparative photoluminescence (PL) spectra measured under 343 nm excitation for differently synthesized CBV: Sm3+ phosphors, which exhibit significantly enhanced emission intensity for SG derived phosphor than other adopted methods. The PL spectra for SG derived 1.0 mol% Sm3+ doped CBV phosphor at λex = 275 and 343 nm exhibit sharp peaks located at 566, 606 and 649 nm along with weak host emission broadband and for λex = 406 nm, similar sharp peaks of Sm3+ transitions are observed without any host emission. Unlike mostly explored Sm3+ doped phosphors, emission peak in red spectral region (649 nm) is more intense as compared to the emission peak in orange region (599 nm) in the present work. The energy transfer mechanism responsible for concentration quenching in CBV phosphors is discussed in detail. The CBV: Sm3+ phosphors manifest color tunability from orange to orange- red region by modulating excitation from 275 nm (0.567, 0.404) to 343 nm (0.591, 0.399) and finally to 406 nm (0.620, 0.376). The temperature-dependent PL studies indicate appreciable thermal stability of as-prepared phosphor. Above mentioned results suggest that CBV: Sm3+ phosphor has great potential for use in white light-emitting diode (w-LED) applications. xi The research work described in this chapter has been published in “Optical Materials 107 (2020) 110119” (Impact factor =3.080). Chapter 5 describes the citrate sol-gel synthesis of Dy3+ activated and Dy3+/Eu3+ bi-activated calcium bismuth vanadate (CBV) phosphor to achieve white light emission and color- tunability. The phase purity and quasi-spherical particle with few agglomerations of the as- prepared CBV phosphors are indicated by structural and morphological characterizations, respectively. The emission spectral properties and energy transfer in Dy3+ doped and Dy3+/Eu3+ co-doped CBV phosphors have been examined extensively. The Dexter and Reisfeld’s approximation applied to emission spectra specifies electric dipolar-dipolar interaction to be accountable for Dy3+ to Eu3+ energy transfer. In CBV: Dy3+ phosphors, co-doping with Eu3+ ion facilitates red component that ensues warm white light emission as well as flexible color tunability with increasing Eu3+ ion concentration under different excitations. The significant findings like warm white light emission and controllable spectral composition in Dy3+/Eu3+ co- doped CBV phosphor by altering the excitation energy and co-dopant (Eu3+) concentration potentiate it as a suitable candidate in the domain of lighting and display devices. The research work described in this chapter is communicated to an Internationally reputed Journal “Solid State Sciences (2021)” (Impact factor = 3.059) Chapter 6 describes about orthorhombic Pr3+ -doped calcium bismuth vanadate (CBV: Pr3+) phosphors synthesized via citrate-gel method. The single-phase formation of CBV: Pr3+ phosphor has been endorsed by XRD analysis. The SEM image reveals dense-particle packaging with the quasi-spherical shape for the prepared CBV: Pr3+ phosphors. Under blue light excitation, CBV: Pr3+ phosphors exhibit intense red emission bands located at 608 and 656 nm wavelengths, overlapping with the absorption spectrum of PR phytochrome, which is present in plants. To achieve the maximum red intensity, the Pr3+ ion concentration is optimized xii to be 1.25 mol% in the CBV host, after which the emission intensity ceases due to the concentration quenching. Dexter's theory disclosed the possibility of d-d multipolar interaction among Pr3+ ions at higher concentrations of Pr3+ ions in the CBV host. The CIE coordinates are found to be positioned in the pure red region for CBV: Pr3+ phosphor and in the proximity of red-emitting commercial phosphor. The temperature dependent spectral studies manifest substantial thermal stability of the as-synthesized phosphor. All the studies mentioned above specify the tremendous potentiality of thermally stable CBV: Pr3+ phosphor in agricultural lighting and w-LED applications. The research work described in this chapter has been accepted to publish in “Journal of the American Ceramic Society 104 (2021) 5764-5775” (Impact factor =3.784). Chapter 7 summarizes the research outcomes of the work described in chapters 3 to 6 and outline the future scope of the thesis work for the expected applications.

Tunable white-armaturer utgör idag en stor del av marknaden och förväntas öka ytterligare under de kommande åren. Då många leverantörer idag producerar och marknadsför sina egna lösningar för att skapa ett dynamiskt ljus kan det vara svårt att veta vilken standard dessa lösningar håller och hur väl den tekniska specifikationen stämmer överens med verkligheten. Syftet med denna studie har varit att undersöka om informationen mot beställare är tillräcklig samt om den redovisade data av Tunable White-armaturer är korrekt. Studien bygger på två delar. En experimentell undersökning genomfördes där fem tunable white-armaturers CRI (färgåtergivning) mättes mellan olika CCT-nivåer (färgtemperatur) och sedan jämfördes det med vad leverantörer har specificerat på deras hemsidor. En enkätundersökning genomfördes sedan som riktades mot 144 ljusdesigners i Sverige, varav 52 valde att besvara enkäten. Frågorna berörde redovisning av Tunable white-armaturer samt vikten av en god ljuskvalitet med inriktning på CRI. Resultaten från författarnas experimentella undersökning visar att alla tunable white-armaturer som testades skiftar i CRI under olika färgtemperaturintervaller. Den största skillnaden som mättes var på fabrikat 3 där det skiftade 9 CRI mellan 2700K-6000K. En jämförelse kunde sedan göras och visade att två av fem leverantörers specifikationer inte stämmer överens med vad som redovisats i respektive produktdatablad. Av att tyda svaren från enkätundersökningen kunde slutsatsen dras att det finns mycket skilda åsikter angående de tekniska specifikationerna gällande tunable white-armaturer. En del ansåg att det redovisas tillräckligt väl idag medan andra ansåg att det inte redovisas tillräckligt väl. Majoriteten ansåg att det är mycket viktigt med en god CRI när man föreskriver tunable white-armaturer i sina projekt. Man kunde också se att många ljusdesigners önskade att man redovisade färgåtergivning i TM-30-15 istället för CRI-metoden eller att man bör redovisa i givna färgtemperaturer. Det som kan fastställas av denna studie är att det finns en tendens till att vissa armaturleverantörer har sämre CRI än vad företaget i fråga redovisat. Denna studie enbart mätt TW-armaturer från fem företag verksamma i Sverige samt endast vid 100% ljusflöde. Författarna anser dock att denna studie kan leda till en diskussion om bättre redovisning av tunable white-armaturer behövs, samt ge läsaren en ökad förståelse för komplexiteten inom området.
Tunable white luminaires today form a large part of the market and are expected to increase further in the upcoming years. As many manufacturers today produce and market their own solutions to create a dynamic light, it can be hard to know what quality these solutions have and how well the technical specification is. The purpose of this study were to investigate whether the information to the user is sufficient and whether the presented data of tunable white luminaires is correct. This study is based on two parts. An experimental study where five tunable white luminaires CRI (color rendering) were measured between different CCT levels (color temperature) and then compared these to what providers have specified on their websites. The second part was a survey was conducted to 144 lighting designers based in Sweden, 52 of whom chose to answer the questionnaire. The questions concerned the presented information of tunable white luminaires as well as the importance of a good light quality focusing on CRI. The results from the authors experimental survey showed that all tunable white luminaires that where tested are changing in CRI under different color temperature intervals. The biggest difference that was measured was on manufacturer 3 where 9 CRI shifted between 2700K-6000K. A comparison could be made and showed that two of five of the suppliers specifications did not match with the authors measurements. By analyzing the answers from the survey, some conclusions could be drawn. There were very different opinions regarding the technical specifications of tunable white luminaires. Some felt that it is enough as it is today, while others felt that more information was needed. The majority considered it very important to have a good CRI when selecting tunable white luminaires in their projects. One could also see that many lighting designers wanted to present color reproduction in TM-30-15 instead of the CRI method or to present CRI at given color temperatures. What can be determined by this study is that there is a tendency for some luminaire suppliers to have worse CRI than presented. This study only measured tunable white fixtures from five companies operating in Sweden and only at 100% luminosity. However, the authors consider that this study could lead to a discussion about better specifications for tunable white luminaires, as well as giving the reader an increased understanding of the complexity of the subject.

Organic semiconducting materials have received a lot of attention in recent years and can now be found in many applications. One of the applications, the light emitting electrochemical cell (LEC) has emerged due to its flat and lightweight device structure, low operating voltage, and possibility to be fully solution processed. Today LECs can emit light of various colors, but to be applicable in the lighting industry, white light need to be produced in an efficient way. White light on the other hand, is one of the toughest "colors" to achieve in an efficient way, and is of particular interest in general lighting applications, where high color-rendering index devices are necessary. In this thesis I show that blue light can be partially converted, into white light, by utilizing the photoluminescence of color conversion layers (CCLs). Furthermore, I show that a high color-quality white light can be attained by adopting a blue-emitting LEC with a CCL. Particularly, three different color-conversion materials were embedded onto a blue bottom-emitting LEC, to study the resulting spectrum. One of the materials, MEH-PPV, have good absorption compatibility with the electroluminescence of the blue emitters, but the materials photoluminescence do not cover the red to deep-red range of the spectrum. These parts of the spectrum are necessary to obtain high color rendering indices (≥80). A single layer of MEH-PPV adapted onto a blue-emitting LEC, led to a cold white LEC with CIE-coordinates x = 0.29, and y = 0.36, color-rendering index = 71, and correlated color temperature = 7200 K. These properties makes it potentially useful in outdoor-lighting applications. The photoluminescence of another studied color-converting material, polymer red, covers the red to deep-red range of the spectrum but the material lacks absorption in the green parts of the blue emitters electroluminescence spectrum. Thus it is necessary to combine it with MEH-PPV to be able to absorb all wavelengths from the blue-emitter and get a broad light-spectrum out of the device. In order to preserve a part of the blue light, a new device configuration was designed. It features a top-emitting blue LEC with a dual-layer CCL which reach an impressive color rendering index = 89 at a correlated color temperature = 6400 K (CIE-coordinates x = 0.31, y = 0.33). The color-rendering index is the highest reported for a white LEC. The absence of UV-, and IR-radiation, together with the high color rendering properties make the white LEC a possible candidate for even the most demanding lighting-applications, such as art galleries, and shop display windows, together with indoor lighting. In this thesis, I show that the CCLs function well. However, for the LECs to be worthy competitors, the efficiency and lifetime of the blue emitter need improvements.

Cette thèse a été réalisée en parallèle avec le projet de recherche « ENG05 lighting », un programme européen de recherche en métrologie réunissant une quinzaine d’instituts nationaux de métrologie en Europe. L'apparition de nouvelles solutions d’éclairage utilisant des diodes à électroluminescence (DEL) n’apporte pas seulement une efficacité en termes de diminution de puissance consommée mais elles doivent également répondre à des critères dequalité delumière pour l’utilisateur selon l’environnement.L'étude se concentre sur les problématiques du confort visuel ainsi que sur les indices du rendu des couleurs conformes à ceux de la Commission International de l'Eclairage (CIE) qui ne permettent pas de prédire une évaluation fiable en ce qui concerne ces nouveaux éclairages à l’état solide.Cette recherche s’appuie sur les calculs informatisés des métriques existantes, les résultats de plusieurs expériences subjectives réalisées dans un environnement contrôlé et reproductible et leurs caractérisations. Un premier modèle capable de prédire le confort visuel d'un scénario d'éclairage est réalisé et décrit. Plusieurs axes d'amélioration des métriques du rendu des couleurs sont étudiés.L'ensemble des expériences intègre des solutions d'éclairages traditionnelles. A l’aide de carte de luminance, les résultats obtenus sont comparés aux performances des sources respectives.Mots-clefs : Rendu des couleurs, confort visuel, qualité des éclairages, expérience subjective, DEL, DEL, UGR, IRC, CRI, éblouissement, carte de luminance
The ENG05 project funded by the European Research Metrology Programme (EMRP) addresses measurement aspects of both quantity and quality of new lighting such as solid-state lighting (SSL).The current Colour Rendering Index (CRI) of the CIE (International Commission on Illumination) fails to predict the subjective ranking of the lighting sources based on DEL (light emitting diode). Along with a study of colour rendering metrics based on an extensive computation of relevant metrics and colorimetric calculations, a study on visual comfort is performed and both are presented in this thesis.For interior lighting standards it doesn’t exist a metric able to predict the visual comfort of an environment. Therefore, the aim of this study consists in a contribution to the human visual comfort characterization according to various realistic configurations considering the comparison between DEL luminaries and traditional lighting technologies (fluorescent, halogen).The analysis of the results DEL to develop a model which could be deemed worthy of consideration by CIE.Keywords: color rendering, visual comfort, lighting quality, subjective experiment, DEL, UGR, CRI, glare, luminance maps

A new red emitting phosphors based on oxyfluoride glass and glassceramics doped with europium and manganese ions were synthesized and their optical properties and structure were studied. The transparent ceramic matrices for phosphors were selected because they overcome traditional powder phosphors due to high chemical and thermal stability and low temperature sensitivity. The fluoride based red emitting phosphors combined with green one and blue emitting chip used to fabricate phosphor converted white LEDs with warm color temperature and improved color rendering indexes. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35375

A solar fiber optic lighting system, SP3 from the Swedish company Parans Solar Lighting AB, has been installed in a study area/corridor test site. A collector is tracking the sun during daytime, focusing the direct sun irradiance via Fresnel lenses into optical fibers, which guide the solar light into the building. The illumination properties of the system have been characterized. The energy saving due to reduced need of artificial lighting have been calculated and methods for balancing the artificial lights in the test site have been evaluated. The illumination at the test site using solar light was at least as high as when using the artificial lights and even higher at very clear days. The luminous flux output (500 lm) was somewhat lower than specified by the manufacturer (550 lm) at 100 000 lx direct sun illuminance. The output at 130 000 lx was high 767±33 lm the sunlight coupling efficiency 23 %. However, for a 20 m SP3 system the luminous flux output (400 lm) at 100 000 lx was higher than specified (350 lm). The SP3 system of Parans provides high quality solar light. It has a fuller spectrum close to the spectrum of the sun compared to the fluorescent lights at the test site. The correlated color temperature of the system was 5800±300 K and the color rendering index 84.9±0.5. The lighting energy saved due to decreased need for artificial light was estimated to 19 % in Uppsala which has 1790 annual sun hours. The savings in Italy, which has 3400 sun hours, is 46 %. Additional saving, especially in warmer countries can be obtained due to decreased need for cooling in the building as the solar luminaires provide negligible heat to the indoor air. Economical saving could also be realized by improved well-being of the occupants spending time under the solar luminaires. Three ways of balancing the artificial light due to sunshine fluctuations have been investigated. The global horizontal irradiance could not be used as a control signal for balancing the artificial lights but a pyranometer attached to the SP3 sun tracking collector was usable. Also the signal from an indoor luxmeter sensor could be used for balancing the light. However the signal from the light sensor which makes the SP3 collector to track the sun is probably the most cost effective method as it would serve two purposes; tracking the sun and balancing the artificial lights.

This thesis deals with the processing of light technical parameters and performance of key LED chips for their applications in lighting systems. The aim is to create a laboratory model for measuring the qualitative and quantitative parameters of highly luminous light LED emitted depending on the angle, using a spherical integrator 0.3 m, goniometer and fiber spektroradiometr /luxmeters. Goniometer is designed using modular optomechanical parts company Thorlabs. Due to the current passing through the LED chips heat up considerably. To light LED chip parameters tested were not affected by heat from the chip is required to pay the heat generated by a passive radiator. Another part of this thesis is the reconstruction of an older model spherical integrator. Reconstruction must be undertaken so as to ensure sufficient cooling again tested LEDs. Light scattered in the ball of the integrator is led by the optical cable to the spektroradiometr that are subsequently recorded its parameters. The second element used to measure the light produced by the LED source is photocell. Spherical integrator must be appropriately modified to indicate the two measuring elements and also meet the standards of determining the correctness of measurement. At the end of the measurement results will be compared with catalog values provided by the manufacturer.

Актуальність теми. Актуальною задачею комп’ютерної графіки являється отримання реалістичних зображень, котрі активно користуються попитом в промисловості, ігровій індустрії та кіно. Фотореалістичне зображення характеризується такими ефектами, як м’які тіні, напівтіні, каустика, динамічне розмиття, глибина різкості, нечіткі відбиття, блиск, напівпрозорість. Серед існуючих підходів фотореалістичної візуалізації методи трасування променів являються найбільш точними, оскільки вони базуються на фізичній моделі поширення світла. Існує багатий спектр різноманітних методів трасування променів, отже з’являється необхідність у вибірці найбільш ефективних точних методів трасування променів, котрі будуть в середній мірі коректно працювати для широкого ряду статичних (в майбутньому і динамічних) сцен, що проходять візуалізацію. Об’єктом дослідження є процес фізично обґрунтованого рендерингу і процес трасування променів. Предметом дослідження є способи трасування променів та методи розрахунку індексу передачі кольору. Мета роботи: дослідження методів PBR (Physical Based Rendering), їх одночасного використання для отримання максимального ефекту реалізму; оцінка здатності джерела світла виявляти всі частоти його кольорового спектру у порівнянні з контрольним світлом. Наукова новизна, а точніше – інноваційне рішення полягає в тому, що розроблений рушій реалізує обчислення індексу передачі кольору (CRI - Color Rendering Index) з високим рівнем точності відносно очікуваних значень контрольних джерел світла. Практична цінність проведених досліджень полягає у розробці нового PBRE, який для рендерингу сцен використовує емпіричні моделі освітлення; реалізовані такі моделі BRDF, як Ламберта, Орена Найара, Торренса Спарроу, дзеркального відбиття, дзеркального пропускання і виміряного BRDF. Реалізована підтримка декількох технік трасування променів: трасування Уайтеда і трасування шляху. Розраховуються кольори з використанням спектральних даних і колірний простір CIE XYZ в сценах PBR для досягнення високої передачі кольору. TTFD також підтримує обчислення індексу передачі кольору (CRI – Color Rendering Index). Цей показник описує здатність джерела світла точно відображати всі частоти його колірного спектра в порівнянні з ідеальним еталонним світлом аналогічного типу. Структура та обсяг роботи. Магістерський дипломний проект складається зі вступу, чотирьох розділів та висновків. У вступі подано загальну характеристику роботи, зроблено оцінку сучасного стану проблеми, обґрунтовано актуальність напрямку досліджень, сформульовано мету і задачі досліджень, показано наукову новизну отриманих результатів і практичну цінність роботи. У першому розділі розглянуто принципи колориметрії та радіометрії. Вони складають основу деяких основних ключових особливостей TTFD. Зокрема, розрахунок кольору і методи освітлення / затінення, реалізовані в TTFD, використовують поняття, представлені даному розділі. У другому розділі розглянуто трасування променів: фотореалістичний рендеринг (візуалізація). Коротка класифікація алгоритмів трасування променів. Вирішення рівняння рендеринга. У третьому розділі наведено особливості реалізації розробленої системи. У четвертому розділі представлено підходи до тестування системи в цілому та окремих модулів. У висновках представлені результати проведеної роботи. Робота представлена на 116 аркушах, містить посилання на список використаних літературних джерел. Ключові слова: фізичний рендеринг (PBR), трасування променів, індекс передачі кольору, емпіричні моделі освітлення, модель Уайтеда, трасування шляху.
Relevance of the topic. The actual task of computer graphics is to obtain realistic images that are actively in demand in industry, gaming and film industry. A photorealistic image is characterized by such effects as soft shadows, partial shade, caustic, dynamic blur, depth of field, fuzzy reflection, shine, translucency. Among the existing approaches of photorealistic visualization, ray tracing methods are the most accurate because they are based on a physical model of light propagation. There is a wide range of different ray-tracing methods, and therefore there is a need to select the most efficient, accurate ray-tracing methods that will, in average, work correctly for a wide range of static (future dynamic) scenes, and are being visualized. The object of the research is the process of physically sound rendering and the ray tracing process. The subject of research is the methods of ray tracing and methods for calculating the color rendering index. Objective: to study the methods of PBR (Physical Based Rendering), their simultaneous use to obtain the maximum effect of realism; assessment of the ability of a light source to detect all the frequencies of its color spectrum compared to the control light. The scientific novelty, or rather, an innovative solution, is that the engine developed implements the calculations of the color rendering index (CRI - Color Rendering Index) with a high degree of accuracy relative to the expected values of the control light sources. The practical value of the research is the development of a new PBRE, which employs empirical lighting models for rendering scenes; BRDF models such as Lambert, Oren Nayar, Torrens Sparrow, specular reflection, specular transmission and measured BRDF are implemented. Implemented support for several ray tracing techniques: Traced by Wyted and path tracing. Colors are calculated using spectral data and CIE XYZ color space in PBR scenes to achieve high color rendering. TTFD also supports Color Rendering Index (CRI) calculations. This indicator describes the ability of a light source to accurately reflect all the frequencies of its color spectrum compared to ideal reference light of a similar type. Structure and scope of work. Master thesis project consists of introduction, four chapters and conclusions. The introduction presents a general description of the work, assesses the current state of the problem, substantiates the relevance of the research area, formulates the goals and objectives of the research, shows the scientific novelty of the results and practical value of the work. The first section discusses the principles of colorimetry and radiometry. They form the basis of some key TTFD key features. In particular, color calculations and lighting / shading methods implemented in TTFD use the concept presented in this section. The second section deals with ray tracing: photorealistic rendering (visualization). Brief classification of ray tracing algorithms. Solution of the rendering equation. The third section presents the features of the implementation of the developed system. The fourth section presents approaches to testing the system as a whole and individual modules. The findings present the results of this work. The work is presented on 116 pages, contains links to the list of references used.
Актуальность темы. Актуальной задачей компьютерной графики является получение реалистичных изображений, которые активно пользуются спросом в промышленности, игровой индустрии и кино. Фотореалистичное изображение характеризуется такими эффектами, как мягкие тени, полутени, каустика, динамическое размытие, глубина резкости, нечеткие отражение, блеск, полупрозрачность. Среди существующих подходов фотореалистичной визуализации методы трассировки лучей являются наиболее точными, поскольку они базируются на физической модели распространения света. Существует богатый спектр различных методов трассировки лучей, следовательно появляется необходимость в выборке наиболее эффективных точных методов трассировки лучей, которые будут в средней степени правильно работать для широкого ряда статических (в будущем и динамических) сцен, проходят визуализацию. Объектом исследования является процесс физически обоснованного рендеринга и процесс трассировки лучей. Предметом исследования являются способы трассировки лучей и методы расчета индекса цветопередачи. Цель работы: исследование методов PBR (Physical Based Rendering), их одновременного использования для получения максимального эффекта реализма; оценка способности источника света выявлять все частоты его цветового спектра по сравнению с контрольным светом. Научная новизна, а точнее - инновационное решение, заключается в том, что разработан двигатель реализует вычисления индекса цветопередачи (CRI - Color Rendering Index) с высокой степенью точности относительно ожидаемых значений контрольных источников света. Практическая ценность проведенных исследований состоит в разработке нового PBRE, который для рендеринга сцен использует эмпирические модели освещения; реализованы такие модели BRDF, как Ламберта, Орена Найара, Торренса Спарроу, зеркального отражения, зеркального пропускания и измеренного BRDF. Реализована поддержка нескольких техник трассировки лучей: трассировки Уайтеда и трассировки пути. Рассчитываются цвета с использованием спектральных данных и цветовое пространство CIE XYZ в сценах PBR для достижения высокой цветопередачи. TTFD также поддерживает вычисления индекса цветопередачи (CRI - Color Rendering Index). Этот показатель описывает способность источника света точно отражать все частоты его цветового спектра по сравнению с идеальным эталонным светом аналогичного типа. Структура и объем работы. Магистерский дипломный проект состоит из введения, четырех глав и выводов. Во введении представлена общая характеристика работы, произведена оценка современного состояния проблемы, обоснована актуальность направления исследований, сформулированы цели и задачи исследований, показано научную новизну полученных результатов и практическую ценность работы. В первом разделе рассмотрены принципы колориметрии и радиометрии. Они составляют основу некоторых основных ключевых особенностей TTFD. В частности, расчет цвета и методы освещения / затенения, реализованные в TTFD, используют понятие, представленные данном разделе. Во втором разделе рассмотрены трассировки лучей: фотореалистичный рендеринг (визуализация). Краткая классификация алгоритмов трассировки лучей. Решение уравнения рендеринга. В третьем разделе приведены особенности реализации разработанной системы. В четвертом разделе представлены подходы к тестированию системы в целом и отдельных модулей. В выводах представлены результаты проведенной работы. Работа представлена на 116 листах, содержит ссылки на список использованных литературных источников.

碩士
大葉大學
電機工程學系碩士在職專班
96
The dissertation will focus on the energy conservation sends the photo source at present the market condition to mix the white light LED technology inking that including Muliti-Chip LED Approach、the chromatic aberration compensation method, the color warm compensation method and so on because of the present high electrovalence and the environmental protection subject.There are some defects of white light LED that heat to drift and serious light fades, this paper will research four colors to mix light LED (R to be red) (the G green) (the B blue color) (the Y yellow) and to use RGBY LED to mix the white light LED test research light to fade the potency and the present market condition fluorescent lamp tube, Cold Cathode Fluorescent Lamp, the white light LED degree of illumination experiment. It is supposed to make the graph its result to study its province electricity potency and the light fades the degree.

碩士
華梵大學
機電工程學系博碩專班
97
In recent years, with the enhancement of material, process and technology, it greatly upgrades the luminous efficacy and power capacity, enables the possibility of having white light - emitting diodes replacing existing lighting sources. A fine quality in indoor lighting source requires conditions of high color rendering index, high luminous efficacy and low manufacturing cost. This research adopts blue light-emitting diodes with 6 lumens per watt in conjunction with market available phosphors with different wavelengths to analyze the synthesized frequency emitted after mixed with phosphors. And the absorptive quotient which the blue light should possesses and the emitted frequency functions for the phosphor will be used as basis to design each type of white light source with high color rendering index so as to promote and upgrade the luminous efficacy for light-emitting diode. From the design method of synthesized frequency for phosphor, the experimentation resulted with emitted color temperature of 3150 K of coloring rendering index of 96.51 and luminous efficacy of 28 lm/w; color temperature at 4700K with color rendering index of 95.5 and luminous efficacy of 30 lm/w; color temperature of 5200K with color rendering index of 94.21 and luminous efficacy of 30 lm/w for white light-emitting diode frequency range. In comparison to typical blue light-emitting diode covered with YAG phosphors, which would emit color temperature of 3800K with color rendering index of 62.6 and luminous efficacy of 44 lm/w, the above indicated that, the research findings point to the fact that, with slightly lowering of the luminous efficacy, it would have better performance in color rendering effect and it could generate the white light spectrum close to that of Planck’s and can readily replace the filament lamp lighting.

碩士
國立臺灣科技大學
光電工程研究所
96
Although white-light light emitting diode (LED) has become a main goal for the new generation of illumination light source in the recent years, the color rendering index (CRI) for the blue LED chips excited yellow phosphors is around 80, and that falls short of the future lighting applications such as the street lighting. In order to achieve high CRI for white-light LEDs, we proposed a new phosphors blend for excitation using ultra violet LED (UV-LED) chips with wavelength around 380 nm, and compared the resultant light source with standard light source. Since the conversion characteristic of commercially available UV excited RGB phosphors may result in a low CRI white light source; on the other hand, use blue LED chips excited YAG based yellow phosphors has high conversion efficiency. We combined the characteristics of these phosphors to achieve phosphors conversion spectra with CRI above 90, the color coordinate approximates to the ideal white point. But we faced another problem “the leakage of UV light”. We use the full band gap idea of the photonic crystal (PhC.) or omni-directional reflector (ODR) by packaging the ODR with the conventional white-light LED. As a result of the UV beams can be omni-directionally reflected at any incidence. In this study the luminous efficiency of different package structures of ODR are also proposed. The ODR package will enhance the white light generation and prevent UV leak from the device. This novel white LED is constructed with an air gap between the phosphors layer and the ODR lead to the highest luminous efficiency. Specifically, the color coordinate for the light source made is (0.319, 0.320), the CRI has a value of 93.7, the correlated color temperature is 6188K and the luminous efficiency is 9.5 lm/W. The experimental data shows that a high CRI light source can be achieved without high quality RGB phosphors, by controlling the composition and concentration of phosphors blend layer.

碩士
元智大學
光電工程學系
106
The project is try to use the different wavelength phosphor to improve the CRI in the led.Althoutgh the led application in the lighting market is more and more,the average CRI is around 80 to 90.Not only the luminous but also the color rendering which is more important. Ther high CRI led can use in the show room,foods light,restroom and bathroom which show deeply connect to our vision and sense.From market requirement I try to improve the CRI 90 led to CRI99. In this Project I compare the conventional lamp’s spectrum (CRI 100) with the led’s spectrum in the 2700K~3500K to make cure the led’s CRI is similar to the conventional lamp’s CRI. In the experiment I try to mix the diffenrent wavelength phosphor like the green and red phosphor with special ratio improve the CRI 90 to the CRI 99.The conventional lamp’s spectrum play a important rule in the CRI 100.Accordning to this spectrum’s data that I have a direction to adjust the phosphor make up the spectrum’s blank. In the final test.Base on the Planckian Radiator.The 3000K CRI is 98~99.High CRI LED have a good result to replace the conventional lamp for sunlight spectrum.

碩士
國立高雄應用科技大學
電子工程系碩士班
102
We demonstrate the electroluminescence (EL) properties of a low power consumption, high efficiency and stability of tandem organic light emitting diode (OLED). Its EL properties were improved by using a charge generation unit (CGU) combining a doped hole transporting layer (HTL) with bipolar transport ability. In addition, the design of a mechanism to align the energy level between the HTL and CGU shows effectively decreasing the operating voltage of the devices.The deposition of a LiF/Al/NPB:HAT-CN CGU in tandem OLED achieves in more than twofold improvement in the current efficiency. Our findings show that bipolar transport ability is a promising approach for easy-fabrication as well as high color rendering index and chromatic-stable tandem white OLED for future display and lighting application.

碩士
義守大學
電子工程學系
102
The high-efficiency blue light-emitting diodes had been successful developed in 1993, The monochromatic light source was still tobe the indicator. Since 1996, the Nichia Chemical launched blue light emitting diodes to produce white LED by exciting yellow phosphor (YAG). From that time , the used LED is as lighting applications. LED brightness is higher than traditional incandescent bulbs, this is a large advantage to replace it. In addition to the brightness, the ability to show the true color of object is also an important consideration. The color Rendering Index (CRI) is defined as the standard of real objects colorimetric. The CRI of sunlight is 100, the CRI of blue LED excitation YAG phosphors is about 60 to 80, which is lower compared with sunlight. In this study, the investigated near-ultraviolet excited grains of red, green, blue phosphors had been used to produce a variety of high CRI white LED. With the proportion deployment of three powders under CCT is 2800K, the CRI of white LED increased to 97. Due to the reduced brightness using by of near-ultraviolet excited tricolor fluorescent powders, in this study, the different dosages of gold nanoparticles had been inserted to the phosphors, depend on the higher refractive phenomenon of gold, the brightness increased from 59 lm to 62 lm, and the CRI of white LED still keeps 97.

碩士
大同大學
工業設計學系(所)
100
In the present study, consumers’ seletivtiy of fruits as affected by color temperature, illumination and color rendering index of LED lights was determined. To evaluate the change of light perception in interior space, the experiment was conducted in the darkroom controlled at Munsell blackness. By using the method of semantic differential, a total of 16 trials consisted of two types of fruits, two levels of color temperature, color rendering index and illumination, respectively, was set. The data obtained were analyzed by ANOVA (Anlysis of Variance) with SPSS software. The changes in phycological condition of consumers as affected by various illumination conditions of LED lights were found as following: 1. The highest transactional value of purchase for fruits under various illumination conditions was obtained when color temperature, illumination and color rendering index of LED light were 4000°K, 70 CRI and 1500 Lux, respectively. 2. The highest transactional value of purchase for guavas was obtained when color temperature, illumination and color rendering index of LED light were 4000°K, 70 CRI and 750 Lux, respectively. 3. The highest transactional value of purchase for apples was obtained when color temperature, illumination and color rendering index of LED light were 4000°K, 70 CRI and 1500 Lux, respectively. The results showed a significant difference in appearance of fruits under various light sources. It was worthy to further investigate the transactional value of purchase for various colors of fruits under various types of light conditions. The results obtained in the present work will provide the information for illumination designers and fruits suppliers to improve the illumination conditions with higher transactional value of purchase.

碩士
國立中興大學
精密工程學系所
99
For the huge demand of lighting and LCD back light area, high power package is needed fot LED light source with good efficiency and good color rendering index (CRI) larger than 85. The most convenient way is using red and green mixed phosphors stimulated with blue LED chip. However, due to the reach sorption of green light for the red phosphor, the efficiency is low. In this thesis, we propose a layered structure that seperates the green and red phosphors. Because of the index difference in each layer, the light extraction efficiency can be improved by about 5 to 8 mW. The simulation tool TracePro is utilige to verify the experiment’s results, and they are consistant. With this novel layered structure, the overall light output power efficiency can be raised by 5% and the CRI is 91.

碩士
臺灣大學
光電工程學研究所
95
The major market of the light-emitting diode was the monochromatic light LED in the past. The application of LED was the indicative light on the products. Until the Nichia chemical company in Japan developed the high efficiency white light LED which was combined the blue LED chip with the yellow phosphor (YAG) in 1996, people started to expect the coming of the white light LED illuminative period. With the improving of the blue LED chip’s efficiency, the luminous efficiency of the high power white light LED is 90lm/W which is higher than the fluorescent lamp. The functions of the illumination are showing the shape, color and size of the object. The ability of showing the true colors is an important assize to estimate an illumination, and the color rendering index (CRI) is a stander to estimate this ability. The CRI of the general white light LED is about 50~70, and it’s not enough for the illumination. This study aims at discuss on the simulation of the high CRI white light LED which was combined the blue chip with multi-color phosphor, and calculate the optical properties of the high CRI white light LED. The accuracy of simulation results is improved by improving the phosphor daub. This study simulates the spectra of high CRI white light LEDs and makes the high CRI white light LEDs with the CCT 3000K CRI 96 and CCT 6500K CRI 87.6 by multi-layers phosphor daub. The simulation results and experimental results are similar. It’s believed this simulation can estimate the phosphors’ abilities to make the high CRI white light LED and the multi-layer phosphor daub can decrease the absorption of the light which is emitted by the phosphors. In the study of high CRI white light source which is formed by multi-color LED chip, I use the Gaussion distribution to simulate the LED’s spectrum. When the temperature is rising, the thermal effects on the LED chip are the decreasing of radiation power, red shift of peak wavelength and increasing of FWHM. By choosing the LEDs combination and using the feedback system the high CRI white light source can be made. The simulation results show that the CRI of four-color LED white light source is higher the three-color one and the four-color LED white light source with the smaller CRI shift when temperature rising. It’s is believed that four-color LED white light sources is a better illumination than three-color one.

碩士
國立雲林科技大學
電子與光電工程研究所碩士班
100
A procedure is the high color rendering index of lamp type hybrid optical modules is discussed in this study. The experiment divided into two steps in this study,first is modules design and simulation. Second is fabrication and measurement.After measure the LED’s property, calculating the ratio of each colored LEDs by using Grassmann’s Law,modeling by Solidworks, and simulating the front study by optical software TracePro. Using four-color mixing with self-developed formula to avoid the present white light emitting diode patent, and the four-color grains are Red, Green, Blue and adding Y to modify the overall quality of the mixed light. The phosphor produce Steabler-Wronsk hardly in the high temperature as compared to four-color mixing.Using four-color mixing to produce higher color rendering index than yellow phosphor. Series-parallel array of grain arrangement adopted to achieve the high demand for uniformity, while simplifying the design conditions by a certain current instead of the general mixed light-driven complex driver circuit, the completion of the mixing module using integrating sphere, light spectrum on the spectrophotometer, optical power, color coordinates values, such as mixing uniformity measurements. The chromaticity coordinates errors after complete results of the mixing module measurement and simulation can be controlled under (0.01x, 0.01y).

碩士
國立臺灣大學
光電工程學研究所
101
Historically, light is the most important invention for human beings. From using fire to using lamps, the lighting technology is becoming more and more advanced. But the energy from earth is not unlimited. It is better to save the energy from lighting. Because LED can save more energy than the conventional lamps, it becomes a good candidate in the future lighting. But not any white light spectrum can be conducted for people. The luminous efficiency and the color rendering index are very essential for the light source. To improve the color rendering index of a LED, conventionally, the red phosphor was added into the white light LED. But it will make the luminous efficiency of LED decreased. This thesis developed the optical model and investigated the dominant factors of CRI. The controlling factors include the thickness and concentration of phosphors layer. The disadvantage caused by the phenomenon of re-absorption is also demonstrated in our model. This thesis proposed a novel structure of both silicone and phosphor and investigated the controlling factors of this new model. Obviously it can reduce the iv phenomenon of re-absorption. We proved that the new structure can increase the color rendering index of LED without decreasing the luminous efficiency. Finally, we propose using more different kinds of phosphors to generate any color of light we wish in the future work.

碩士
國立虎尾科技大學
電子工程系碩士班
101
In this thesis, we propose three methods to improve the color rendering index (Ra) of phosphor plates in white light-emitting diodes (WLEDs). The phosphor plates throughout this thesis were prepared by using the electrophoretic deposition (EPD) technique. The first method is by electroplating a thin gold layer, the second is using the mixed-color (Red and yellow) phosphors, and the third is that the EPD phosphors were deposited layer-by-layer. Three kinds of structures of the layer-by-layer EPD phosphors were performed to compare with other methods. The electrophoretic deposition technique was a non-aqueous suspension solution, and given a constant voltage, thus the phosphor plate was uniformly deposited on the cathode. After that, in order to completely lift off the phosphor layer from the cathode, the thin silicon paste was firstly coated onto the phosphor layer. Then, the acid solution was used to lift off the phosphor plate. In the final, the phosphor plate was packaged with the blue LED die to form the white light. After the EPD process, in the acid reaction, the more time need to lift off the phosphor plate results in the more lost in thickness of phosphor plate. Therefore, it was found that in the red phosphor plate deposition experiment, the red phosphor will be lost more so the Ra value obtained cannot reach enough. Compared to five structures(method I(1), method II(1), and method II(3)) of EPD deposition and measured its color rendering index of the packaged LED, it is obviously found that the Red-Yellow-Red (RYR) three-layer structure has the best Ra value.

碩士
國立中央大學
光電科學與工程學系
104
This thesis aims to improve the packaging efficiency and the CRI of LEDs. In the beginning, we studied the efficiency of two YAG phosphors in different radiuses. By applying professor Sun phosphor optical model to generate two models for both phosphors, it can be concluded that the packing efficiency of the wider radius phosphor was better than the narrow one. Additionally, the yellow phosphor optical model of the wider phosphor was used to simulate a chessboard structure LED package. In order to improve the packaging efficiency of the white light LED and to analyze the influence caused by the distribution of the chessboard structure LED package. Yet, with consideration of its CRI, by improving the packaging method of the chessboard structure LED, adding both red and green phosphors into the study, and applying with addition simulation optimization and analyzation, a high packaging efficiency and high CRI LED can be manufactured.

碩士
國立臺南大學
電機工程學系碩博士班
102
In this study, CuInS2/ZnS quantum dots (CIS/ZnS QDs) were synthesized via non-coordinated system. We used polyetheramine (D400) and Octadecene (ODE) as solvent. We compared with their material and optical Characterization. The CIS QDs reaction temperature of D400 is better than ODE. We successfully synthesized CIS QDs. The structural model of CIS/ZnS QDs was established by using composition analysis, absorption spectroscopy and emission spectroscopy, and investigated their applications as light emitting devices. The emission wavelength of CIS/ZnS QDs shifted to short wavelength and Photoluminescence (PL) quantum yield (QY) could increase the composition of Zn. The results demonstrated that the band gap of CIS/ZnS QDs was not only tunable with size, but also with composition of reactant. In this work, we also used composition analysis, absorption and emission spectroscopy to speculate the structural model of CIS/ZnS QDs by gradient or core-shell model successfully. XRD could demonstrate CIS/ZnS with between chalcopyrite and zinc blende structure. Finally, we fabricated CIS/ZnS QDs as phosphor and packaged in the light emitting diode. With an appropriate external current, the CIS/ZnS QDs-based LED could emit a wide range of colors. Elelctroluminescent (EL) properties of the resulting white LED are described, and compared to a blue LED-pumped, too. CIS/ZnS QDs-based white LED with a limited color-rendering-index (CRI) property, and results demonstrated that the CRI of CIS/ZnS QDs-based white LED was higher than phosphor-based white LED.

碩士
國立臺灣科技大學
色彩與照明科技研究所
101
The glare and color rendering in lighting environment are the factors considered in interior lighting design. In order to reduce the costs of estimation, the study propose a method based on digital camera can easily estimate the glare and color rendering of light source. To estimate the CIE UGR and Color Rendering Index accurately, the digital camera should be calibrated in priority. In the study, the XYZ chromatic values of HDR image could be acquired with the methods of multiple exposure and polynomial regression at first. To improve visual comfort of our living environment, a colorimetric imaging device is designed to capture scene luminance and chromaticity of HDR panoramic image for evaluating visual responses to the scene. Basically, quote the calculation principle of CIE unified glare rating to calculate the UGR values of any gaze points in a scene by illuminance estimation, camera geometric correction and watershed algorithm. Two psychophysical experiments were conducted to fine-tune the glare thresholds. The results confirm the usability of the Index and it can be used to evaluate visual discomfort of a living environment in night time. To calculate CRIs, a spectroradiometer is normally used to measure the spectral power distribution of a light source. However, the spectral data cannot be acquired by a RGB camera directly. The aim of this study is thus to provide a method to accurately estimate CRIs using calibrated RGB camera with the widespread ColorChecker. It involves colorimetric camera calibration, camera-based CCT estimation, reference color prediction, chromatic adaptation, color difference calculation, and CRI fitting. Once the color differences of the patches can be accurately measured, it’s possible to transfer the color of the image to any given light source while the spectral reflectances of the scene are similar to that of the ColorChecker.

碩士
國立交通大學
顯示科技研究所
96
OLED panels might become a booming future for next generation displays or solid state lighting. This study fabricated a highly efficient and improved color rendering index white OLED device with a “tetra-chromatic” emission system. The device achieved a CRI of 87, and is tuneable from the twilight to daylight sky color. However, due to the low efficiencies, phosphorescent based device structures were hence developed. A fluorescent blue plus phosphorescent green and red emission layer device is demonstrated to have an efficiency of 13.5 cd/A and color rendering index over 80, which is acceptable for illumination. We also adopted a phosphorescent sensitizer to excite a fluorescent dye through resonant energy transfer by replacing the phosphorescent red material Ir(piq)3 into a fluorescent red material DCJTB. By using this mechanism and by inefficient transfer from the green to red, a higher efficiency of 16.7 cd/A was reached due to the higher eye sensitivity of the orange-reddish emission color of DCJTB. Finally, an external color tuning layer to simplify the fabrication process of white devices by using a blue device plus yellow down conversion layer, which is a common technology in LED industry was developed. By the concept of complementary colors, these two colors produced white emission. In this part, we also studied the effect of graded devices, and found that a graded phosphorescent blue device provided a higher efficiency.

碩士
國立臺南大學
電機工程學系碩士班
101
In this study, CuInS2 quantum dots (QDs) were synthesized via non-coordinated system. The structural model of CuInS2 QDs was established by using composition analysis, absorption spectroscopy and emission spectroscopy. When the molar ratio of I group element, III group element and VI group element was employed to control the structure of CuInS2 QDs, we found that CuInS2 QDs would precipitate easily if I group element was excess and CuInS2 QDs with high photoluminescence quantum yield (PL QY) could be produced if I group element was excess. In addition, the emission wavelength and PL QY could be modulated by controlling the composition ratio of Cu and In in the injection stock solution. The emission wavelength of CuInS2 QDs shifts to short wavelength and PL QY could also increase with increasing the composition of In. The results demonstrated that the band gap of CuInS2 QDs was not only tunable with size, but also with composition of reactant. In the study, we also used composition analysis, size distribution and absorption spectroscopy to speculate the structural model of CuInS2 QDs by gradient or core-shell model successfully. This study proved higher temperature that we get better results, about quantum dots synthesized under vacuum in the non-oil phase chemistry, affecting the merits of its synthetic product, discuss the following three ways. Investigate the influence of temperature on QDs. Similar sized CIS cores, which were confirmed by TEM. The CuInS2 cores have a gradient diameter that is different and shapes to the surface of the core, which explains the broad emission spectrum.

碩士
國立臺北科技大學
光電工程系研究所
104
In this paper, we use the white light of CCFL-backlight to excite the quantum dots (QDs) which are the fluorescent materials. The fluorescent of QDs will mix the light of backlight and improve the color rendering index. About the experiments, we put QDs layers on the top of liquid crystal (LC) cell. The fluorescent of QDs layers will be excited when the white light of backlight through the QDs layers. After using an integrating sphere to mix light and be linked the spectrometer by optical fiber, we measure the color rendering index. Further, we mix the QDs and LC, into LC cell. The fluorescent of QDs will be excited when the white light of backlight gets through the LC cell. We measure after using an integrating sphere to mix light and be linked the spectrometer by optical fiber, the color rendering index. The color rendering index improve to 85 at the last.

碩士
國立臺南大學
電機工程學系碩博士班
103
In this study, CuInS2/ZnS quantum dots (CIS/ZnS QDs) and InP/ZnS quantum dots (InP/ZnS QDs) were synthesized via non-vaccum system, we used Octadecene (ODE) as solvent, we compared with their material and optical Characterization. The QDs quantum yield of InP is better than CIS. We successfully synthesized CIS and InP QDs. The structural model of CIS and InP QDs was established by using composition analysis, absorption spectroscopy and emission spectroscopy, and investigated their applications as light emitting devices. The emission wavelength of QDs shifted to short wavelength and Photoluminescence (PL) quantum yield (QY) could increase the composition of Zn. The results demonstrated that the band gap of QDs was not only tunable with size, but also with composition of reactant. In this work, we also used XRD (X-ray diffraction) and TEM (Transmission Electron Microscopy) to speculate the structural model of QDs by gradient or core-shell model successfully. XRD could demonstrate CIS and InP with between chalcopyrite and zinc blende structure. Finally, we will encapsulate CuInS2/ZnS and InP/ZnS quantum dots in the light-emitting diodes. CuInS2 quantum dots with mixed appropriate phosphor and direct using InP quantum dots, Quantum dots can emit a broad range of colors on a light-emitting diode. The experimental results can proved quantum dot in LED's Packages CRI will be higher than phosphor-based white LED.

碩士
國立成功大學
電機工程學系碩博士班
100
Yttrium aluminum garnet (YAG) phosphor powders have always been the mainstream material for the fabrication of white light-emitting diodes (WLEDs). Such phosphors were applied to WLED because of their high quantum efficiency and low cost. However, a commercial yellow phosphor YAG:Ce3+-based WLED with a blue-LED chip has disadvantage of poor color rendering index (CRI) due to the lack of red components in its emission spectrum. In this study, an attempt was made to improve the CRI value of YAG:Ce3+-based WLEDs by doping Gd3+、Pr3+ and Si4+ (N3-) ions into YAG:Ce3+ phosphors using the solid-state reaction. As Pr3+ ions were co-doped in the system, a red emission peak at 610-nm appeared in the emission spectrum under 450-nm excitation. Furthermore, Y2.95-mGdmAl5O12:0.05Ce3+ and Y2.95Al5-nSirO12-nNr:0.05Ce3+ phosphors produced red-shift in their emission spectra under 450-nm excitation because of the crystal field variation and the presence of Ce3+ ion around the Si-N bond, respectively. For the purpose of energy saving, 7 wt% boric acid flux was added to reduce the required calcined temperature. And the pure YAG phase could be obtained under 1500oC for 2 h. Compared with the sample without the addition of the flux, the external quantum efficiency (EQE) of the YAG:Ce3+ phosphor was increased up to 10% using 7 wt% boric acid as the flux. In order to evaluate the feasibility of our synthesized phosphors for the application of phosphor-converted WLEDs (pc-WLEDs), the C.I.E. chromaticity coordinate, EQE, and lumen equivalent (LE) were taken into consideration. Moreover, pc-WLEDs were fabricated using phosphors synthesized herein with 450-nm blue chips. By utilizing the remote phosphor-converted technology and the optimum curvature of the phosphor gel, the luminous efficacy of conventional WLEDs could be improved by 6% and 17.4%, respectively. Noteworthily, the correlated color temperatures (CCTs) of all the WLEDs were fixed in the range of 4214-4243 K. The WLED with YAG:Ce3+ phosphors exhibited the luminous efficacy of 71.761 lm/W, CCT at 4227 K, CRI at 63, and chromaticity coordinates at (0.387, 0.4409) at 350-mA driving current. The CRI could be increased to 73.7 by using the composition-modified YAlSiON:Ce3+ instead of YAG:Ce3+.

碩士
長庚大學
光電工程研究所
99
This research is using optical simulation software “FRED” to study and analyze the light space of surgical light lamp module with LED light source. Nowadays, the degree of accuracy of optical simulation software already has high dependability; moreover, before developing a new process, using optical simulation software can effectively reduce errors, time and cost. In this paper, we use cool white and warm white LEDs to be the lighting sources and mix two kinds of LEDs color to design the surgical light lamp for increasing color rendering index. The process of design can be divided into two steps: First, calculating and designing the TIR lensand reflector for LED single module. Second, using single module of TIR lens and reflector designs the entirety module to achieve the goals of the color rendering index: 130000 lux, the color rendering index Ra 91.4 and the color temperature 4370.7k at the goals of the color rendering index.