• Title/Summary/Keyword: Color rendering index (CRI)

Search Result 34, Processing Time 0.023 seconds

Fluorescent White OLEDs with a High Color-rendering Index Using a Silicon-Cored Anthracene Derivative as a Blue Host

  • Kwak, Jeong-Hun;Lyu, Yi-Yeol;Lee, Hyun-Koo;Char, Kook-Heon;Lee, Chang-Hee
    • Journal of Information Display
    • /
    • v.11 no.3
    • /
    • pp.123-127
    • /
    • 2010
  • Fluorescent white organic light-emitting diodes showing high color-rendering indices (CRIs) of up to 81 was demonstrated, with a silicon-cored anthracene derivative (PATSPA) doped with DPAVBi utilized as the deep-blue host and dye materials, and the commercial dyes rubrene and DCM2 utilized as the orange- and red-light-emitting dyes. The devices, consisting of three emissive layers, showed bright-white-light emission, but the ratio of the blue peak to the orange and red peaks changed with the current density and the thickness of the blue emissive layer. A high CRI was achieved with the use of a deep-blue emitter doped in a novel host and by optimizing the blue-layer thickness. The device with a blue-layer thickness of 10 nm showed the Commission Internationale de l'Eclairage (CIE) color coordinate of (0.33, 0.35), a high CRI of 81, and a moderate external quantum efficiency of 2% at a current density of $2.5\;mA/cm^2$.

Exhibition Hall Lighting Design that Fulfill High CRI Based on Natural Light Characteristics - Focusing on CRI Ra, R9, R12 (자연광 특성 기반 고연색성 실현 전시관 조명 설계 - CRI Ra, R9, R12를 중심으로)

  • Ji-Young Lee;Seung-Teak Oh;Jae-Hyun Lim
    • Journal of Internet Computing and Services
    • /
    • v.25 no.4
    • /
    • pp.65-72
    • /
    • 2024
  • To faithfully represent the intention of the work in the exhibition space, lighting that provides high color reproduction like natural light is required. Thus, many lighting technologies have been introduced to improve CRI, but most of them only evaluated the general color rendering index (CRI Ra), which considers eight pastel colors. Natural light provides excellent color rendering performance for all colors, including red and blue, expressed by color rendering index of R9 and R12, but most artificial lighting has the problem that color rendering performance such as R9 and R12 is significantly lower than that of natural light. Recently, lighting technology that provides CRI at the level of natural light is required to realistically express the colors of works including primary colors but related research is very insufficient. Therefore this paper proposes exhibition hall lighting that fulfills CRI with a focus on CRI Ra, R9, and R12 based on the characteristics of natural light. First reinforcement wavelength bands for improving R9 and R12 are selected through analysis of the actual measurement SPD of natural and artificial lighting. Afterward virtual SPDs with a peak wavelength within the reinforcement wavelength band are created and then SPD combination conditions that satisfy CRI Ra≥95, R9, and R12≥90 are derived through combination simulation with a commercial LED light source. Through this, after specifying two types of light sources with 405,630nm peak wavelength that had the greatest impact on the improvement of R9 and R12, the exhibition hall lighting applied with two W/C White LEDs is designed and a control Index DB of the lighting is constructed. Afterward experiments with the proposed method showed that it was possible to achieve high CRI at the level of natural light with average CRI Ra 96.5, R9 96.2, and R12 94.0 under the conditions of illuminance (300-1,000 Lux) and color temperature (3,000-5,000K).

Optimization and Fabrication of Color Temperature Tunable White LED Luminaires (색온도 가변 LED 조명 최적화 설계 및 제작)

  • Kang, Da-Il;Kim, Kun-Yul;Yu, Young-Moon;Choi, Hee-Lack
    • Korean Journal of Optics and Photonics
    • /
    • v.25 no.2
    • /
    • pp.102-107
    • /
    • 2014
  • In this paper the spectra of correlated color temperature (CCT) tunable white light-emitting diode (LED) luminaires, consisting of commercial red, green, blue, and amber LED chips, were optimized to increase color rendering index (CRI), and a special CRI of R9 for deep red color was obtained. To improve the design's accuracy, measured LED spectra were used instead of mathematically modeled ones. Real CCT tunable LED luminaires with CRIs of 87-90 and R9s of 34-93 were fabricated and demonstrated at CCTs of 3000-6000 K.

Development & Reliability Verification of Ultra-high Color Rendering White Artificial Sunlight LED Device using Deep Blue LED Light Source and Phosphor (Deep Blue LED 광원과 형광체를 이용한 초고연색 백색 인공태양광 LED 소자의 개발)

  • Jong-Uk An;Tae-Kyu Kwon
    • Journal of Korean Society of Industrial and Systems Engineering
    • /
    • v.46 no.3
    • /
    • pp.59-68
    • /
    • 2023
  • Currently, yellow phosphor of Y3Al5O12:Ce3+ (YAG:Ce) fluorescent material is applied to a 450~480nm blue LED light source to implement a white LED device and it has a simple structure, can obtain sufficient luminance, and is economical. However, in this method, in terms of spectrum analysis, it is difficult to mass-produce white LEDs having the same color coordinates due to color separation cause by the wide wavelength gap between blue and yellow band. There is a disadvantage that it is difficult to control optical properties such as color stability and color rendering. In addition, this method does not emit purple light in the range of 380 to 420nm, so it is white without purple color that can not implement the spectrum of the entire visible light spectrum as like sunlight. Because of this, it is difficult to implement a color rendering index(CRI) of 90 or higher, and natural light characteristics such as sunlight can not be expected. For this, need for a method of implementing sunlight with one LED by using a method of combining phosphors with one light source, rather than a method of combining red, blue, and yellow LEDs. Using this method, the characteristics of an artificial sunlight LED device with a spectrum similar to that of sunlight were demonstrated by implementing LED devices of various color temperatures with high color rendering by injecting phosphors into a 405nm deep blue LED light source. In order to find the spectrum closest to sunlight, different combinations of phosphors were repeatedly fabricated and tested. In addition, reliability and mass productivity were verified through temperature and humidity tests and ink penetration tests.

Study of the Effect of the Transmittance of a Diffuser Plate on the Optical Characteristics of High-power Quantum-dot Illumination (확산판의 투과율이 고출력 양자점 조명의 광특성에 미치는 영향에 대한 연구)

  • Kim, Hye-Rin;You, Dong Geun;You, Jae Hwan;Jang, Jun Won;Choi, Moo Kyu;Hong, Seung Chan;Ko, Jae-Hyeon;Joe, Sung-Yoon;Kim, Yongduk;Park, Taehee;Ko, Young Wook
    • Korean Journal of Optics and Photonics
    • /
    • v.32 no.5
    • /
    • pp.220-229
    • /
    • 2021
  • The optical characteristics of high-power direct-lit white light-emitting diode (LED) lighting were investigated, where a quantum dot (QD) film was adopted to enhance the color-rendering index (CRI). The transmittance of the diffuser plate and the concentration of the QD film were varied in this study. The color coordinates and the correlated color temperature (CCT) did not show any appreciable change, while the CRI values increased slightly as the transmittance of the diffuser plate decreased. The investigated optical properties were nearly independent of the viewing angle, and the luminance distribution was close to Lambertian. The CCT decreased from approximately 6000 K to approximately 4000 K as the concentration of the QD film increased from 0 to 7.5 wt%, which was due to the enhanced red component in the emission spectrum. The CRI increased to approximately 95 for some optical configurations of the lighting. These results demonstrate that glare-free, color-changeable, high-rendering LED lighting can be realized by using a combination of a diffuser plate of appropriate transmittance and a red QD film.

White ACPEL Device with ZnS:Cu,Cl, $Tb_3Al_5O_{12}:Ce^{3+}$, and CaS:$Eu^{2+}$ Phosphors Using a Layered Structure

  • Park, Bong-Je;Seo, Hong-Seok;Ahn, Jun-Tae;Oh, Dae-Kon;Chung, Woon-Jin;Han, Ji-Yeon;Jang, Ho-Seong;Jeon, Duk-Young
    • ETRI Journal
    • /
    • v.31 no.6
    • /
    • pp.803-805
    • /
    • 2009
  • Improvement of the color rendering index (CRI) and luminance of a white alternate current powder electroluminescent (ACPEL) device has been attempted using ZnS:Cu,Cl, $Tb_3Al_5O_{12}$:Ce (TAG:Ce), and CaS:Eu phosphors with a layered structure. The device with TAG:Ce and ZnS:Cu,Cl phosphors showed a CRI of 75, with a luminance increase of about 30% depending on the thickness of the TAG:Ce. Further CRI improvement was attempted using CaS:Eu. When they were separately screen-printed, the CRI was increased up to 89 with no decrease in luminance.

Optical Design of Multimedia-Embedded LED Dental Astral Lighting using the Reverse Dual Reflector Method

  • Kwon, Young Hoon;Hwang, Hyo Chang;Jun, Hwa Joon;Kwon, Jin Hyuk
    • Journal of the Optical Society of Korea
    • /
    • v.19 no.4
    • /
    • pp.409-414
    • /
    • 2015
  • Light-emitting diodes (LED) have many advantages for dental astral lighting because of their high color rendering index (CRI), low power consumption, light weight and longer life. A dental astral lamp is specially designed and simulated for securing the extra space for installing a multimedia display that will be helpful for treating young patients. The optical system using the reverse dual reflection method consisted of four illumination modules disposed at the four corners of the dental astral lamp, and each module comprises a high power LED, an elliptical mirror, and a multifacet reflector assembly using eight cylindrical mirrors. It is shown that the required illuminance, illumination pattern, and the illumination uniformity are well satisfied.

A Study on Electrodeless InBr Lamps Using Circularly Polarized Microwaves (원편파 마이크로파 방전에 의한 InBr방전등 발광 특성 연구)

  • Won, Dong-Ho;Ko, Jung-Tae;Kim, Jung-Young;Kim, Jin-Joong;Kim, Jeong-Won
    • Proceedings of the KIEE Conference
    • /
    • 2003.07c
    • /
    • pp.1864-1866
    • /
    • 2003
  • 최근 마이크로파 방전에 의한 고압 2-원자 분자인 InBr중기는 고연색성(high color rendering index, CRI)의 백색광 발광원으로 주목 받고 있다. 잘알려진 무전극 황전등은 최고 효율이 173 lm/W까지 시연되어 알려진 모든 인조 광원 중에서 가장 높은 효율을 보인 혁신적인 광원이다. 이에 비해 InBr방전등은 무전극 황전등에 비해 효율은 떨어지지만 거의 완벽한 CRI(95이상)를 보이기 때문에 차세대 projection display의 발광원으로 대두되고 있다. 본 논문에서는 원편파 마이크로파 이용하여 무전극 InBr방전등의 입력전력의 변화와 InBr의 양 변화에 대한 특성(휘도, 상관색온도, 스펙트럼, 등)에 관한 실험결과를 보고한다.

  • PDF

Effect of Glass Composition on the Optical Properties of Color Conversion Glasses for White LED (유리조성에 따른 백색 LED용 색변환 유리의 광특성)

  • Huh, Cheolmin;Hwang, Jonghee;Lim, Tae-Young;Kim, Jin-Ho;Lee, MiJai;Yoo, Jong-Sung;Park, Tae-Ho;Moon, Jooho
    • Korean Journal of Materials Research
    • /
    • v.22 no.12
    • /
    • pp.669-674
    • /
    • 2012
  • Yellow phosphor dispersed color conversion glasses are promising phosphor materials for white LED applications because of their good thermal durability, chemical stability, and anti-ultraviolet property. Six color conversion glasses were prepared with high Tg and low Tg specimens of glass. Luminous efficacy, luminance, CIE (Commission Internationale de l'Eclairage) chromaticity, CCT (Correlated Color Temperature), and CRI (Color Rendering Index) of the color conversion glasses were analyzed according to the PL spectrum. Color conversion glasses with high Tg glass frit, sintered at higher temperature, showed better luminous properties than did color conversion glasses with low Tg glass frit. The characteristics of the color conversion glass depended on the glass composition rather than on the sintering temperature. The XRD peaks of the YAG phosphor disappeared in the color conversion glass with major components of $B_2O_3$-ZnO-$SiO_2$-CaO and, in the XRD results, new crystalline peaks of $BaSi_2O_5$ appeared in the color conversion glass with major components of $Bi_2O_3$-ZnO-$B_2O_3$-MgO. The characteristics of CIE chromaticity, CCT, and the CRI of low Tg color conversion glasses showed worse color properties than those of high Tg color conversion glasses. However, these color characteristics of low Tg glasses were improved by thickness variation. So color conversion glasses with good characteristics of both luminous and color properties were attained.

Red-emitting α-SrO·3B2O3:Sm2+ Phosphor for WLED Lamps: Novel Lighting Properties with Two-layer Remote Phosphor Package

  • Tin, Phu Tran;Nguyen, Nhan K.H.;Tran, Minh Q.H.;Lee, Hsiao-Yi
    • Current Optics and Photonics
    • /
    • v.1 no.4
    • /
    • pp.389-395
    • /
    • 2017
  • This paper investigates a method to improve the lighting performance of white light-emitting diodes (WLEDs), which are packaged using two separate remote phosphor layers, a yellow-emitting YAG:Ce phosphor layer and a red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor layer. The thicknesses of these two layers are $800{\mu}m$ and $200{\mu}m$, respectively. Both of them are examined in conditions where the average correlated color temperatures (CCT) are 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor is varied from 2% to 30% in the upper layer, while in the lower layer the yellow phosphor concentration is kept at 15%. It was found interestingly that the lighting properties such as color rendering index (CRI) and luminous flux are enhanced significantly, while the color uniformity is maintained in a relatively close range to the one of one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer are revised by combining Kubelka-Munk and Mie-Lorenz theories. Through analysis, it is demonstrated that the packaging configuration of two-layer remote phosphor that employs red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor particles provides a practical solution for general WLEDs lighting.