• Title/Summary/Keyword: remote phosphor

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Evaluation of White LED Package Characteristics in Remote Phosphor Structure Depending on Phosphor Coatings (형광체 코팅에 따른 Remote Phosphor 구조의 백색 LED 패키지 특성 평가)

  • Jeong, Hee-Suk;Lee, Jung-Geun;Kang, Han-Lim;Hwang, Myung-Keun;Lee, Mi-Jae;Kim, Jin-Ho;Chae, Yoo-Jin;Lee, Young-Sik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.4
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    • pp.330-334
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    • 2013
  • We developed a package of remote phosphor structure having blue LED chips and phosphors physically separated, and the characteristics were evaluated according to different classifications of phosphor coatings. Remote phosphor was produced by screen printing coating on glass substrate with phosphor content rated paste and heat treatment. After mounting Remote phosphor, which has been classified according to number of coatings, on top of blue LED chips, luminous flux, luminous efficacy, CCT and CRI were measured. The measurement results showed the most suitable characteristics of white LED package as a general light source when the content rate of phosphor in Remote phosphor was 80 wt.% with 3 layers of coatings and thickness over $12{\mu}m$.

Optimization of Phosphor Contents and Heat-treatment Temperature in White LED Package with Glass Remote Phosphor Structure (Glass Remote Phosphor 구조를 갖는 백색 LED 패키지의 형광체 함량과 열처리 온도 최적화)

  • Jeong, Hee-Suk;Hong, Seok-Gi;Ryeom, Jeongduk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.30 no.3
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    • pp.30-38
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    • 2016
  • In this research, a 6W white LED package with a Glass Remote Phosphor was developed to improve the life of an LED package. The Glass Remote Phosphor was fabricated by the Phosphor in Glass (PiG) method, wherein phosphor YAG:Ce was mixed with glass frit and then heat treated. A paste with 75wt.% of a phosphor substance and 25wt.% glass frit was coated on a glass substrate two times using the screen-printing technique and heat-treated at $800^{\circ}C$ ; this structure gave a luminous efficacy of 136.1lm/W, color rendering index of 74Ra, and color temperature of 5,342K, thus satisfying the requirements as a light source for lighting. Moreover, an IES LM-80 accelerated life test was conducted on the same LED package for 6,000h in order to estimate the L70 lifetime based on IES TM-21. The results showed guaranteed lifetimes of 213,000h at $55^{\circ}C$, 245,000h at $85^{\circ}C$, and 209,000h at $95^{\circ}C$.

Optical Properties of Color Conversion Lens for White LED Using B2O3-Bi2O3-ZnO Glass (B2O3-Bi2O3-ZnO계 유리를 이용한 백색 LED용 색변환 렌즈의 광 특성)

  • Chae, Yoo-Jin;Lee, Mi-Jai;Kim, Jin-Ho;Hwang, Jong-Hee;Lim, Tae-Young;Jeong, Hee-Suk;Lee, Young-Sik;Kim, Deuk-Jung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.8
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    • pp.614-619
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    • 2013
  • Recently, remote phosphor is reported for white LED enhancing of phosphor efficiency compared with conventional phosphor-based W-LED. In this study, Remote phosphor was produced by screen printing coating on glass substrate with phosphor contents rated paste and heat treatment. The paste consists of phosphor, lowest softening glass frit and organic binders. Remote phosphor can be well controlled by varying the phosphor content rated paste. After mounting remote phosphor on top of blue LED chip, CCT, CRI, and luminance efficiency were measured. The measurement results showed that CCT, CRI, and luminance efficiency were 6,645, 68, and 1,16l m/W in phosphor 80 wt.% remote phosphor sintered at $600^{\circ}C$.

Fabrication of Mixed and Patterned Type of Remote Phosphors by Screen Printing Process and their Optical Properties

  • Kim, Byung-Ho;Hwang, Jonghee;Lee, Young Jin;Kim, Jin-Ho;Jeon, Dae-Woo;Lee, Mi Jai
    • Journal of the Korean Ceramic Society
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    • v.53 no.4
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    • pp.381-385
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    • 2016
  • Recently, white LEDs, especially, warm white LEDs have been intensively investigated due to outstanding optical properties, long term stability and low power consumption. In this study, mixed type and patterned type of remote phosphors were prepared by screen printing process employing green and red phosphor. Each type of remote phosphor exhibited distinctive photoluminescence spectrum. For example, the mixed type of remote phosphor exhibited unique spectrum, while the patterned type showed expectable spectrum depending on the concentration of phosphors. This indicates that a small amount of red phosphor dramatically reduced the green photoluminescence in the case of mixed-type remote phosphor, whereas the effect was negligible in the patterned-type remote phosphor. The possibility of undesirable chemical reaction was further investigated by using scanning electron microscopy and X-ray diffraction.

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
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    • v.1 no.4
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    • pp.389-395
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    • 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.

Selection of a Remote Phosphor Configuration to Enhance the Color Quality of White LEDs

  • Anh, Nguyen Doan Quoc;Le, Phan Xuan;Lee, Hsiao-Yi
    • Current Optics and Photonics
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    • v.3 no.1
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    • pp.78-85
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    • 2019
  • The remote phosphor structure has been proven to bear greater luminous efficiency than both the conformal phosphor and in-cup phosphor structures; however, controlling its color quality is much more challenging. To solve this dilemma, various researchers have proposed dual-layer phosphor and triple-layer phosphor configuration as techniques to enhance the display brightness of white LEDs (WLEDs). Likewise, this study picked one of these configurations to utilize in multichip WLEDs with five distinct color temperatures in the range from 5600 to 8500 K, for the purpose of improving the optical properties of WLEDs, such as color rendering index (CRI), color quality scale (CQS), luminous efficacy (LE), and chromatic homogeneity. According to the results of this research, the triple-layer phosphor configuration has superior performance compared to other configurations in terms of CRI, CQS, and LE, and yields higher chromatic stability for WLEDs.

Optical Properties as Process Condition of Color Conversion Lens Using Low-softening Point Glass for White LED (백색 LED용 저 연화점 유리를 이용한 색 변환 렌즈의 제조 조건에 따른 광 특성)

  • Chae, Yoo-Jin;Lee, Mi-Jai;Hwang, Jong-Hee;Lim, Tae-Young;Kim, Jin-Ho;Jeong, Hee-Suk;Lee, Young-Sik;Kim, Deug-Joong
    • Journal of the Korean Ceramic Society
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    • v.50 no.6
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    • pp.454-459
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    • 2013
  • Recently, remote phosphors have been reported for application to white LEDs to provide enhanced phosphor efficiency compared with conventional phosphor-based white LEDs. In this study, a remote phosphor was produced by coating via screen printing on a glass substrate with different numbers of phosphor coating. The paste consists of phosphor, lowest softening glass frits, and organic binders. The remote phosphor could be well controlled by varying the phosphor content rated paste. After mounting the remote phosphor on top of a blue LED chip, CCT, CRI, and luminance efficiency were measured and values of 5300 K, 62, and 117 lm/W were respectively obtained in the 80 wt% phosphor with 3 coating layers sintered at $800^{\circ}C$.

Bi-layers Red-emitting Sr2Si5N8:Eu2+ Phosphor and Yellow-emitting YAG:Ce Phosphor: A New Approach for Improving the Color Rendering Index of the Remote Phosphor Packaging WLEDs

  • Nhan, Nguyen Huu Khanh;Minh, Tran Hoang Quang;Nguyen, Tan N.;Voznak, Miroslav
    • Current Optics and Photonics
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    • v.1 no.6
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    • pp.613-617
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    • 2017
  • Due to optimal advances such as chromatic performance, durability, low power consumption, high efficiency, long-lifetime, and excellent environmental friendliness, white LEDs (WLEDs) are widely used in vehicle front lighting, backlighting, decorative lighting, street lighting, and even general lighting. In this paper, the remote packaging WLEDs (RP-WLEDs) with bi-layer red-emitting $Sr_2Si_5N_8:Eu^{2+}$ and yellow-emitting YAG:Ce phosphor was proposed and investigated. The simulation results based on the MATLAB software and the commercial software Light Tools indicated that the color rendering index (CRI) of bi-layer phosphor RP-WLEDs had a significant increase. The CRI had a considerable increase from 72 to 94. In conclusion, the results showed that bi-layer red-emitting $Sr_2Si_5N_8:Eu^{2+}$ and yellow-emitting YAG:Ce phosphor could be a prospective approach for manufacturing RP-WLEDs with enhanced optical properties.

Effect of Temperature on the Luminous Properties of Remote-Phosphor White Light-Emitting Diodes (이격 형광체 구조가 적용된 백색 LED 광원의 온도변화에 따른 발광 특성 분석)

  • Choi, Min-Hyouk;Lee, Hun Jae;Ko, Jae-Hyeon
    • Korean Journal of Optics and Photonics
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    • v.25 no.5
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    • pp.254-261
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    • 2014
  • Two types of white light-emitting diodes (LEDs) with different phosphor structures were fabricated and compared in terms of their optical characteristics. Their spectroscopic properties were analyzed as a function of temperature, from room temperature to $80^{\circ}C$. The temperature dependence of the luminance and the color coordinates showed that the decrease in luminance and change in the color coordinates of the remote-phosphor type LED were much smaller compared to the conventional white LED. These improvements were attributed to the decrease in phosphor temperature, due to the distance between the LED chip and the phosphor layer, as well as to the reduced absorption by the LED chip of the light emitted from the phosphor layer.

Remote Phosphor with Array of Blue Light-emitting Diodes on Board Used in Liquid-crystal Backlight Module

  • Huang, Hsin-Tao;Tsai, Chuang-Chuang;Huang, Yi-Pai;Lin, Jeremy;Chang, Wen-Chi
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.79-82
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    • 2009
  • This work presents a novel lighting technology based on a YAG:$Ce^{3+}$ phosphor converter with micro line lenticular structure, to accompany an array of bare LED chips on a board. This technology is especially effective in TFT-LCD backlight applications as it offers the advantages of high light radiation efficiency, low color deviation, uniform luminance distribution and compact backlight thickness. Additionally, the proposed configuration is low-cost, can be manufactured quickly, and can be mass-produced economically.

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