• Title/Summary/Keyword: Light-emitting diode(LED)

Search Result 856, Processing Time 0.026 seconds

A Synthesis Ratio of Light Emitting Diodes and Quantization Noise for Increasing Brightness of Head-up Displays (헤드업 디스플레이 휘도 증가를 위한 LED 합성비율과 영상잡음에 대한 연구)

  • Chi, Yongseok
    • Journal of Broadcast Engineering
    • /
    • v.21 no.5
    • /
    • pp.816-823
    • /
    • 2016
  • This paper studies a light emitting diode(LED) overlapping method of a head-up display that consists of a digital micro device(DMD) panel and a red, green, blue LED in order to increase the brightness of display system and optical output power. This optimization overlapping method removes a quantization noise which occur due to LED overlapping too excessive and stabilizes the junction temperature of LED. In order to reduce junction temperature of LED, the a correlation between a green duty and LED overlapping ratio is studied. Throughout this study, the brightness of head-up display exhibited high increasement ratio of luminance around 33.3 percent at 39 percent overlapping method.

White Light Emission with Quantum Dots: A Review

  • Kim, Nam Hun;Jeong, Jaehak;Chae, Heeyeop
    • Applied Science and Convergence Technology
    • /
    • v.25 no.1
    • /
    • pp.1-6
    • /
    • 2016
  • Quantum dots (QDs) are considered as excellent color conversion and self-emitting materials for display and lighting applications. In this article, various technologies which can be used to realize white light emission with QDs are discussed. QDs have good color purity with a narrow emission spectrum and tunable optical properties with size control capabilities. For white light emission with a color-conversion approach, QDs are combined with blue-emitting inorganic and organic light-emitting diodes (LED) to generate white emission with high energy conversion efficiency and a high color rendering index for various display and lighting applications. Various device structures for self-emitting white QD light-emitting diodes (QD-LED) are also reviewed. Various stacking and patterning technologies are discussed in relation to QD-LED devices.

Two Cases of Pressure Ulcer Patients Treated with Acupuncture and Light Emitting Diode Light Therapy (침치료와 Light Enitting Diode 광선치료를 병행한 욕창 치료 2례)

  • Jo, Seoung Eun;Lee, Hyun;Hong, Seo Jin;Kang, Jae Hui
    • Journal of Acupuncture Research
    • /
    • v.32 no.3
    • /
    • pp.211-220
    • /
    • 2015
  • Objectives : We report two cases of pressure ulcer patients to show the efficacy of treatment with acupuncture and Light Enitting Diode(LED) light therapy. Methods : We treated two pressure ulcer patients with acupuncture, LED light therapy, herbal medication and with a simple dressing. LED light with up to $4J/cm^2$ of energy irradiated the pressure ulcer site once a day for fifteen minutes. All patients received acupuncture treatment and simple dressing for wound care. We measured phase change of the pressure ulcer in terms of ulcer size, The National Pressure Ulcer Advisory Panel(NPUAP) stage and with the The Pressure Ulcer Scale for Healing(PUSH) tool(3.0). Results & Conclusions : In each of the two cases, pressure ulcer size and total score of the PUSH tool decreased and NPUAP stage was improved from II to I. This shows that acupuncture treatment and LED light therapy may have a considerable effect in healing on the pressure ulcer.

Effect of Monochromatic Light Emitting Diode on the Growth of Four Microalgae Species (Chlorella vulgaris, Nitzschia sp., Phaeodactylum tricornutum, Skeletonema sp.) (미세조류 4종(Chlorella vulgaris, Nitzschia sp., Phaeodactylum tricornutum, Skeletonema sp.)의 성장에 미치는 발광다이오드 단일파장의 영향)

  • Oh, Seok-Jin;Kwon, Hyeong-Kyu;Jeon, Jin-Young;Yang, Han-Seob
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.21 no.1
    • /
    • pp.1-8
    • /
    • 2015
  • We investigated the effect of monochromatic light emitting diode (LED) on the growth of diatoms Nitzschia sp., Phaeodactylum tricornutum, Skeletonema sp. and green algae Chlorella vulgaris. The four microalgae species were cultured under blue LED (450 nm), yellow LED (590 nm), red LED (650 nm) and fluorescent lamp (mixed wavelengths). The maximum growth rates and cell densities of Nitzschia sp., P. tricornutum and Skeletonema sp. were highest under blue LED, followed by fluorescent lamp, red LED and then yellow LED, however those of C. vulgaris were highest under red LED. This result indicates that blue LED is favorable for the growth of diatoms. Thus, the growth of microalgae under monochromatic light might be species-specific or taxon-specific. Also, these results could be used as an important information in future for remediation of heavy metal contamination in the sediments using LED and microalgae.

Study on the Current Spreading Effect of Blue GaN/InGaN LED using 3-Dimensional Circuit Modeling (3차원의 회로 모델링을 이용한 청색 GaN/InGaN LED의 전류 확산 효과에 관한 연구)

  • Hwang, Sung-Min;Shim, Jong-In
    • Korean Journal of Optics and Photonics
    • /
    • v.18 no.2
    • /
    • pp.155-161
    • /
    • 2007
  • A new and simple method of 3-dimensional circuit modeling and analysis is proposed and verified experimentally for the first time by determining 3-dimensional current flow and 2-dimensional light distribution in blue InGaN/GaN multi-quantum well (MQW) light emitting diode (LED) devices. Circuit parameters of the LED consist of the resistance of the metallic film and epitaxial layer, and the intrinsic diode which represents the active region emitting the light. The circuit parameters are extracted from the transmission line model (TLM) and current-voltage relation. We applied the >> proposed method and extracted circuit parameters to obtain the light emission pattern in a top-surface emitting-type LED. The current spreading effect is analyzed theoretically and quantitatively with a variation of the resistance of metallic and epitaxial layers. The emitting-light distribution of the fabricated blue LED showed a good agreement with the analyzed result, which shows the dark emission intensity at the corner of the p-electrode.

An Indoor Broadcasting System Using Light-Emitting Diode Lamps Coupled with Power Line

  • Lee, Seong-Ho
    • Journal of Sensor Science and Technology
    • /
    • v.24 no.5
    • /
    • pp.342-347
    • /
    • 2015
  • We introduce an indoor broadcasting system using light-emitting diode (LED) lamps coupled with a 220 V power line. Two couplers connected to the power line constitute a power line communication (PLC) link. The transmission path from an LED lamp to a photodetector forms a visible light communication (VLC) link in free space. When the LED lamp is coupled to the power line, a composite PLC-VLC link is formed, making it possible to transmit a VLC signal beyond line-of-sight. In experiments, a 4 kHz analog signal modulated with a 100 kHz carrier was sent to the power line by a PLC coupler, and LED lamps coupled to the power line detected the signal and radiated it to multiple VLC receivers in the room. This configuration is useful in expanding an indoor VLC sensor network to adjacent rooms or constructing a voice broadcasting system in a building or apartments with existing power lines.

Performance Improvement of Polymer Light Emitting Diodes by Insertion of a Silane Layer

  • Lee, Jun-Yeob
    • Journal of Information Display
    • /
    • v.8 no.3
    • /
    • pp.1-4
    • /
    • 2007
  • The influence of a silane layer on the performances of polymer light emitting diode(pLED)s has been studied. Glycidoxypropyltrimethoxysilane(GPS) with an epoxy functional group was used as a surface modifier for ITO substrates. The GPS layer was inserted between an ITO and a poly(3,4)-ethylenedioxythiophene/polystyrenesulfonate(PEDOT) by wet process and the performances of PLEDs were investigated. The introduction of GPS layer increased the brightness and efficiency of PLEDs by 30%. In addition, the lifetime of PLEDs was also improved considerably by using GPS as a surface modifier.

Effects of Light Quality of a Light-Emitting Diode (LED) on Carbohydrate, Protein, and Lipid Contents of Tetraselmis suecica and T. tetrathele (발광다이오드(LED) 파장에 따른 Tetraselmis suecica와 T. tetrathele의 탄수화물, 단백질 및 지질 함량에 미치는 영향)

  • Kyong Ha Han;Seok Jin Oh
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.29 no.1
    • /
    • pp.36-43
    • /
    • 2023
  • To establish a culture system with enhanced cellular nutrition, we investigated the effects of light quality (blue, 450 nm; yellow, 590 nm; and red, 630 nm) of a light-emitting diode (LED) on the biochemical composition of Tetraselmis suecica and T. tetrathele. The protein content of both species was higher (42-69%) than the content of other biochemical substances under all wavelengths. Carbohydrate, protein, and lipid contents were higher under the yellow wavelength, which showed a low growth rate, than those under other wavelengths. The contents of all biochemical substances were low under the red wavelength, which showed a high growth rate. These results indicated that protein synthesis occurs in response to decreased cell division rate, while lipid and carbohydrate synthesis occurs owing to altered chemical composition and enzymatic activity. Therefore, we suggested a two-phase LED culture system, which emitted red LED during the early-middle exponential phase and yellow LED during the late exponential and stationary phases, to increase the yield of useful biochemical substances of T. suecica and T. tetrathele.

A Study on the Lighting Component of Marine Lattern using Light Emitting Diodes (중.소형 해상용 등명기 대체용 LED 광원 설계에 대한 연구)

  • Jeong, Hak-Geun;Jung, Bong-Man;Han, Soo-Bin;Park, Suk-In;Kim, Hoon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.20 no.1
    • /
    • pp.1-6
    • /
    • 2006
  • The advantages of LED(Light Emitting Diode) are low electric power consumption long life time and excellent visibility. In order to design and develope the marine lantern using LED, technical trends and standards about the marine lantern were analyzed and sample products were manufactured and evaluated in comparing with existing marine lantern The performance of developed LED lantern is better than that of the existing marine lantern using an incandescent lamp. The electric power consumption of our products is 30[%] and the luminous intensity is two or fen times brighter than existing marine lantern.

Wide Color Gamut Backlight from Three-band White LED

  • Kim, Il-Ku;Chung, Kil-Yoan
    • Journal of the Optical Society of Korea
    • /
    • v.11 no.2
    • /
    • pp.67-70
    • /
    • 2007
  • A Wide Color Gamut Backlight system was studied using a three-band white Light-Emitting Diode. A three-band white light-emitting diode (LED) was fabricated using an InGaN-based blue LED chip that emits 445-nm blue peak, and a green phosphor and red phosphor that emit 535-nm green and 621-nm red peak emissions, respectively, when excited by 450-nm blue light. Using for this three-band white LED, wide color gamut backlight unit (BLU) was attained. The luminance of BLU and CIE 1931 chromaticity coordinates was $1,700Cd/m^2$ and (0.337, 0.346). Color filter matching simulations for this configuration show that the three-band white LED backlight can be enhanced by up to 16% over conventional white LED backlight color gamut.