scholarly journals Optimization of LED Lighting for Clinical Settings

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Snjezana Soltic ◽  
Andrew Chalmers
Keyword(s):  
Light Source ◽  
Performance Criteria ◽  
Source Spectrum ◽  
Clinical Settings ◽  
Colour Properties ◽  
Led Lighting ◽  
Led Light ◽  
De Algorithm ◽  
Lighting Systems ◽  
Spectral Design

The advent of the LED light source has promoted the concept of human-centric lighting (HCL). The LED has also been responsible for increases in the electrical efficiency of lighting systems, coupled with recent improvements in their colour properties. We have found that it is also possible to create a lit environment with enhanced clinical attributes by providing a source spectrum that meets the requirements of the Cyanosis Observation Index (COI). This paper describes the use of a differential evolution (DE) algorithm for the spectral design of a mixed LED light source capable of meeting COI recommendations as well as HCL performance criteria.

scholarly journals Towards the Optimum Light Source Spectrum

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Andrew Chalmers ◽  
Snjezana Soltic
Keyword(s):  
Light Source ◽  
Large Scale ◽  
Source Spectrum ◽  
Light Sources ◽  
Luminous Efficacy ◽  
Light Emitting ◽  
Spectral Bands ◽  
Good Energy ◽  
Lighting Systems ◽  
Colour Rendering

This paper is concerned with designing light source spectra for optimum luminous efficacy and colour rendering. We demonstrate that it is possible to design light sources that can provide both good colour rendering and high luminous efficacy by combining the outputs of a number of narrowband spectral constituents. Also, the achievable results depend on the numbers and wavelengths of the different spectral bands utilized in the mixture. Practical realization of these concepts has been demonstrated in this pilot study which combines a number of simulations with tests using real LEDs (light emitting diodes). Such sources are capable of providing highly efficient lighting systems with good energy conservation potential. Further research is underway to investigate the practicalities of our proposals in relation to large-scale light source production.

LRT Digest 3: New colour metrics and their use

2019 ◽  
Vol 51 (5) ◽  
pp. 657-681 ◽  
Author(s):  
PR Boyce ◽  
JR Stampfli
Keyword(s):  
Light Source ◽  
Comprehensive Approach ◽  
Source Spectrum ◽  
Light Sources ◽  
Colour Properties ◽  
Executive Summary ◽  
Colour Temperature ◽  
Test Light ◽  
High Level ◽  
Colour Rendering

Executive summary The two metrics traditionally used to quantify the colour properties of light sources are the correlated colour temperature and the CIE General Colour Rendering Index. With the arrival of LEDs as a major light source questions began to be asked about the merits of both of these metrics. The question asked about correlated colour temperature was how far should the chromaticity of a light source be allowed to depart from the Planckian locus before the light emitted could no longer be said to be white? A tolerance to such a departure ( Duv) already existed but now gathered much more attention. The questions asked about the CIE General Colour Rendering Index were more searching. The limitations of the CIE General Colour Rendering Index were explored and, as a result, several alternative approaches to quantifying the colour rendition properties of light sources were proposed. The most comprehensive approach was produced by the Illuminating Engineering Society of North America, first in its Technical Memorandum IES TM-30-15 and more recently in its revision, Technical Memorandum ANSI/IES TM-30-18, which has been accepted as an American Standard. Both these documents describe a system that contains two high-level summary metrics: One for the average fidelity, i.e. how accurately a test light source renders 99 colour samples relative to how they are rendered under a reference illuminant, and the other for the average colourfulness, i.e. the overall increase or decrease in colourfulness of the same colour samples under the same test light source compared to the same reference illuminant. Associated with these overall average metrics are a number of more detailed metrics and graphical presentations. These aim to quantify and illustrate the variations in fidelity and the direction and magnitude of the shifts in chroma and hue around the hue circle. Compared to the CIE General Colour Rendering Index or the CIE Fidelity Index, a metric published by the CIE in 2017, ANSI/IES TM-30-18 provides a more comprehensive approach to quantifying and understanding the effects of light source spectrum on the perception of colour. Unfortunately, the new colour metrics described in IES TM-30-15 and ANSI/IES TM-30-18 have not yet been accepted by the CIE. Despite this, some light source manufacturers have started to provide information on their products expressed in terms of the ANSI/IES TM-30-18 colour metrics and designers are beginning to request them. The expectation is that, eventually, the ANSI/IES TM-30-18 metrics will be adopted by many countries and authorities, because they provide a much more comprehensive description of the colour properties of a light source than the CIE General Colour Rendering Index. This will be of value to light source manufacturers and lighting designers as well as those who prepare lighting codes and guides. It is expected that in the future the minimum set of data considered acceptable for describing the colour properties of a light source are likely to be the correlated colour temperature and the associated Duv value, the CIE Fidelity Index or the matching ANSI/IES TM-30-18 Fidelity Index, together with the ANSI/IES TM-30-18 Gamut Index and the ANSI/IES TM-30-18 Colour Vector Graphic.

Research and Implementation on Methods of Evaluating Lifetime of LED Light Source for LED Lighting System

2014 ◽  
Vol 941-944 ◽  
pp. 635-639
Author(s):  
Rong Wang ◽  
Hai Bo Ma ◽  
Bin Qu
Keyword(s):  
Light Source ◽  
Comprehensive Evaluation ◽  
Real Life ◽  
Practical Work ◽  
Lighting System ◽  
Led Lighting ◽  
Led Light ◽  
The Real ◽  
Attenuation Rate

This research adopts comprehensive evaluation to evaluate lifetime of LED light source for lighting system. By the method, under the condition of LED light source working outside, the situations of LED light source lifetime are analyzed with attenuation rate of illumination got from illumination data of LED light source in practical work. The real lifetime characteristics and real life curve of the LED light source are obtained eventually.

Effects of light source spectrum and background colour on the perception of paintings

2019 ◽  
Vol 52 (1) ◽  
pp. 36-63
Author(s):  
L Bellia ◽  
F Fragliasso ◽  
E Stefanizzi
Keyword(s):  
Light Source ◽  
Light Emitting Diode ◽  
Source Spectrum ◽  
Light Emitting ◽  
Colour Temperature ◽  
Test Room ◽  
Led Light ◽  
Lighting Conditions ◽  
Set Up ◽  
Effect Of Light

This paper presents an experiment on the effect of light on the perception of paintings. The experiment was performed in a test-room where a typical museum exhibition set-up was simulated. Two different paintings were shown to 44 participants, under different light scenes obtained by using tuneable LED (Light Emitting Diode) wallwashers. To set the light scenes, the following parameters were modified: correlated colour temperature of the lighting, illuminance on the painting and the colour of the background wall. Participants answered a questionnaire to assess the perception of the paintings’ colours, the lighting conditions and the pleasantness of the exhibition set-up. The results demonstrated that illuminance is the parameter mainly affecting perception, for both paintings. However, correlated colour temperature and wall colour, as well as the combination of the three different considered parameters, can more or less influence perception depending on the chromatic composition of the painting.

scholarly journals Designing Safe General LED Lighting that Provides the UVB Benefits of Sunlight

2019 ◽  
Vol 9 (5) ◽  
pp. 826 ◽  
Author(s):  
Seung-Taek Oh ◽  
Dae-Hwan Park ◽  
Jae-Hyun Lim
Keyword(s):  
Vitamin D ◽  
Light Source ◽  
Safety Evaluation ◽  
Spectral Irradiance ◽  
Evaluation Standard ◽  
Led Lighting ◽  
Led Light ◽  
Uvb Exposure ◽  
Indoor Lighting ◽  
Uv Rays

The ultraviolet (UV) rays emitted from sunlight greatly influence human health. Excessive exposure to UV rays can be harmful to eyes and skin; however, limited UVB exposure is essential for the synthesis of vitamin D. Nowadays, owing to insufficient exposure to natural light, there is increasing concerns about low vitamin D amongst individuals. To address this issue, many lighting devices that provide UVB doses have been released; however, such devices are only used for treatments or for special purposes. This study proposes a general indoor lighting system with a UVB LED light source to provide safe UVB doses to users who spend large amounts of time indoors. The optical characteristics of two UVB LEDs with output of 20 and 100 mW were analyzed based on their distances and applied currents. The light source combination of UVB LEDS that meets the UV hazard standard of IEC-62471 was derived; this is a photobiological safety evaluation standard of LED lighting devices. We then produced a lighting module in which the UVB LED light source was applied to general LED lighting and measured and analyzed the spectral irradiance of the proposed lighting according to the measurement standard for the general lighting of IEC 62471. The actinic UV hazard (AUV) and near-UV hazard (NUV) were calculated to be 0.001 and 10 W/m2, respectively. Thus, the provision of UVB dose did not pose any risks. In addition, the total EUV (Erythemal weighted UV) dose when the proposed lighting was implemented for 16 h was 187.66 J/m2, confirming that this dose did not cause erythema for the general skin types (Skin Types 1–6). Further, the design plan of general indoor lighting with a UVB LED light source is presented.

scholarly journals Electro-optical characteristics of an innovative LED luminaire with an LED matrix cooling system based on heat pipes

2020 ◽  
Vol 23 (04) ◽  
pp. 415-423
Author(s):  
D.V. Pekur ◽  
◽  
V.M. Sorokin ◽  
Yu.E. Nikolaenko ◽  
V.P. Kostylyov ◽  
...  
Keyword(s):  
Light Source ◽  
Cooling System ◽  
Renewable Energy Sources ◽  
Heat Pipes ◽  
Luminous Flux ◽  
Optical Characteristics ◽  
Led Light ◽  
Lighting Systems ◽  
Led Matrix ◽  
Led Luminaire

Widespread use of energy-saving LED lighting systems powered by renewable energy sources, solar energy in particular, will contribute to the improvement of global ecology. One of the structural elements of such lighting systems is LED luminaire. The authors of this article perform a first ever experimental study of electro-optical characteristics of the basic version of a compact high-power LED luminaire for indoor use. The particular feature of this lighting device is that its cooling system for the LED light source is based on heat pipes and concentric cooling rings. Such design allows ensuring the required cooling efficiency of the LED matrix. The revealed trends in optical and electrical parameters during temperature stabilization indicate that the proposed cooling system is highly efficient in maintaining normal thermal conditions of LED light sources with a power of up to 140.7 W and a luminous flux of up to 15083 lm. The results on determining spatial distribution of luminous flux of these luminaires indicate that they may be used for lighting large rooms with high ceilings. Scaling the basic modular design version of the cooling system allows increasing the power of the LED light source up to 600 W.

scholarly journals On the Technical Performance Characteristics of Horticultural Lamps

2021 ◽  
Vol 3 (4) ◽  
pp. 716-727
Author(s):  
Timothy J. Shelford ◽  
Arend-Jan Both
Keyword(s):  
Light Source ◽  
Light Emitting Diode ◽  
Performance Characteristics ◽  
Plant Production ◽  
Sufficient Information ◽  
Light Emitting ◽  
Led Lighting ◽  
Technical Performance ◽  
Lighting Systems ◽  
Greenhouse Growers

Recent advances in light emitting diode (LED) technology have provided exciting opportunities for plant lighting applications, and it is expected that LED lighting will soon overtake the still common use of high-intensity discharge (HID) lighting technology. Because LED lighting offers novel capabilities, extensive research is needed to identify optimal lighting practices for the large number of crops grown by commercial greenhouse growers. Plant scientists and growers facing decisions about plant lighting systems do not always have sufficient information about lamp performance characteristics. In this paper, we reported on various technical performance characteristics for 18 lamp types commonly used for plant production, and compared these characteristics with the characteristics of sunlight. The results showed a substantial range of performance characteristics, highlighting the importance of a careful assessment before selecting a light source for horticultural applications. The data presented in this paper can be used to assess the suitability of a specific light source for a particular horticultural application.

scholarly journals Application of color temperature controllability in LED lighting environment of highway tunnel

2021 ◽  
Vol 233 ◽  
pp. 01101
Author(s):  
Zhiqiang Liu ◽  
Peifeng Li ◽  
Haifeng Jiang ◽  
Dan Wang
Keyword(s):  
Light Source ◽  
Visual Recognition ◽  
Control Function ◽  
Light Environment ◽  
Color Temperature ◽  
Led Lighting ◽  
Led Light ◽  
Dimming Control ◽  
Lighting Environment ◽  
Light Color

In recent years, tunnel LED lighting has been widely used in tunnel lighting engineering because of its advantages such as fast start, low energy consumption and good light color controllability. However, at present, the tunnel LED lighting mostly adopts the single dimming control function of light brightness, which does not give full play to the technical advantages of the tunnel LED lighting with two indicators of light brightness and light color temperature control, and does not consider the influence of the color temperature and spectral distribution of the LED light source on the safety and comfort of the tunnel LED lighting environment. Therefore, this paper studies the relationship between the color temperature of tunnel LED lighting source and the visual comfort and visual recognition distance, analyzes the actual impact of the color temperature of LED light source on the tunnel lighting light environment, and puts forward the color temperature index applicable to the entrance and exit sections of tunnel LED lighting, which provides a theoretical basis for building a safe and comfortable "two types" tunnel LED lighting light environment.

Organic Light Emitting Diodes - Innovative Light Sources

2019 ◽  
pp. 101-107
Author(s):  
Sergei A. Stakharny
Keyword(s):  
Light Source ◽  
Organic Light Emitting Diodes ◽  
Organic Leds ◽  
Light Sources ◽  
High Quality ◽  
Light Emitting ◽  
Organic Light ◽  
Lighting Systems ◽  
Physical Principles ◽  
Prospects Of Application

This article is a review of the new light source – organic LEDs having prospects of application in general and special lighting systems. The article describes physical principles of operation of organic LEDs, their advantages and principal differences from conventional non-organic LEDs and other light sources. Also the article devoted to contemporary achievements and prospects of development of this field in the spheres of both general and museum lighting as well as other spheres where properties of organic LEDs as high-quality light sources may be extremely useful.

Design of Solar-Powered LED Road Lighting System

2019 ◽  
pp. 75-85
Author(s):  
Canan Perdahci ◽  
Hamdi Ozkan
Keyword(s):  
High Pressure ◽  
Renewable Energy Sources ◽  
Junction Temperature ◽  
Mercury Vapour ◽  
Light Sources ◽  
Street Lighting ◽  
Led Light ◽  
Road Lighting ◽  
Lighting Systems ◽  
High Pressure Sodium Lamp

Turkey is rich in terms of renewable energy sources and, therefore, is now encouraging the use of sustainable clean lighting systems in road applications. High pressure sodium lamp is the most widely used type in main roads, but other types of lamps such as mercury vapour lamps or metal halide lamps can be utilized for street lighting. Since it enables energy and money saving, LED light technology has replaced high pressure sodium lamps nowadays. Once solar power system (PV) is integrated with LED lamp for street lighting, the amount of saving and local impact might be enriched. LEDs used as light sources in road lighting luminaires with rising lumen values, decreasing junction temperature, higher colour rendering efficiency, longer lifetime have become more efficient than many light sources with the latest developments. Since the structure of the luminaires in which the LED light sources are used differs from that of the conventional light sources, the optical, thermal and electrical design of the LED luminaires must be considered differently. Thus, this study concentrates upon design considerations and the operating principle of solarpowered LED road lighting luminaire in details. Also, a simple solar panel system was designed and the economical values obtained at the end of 20 years were compared when using the ongrid system and the off-grid system.

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