scholarly journals Low-Cost Extra-Low Voltage LED Dimmer for Tuneable White Lighting

2019 ◽  
Vol 25 (3) ◽  
pp. 43-49
Author(s):  
Roman Hrbac ◽  
Tomas Mlcak ◽  
Vaclav Kolar ◽  
Tomas Vantuch
Keyword(s):  
White Light ◽  
Low Voltage ◽  
Low Cost ◽  
Light Output ◽  
Electrical Performance ◽  
Light Sources ◽  
Colour Temperature ◽  
Lighting Systems ◽  
Module Efficiency ◽  
The Right

The colour appearance of light sources has a major impact on how people perceive space. With LED illumination lighting, the colour output can be tuned to virtually any perceivable colour, including any hue of white light. It has been established that the right shade of white light during the 24-hour day cycle has a positive effect on the human body's biological system. For this reason, it is very important to focus on the development and application of new lighting systems that have dynamically variable light outputs in order to imitate the sunlight. Circadian regulation is most responsive to short-wavelength light (460 nm = blue colour). This paper describes the development of a low-cost extra-low voltage LED dimmer for tunable white lighting systems aiming to achieve maximum electrical performance and light-output. This dimming module has two independent LED control channels and allows for a variable colour temperature control from warm white to cold white light. Experimental results of the dimming module efficiency measurements, correlated colour temperature (CCT), colour rendering index (CRI), illuminance and power consumption of the luminaire depending on the duty cycle for different control frequencies (200 Hz, 1.5 kHz, 5 kHz, 10 kHz and 20 kHz) are presented. The paper further describes the principle of creating control curves for an independent regulation of correlated colour temperature and illuminance. In the form of a table, the control curve outputs may be uploaded into a microcontroller. The paper details the construction, function and the advantages of this LED dimmer prototype.

LED life prediction based on lumen depreciation and colour shift

2016 ◽  
Vol 49 (1) ◽  
pp. 84-99 ◽  
Author(s):  
AN Padmasali ◽  
SG Kini
Keyword(s):  
Life Prediction ◽  
Energy Savings ◽  
Light Emitting Diode ◽  
Light Output ◽  
Light Sources ◽  
Colour Stability ◽  
Light Emitting ◽  
Colour Temperature ◽  
Life Estimation ◽  
Chromaticity Coordinates

Light emitting diodes, with advantages in energy savings, luminous efficacy and greater reliability, are becoming preferred over conventional white light sources. Currently, only light output depreciation is considered for life estimation of light emitting diode luminaires but it is recommended to include colour shift variations for applications demanding colour stability. In this paper, an extended Kalman filter is employed to determine L70 life and colour temperature degradation over life of a light emitting diode luminaire. The colour shift in terms of Duv is determined by statistical polynomial cure fitting. The variation in chromaticity coordinates over life is determined and life based on colour shift is determined by acceptable Duv limits. The results are compared to life determined by the IES-TM-21 method and the correlated colour temperature limits taken from the luminaire data sheet.

Transmission Proprieties of Overhead and Cable LV Power Lines – The Comparison in the Frequency Spectrum from 3 kHz to 150 kHz

2015 ◽  
Vol 237 ◽  
pp. 251-256 ◽  
Author(s):  
Piotr Kiedrowski
Keyword(s):  
Low Voltage ◽  
Low Cost ◽  
Power Lines ◽  
Overhead Lines ◽  
Smart Lighting ◽  
Comparison Results ◽  
Transmission Quality ◽  
Lighting Systems ◽  
Cable Lines ◽  
Made In

In the present paper, the comparison results of two main kinds of the power lines are presented, namely, overhead lines and cable lines. The analysis was done in the low-voltage mains network in the frequencies identified by the CENELEC organization for a narrowband transmission using low-cost PLC modems. The currently data transmission with the use of the PLC technique finds increasing use in the area of the communication for the Smart Grid, especially because of Smart Metering and Smart Lighting systems development. Independently form the implementation of the PLC transmission technique, a process of replacement of overhead lines with cable ones is carried out. Undoubtedly this process must have an influence on the transmission prosperities over the mains network. This paper is aimed to show differences in the secondary transmission parameter of the two main constructional types of low-voltage lines, which have the same electro-power parameter. The influence of these differences on the transmission quality is also discussed. The study has been limited to aluminium and copper wires and was made in the low-voltage mains network.

scholarly journals Influence of Peak Wavelengths on Properties of Mixed-LED White-Light Sources

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Snjezana Soltic ◽  
Andrew N. Chalmers
Keyword(s):  
Light Source ◽  
White Light ◽  
Light Sources ◽  
Peak Wavelength ◽  
White Light Source ◽  
Luminous Efficacy ◽  
Colour Temperature ◽  
Colour Rendering

The purpose of this investigation is to quantify the influence of the peak wavelength shifts in commercially available LEDs on the characteristics of the mixed-LED white-light sources. For this purpose, a tetrachromatic spectrum was optimized and then subjected to deviations in the peak wavelengths. A total of 882 combinations of peak wavelength values were evaluated, and the results are reported in terms of correlated colour temperature, colour-rendering properties, and radiant luminous efficacy. The results show that there can be significant changes in the characteristics of the source under these conditions. Such changes are highly likely to present problems when dealing with applications where an effective and accurate white-light source is important.

scholarly journals СУЧАСНЕ ОСВІТЛЕННЯ В ДИЗАЙНІ МУЗЕЙНИХ ЕКСПОЗИЦІЙ

2018 ◽  
pp. 89-98
Author(s):  
В. Д. Северин
Keyword(s):  
Light Output ◽  
Active Role ◽  
Psychological Effect ◽  
Specific Information ◽  
Natural Light ◽  
Light Sources ◽  
Leading Role ◽  
Lighting Systems ◽  
Dynamic Lighting ◽  
Technological Achievement

In modern design practice lighting plays an important role. Lighting means intensification of visual and psychological effect of museum exposition. Light plays an active role in perception of exhibit, revealing its shape, texture and color. Natural light is used to create a broad background, and artificial – to focus attention on specific information. The best way is the combination of artificial and natural light. This balance is possible due to technological achievement. New ways of lighting create the conditions for better preservation of objects.Lighting techniques give the possibility to make the exposure dynamic, without resorting to mechanical kinematic schemes. Since the motion of light attracts the attention of the viewer more than the movement of objects, this fact became the basis for development of a number of interesting schemes of dynamic lighting. Stands and showcases with dynamic illumination leave a brighter footprint in memory.The choice of the lighting system is closely linked with the architecture of the museum building and with the system of museum lighting (natural, artificial and combined). In this case, it is necessary to take into account the complexity of specifics of the museum exposition – the need to create the best illumination of exhibits and at the same time to protect them from the harmful effects of light rays. Lighting systems are based on the composition and properties of exhibited museum objects and the acceptable level of lighting for various categories of exhibits.Artificial lighting must be carried out mainly by sources of light, whose radiation in the spectrum is close to the daytime. For illumination special lighting fittings, which are usually hidden from visitors (behind suspended ceilings, embedded in furniture or exhibition equipment) should be used.Nowadays there is a wide arsenal of lighting means aimed to increase the visual and psychological effect of museum exposition, various types of lighting fixtures and lamps used to illuminate expositions. Among the lighting products, the leading role belongs to LED technologies. These technologies are characterized by qualities that are decisive in the organization of the museum environment. This is the ability to give white light to each exhibit, high light output at low power consumption, fire safety, the possibility of tape mounting of light sources, the implementation of programmable light scenarios with a change in color gamut. The latest technologies in lighting systems play an important role in design of museum exposition.

Colour preference, naturalness, vividness and colour quality metrics, Part 3: Experiments with makeup products and analysis of the complete warm white dataset

2016 ◽  
Vol 50 (2) ◽  
pp. 218-236 ◽  
Author(s):  
TQ Khanh ◽  
P Bodrogi
Keyword(s):  
Linear Combination ◽  
White Light ◽  
Light Sources ◽  
Complex Phenomenon ◽  
Cosmetic Products ◽  
Colour Preference ◽  
Colour Temperature ◽  
Cognitive Components ◽  
Warm White Light ◽  
Moderate Range

Light source colour quality is a complex phenomenon with several visual and cognitive components. Subjective colour preference, naturalness and vividness assessments of reddish cosmetic products in a viewing booth lit by light sources with a correlated colour temperature of 3200 K and to 550 lx were analysed and modelled by a new combined colour quality formula – a linear combination of a colour fidelity index and a measure of chroma change. Results of the warm white light sources described in all three parts of this work were merged. They were modelled by optimising the parameters of the same formula. The formula supports multi-LED light sources with moderately accentuated local spectral maxima to enhance object chroma over a moderate range.

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.

Luminous Environment and the Perceived Environment

2019 ◽  
pp. 15-21
Author(s):  
Banu Manav
Keyword(s):  
Experimental Studies ◽  
Light Output ◽  
Lighting Design ◽  
Lighting System ◽  
Main Concept ◽  
Healthy Environment ◽  
Perceived Environment ◽  
Efficiency Cost ◽  
Lighting Systems ◽  
User Friendly

In lighting design, the main concept is to achieve a healthy environment, which addresses energy efficiency, cost, maintenance, and quality. User-friendly lighting systems shall be adopted to architecture and interior architecture. User control over the lighting system is important, by dimming or increasing light output, by changing the colour of the light sets the inner atmosphere and affects user mood. Standards and codes on lighting shall also be evaluated by means of these topics. The paper aims to analyse how the luminous environment is affective on the perceived environment. Hence, a series of experimental studies and recent research will be evaluated in regard to understanding and designing luminous environment.

The Influence Of The Led Luminaires Electrical Parameters On Their Correlated Colour Temperature During Operation Mode

2020 ◽  
pp. 89-96
Author(s):  
Sergei S. Kapitonov ◽  
Alexei S. Vinokurov ◽  
Sergei V. Prytkov ◽  
Sergei Yu. Grigorovich ◽  
Anastasia V. Kapitonova ◽  
...  
Keyword(s):  
Operation Mode ◽  
Light Sources ◽  
Electrical Parameters ◽  
Colour Temperature ◽  
Radiation Spectra ◽  
Service Period ◽  
Close Proximity ◽  
Definition Of ◽  
Comprehensive Study

The article describes the results of comprehensive study aiming at increase of quality of LED luminaires and definition of the nature of changes in their correlated colour temperature (CCT) in the course of operation. Dependences of CCT of LED luminaires with remote and close location of phosphor for 10 thousand hours of operation in different electric modes were obtained; the results of comparison between the initial and final radiation spectra of the luminaires are presented; using mathematical statistics methods, variation of luminaire CCT over the service period claimed by the manufacturer is forecast; the least favourable electric operation modes with the highest CCT variation observed are defined. The obtained results have confirmed availability of the problem of variation of CCT of LED luminaires during their operation. Possible way of its resolution is application of more qualitative and therefore expensive LEDs with close proximity of phosphor or LEDs with remote phosphor. The article may be interesting both for manufacturers and consumers of LED light sources and lighting devices using them.

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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