Smart Light-emitting Diode Research Articles

Design and Development of an Efficient, High Power Factor, Low-Cost, RGB LED System for Tuneable Lighting Application

Branded smart red (R) – green (G) – blue (B) light emitting diode (LED) products commercially available in developing countries are too costly to afford for most of the population, especially for household applications. Locally manufactured cheaper alternatives of such products suffer from poor power factor and reduced circuit efficiency. To address these technical issues, a smart RGB LED system is presented here which offers high input power factor, good circuit efficiency, and at the same time lower fabrication cost and user-friendly control interface. The unique features of the proposed system are the front-end AC/DC converter is a constant-voltage, multiple-output flyback converter that mitigates the need of multiple drivers and inductors. The second is that the same converter is operated in discontinuous conduction mode to achieve a high input power factor. The third is that for dimming and colour tuning, pulse width modulation (PWM) control of the MOSFET switches is accomplished by an Arduino Mega 2560 microcontroller instead of other costlier and more sophisticated options. And the fourth is that the microcontroller gets its command signal from a smartphone or computer through an HC‑05 Bluetooth module. Through laboratory testing, it is confirmed that the LED system offers close-to-unity input power factor (0.928–0.985) and high efficiency of (88.14–95.46) % for a wide range of colour and luminous intensity. A comparative study reveals that the developed system is a better option than the earlier reported prototypes of multicolour LED systems in terms of the bill of material, economy, power factor, and efficiency.

Smart Dimmable LED Lighting Systems.

This paper proposes energy-efficient solutions for the smart light-emitting diode (LED) lighting system, which provides minimal energy consumption while simultaneously satisfying illuminance requirements of the users in a typical office space. In addition to artificial light from dimmable LED lamps, natural daylight coming from external sources, such as windows, is considered as a source of illumination in an indoor environment. In order to reduce total energy consumption, the smart LED system has the possibility to dim LED lamps, resulting in reduced LED output power. Additionally, various LED lamps' functionality, such as semi-angle of the half illuminance and LED tilting, are introduced as an additional parameter to be optimized to achieve greater energy saving of the designed system. In order to properly exploit external lighting, the idea to reduce overall daylight intensity at a users' location is realized by the option to dim the windows with a shading factor. Based on the users' requirements for a minimal and desired level of illumination, the proposed optimization problems can be solved by implementing different optimization algorithms. The obtained solutions are able to give instructions to a smart LED system to manage and control system parameters (LEDs dimming levels, semi-angles of the half illuminance, orientation of LEDs, the shading factor) in order to design total illumination, which ensures minimal energy consumption and users' satisfaction related to illuminance requirements.

Smart Wireless Near-Infrared Light Emitting Contact Lens for the Treatment of Diabetic Retinopathy.

Diabetic retinopathy is currently treated by highly invasive repeated therapeutic injections and surgical interventions without complete vision recovery. Here, a noninvasive smart wireless far red/near‐infrared (NIR) light emitting contact lens developed successfully for the repeated treatment of diabetic retinopathy with significantly improved compliance. A far red/NIR light emitting diode (LED) is connected with an application‐specific integrated circuit chip, wireless power, and communication systems on a PET film, which is embedded in a silicone elastomer contact lens by thermal crosslinking. After in vitro characterization, it is confirmed that the retinal vascular hyper‐permeability induced by diabetic retinopathy in rabbits is reduced to a statistically significant level by simply repeated wearing of smart far red/NIR LED contact lens for 8 weeks with 120 µW light irradiation for 15 min thrice a week. Histological analysis exhibits the safety and feasibility of LED contact lenses for treating diabetic retinopathy. This platform technology for smart LED contact lens would be harnessed for various biomedical photonic applications.

Design of a smart LED lamp to monitor insect populations in an integrated pest management approach

ABSTRACT This study aimed to present the design and field test results of an LED (light emitting diode) lamp for integrated pest management (IPM) and other entomological studies. The light spectrum of the LEDs was tuned to optimize insect attraction and lower energy consumption. An electronic circuit with control software was integrated with the lamp, enabling it to operate in standalone mode, automatically identify night and day, monitor and control the battery charge with energy from a photovoltaic solar panel, protect the battery against over-discharge, and provide feedback about the operating status of the system. Additionally, energy consumption is about five times lower than that of the fluorescent lamp, reducing the battery and solar panel size needed for its energy supply. In the 2017/2018 growing season, the smart LED lamp was installed in a Sonne light trap in an irrigated rice field, and the total number of insects captured was compared with the number collected in a conventional light trap fitted with a traditional 15 W black light fluorescent lamp. Total captures in the Sonne trap were approximately three times greater than in the conventional system.

LED lighting systems for smart buildings: a review

This study presents a review of smart light-emitting diode (LED) lighting systems applied to smart buildings. The study is focused on drivers, protocols, technologies, communication networks and applications. An extended overview of the methodologies used for LED lighting control in smart buildings is addressed. The study also presents an integrated architecture able to achieve the necessary services and control methodologies for intelligent building energy management system for LED lightings systems in smart buildings.

Economic efficiency and energy security of smart cities

The aim of this paper is to provide an analysis of the determinants of economic efficiency and to assess the prerequisites for the energy security of smart cities. The main methods of the paper include an economic analysis of the infrastructure improvements that result in reducing the energy demand of the smart cities represented by the intelligent light-emitting diode (LED) street lighting system. Smart LED streetlights are getting increasingly popular in the world’s major metropolises as one of the leading components of the “smart” city. We compare the efficiency of LED street lighting used in smart cities with a commonly used lighting system based on sodium lamps. Our results demonstrate that LED street lighting system can significantly reduce the energy demand of any modern city. Moreover, we show that smart grids might help distribution systems within smart cities to better integrate intermittent renewable energy sources such as wind and solar. The main research novelty of our study compared to previous studies from the literature is the estimation of net profit (NP), Net Discounted Savings (NDS), as well as the total savings (TS) using the example of an average European metropolis. Our findings show that there is a need for better management including strong networks of leaders to drive smart city policies and investments and to cover wider city areas with economically sustainable projects and plans. In addition, our findings yield that smart city projects should aim at finding solution for smart connected local energy storage systems to support more renewable energy sources on the power grids. Our results might be of a special interest for city planners, local government stakeholders, as well as urban policy makers dealing with planning and managing smart cities.

Revision of Smart Street Lighting LED

Introduction: This Literature Review article is the result of a research on the current situation of smart public lighting systems with light-emitting diode (LED) technology in cities around the world.
 Problem: How convenient is it to use smart public lighting system with LED luminaires?
 Objective: To review the context of smart public lighting with LED technology.
 Methodology: Within this project, a lit review was conducted with more than 50 academic articles found in different databases such as: IEEE Xplore, Scopus, ScienceDirect etc. The selection criteria of the information followed the revision of articles from 2006 to 2018, and also, took into account their installation and performance in different cities and places of the world. Furthermore, articles on polluting and inefficient technologies were excluded.
 Conclusion: Considering the current context in which LED smart public lighting is, it is more likely to be implemented in the future.
 Results: Smart LED street lighting systems are more efficient in energy use, leads to savings in costs in medium terms, and finally, present a lower environmental impact compared to conventional lighting systems.
 Limitations: The review focuses on energy efficiency and economic aspects, not on social aspects.
 Originality: Smart LED public lighting systems have been researched within the economic and energy efficiency context.

Evaluating the standby power consumption of smart LED bulbs

There is an increasing demand for smart devices in recent years. One of the latest additions to the long list of these smart devices is the smart light-emitting diode (LED) light sources. They offer many additional features in addition to provide light. However, like all other smart devices, when they are turned off by the user through a smart device, they still consume energy. That standby power consumption, when the bulbs are off, soon becomes an increasing load to the grid.In this study, we investigated the current smart residential LED bulb market and selected three samples from 30 models that are available to Canadian consumers. We tested the standby power consumption of those samples by following the IEC 62301 standard.The results showed that the standby power consumption of 21 Smart LED bulb models (out of 30) was less than 0.5 W, which resembles the maximum allowable standby power consumption amount of a smart LED bulb, if the manufacturers intend to carry the Energy Star logo on their product. Although most products are not Energy Star rated, it is a promising result.We also found that the standby power consumption of the three bulb samples tested for each model was generally consistent (the standard deviation was less than 0.02). Only three models had one sample measured with a higher or lower consumption than the other two samples (highest difference 0.43 W, lowest difference: 0.06 W, standard deviation higher than 0.03). This internal consistency or standby power consumption amount in between samples are worrisome.Although our sample size was small, we believe that the findings from our study enabled to gather enough information to have a basic idea about the status of current standby power consumption of the smart LED bulbs in Canadian residential market

Smart Lighting Systems as a Demand Response Solution for Future Smart Grids

Massive deployment of distributed and intermittent renewable energy sources cause instability in the power system because of the mismatch between the power generation and load consumption. In order to solve this problem, smart loads embedded with modern power electronic converters and communication devices are being developed. They are able to communicate with the utility and perform automatic demand response. In this paper, we propose a smart light-emitting diode (LED) driver for lighting. This smart LED driver adjusts its electricity usage in response to the utility without the expense of human visual comfort. To achieve this goal, a new control method is developed and a typical rate of change of LED power is determined through conducting a series of visual assessments with interviewees. An experimental smart LED driver is built to validate the new control method. Experimental report from the visual assessments has confirmed that the proposed control method can significantly reduce the light flickering caused by the change of LED power.

Spectrum optimization of light-emitting diode insecticide lamp based on partial discharge evaluation

The spectrum distribution of light-emitting diodes (LEDs) is a critical issue in adopting LEDs as an attractant in insect-catching apparatuses via phototaxis effects. Numerous research efforts have attempted to configure the LED spectrum in line with the insect-sensitive spectrum under designed test conditions. Although successful methods have achieved a stationary spectrum configuration, it is less effective when applied directly to an LED insecticide lamp due to the time-variant behaviors of insects in complex environments. Therefore, dynamic optimization for spectrum distribution of the LED insecticide lamp in practical fields remains essential to improve energy efficiency and the control quality of insects. In this paper, an online learning and dynamic control method has been proposed, where dead insects are evaluated by a partial discharge waveform and a cost function derived from the lamp’s safety, efficiency, and effectiveness is optimized using a proposed jumping-predication algorithm. Then, a detailed procedure for developing a smart and effective LED insecticide lamp based on photovoltaic power supply is illustrated, and finally the LED insecticide lamp is validated. The suggested methodology and experimental results shed light on controlling insects and pests using an LED insecticide lamp in green agriculture.

Future indoor light and associated energy consumption based on professionals' visions: A practice- and network-oriented analysis

Through the insight and visions of Danish lighting experts, this manuscript investigates relationships between future lighting technologies and practices and the expected impacts on energy and lighting consumption. The light-emitting diode (LED) will be the dominant technology of the future smart light systems. Though, energy efficiency is expected to improve, new market players will appear and new lighting opportunites will be exploited that, in turn, will increase the demand for light. A rebound effect is expected. The overall impact on the future consumption of energy is uncertain, so we conclude that political guidance is needed if society wants to assure the reduction of energy consumption through widespread diffusion of smart LED lights.

A micro-distributed ESS-based smart LED streetlight system for intelligent demand management of the micro grid

Currently, many researchers worldwide are focusing on creating a novel service model by integrating IoT (Internet of Things) technologies with ICT (Information and Communications Technologies) to increase energy efficiency by reducing power consumption and greenhouse gas emissions. This paper examines the problems related to the current integrated ESS (Energy Storage System) in a smart grid: high installation costs and low management efficiency. To solve these problems, this paper studies the development of a micro-distributed ESS in an intelligent LED (Light Emitting Diode) streetlight system, and its low-cost installation and high management efficiency in a micro grid. Through the application of this system, the initial installation costs can be reduced by using micro-distributed ESS and IoT-based intelligent energy management, facilitating power monitoring of the streetlights and energy efficient demand resource management in the micro grid. This provides a more intelligent and efficient environment, such as in a smart-city.

Technology Analysis of Global Smart Light Emitting Diode (LED) Development Using Patent Data

Technological developments related to smart light emitting diode (LED) systems have progressed rapidly in recent years. In this paper, patent documents related to smart LED technology are collected and analyzed to understand the technology development of smart LED systems. Most previous studies of the technology were dependent on the knowledge and experience of domain experts, using techniques such as Delphi surveys or technology road-mapping. These approaches may be subjective and lack robustness, because the results can vary according to the selected expert groups. We therefore propose a new technology analysis methodology based on statistical modeling to obtain objective and relatively stable results. The proposed method consists of visualization based on Bayesian networks and a linear count model to analyze patent documents related to smart LED technology. Combining these results, a global hierarchical technology structure is created that can enhance the sustainability in smart LED system technology. In order to show how this methodology could be applied to real-world problems, we carry out a case study on the technology analysis of smart LED systems.

White light‐emitting diodes: History, progress, and future

AbstractAbout twenty years ago, in the autumn of 1996, the first white light‐emitting diodes (LEDs) were offered for sale. These then‐new devices ushered in a new era in lighting by displacing lower‐efficiency conventional light sources including Edison's venerable incandescent lamp as well as the Hg‐discharge‐based fluorescent lamp. We review the history of the conception, improvement, and commercialization of the white LED. Early models of white LEDs already exceeded the efficiency of low‐wattage incandescent lamps, and extraordinary progress has been made during the last 20 years. The review also includes a discussion of advances in blue LED chips, device architecture, light extraction, and phosphors. Finally, we offer a brief outlook on opportunities provided by smart LED technology. image

The design and implementation of PV-based intelligent distributed sensor LED lighting in daylight exposed room environment

Decreasing of energy consumption and environmentally friendly energy resources are the issues in the foreground nowadays. As the electric energy consumed for the illumination is high, long-lasting and low-consumption LED (light-emitting diode) technology gets prominent. There have been made much reseacrh regarding the use of photovoltaic sytems in meeting the energy demand in housing and industry. However, there is need for more research with regards to photovoltaic sytems’ integration with energy efficiency sytems. In this study, for the environments which have different lighting levels due to daylight factor, there has been proposed a low-cost PV (photovoltaics) based and distributed sensor smart LED illuminating system and there has been acquired 72.075% more energy saving in comparison with conventional LED illuminating system.

Establishment of Vision Effect Diagram for Optimization of Smart LED Lighting

In this paper, a diagram illustrating the combined circadian effect and mesopic vision effect caused by cirtopic, scotopic, and photopic photoreceptors, i.e., a vision effect diagram, was established using a chromaticity diagram based on $L$ , $M$ , and $S$ cone cells for reference. The characteristics of the vision effect diagram were studied, and many features were found to be similar to those of the reference chromaticity diagram. The relationship between the vision effect and the chromaticity diagrams was also studied to ensure that the circadian and mesopic vision effects would be present in the desired chromaticity range. The vision effect diagram is a mathematical tool that can be used to calculate and predict circadian and mesopic vision effects of light sources, as well as to optimize light sources to induce these effects. Optimized light sources with both desirable circadian and mesopic vision effects would not only be useful when these two vision effects are stimulated together but would do well in future smart light-emitting diode (LED) lighting with adjustable luminance in many outdoor applications as well.

Energy-Efficient Intelligent Street Lighting System Using Traffic-Adaptive Control

Lighting, both indoor and outdoor, consumes a substantial amount of energy, making improved efficiency a significant challenge. A promising approach to address outdoor lighting is the smart control of public lighting. Smart lighting using electronically controlled light-emitting diode (LED) lights for adaptable illumination and monitoring is being used to achieve an energy efficient system. However, the traffic engineering integrated with smart control for energy optimization has not been widely used. In this paper, a novel concept of traffic-flow-based smart (LED) street lighting for energy optimization is proposed. The developed smart grid architecture-based system uses low power ZigBee mesh network to provide maximum energy efficiency in response to adaptive traffic on the road. Moreover, the scalable wireless network of smart LED lights offers improved reliability, reduced cost, and more user satisfaction. In order to validate the performance, the proposed system was implemented and tested in a real environment inside a university campus. Experimental results show that in comparison with the replaced conventional metal halide lighting, our system is capable of 68%–82% energy savings depending on the variations in daylight hours between summer and winter. A significant reduction in greenhouse gases, improved overall system reliability, and reduced maintenance due to smart control suggests promising results for future wide-area deployment.

Solution-Grown ZnO Films toward Transparent and Smart Dual-Color Light-Emitting Diode.

An individual light-emitting diode (LED) capable of emitting different colors of light under different bias conditions not only allows for compact device integration but also extends the functionality of the LED beyond traditional illumination and display. Herein, we report a color-switchable LED based on solution-grown n-type ZnO on p-GaN/n-GaN heterojunction. The LED emits red light with a peak centered at ∼692 nm and a full width at half-maximum of ∼90 nm under forward bias, while it emits green light under reverse bias. These two lighting colors can be switched repeatedly by reversing the bias polarity. The bias-polarity-switched dual-color LED enables independent control over the lighting color and brightness of each emission with two-terminal operation. The results offer a promising strategy toward transparent, miniaturized, and smart LEDs, which hold great potential in optoelectronics and optical communication.

A Spectrally Tunable Smart LED Lighting System With Closed-Loop Control

Light emitting diodes (LEDs), with their ability to produce tunable light spectrums, present a significant opportunity to improve on existing lighting systems. They can be applied to smart and specialized lighting, which can be highly beneficial in the residential, commercial, and industrial sectors. In this paper, we present a novel closed-loop control algorithm with feedback from a spectral sensor, which allows the light output spectrum to converge toward a target spectrum. The control system was experimentally validated by the hardware implementation of a wireless smart lighting system with the eight tunable LED channels with different dominant wavelengths (450-650 nm) designed to cover a large portion of the visible light spectrum. Experimental results show a near perfect replication of target spectra, with an accuracy within 5% for the correlated color temperatures and Euclidean distances which fall well within a five-step u'v' unit circle.

<italic>In-Situ</italic> Measurement of Junction Temperature and Light Intensity of Light Emitting Diodes With an Internal Sensor Unit

This study designed and tested an innovative light-emitting diode (LED) chip with a built-in sensor. Two electrically isolated units, the LED (for light emission) and the sensor (for monitoring junction temperature and light intensity), were integrated on a single chip. The sensor unit determines the junction temperature by measuring the forward voltage; the light output power of the LED unit can be precisely extrapolated with a polynomial function based on the photocurrent and junction temperature. This novel structure enables the in-situ real-time monitoring of the LED junction temperature and light output power, which allows a highly detailed and/or in-field LED reliability analysis and provides valuable feedback information for smart LED lighting systems.