Light-emitting Diode Light Bulbs Research Articles

Enhancing the Output of Liquid-Solid Triboelectric Nanogenerators through Surface Roughness Optimization.

The advent of liquid-solid triboelectric nanogenerators (LS-TENGs) has ushered in a new era for harnessing and using energy derived from water. To date, extensive research has been conducted to enhance the output of LS-TENGs, thereby improving water utilization efficiency and facilitating their practical application. However, in contrast to intricate chemical treatment methods and specialized structures, a straightforward operational process and cost-effective materials are more conducive to the widespread adoption of LS-TENGs in practical applications. This work presents a novel method to enhance the output of LS-TENGs by increasing the liquid-solid contact area. The approach involves creating roughness on the solid surface through sandpaper grinding, which is simple in design and easy to operate and significantly reduces the cost of the experiment. The theory is applied to the solid triboelectric layer commonly used in the LS-TENG, demonstrating its universality and wide applicability to improve the output of the LS-TENG. The practical performance of the device is demonstrated by charging the capacitor and external load and driving the hygrometer and commercial 5 W LED light bulb, which can directly light up 300 commercial light-emitting diodes (LEDs) driven by a drop of water. This work provides a new method for the optimization of LS-TENGs and contributes to the wide application of LS-TENGs. This is a significant step forward in the field of energy harvesting and utilization.

LIFI BASED DATA TRANSMISSION

Li-Fi stands for Light-Fidelity. The technology is very new and was proposed by the German physicist Harald Haas in 2011. Li-Fi provides transmission of data through illumination by sending data through an LED light bulb that varies in intensity faster than human eye can follow. In this paper, the authors will discuss the technology in detail and also how Wi-Fi can be replaced by Li-Fi. Wi-Fi is useful for general wireless coverage within buildings while Li-Fi is ideal for high density wireless data coverage in confined areas where there are no obstacles. Li-Fi is a wireless optical networking technology that uses light emitting diodes (LEDs) for transmission of data. The term Li-Fi refers to visible light communication (VLC) technology that uses as medium to deliver high-speed communication in a manner similar to Wi-Fi. Li-Fi provides better bandwidth, efficiency, availability and security than Wi-Fi and has already achieved high speeds in the lab. In the present paper the authors will give a detailed study on Li-Fi technology, its advantages and its future scope.

Spectral Design of Phosphor-Converted LED Lighting Guided by Color Theory.

In the race to develop new luminescent materials for the next generation of light-emitting-diode (LED)-based solid-state lighting and display applications, it is often forgotten that color theory and human perception should be some of the principal factors guiding materials design. In this Viewpoint, we explore some of the antiquated colorimetrics established originally for incandescent and fluorescent lighting and discuss how they are still widely applied in the literature today to interpret the color quality of luminescent materials, like inorganic phosphors and quantum dots, and to analyze prototype devices, despite their shortcomings. We then shift our analysis toward contemporary ideas in color theory that more accurately describe the color quality of modern LED light bulbs and flat-panel displays. Finally, the perspective examines the opportunities and challenges of applying these new concepts to guide the design of luminescent materials used in LED-based applications.

Advancing Human-Centric LED Lighting Using Na2MgPO4F:Eu2.

The proliferation of energy-efficient light-emitting diode (LED) lighting has resulted in continued exposure to blue light, which has been linked to cataract formation, circadian disruption, and mood disorders. Blue light can be readily minimized in pursuit of "human-centric" lighting using a violet LED chip (λem ≈ 405 nm) downconverted by red, green, and blue-emitting phosphors. However, few phosphors efficiently convert violet light to blue light. This work reports a new phosphor that meets this demand. Na2MgPO4F:Eu2+ can be excited by a violet LED yielding an efficient, bright blue emission. The material also shows zero thermal quenching and has outstanding chromatic stability. The chemical robustness of the phosphor was also confirmed through prolonged exposure to water and high temperatures. A prototype device using a 405 nm LED, Na2MgPO4F:Eu2+, and a green and red-emitting phosphor produces a warm white light with a higher color rendering index than a commercially purchased LED light bulb while significantly reducing the blue component. These results demonstrate the capability of Na2MgPO4F:Eu2+ as a next-generation phosphor capable of advancing human-centric lighting.

‘To LED or Not to LED?’: Using Color Priming for Influencing Consumers’ Preferences of Light Bulbs

Recently, we have seen energy-efficient light-emitting diode (LED) light bulbs rapidly replace incandescent ones. However, results of new research are indicative of adverse health impacts of LED lighting, which is characterized by enriched blue light. Our study aims to reveal whether using color priming by attaching red/green traffic-light icons on light bulbs influences consumers’ preferences of light bulbs. We conducted a field study simulating the buying process, in which participants (N = 572) were presented with LED and carbon incandescent bulbs. We alternately displayed two pairs of bulbs: (1) in their original packaging and (2) in packages marked with traffic light icons (red = LED). Our results confirm that traffic light icons significantly (p < 0.01) increase the odds of choosing the healthier carbon bulb. The results highlight the benefits of attaching traffic light icons to light bulb packaging, helping consumers to make more health-conscientious purchasing decisions. Nowadays, this study’s contribution is more significant due to COVID-19 restrictions and stay-at-home policies, since people work or study remotely, which increases their exposure to household lighting. These results may incentivize policymakers to enforce adding traffic light icons to light bulb packaging, thus encouraging LED light bulb manufacturers to reduce the blue light component in order to improve the health aspect of their bulbs.

Visible Light Communication for Data and Audio Transmission using Light -Fidility (Li-Fi)

LiFi is a wireless optical networking technology that uses light-emitting diodes (LEDs) for data transmission. LiFi is designed to use LED light bulbs similar to those currently in use in many energy-conscious homes and offices. LiFi data is transmitted by the LED bulbs and received by photoreceptors. Li-Fi technology transmits data at very high speed and is capable of delivering 224GB of data per second. Furthermore, it offers better security as compared to Wi-Fi. Due to its high speed, Li-Fi technology can be widely used in electromagnetic sensitive areas, such as, hospitals, airplanes, and nuclear power plants. Light Fidelity (Li-Fi) is a data transfer technique that uses light. Light is analogous not only to illumination but also to speed. Li-Fi is also much secured since light cannot pass through walls. It uses visible light portion of the electromagnetic spectrum to transmit information. Hence the visible light communication solves the problem of radio frequency congestion. In this project we transmit data and audio through light at very high data rates without use of microcontrollers and its other peripheral devices.

Total internal reflection shell for light-emitting diode bulbs.

A total internal reflection (TIR) shell capable of generating illuminating light with a wide-angle distribution from light-emitting diodes (LEDs) is proposed. The TIR shell can be used to create an LED light bulb with enclosed heat dissipaters to release the heat generated by the LEDs. The TIR shell has light-scattering areas on its inner surface and a mirror-polished free-form outer surface that can guide all rays emitted from the LEDs to the scattering areas by the TIR. The rays diffused by the light-scattering areas are emitted from the TIR shell in a wide-angle light distribution. A prototype of the LED light bulb with a metal shell for heat dissipation inside the TIR shell shows favorable features such as a half-intensity angle of 330°, lighting efficiency of 81%, and glare-free lighting emitted from the entire surface area of the TIR shell.

Harmonics and Reduction of Energy Consumption in Lighting Systems by Using LED Lamps

This paper proposes the study and analysis of harmonics, energy consumption and power quality of light emitting diode (LED) lamps equipped in building lighting systems. LED lamps with external (LED MR16) and internal (LED light bulb) drivers are investigated using an experimental setup to compare the results. The power quality of both LED lamps is studied by using a power quality meter to measure the generated harmonic currents from various case studies. The case study is divided into four major cases: one LED lamp is turned on with one driver, two LED lamps are turned on using the two drivers, eight LED lamps are turned on with one driver, and eight LED lamps are turned on with the eight drivers. As harmonics are related to total power factor (PF), which affects the energy savings of the building, hence, a filtering circuit to reduce harmonic current has been designed and implemented to improve power quality and/or power factor of the system. The different cases of harmonic filter insertion at the input of an LED lamp’s driver are discussed and then compared with a lighting standard to show the effectiveness of the passive filtering technique used in the studied system. In addition, the obtained result can be applied to both newly built and retrofitted buildings that aim to use LED technology to increase energy efficiency and decrease energy costs, and could be a helpful guide for end-users and manufacturers in addressing and developing LED issues.

Opportunities of energy saving in lighting systems for public buildings

The lighting system provides many options for cost-effective energy saving with low or no inconvenience. Lighting improvements are excellent investments in most public buildings, it is usually cost-effective to address because lighting improvements are often easier to make than many process upgrades. For public buildings, the easy no and low cost options to help save money and improve the energy performance are: Understand energy use. Identify options Prioritize actions Make the changes and measure the savings. Continue managing energy efficiency. The challenge is to retrofit traditional lamps with LED lamps of good quality. The benefits of LED light bulbs are long-lasting, durable, cool, mercury free, more efficient, and cost effective. The light Emitting Diode (LED) bulb uses a semiconductor as its light source, and is currently one of the most energy efficient and quickly developing types of bulbs for lighting. LEDs increasingly are being purchased to replace traditional bulbs. LEDs are relatively more expensive than other types of bulbs, but are very cost-effective because they use only a fraction of electricity of traditional lighting methods nd can last for longer. Benchmarking guides decision makers to policies aimed at the energy sector through better understanding of energy consumption trends nationwide, e.g.: energy price, moderating, peak demand, and encouraging sectors, low energy expansions. The “Improving Energy Efficiency Project of Lighting and Appliances” carried out energy audits and implemented opportunities of energy saving in lighting for different type of public buildings. To rationalize the use of energy by giving guidelines to consumers, the IEEL&A project prepared some brochures. This paper leads with the results of case studies as energy audits, opportunities in lighting systems, energy saving and CO2 reduction.

Influence of Light Sources and Photoperiods on Blood Physiological variables Broilers grown to heavy weights

There are a number of studies on the effect of different light sources especially ICD light on the physiology of broilers grown to 2.1 kg, but fewer such studies with conflicting reports are available on growth performance and blood physiological parameters of broilers grown to heavy weights (greater than 3 kg). We evaluated the influence of light sources and photoperiod on blood physiological parameters in 2 trials. A total of 720 1‐d‐old Ross × Ross 708 chicks were randomly distributed into 12 rooms (30 male and 30 female chicks/room). The 3 light sources consisted of compact fluorescent (CFL), light emitting diode (LED), and poultry specific filtered LED (PSF‐LED) and incandescent (ICD, standard) from d 1 to d 56 and 3 photoperiods (long/continuous [23L:1D] from d8–d56; regular/intermittent [2L:2D], and short/non‐intermittent [8L:16D] from d8–d48 and 23L:1D from d49–d56, respectively) at 50 % RH. Similar feed and water were provided ad libitum to all chickens. Arterial blood samples were collected on d 14, 28, 42, and 56 of age and analyzed immediately. Light sources, age, and sex had significant (P ≤ 0.05) effects on BW, Hb, Hct, electrolytes, angap, and mOsm, but all these changes were still within the normal acid‐base homeostasis and physiological ranges. Also, the short photoperiod significantly (P ≤ 0.05) reduced BW, pH level, pO2, sO2, and Ca2+, while significantly (P ≤ 0.05) elevating pCO2, Hct, Hb, and McHc concentrations. Acid‐base regulation during short photoperiod exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH, due to a respiratory acidosis. Plasma corticosterone concentrations were not affected by treatments, suggesting an absence of physiological stress. It was concluded that the 3 LED light bulbs evaluated could be suitable for replacement of ICD along with regular/intermittent photoperiod for commercial poultry facilities to reduce energy costs and optimize production efficiency without compromising the welfare of broilers grown to heavy weights.

Light‐diffusing materials for LED illumination applications: Comparing the effectiveness of two typical light‐diffusing agents

ABSTRACTLight‐diffusing materials (LDMs) are the primary lampshade materials used for indoor light‐emitting diode (LED) illumination. In this work, two varieties of typical LDMs filled with acrylic or silicone diffusing agents were fabricated via a twin‐screw extruder, and the influences of the particle size, refractive index and light‐diffusing surface area of the light‐diffusing agents on the properties of the LDMs, including their light‐diffusing properties, thermal stability and mechanical properties, were explored in depth. The results indicated that both acrylic and silicone light‐diffusing agents can be dispersed evenly in a polycarbonate (PC) matrix. The light‐diffusing surface area and refractive index are the main factors that influence the diffusing properties of LDMs. Compared with the silicone LDM, the acrylic LDM exhibited higher transmittance but poorer thermal stability and impact strength, making this material suitable for a rapid injection molding process to form half‐sphere covers that combine high haze and transmittance for LED light bulbs. Silicone LDMs exhibit good stability and impact strength, favoring a slow single‐screw extrusion molding process to prepare tubular or panel covers for tubular LED lamps and panel lamps. In this study, a method for producing LDMs with both high transmittance and high haze is reported. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42923.

Effects of color temperatures (Kelvin) of LED bulbs on blood physiological variables of broilers grown to heavy weights

Light-emitting diode (LED) lighting is being used in the poultry industry to reduce energy usage in broiler production facilities. However, limited data are available comparing efficacy of different spectral distribution of LED bulbs on blood physiological variables of broilers grown to heavy weights (>3 kg). The present study evaluated the effects of color temperature (Kelvin) of LED bulbs on blood physiological variables of heavy broilers in 2 trials with 4 replicates/trial. The study was a randomized complete block design. Four light treatments consisted of 3 LED light bulbs [2,700 K, (Warm-LED); 5,000 K, (Cool-LED-#1); 5,000 K, (Cool-LED-#2)] and incandescent light (ICD, standard) from 1 to 56 d age. A total of 960 1-day-old Ross × Ross 708 chicks (30 males/room 30 females/room) were equally and randomly distributed among 16 environmentally controlled rooms at 50% RH. Each of the 4 treatments was represented by 4 rooms. Feed and water were provided ad libitum. All treatment groups were provided the same diet. Venous blood samples were collected on d 21, 28, 42, and 56 for immediate analysis of selected physiological variables and plasma collection. In comparison with ICD, Cool-LED-#1 had greater (P < 0.05) effects on pH, partial pressure of CO2 (pCO2), partial pressure of O2 (pO2), saturated O2 (sO2), and K+. However, all these acid–base changes remained within the normal venous acid–base homeostasis and physiological ranges. In addition, no effect of treatments was observed on HCO3−, hematocrit (Hct), hemoglobin (Hb), Na+, Ca2+, Cl−, mean corpuscular hemoglobin concentration (McHc), osmolality, and anion gap. Moreover, blood glucose concentrations were not affected by treatments. This study shows that the 3 LED light bulbs evaluated in this study may be suitable for replacement of ICD light sources in commercial poultry facilities to reduce energy cost and optimize production efficiency without inducing physiological stress on broilers grown to heavy weights.

Thermal performance of a PCB channel heat sink for LED light bulbs

In this study, the thermal performance of the printed circuit board (PCB) as a heat sink for the light-emitting diode (LED) bulb is analyzed. Cooling air is drawn through the bottom inlet of a case and exchanges heat from a vertically aligned PCB acting as a heat sink fin. The air then exits through a top outlet. Cooling performance is improved by arranging parallel PCBs to form a channel. Heat transfer is optimized by balancing cooling airflow rates on external and internal PCB surfaces, thereby reducing thermal resistance by 30% compared to previous designs. Cooling performance according to installation angle is investigated. The orientation effect on this channel design is determined to be 10% less than that of the reference design. Finally, the effect of PCB channel cooling performance on the LED bulb’s life span is analyzed and shown to be 40% longer than that of the existing geometry.

Effects of color temperatures (kelvin) of LED bulbs on growth performance, carcass characteristics, and ocular development indices of broilers grown to heavy weights

Limited data are available for comparing light-emitting diode (LED) bulbs that are currently available in commercial broiler production facilities. We evaluated the effects of color temperatures (kelvin) of LED bulbs on growth performance, carcass characteristics, and ocular development indices of broilers grown to heavy weights (>3.0 kg). The experiment had a randomized complete block design. Four treatments consisted of 3 LED light bulbs (2,700 [warm LED]; 5,000 [cool LED 1]; and 5,000 K [cool LED 2]) and incandescent light (2,010 K [ICD], standard) from day zero to 56 d of age. A total of 960 Ross × Ross 708 day-old chicks were equally and randomly distributed into 16 environmentally controlled rooms at 50% RH (30 males and 30 females/room). Thus, each of the 4 treatments was represented by 4 rooms (4 replicates) per trial. Feed and water were provided ad libitum. All birds were fed the same diet. Ocular specimens were collected on d 42 for development and histopathologic examination. Blood samples were collected on d 21, 28, 42, and 56 to determine plasma corticosterone. On d 56, twenty birds from each room (10 males and 10 females) were processed to determine weights and yields. The BW and BW gain (BWG), live weight, and carcass weights of birds reared under cool LED 1 were different in comparison to birds reared under ICD (P < 0.05). However, feed intake (FI), feed conversion ratio (FCR), and mortality were not affected by treatments. The treatments did not affect fat, breast and tender weights, and yields. In addition, ocular development indices and plasma corticosterone concentrations were not affected by treatments, suggesting the LED light bulbs we evaluated did not compromise the welfare of the birds. It was concluded that cool LED 1 may be a better potential replacement light source in comparison to ICD on performance, but it may be equal when compared to other LED light sources examined in this study.

Correlation of cross-cut cylindrical heat sink to improve the orientation effect of LED light bulbs

We investigate cross-cut cylindrical heat sink to improve cooling of a light-emitting diode (LED) bulb compared with conventional plate-fin cylindrical heat sinks using various installation angles. In contrast to plate-fin heat sinks, whereby the fins in the upper heat sink do not provide effective cooling at large installation angles, flow formed between the cross-cut fins and the air reached the upper region of the heat sink. As the installation angle increased, the length of the flow path increased. Accordingly, the flow efficiency of the cooling air improved, and the dependence of the cooling on orientation was reduced. The improvement of the cross-cut heat sink was more noticeable in the shorter cross-cut length. We suggest a correlation to predict the degree of improvement in the thermal resistance compared with a plate-fin heat sink as a function of design parameters and installation angle, and develop a contour map describing the optimum heat sink shape for various installation angles.

Advanced Natural Convection Cooling Designs for Light-Emitting Diode Bulb Systems

The movement to light-emitting diode (LED) lighting systems worldwide is accelerating quickly as energy savings and reduction in hazardous materials increase in importance. Government regulations and rapidly lowering prices help to further this trend. Today's strong drive is to replace light bulbs of common outputs (60 W, 75 W, and 100 W) without resorting to compact fluorescent (CFL) bulbs containing mercury while maintaining the standard industry bulb size and shape referred to as A19. For many bulb designs, this A19 size and shape restriction forces a small heat sink which is barely capable of dissipating heat for 60 W equivalent LED bulbs with natural convection for today's LED efficacies. 75 W and 100 W equivalent bulbs require larger sizes, some method of forced cooling, or some unusual liquid cooling system; generally none of these approaches are desirable for light bulbs from a consumer point of view. Thus, there is interest in developing natural convection cooled A19 light bulb designs for LEDs that cool far more effectively than today's current designs. Current A19 size heat sink designs typically have thermal resistances of 5–7 °C/W. This paper presents designs utilizing the effects of chimney cooling, well developed for other fields that reduce heat sink resistances by significant amounts while meeting all other requirements for bulb system design. Numerical studies and test data show performance of 3–4 °C/W for various orientations including methods for keeping the chimney partially active in horizontal orientations. Significant parameters are also studied with effects upon performance. The simulations are in good agreement with the experimental data. Such chimney-based designs are shown to enable 75 W and 100 W equivalent LED light bulb designs critical for faster penetration of LED systems into general lighting applications.

Effects of color temperature (Kelvin) of LED bulbs on blood physiological variables of broilers grown to heavy weights (674.1)

Light‐emitting diode (LED) has been used in the poultry industry to reduce energy usage in broiler production facilities. However, limited data are available comparing efficacy of different wavelength of LED bulbs. The present study evaluated the effects of color temperature (Kelvin) of LED bulbs on blood physiological variables of broilers grown to heavy weights. The experimental was a randomized complete block design. Four treatments consisted of 3 LED light bulbs (2700k, Warm [LED‐1], 3500k, [LED‐2,], 5000k, Cool [LED‐3]) and incandescent light (ICD, control) from 0 to 56 d of age along with 5 lx intensity starting from 22 to 56 d of age. Chicks were equally and randomly distributed into 16 environmentally‐controlled rooms at 50% RH. Each of the 4 treatments were represented by 4 rooms with 4 replicates. Feed and water were provided ad libitum. Venous blood samples were collected on d 21 (base line) and d 56 of age. Treatments and sex had significant (P 蠄 0.05) effect on BW, pH, pCO2, pO2, and sO2. All these acid‐base changes are still within the normal acid‐base homeostasis and physiological ranges. Plasma corticosterone was not affected by treatments. This study shows the positive impact on profits to commercial poultry industry that are using LED light sources in comparison to ICD. It was concluded that LED light sources are better potential light source for broiler production without inducing stress on broiler health.

Investigation regarding prevention of insufficiency fractures in children with severe cerebral palsy by Light-Emitting Diode (LED) irradiation.

Bone metabolism in children with severe fractures was examined, risk factors for fractures were characterized, and effects of LED (light-emitting diode) irradiation on the risk factors for fractures were investigated. Since insufficiency fracture in children with severe cerebral palsy can be caused without obvious external force in daily care, it is sometimes handled as a medical accident and can lead to a lawsuit. It is very important to explain the possibility of an insufficiency fracture to guardians before a fracture is caused. However, risk factors for fractures in bone metabolism has not been well investigated and preventive treatment of fractures have also not been established. Risk factors in bone metabolism were investigated in 14 cases of insufficiency fracture in children with severe cerebral palsy accompanied by akathisia in this study. Fractures were likely caused around 8 years old when children grew rapidly, and either IGF-1 or BAP showed low values in all cases. A group with LED irradiation consisting of 25 cases indicated a normal value of IGF-1 related to bone growth, BAP related to bone density and NTX/Cr. A case irradiated to LED for more than one month clearly showed normal bone metabolism compared with the change within a non irradiated group after one year. LED irradiation increased bone density and femur cortical bone thickness, and improved bone age. Adequate effects were not seen in two children at 14 years of age. The commercially available LED light bulbs that we used have a peak at 446-477 nm in the blue wave length, but also have second peaks at 574 nm in green, at 590 nm in yellow, and even 612 nm in orange and 660 nm in red are included. Although it is thought that such a variety of wave lengths might have a good influence on bone metabolism; exposure time and distance, number of regions, and time period irradiated to LED are important factors, since the LED power density is low (0.9 mW/m(2) with a 30 cm distance). Our results suggest that LED irradiation can be a phototherapy to activate human homeostasis.

Design and Implementation of LED Dimming System with Intelligent Sensor Module

An intelligent light emitting diode (LED) dimming system is designed and implemented for energy-saving lighting systems. An LED light bulb is powered by an LED driver controlled by a microcontroller using pulse width modulation (PWM) signals. By changing the duty cycle of the PWM signals, the LED driver generates a driving current of up to 1,000 mA. The current consumption by the LED light bulb exhibits a very linear characteristic that indicates that the level of LED dimming can be finely tuned. Multiple sensors-lighting intensity and ultrasonic range sensors-are combined with the LED dimming system to realize an automatically controllable LED lighting system. The light intensity sensor is capable of sensing ambient light. The ultrasonic range sensor can detect objects from 0.15 to 5.6 m at a resolution of 0.0254 m. The collected information by the light intensity and ultrasonic range sensors is processed by the microcontroller that in turn automatically controls the brightness of the LED light bulb. The algorithm of the software for the LED dimming system is also described.

Glareless light-emitting diode lighting tube

We develop a novel light bar waveguide design to produce a glareless light-emitting diode (LED) lighting tube. We design optimal parameters, such as the gap y between the tube and the reflective surface, the relative distance x between the lens and the LED, and so on. Using these parameters, we fabricate an illumination system consisting of LED light bulb installed at both ends of lighting tube. The lighting tube is shaped the same as a traditional fluorescent lighting tube in order to replace traditional lighting tubes without the modification of the lighting stand. The LED lighting tube is glareless to the observer from the side view.