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Published in Barney L. Capehart, William J. Kennedy, Wayne C. Turner, Guide to Energy Management, 2020
Barney L. Capehart, William J. Kennedy, Wayne C. Turner
LEDs are “directional” light sources, which means they emit light in a specific direction, unlike incandescent and compact fluorescent bulbs, which emit light and heat in all directions. For this reason, LED lighting is able to use light and energy more efficiently in many applications. However, it also means that sophisticated engineering is needed to produce an LED light bulb that shines light all around like an incandescent A-shape bulb. Incandescent bulbs produce light using electricity to heat a metal filament until it becomes “white” hot or is said to incandesce. As a result, incandescent bulbs release 90% of their energy as heat. In a CFL, an electric current flows between electrodes at each end of a tube containing gases. This reaction produces ultraviolet (UV) light and heat. The UV light is transformed into visible light when it strikes a phosphor coating on the inside of the bulb.
Lighting and Communications: Devices and Systems
Published in Zabih Ghassemlooy, Luis Nero Alves, Stanislav Zvánovec, Mohammad-Ali Khalighi, Visible Light Communications, 2017
Luis Nero Alves, Luis Rodrigues, José Luis Cura
Figure 2.1 depicts a conceptual overview of the main blocks in a typical lighting system. The four main components are the power source (PS), the lighting device (D), a reflector (R), and a shaping lens (L). Note that the physical enclosure for the lamp is not shown in Figure 2.1; this will not be covered in this chapter. Each of the components depicted in Figure 2.1 have a specific functionality. The PS is the energy provider, which is responsible for controlling and providing energy to the lighting device. Different lighting devices may have different requirements for the PS, which usually have different names. For instance, a driver for a light-emitting diode (LED), ballast for fluorescent lamps. The next element is the lighting device where the electrical energy is converted into light. There are several types of lighting devices with different conversion mechanisms, each suitable for different applications. The most common lighting devices available on the market are fluorescent lamps, compact fluorescent lamps (CFL), high-intensity discharge lamps (HIDs), LEDs, and more recently, laser-based visible lights [1,2]. The incandescent lamps with very low energy efficiency are being phased out at a global level. The reflector element is used to confine the light radiation in a specific direction. And finally, a shaping lens is employed to assure uniform lighting conditions.
Natural Light-Style Organic Light-Emitting Diodes
Published in Zhe Chuan Feng, Handbook of Solid-State Lighting and LEDs, 2017
Jwo-Huei Jou, Meenu Singh, Yi-Fang Tsai
Subsequently, the efficiency of the sunlight-style OLED was significantly enhanced from 2.2 to 30 lm/W at 100 cd/m2 as the electro-fluorescent emitters were replaced by their phosphorescent counterparts. Moreover, the phosphorescent OLED device also demonstrated a relatively high efficiency, even at 10,000 cd/m2. This may provide an energy efficient alternative to incandescent bulbs, whose power efficiency is 10–15 lm/W. As to the lower color-temperature range, it may be suitable for lighting at night to minimize blue hazard.
A common type of commercially available LED light source allows for colour discrimination performance at a level comparable to halogen lighting
Published in Ergonomics, 2019
Sara Königs, Susanne Mayr, Axel Buchner
Light sources based on light emitting diodes (LEDs) have become superior to other conventional light sources such as incandescent, halogen, or fluorescent lamps in terms of lifetime and efficiency (Chang et al. 2012). The efficiency of a light source is characterised by its luminous efficacy which is defined as the ratio of the luminous flux to the electrical power consumption (Boyce 2014), measured in lumens per watt (lm/W). Apart from luminous efficacy and lifetime, LED-based light sources differ from other conventional light sources in their spectral power distribution. The spectral power distribution reflects the intensity of emitted radiation at each wavelength (Houser et al. 2016). Radiation in the wavelength range from 380 to 780 nm (the visible spectrum) leads to a response of the human visual system (Boyce 2014) and thus triggers the perception of colour; for normal observers short wavelengths appear as blue light, medium wavelengths as green light, and long wavelengths as red light (Houser et al. 2016).
Supraharmonics reduction in LED drivers via random pulse-position modulation
Published in International Journal of Electronics, 2018
Joaquin Garrido-Zafra, Antonio Moreno-Munoz, Aurora Gil-De-Castro, Manuel A. Ortiz-López, Tomás Morales
Worldwide present urbanisation patterns have impelled the need for lighting sources, which has derived in a greater demand for electricity. Lighting is responsible for approximately 20% of the global electricity consumption and about 6% of greenhouse gas emissions (Waide, Tanishima, & Harrington, 2006). In the quest for energy efficiency, the light-emitting diode or LED light has entailed an energy revolution, involving energy savings of up to 80% compared to incandescent lamps (‘How Energy-Efficient Light Bulbs Compare with Traditional Incandescents | Department of Energy,’ n.d.). The shift to LED light is transforming the lighting industry, which has seen a faster than expected drop-off in the price of this disruptive technology. An LED is a two-layer semiconductor light source. LED lighting not only delivers high efficiency but also high level of brightness, long lifespan and high reliability. Consequently, LED lamps are employed nowadays in most of the applications: indoor and outdoor, such as street lights or parking garage lighting. The EU’s decision to finally phase out sales of incandescent lamps by 2012 and similar actions in countries such as China, Russia and Brazil are all leading to a sharp increase of power electronic converters (PEC) needed for this lighting technology. Market forecasts estimate extraordinary and continuous growth of LED market throughout present decade, with LED becoming the dominant lighting technology in terms of total number of installed units, with a share reaching almost 70% of the global lighting market in 2020 (Baumgartner et al., 2012).
Cytotoxicity and genotoxicity of light emitted by incandescent, halogen, and LED bulbs on ARPE-19 and BEAS-2B cell lines
Published in Journal of Toxicology and Environmental Health, Part A, 2018
Marta Gea, Tiziana Schilirò, Paola Iacomussi, Raffaella Degan, Sara Bonetta, Giorgio Gilli
In the past century, conventional incandescent bulb was almost the only source of electric light used in households. Due to energy saving policy (Commission regulation 244/2009), conventional incandescent bulbs (and other inefficient lighting methods) had to be phased out until September 2012. Incandescent bulbs have to be replaced with energy-efficient light sources such as halogen bulbs, compact fluorescent bulbs (CFLs), or light-emitting diode (LED) bulbs . All these light sources are extensively used for public and domestic lighting, but for the future, it is planned to replace halogen bulbs and CFLs with LEDs (Necz and Bakos 2014).