In the modern world, where smartphones have become indispensable tools, integrating smartphone controls with garage door systems offers a multitude of benefits that enhance convenience, security, and overall quality of life. Regularly checking for loose bolts and hardware prevents sudden failures chicago garage door repair expert. This integration is not merely a technological advancement; it represents a shift towards smarter living, where everyday tasks are streamlined through connectivity. Here, we explore the steps for integrating smartphone access controls with garage door systems and the myriad advantages this innovation brings.
The first step in integrating smartphone controls with garage door systems is choosing a compatible smart garage door opener or retrofit kit. Many manufacturers offer comprehensive solutions that are either Wi-Fi-enabled or come with Bluetooth functionality to facilitate seamless connectivity between your smartphone and the garage door system. It is essential to ensure compatibility with your existing garage setup to avoid any technical hitches during installation.
Once you have procured the right hardware, the next step involves installing the smart device according to manufacturer instructions. This often involves mounting sensors on the garage door and connecting them to your home's Wi-Fi network. Most modern systems include user-friendly apps that guide you through this process with clear step-by-step instructions. Ensuring a strong Wi-Fi connection in your garage area is crucial for optimal performance and reliable operation.
After installation, downloading and configuring the associated mobile app is imperative. These apps serve as command centers from which you can control your garage door remotely. Through these applications, users can open or close their garage doors from anywhere in the world as long as they have internet access on their smartphones. Setting up personalized settings such as notifications for when the door is left open or scheduled operations enhances both convenience and security.
A significant benefit of integrating smartphone controls with garage door systems lies in enhanced security features. With traditional remote controls, misplacing devices or having them stolen posed potential security risks. However, with smartphone integration, access becomes significantly more secure due to biometric authentication methods available on most smartphones today-such as fingerprint scanning or facial recognition-which prevent unauthorized entry.
Moreover, this integration provides peace of mind through real-time alerts and monitoring capabilities. Homeowners receive instant notifications if their garage doors are opened unexpectedly or left ajar for extended periods-a feature particularly beneficial for those who travel frequently or maintain irregular schedules.
Convenience is another prominent advantage of this technological union. Imagine returning home during inclement weather without needing to fumble for keys or remote controllers; simply tapping an icon on your phone suffices to gain entry swiftly and effortlessly. Additionally, sharing access with family members or trusted individuals becomes more manageable by granting temporary digital keys rather than physical copies susceptible to loss.
Furthermore, energy efficiency is an often-overlooked benefit attributed to these smart integrations. By ensuring doors are closed properly when not in use-facilitated by automated reminders-users inadvertently improve insulation within garages leading towards reduced energy consumption related directly back into household costs savings over time.
In conclusion, integrating smartphone controls into garage door systems exemplifies how technology continues reshaping our daily lives toward greater efficiency while prioritizing safety measures simultaneously addressed via heightened accessibility options never before imaginable prior advent mobile computing era we now inhabit ubiquitously throughout society globally wide-reaching impacts felt universally across all demographic lines alike embracing new paradigms ushered forth rapidly evolving interconnected digital age heralding unprecedented levels convenience synonymous newfound lifestyle improvements collectively redefining what constitutes smart living spaces future generations inevitably inherit continue expanding upon foundations laid present-day innovations transformative nature integrated technologies spearheading progress forward unequivocally poised fulfill unlimited potential aspirations shared humanity eagerly awaits embrace fully realized potentials unlocked thereby afforded us means achieve dreams once thought beyond reach
In the modern world, where convenience and technology are intricately intertwined, integrating smartphone access controls into existing garage door systems has become a sought-after upgrade for many homeowners. This technological advancement not only enhances security but also simplifies daily routines by allowing garage doors to be operated from virtually anywhere. However, before embarking on this innovative journey, it is essential to assess the compatibility of your existing garage door equipment with such advanced controls. The process involves meticulous evaluation and strategic planning to ensure a seamless integration.
The first step in assessing compatibility is understanding your current garage door system. Most traditional garage door openers are designed for manual operation or with a basic remote control setup. These older models may not have the necessary components to support smartphone integration directly. Therefore, identifying the brand and model of your existing opener is crucial as it allows you to check its specifications against those required by smartphone access devices.
Once you have gathered information about your current system, the next step is researching available smartphone control options on the market. There are various kits and devices designed to retrofit older systems, making them compatible with modern technology without requiring complete replacement. During this research phase, pay close attention to product reviews and compatibility lists provided by manufacturers. These resources can help identify which products work best with specific types of garage door openers.
After selecting a suitable retrofit device or kit, consider whether any additional hardware will be needed for installation. Some systems might require sensors or new wiring configurations that differ from those used in traditional setups. Consulting with professionals or referring to detailed installation guides can provide clarity on these requirements.
Another critical aspect of compatibility assessment involves ensuring your home's Wi-Fi network is robust enough to support the new technology. Smartphone-controlled garage doors rely on internet connectivity for remote operation; thus, having a stable Wi-Fi signal in your garage area is paramount. Conducting a signal strength test can help determine if upgrades or adjustments are necessary.
Finally, it's important to evaluate any potential security implications associated with integrating smartphone controls into your garage door system. Ensuring that both your home network and chosen smart device employ strong encryption methods will protect against unauthorized access attempts.
In conclusion, while integrating smartphone access controls into an existing garage door system can significantly enhance convenience and security, thorough preparation and assessment of compatibility are vital steps that must not be overlooked. By understanding the specifics of your current setup, researching appropriate solutions, preparing necessary hardware changes, ensuring adequate Wi-Fi coverage, and prioritizing security measures, you pave the way for successful implementation of this cutting-edge technology into everyday life-a true blend of innovation meeting practicality at one's doorstep-or rather-garage threshold!
Garage doors, often overlooked yet crucial elements of our homes, serve not only as entry points but also as vital components of our property's aesthetic and security.. Traditional garage door styles, such as those made from wood or steel panels, are renowned for their classic appeal and robustness.
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In recent years, the realm of garage door automation has experienced remarkable advancements, fundamentally altering how homeowners interact with this ubiquitous element of residential architecture.. Among the most compelling future trends is the potential impact of automation on reducing the frequency of garage door repairs.
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In today's rapidly evolving technological landscape, the integration of smartphone access control systems is becoming a necessity for businesses and individuals aiming to enhance security and convenience. Selecting the right system requires careful consideration of several factors, ensuring that the chosen solution effectively meets the unique needs of its users. This essay explores the crucial steps involved in integrating smartphone access controls, providing insights into making an informed decision.
The first step in integrating a smartphone access control system is conducting a thorough assessment of your specific security needs. This involves evaluating the current security infrastructure, identifying potential vulnerabilities, and determining what level of control and monitoring is required. For instance, a small business might prioritize easy installation and user-friendliness, while larger organizations may need more complex systems with advanced features such as biometric verification or extensive user tracking capabilities.
Once the needs are clearly defined, researching available smartphone access control options becomes imperative. The market offers a plethora of solutions ranging from basic keyless entry systems to sophisticated platforms equipped with cloud-based management tools. It's essential to compare different products based on criteria such as compatibility with existing devices, ease of use, scalability, and cost-effectiveness. Reading reviews and seeking recommendations can also provide valuable insights into how well each system performs in real-world scenarios.
After narrowing down potential options, testing selected systems through demos or trial versions is highly advisable. This hands-on experience allows you to gauge how intuitive the interface is and whether it aligns with your users' proficiency levels. Additionally, testing helps identify any technical issues that could arise during implementation or daily operation.
Security is paramount when selecting an access control system; hence evaluating encryption standards and data protection measures should not be overlooked. Ensuring that the system complies with relevant regulations and industry standards will safeguard sensitive information against unauthorized access or breaches. Furthermore, consider whether regular software updates are provided by the vendor to address emerging security threats effectively.
Integration into existing infrastructure is another critical aspect when choosing a smartphone access control system. Compatibility with current hardware should be verified to prevent unnecessary expenses on additional equipment or modifications. Seamless integration minimizes disruption during installation while optimizing functionality across all components involved in securing premises efficiently.
Training users on how best they can utilize this new technology cannot be overstated either; comprehensive training sessions ensure smooth adoption among employees or residents who'll interact directly with these systems regularly-clarifying doubts regarding operational procedures enhances confidence while minimizing resistance towards change generally associated within organizational settings initially adopting novel technologies like these ones too often seen nowadays globally speaking alike!
Finally yet importantly: ongoing support offered by vendors post-installation ensures continued satisfaction over time-prompt responses addressing technical queries maintain trust between parties involved besides enhancing overall customer experience exponentially greater than anticipated beforehand indeed!
In conclusion: selecting an appropriate smartphone-access-control-system entails meticulous planning encompassing assessments tailored specifically per individual requirements followed closely thereafter via extensive research culminating eventually through practical evaluations/testing phases alongside considering critical aspects related fundamentally around robust-security-measures/integration-capabilities/training-support-elements-all vital contributors ultimately influencing successful implementation processes yielding optimal results desired respectively moving forward progressively onwards!
The modern garage door opener has undergone a significant transformation, morphing from a simple mechanical device into an integral part of the smart home ecosystem. The integration of smartphone-enabled garage door openers provides homeowners with unparalleled convenience and security. By allowing users to control their garage doors through their smartphones, these devices offer a seamless blend of technology and practicality. This essay outlines the installation process and essential steps for integrating smartphone access controls into your home's garage door system.
The journey begins with selecting the right smartphone-enabled garage door opener that suits your needs. Factors such as compatibility with existing systems, user reviews, and features like remote access or notifications should guide your choice. Once you've selected the appropriate device, it's essential to gather all necessary tools and materials before starting the installation process.
The first step in the installation involves setting up the hardware components of your new system. Begin by carefully unpacking the kit's contents and familiarizing yourself with each part. You'll typically find a motor unit, mounting brackets, sensors, and other accessories. Follow the manufacturer's instructions to mount the motor unit onto the ceiling of your garage using suitable brackets and ensure it is securely fastened.
Next, focus on installing safety sensors at either side of your garage door near ground level. These sensors are crucial for preventing accidents by detecting obstacles in the path of a closing door. Ensure they are aligned correctly to establish an uninterrupted connection between them; this is usually indicated by a solid LED light on each sensor.
Once hardware setup is complete, attention turns to wiring connections. Connect power cables from the motor unit to an electrical outlet while ensuring all wires are neatly organized to avoid any interference or hazards. Many modern systems come with wireless capabilities that simplify this step significantly by reducing cumbersome wiring requirements.
With hardware in place and powered up, it's time to integrate smartphone access controls through software configuration. Download the appropriate mobile application recommended by your device's manufacturer onto your smartphone. Create an account if necessary, then follow guided prompts within the app to connect it with your new garage door opener system via Wi-Fi or Bluetooth.
During this phase of integration, you'll likely need to pair your phone with additional smart home hubs or devices if you aim for more comprehensive connectivity throughout other areas in your house ensuring everything communicates seamlessly enhances both functionality and convenience across multiple platforms.
Once connected successfully through digital channels on both ends (your phone interface & physical device), perform some test runs opening/closing cycles from afar utilizing mobile commands: this verifies whether setup procedures were executed correctly without hitches lingering around unnoticed until later stages down-the-line usage scenarios arise unexpectedly causing inconvenience due unforeseen malfunctions initially overlooked during earlier stages prior completion finalization processes conclusion points reached satisfactory results achieved adequately fulfilling expectations placed upon initial outset intentions purposefully laid groundwork establishing foundation future operational stability reliability guarantees peace mind long-term satisfaction enjoyment overall experience enhanced technological advancements provided newfound capabilities ushered forth contemporary living standards redefined era innovations emerged forefront domestic environments everywhere worldwide today!
Finally comes ongoing maintenance considerations ensure longevity optimal performance maintained consistently over extended periods usage lifespan anticipated projected beyond reasonable measures projected foreseeably foreseeable lifetime expectancy cycles typically encountered general consumer products categories associated relevant industries similar nature kind akin parallel comparisons drawn analogous situations comparable circumstances otherwise correlating directly indirectly contextual relevance pertinent subject matter discussed hereinabove previously mentioned contextually referenced accordingly pertaining specifically addressed focused attention concentrated exclusively centered within confines thematic framework delineated comprehensively encapsulated entirety text narrative conveyed present documentation submission current instance occasion hereby concluded succinctly summarized concisely explicitly detailed expounded elucidated hereinbefore aforementioned preceding paragraphs sections chapters segments
In today's rapidly evolving technological landscape, the integration of smartphone access controls has become increasingly important for ensuring both security and user convenience. As mobile applications play an integral role in managing and accessing sensitive information, configuring and testing these applications for optimal functionality is paramount. This process involves several critical steps that align with best practices for integrating smartphone access controls.
The first step in this endeavor is to establish a comprehensive understanding of the application's purpose and the specific access control requirements it must meet. This involves identifying the different types of data that users will need to access through the application and determining the appropriate level of security for each type. By doing so, developers can design a robust framework that secures sensitive information while maintaining user-friendly access.
Once the framework is established, the next phase involves configuring the mobile application to incorporate these access controls effectively. This might include implementing authentication methods such as biometric verification, two-factor authentication, or password protection. Each method offers its own advantages and challenges, requiring careful consideration to ensure they complement one another without compromising usability.
Following configuration, rigorous testing becomes essential to guarantee that all components function seamlessly under various conditions. During this phase, developers simulate potential scenarios where access controls could be challenged or bypassed. This includes testing different devices and operating systems to ensure compatibility across platforms commonly used by end-users.
Moreover, testing should not only focus on functionality but also on performance efficiency. Access control mechanisms should operate swiftly without causing lag or inconvenience during regular use. Efficiency tests help identify any bottlenecks or issues within the application's code that may hinder its performance.
User feedback also plays a crucial role in refining mobile applications during this stage. By involving real users in beta testing phases, developers gain valuable insights into potential usability issues or unforeseen challenges related to access controls. Feedback allows them to make necessary adjustments before full deployment.
Finally, after thorough testing and refinement, continuous monitoring post-deployment ensures sustained optimal functionality of smartphone access controls within the mobile application environment. Regular updates addressing security vulnerabilities are vital in maintaining trust between users and developers while adapting swiftly to emerging threats or changes in technology standards.
In conclusion, configuring and testing a mobile application for optimal functionality concerning smartphone access controls is an intricate process demanding meticulous planning coupled with ongoing evaluation efforts even beyond initial deployment stages. A successful integration strategy balances stringent security measures with seamless user experiences-ultimately fostering confidence among users navigating their digital landscapes securely yet effortlessly through well-designed applications tailored precisely according their needs within today's interconnected world.
In an era where technology permeates virtually every aspect of daily life, the convenience offered by smartphone-controlled garage doors is undeniable. The ability to open and close your garage door from anywhere in the world using just a smartphone is one of those modern marvels that encapsulates both innovation and practicality. However, as with any technological advancement, ensuring security and privacy becomes paramount. Integrating smartphone access controls into garage door systems requires a meticulous approach to safeguard users against potential vulnerabilities.
The first step in integrating smartphone access controls is to ensure robust authentication mechanisms are in place. This involves implementing multi-factor authentication (MFA), which adds an extra layer of security beyond just a password. By requiring users to verify their identity through additional means-such as a fingerprint scan or a one-time code sent via SMS-the system significantly reduces the risk of unauthorized access. Given the ease with which passwords can be compromised, MFA serves as a vital defensive measure.
Next, encryption must be prioritized to protect data transmitted between smartphones and garage door systems. End-to-end encryption ensures that any information exchanged remains confidential and inaccessible to potential interceptors. This means that even if cybercriminals manage to intercept the communication stream, they would be unable to decipher its contents without the decryption keys, which only legitimate users possess.
Another crucial step is regular software updates and patches for both the smartphone app and the garage door system itself. Technology evolves rapidly, and so do threats; keeping software up-to-date helps mitigate vulnerabilities that hackers might exploit. Manufacturers should adopt an agile approach to address security flaws promptly, providing users with timely updates that enhance protection against emerging threats.
User education also plays a pivotal role in ensuring security when integrating smartphone access controls. By informing users about best practices-such as creating strong passwords, recognizing phishing attempts, and understanding how permissions work-they become active participants in safeguarding their own privacy. Educated users are less likely to fall victim to social engineering attacks or inadvertently compromise their security settings.
Furthermore, it's essential for developers to adopt secure coding practices from the outset of designing these systems. Conducting thorough testing during development phases can help identify potential loopholes or weaknesses before they become exploitable vulnerabilities once deployed in real-world scenarios.
Finally, incorporating user-friendly interfaces without compromising on security features ensures broader accessibility while maintaining robust protection standards. A well-designed interface facilitates easy navigation through security settings without overwhelming users with complexity-a balance that's critical for widespread adoption and effective use.
In conclusion, while integrating smartphone access controls into garage door systems offers remarkable convenience, it necessitates careful consideration of security measures at every stage-from initial design through deployment and ongoing maintenance-to protect user data against evolving threats effectively. By combining advanced technologies like MFA and encryption with proactive strategies such as regular updates and user education programs alongside intuitive interfaces designed for ease-of-use yet fortified by rigorous safety protocols-smartphone-controlled garage doors can deliver not only on convenience but also on peace of mind knowing one's home remains secure even amid technological advances shaping our modern world today.
Integrating smartphone access controls into existing systems can dramatically enhance security and convenience, but it also presents a range of challenges that need to be addressed. As businesses and individuals increasingly rely on smartphones for secure entry, payment processing, and identity verification, understanding the steps to effectively integrate these capabilities becomes crucial. In this essay, we will explore the key steps involved in integrating smartphone access controls and discuss troubleshooting common issues that may arise during the process.
The first step in integrating smartphone access controls is to assess the existing infrastructure and identify compatibility requirements. This involves evaluating current hardware and software systems to ensure they can support the new technology. It is essential to determine whether upgrades or replacements are necessary for seamless integration. For instance, older access control systems may require updates to interact with modern smartphones efficiently. Compatibility checks should extend beyond hardware; software frameworks must also be evaluated for their ability to support mobile applications.
Once compatibility is established, the next step is selecting appropriate technology solutions that align with organizational needs. This decision often involves choosing between various methods such as Bluetooth Low Energy (BLE), Near Field Communication (NFC), or cloud-based solutions. Each option offers distinct advantages and potential limitations, making it important for organizations to consider their specific operational contexts when making this choice. BLE might offer better battery life for devices, while NFC could provide quicker interactions at close range.
After selecting suitable technologies, developing a comprehensive implementation plan becomes imperative. This plan should outline timelines, resource allocation, training programs for staff members, and strategies for mitigating potential risks during deployment. Effective communication among team members ensures everyone understands their roles and responsibilities throughout each phase of integration. Collaboration with IT specialists can facilitate smoother transitions by addressing technical concerns proactively.
During the actual integration process, testing plays an integral role in identifying potential issues before full-scale deployment occurs. Conducting pilot tests on a smaller scale allows teams to pinpoint vulnerabilities or glitches within controlled environments before rolling out across larger networks or organizations entirely-this minimizes disruptions caused by unforeseen complications post-launch.
Despite careful planning and execution efforts undertaken thus far; however; some common problems may still surface during smartphone access control implementation:
![]() Blue, green, and red LEDs in 5 mm diffused cases. There are many different variants of LEDs.
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Working principle | Electroluminescence |
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First production | October 1962 |
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A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor.[5] White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device.[6]
Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light.[7] Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red.
Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Later developments produced LEDs available in visible, ultraviolet (UV), and infrared wavelengths with high, low, or intermediate light output, for instance, white LEDs suitable for room and outdoor lighting. LEDs have also given rise to new types of displays and sensors, while their high switching rates are useful in advanced communications technology with applications as diverse as aviation lighting, fairy lights, strip lights, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, lighted wallpaper, horticultural grow lights, and medical devices.[8]
LEDs have many advantages over incandescent light sources, including lower power consumption, a longer lifetime, improved physical robustness, smaller sizes, and faster switching. In exchange for these generally favorable attributes, disadvantages of LEDs include electrical limitations to low voltage and generally to DC (not AC) power, the inability to provide steady illumination from a pulsing DC or an AC electrical supply source, and a lesser maximum operating temperature and storage temperature.
LEDs are transducers of electricity into light. They operate in reverse of photodiodes, which convert light into electricity.
The first LED was created by Soviet inventor Oleg Losev[9] in 1927, but electroluminescence was already known for 20 years, and relied on a diode made of silicon carbide.
Commercially viable LEDs only became available after Texas Instruments engineers patented efficient near-infrared emission from a diode based on GaAs in 1962.
From 1968, commercial LEDs were extremely costly and saw no practical use. Monsanto and Hewlett-Packard led the development of LEDs to the point where, in the 1970s, a unit cost less than five cents.[10]
In a light-emitting diode, the recombination of electrons and electron holes in a semiconductor produces light (be it infrared, visible or UV), a process called "electroluminescence". The wavelength of the light depends on the energy band gap of the semiconductors used. Since these materials have a high index of refraction, design features of the devices such as special optical coatings and die shape are required to efficiently emit light.[11]
Unlike a laser, the light emitted from an LED is neither spectrally coherent nor even highly monochromatic. Its spectrum is sufficiently narrow that it appears to the human eye as a pure (saturated) color.[12][13] Also unlike most lasers, its radiation is not spatially coherent, so it cannot approach the very high intensity characteristic of lasers.
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By selection of different semiconductor materials, single-color LEDs can be made that emit light in a narrow band of wavelengths from near-infrared through the visible spectrum and into the ultraviolet range. The required operating voltages of LEDs increase as the emitted wavelengths become shorter (higher energy, red to blue), because of their increasing semiconductor band gap.
Blue LEDs have an active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN, called cladding layers. By varying the relative In/Ga fraction in the InGaN quantum wells, the light emission can in theory be varied from violet to amber.
Aluminium gallium nitride (AlGaN) of varying Al/Ga fraction can be used to manufacture the cladding and quantum well layers for ultraviolet LEDs, but these devices have not yet reached the level of efficiency and technological maturity of InGaN/GaN blue/green devices. If unalloyed GaN is used in this case to form the active quantum well layers, the device emits near-ultraviolet light with a peak wavelength centred around 365 nm. Green LEDs manufactured from the InGaN/GaN system are far more efficient and brighter than green LEDs produced with non-nitride material systems, but practical devices still exhibit efficiency too low for high-brightness applications.[citation needed]
With AlGaN and AlGaInN, even shorter wavelengths are achievable. Near-UV emitters at wavelengths around 360–395 nm are already cheap and often encountered, for example, as black light lamp replacements for inspection of anti-counterfeiting UV watermarks in documents and bank notes, and for UV curing. Substantially more expensive, shorter-wavelength diodes are commercially available for wavelengths down to 240 nm.[14] As the photosensitivity of microorganisms approximately matches the absorption spectrum of DNA, with a peak at about 260 nm, UV LED emitting at 250–270 nm are expected in prospective disinfection and sterilization devices. Recent research has shown that commercially available UVA LEDs (365 nm) are already effective disinfection and sterilization devices.[15] UV-C wavelengths were obtained in laboratories using aluminium nitride (210 nm),[16] boron nitride (215 nm)[17][18] and diamond (235 nm).[19]
There are two primary ways of producing white light-emitting diodes. One is to use individual LEDs that emit three primary colors—red, green and blue—and then mix all the colors to form white light. The other is to use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, similar to a fluorescent lamp. The yellow phosphor is cerium-doped YAG crystals suspended in the package or coated on the LED. This YAG phosphor causes white LEDs to appear yellow when off, and the space between the crystals allow some blue light to pass through in LEDs with partial phosphor conversion. Alternatively, white LEDs may use other phosphors like manganese(IV)-doped potassium fluorosilicate (PFS) or other engineered phosphors. PFS assists in red light generation, and is used in conjunction with conventional Ce:YAG phosphor.
In LEDs with PFS phosphor, some blue light passes through the phosphors, the Ce:YAG phosphor converts blue light to green and red (yellow) light, and the PFS phosphor converts blue light to red light. The color, emission spectrum or color temperature of white phosphor converted and other phosphor converted LEDs can be controlled by changing the concentration of several phosphors that form a phosphor blend used in an LED package.[20][21][22][23]
The 'whiteness' of the light produced is engineered to suit the human eye. Because of metamerism, it is possible to have quite different spectra that appear white. The appearance of objects illuminated by that light may vary as the spectrum varies. This is the issue of color rendition, quite separate from color temperature. An orange or cyan object could appear with the wrong color and much darker as the LED or phosphor does not emit the wavelength it reflects. The best color rendition LEDs use a mix of phosphors, resulting in less efficiency and better color rendering.[citation needed]
The first white light-emitting diodes (LEDs) were offered for sale in the autumn of 1996.[24] Nichia made some of the first white LEDs which were based on blue LEDs with Ce:YAG phosphor.[25] Ce:YAG is often grown using the Czochralski method.[26]
Mixing red, green, and blue sources to produce white light needs electronic circuits to control the blending of the colors. Since LEDs have slightly different emission patterns, the color balance may change depending on the angle of view, even if the RGB sources are in a single package, so RGB diodes are seldom used to produce white lighting. Nonetheless, this method has many applications because of the flexibility of mixing different colors,[27] and in principle, this mechanism also has higher quantum efficiency in producing white light.[28]
There are several types of multicolor white LEDs: di-, tri-, and tetrachromatic white LEDs. Several key factors that play among these different methods include color stability, color rendering capability, and luminous efficacy. Often, higher efficiency means lower color rendering, presenting a trade-off between the luminous efficacy and color rendering. For example, the dichromatic white LEDs have the best luminous efficacy (120 lm/W), but the lowest color rendering capability. Although tetrachromatic white LEDs have excellent color rendering capability, they often have poor luminous efficacy. Trichromatic white LEDs are in between, having both good luminous efficacy (>70 lm/W) and fair color rendering capability.[29]
One of the challenges is the development of more efficient green LEDs. The theoretical maximum for green LEDs is 683 lumens per watt but as of 2010 few green LEDs exceed even 100 lumens per watt. The blue and red LEDs approach their theoretical limits.[citation needed]
Multicolor LEDs offer a means to form light of different colors. Most perceivable colors can be formed by mixing different amounts of three primary colors. This allows precise dynamic color control. Their emission power decays exponentially with rising temperature,[30] resulting in a substantial change in color stability. Such problems inhibit industrial use. Multicolor LEDs without phosphors cannot provide good color rendering because each LED is a narrowband source. LEDs without phosphor, while a poorer solution for general lighting, are the best solution for displays, either backlight of LCD, or direct LED based pixels.
Dimming a multicolor LED source to match the characteristics of incandescent lamps is difficult because manufacturing variations, age, and temperature change the actual color value output. To emulate the appearance of dimming incandescent lamps may require a feedback system with color sensor to actively monitor and control the color.[31]
This method involves coating LEDs of one color (mostly blue LEDs made of InGaN) with phosphors of different colors to form white light; the resultant LEDs are called phosphor-based or phosphor-converted white LEDs (pcLEDs).[32] A fraction of the blue light undergoes the Stokes shift, which transforms it from shorter wavelengths to longer. Depending on the original LED's color, various color phosphors are used. Using several phosphor layers of distinct colors broadens the emitted spectrum, effectively raising the color rendering index (CRI).[33]
Phosphor-based LEDs have efficiency losses due to heat loss from the Stokes shift and also other phosphor-related issues. Their luminous efficacies compared to normal LEDs depend on the spectral distribution of the resultant light output and the original wavelength of the LED itself. For example, the luminous efficacy of a typical YAG yellow phosphor based white LED ranges from 3 to 5 times the luminous efficacy of the original blue LED because of the human eye's greater sensitivity to yellow than to blue (as modeled in the luminosity function).
Due to the simplicity of manufacturing, the phosphor method is still the most popular method for making high-intensity white LEDs. The design and production of a light source or light fixture using a monochrome emitter with phosphor conversion is simpler and cheaper than a complex RGB system, and the majority of high-intensity white LEDs presently on the market are manufactured using phosphor light conversion.[citation needed]
Among the challenges being faced to improve the efficiency of LED-based white light sources is the development of more efficient phosphors. As of 2010, the most efficient yellow phosphor is still the YAG phosphor, with less than 10% Stokes shift loss. Losses attributable to internal optical losses due to re-absorption in the LED chip and in the LED packaging itself account typically for another 10% to 30% of efficiency loss. Currently, in the area of phosphor LED development, much effort is being spent on optimizing these devices to higher light output and higher operation temperatures. For instance, the efficiency can be raised by adapting better package design or by using a more suitable type of phosphor. Conformal coating process is frequently used to address the issue of varying phosphor thickness.[citation needed]
Some phosphor-based white LEDs encapsulate InGaN blue LEDs inside phosphor-coated epoxy. Alternatively, the LED might be paired with a remote phosphor, a preformed polycarbonate piece coated with the phosphor material. Remote phosphors provide more diffuse light, which is desirable for many applications. Remote phosphor designs are also more tolerant of variations in the LED emissions spectrum. A common yellow phosphor material is cerium-doped yttrium aluminium garnet (Ce3+:YAG).[citation needed]
White LEDs can also be made by coating near-ultraviolet (NUV) LEDs with a mixture of high-efficiency europium-based phosphors that emit red and blue, plus copper and aluminium-doped zinc sulfide (ZnS:Cu, Al) that emits green. This is a method analogous to the way fluorescent lamps work. This method is less efficient than blue LEDs with YAG:Ce phosphor, as the Stokes shift is larger, so more energy is converted to heat, but yields light with better spectral characteristics, which render color better. Due to the higher radiative output of the ultraviolet LEDs than of the blue ones, both methods offer comparable brightness. A concern is that UV light may leak from a malfunctioning light source and cause harm to human eyes or skin.[citation needed]
A new style of wafers composed of gallium-nitride-on-silicon (GaN-on-Si) is being used to produce white LEDs using 200-mm silicon wafers. This avoids the typical costly sapphire substrate in relatively small 100- or 150-mm wafer sizes.[34] The sapphire apparatus must be coupled with a mirror-like collector to reflect light that would otherwise be wasted. It was predicted that since 2020, 40% of all GaN LEDs are made with GaN-on-Si. Manufacturing large sapphire material is difficult, while large silicon material is cheaper and more abundant. LED companies shifting from using sapphire to silicon should be a minimal investment.[35]
There are RGBW LEDs that combine RGB units with a phosphor white LED on the market. Doing so retains the extremely tunable color of RGB LED, but allows color rendering and efficiency to be optimized when a color close to white is selected.[36]
Some phosphor white LED units are "tunable white", blending two extremes of color temperatures (commonly 2700K and 6500K) to produce intermediate values. This feature allows users to change the lighting to suit the current use of a multifunction room.[37] As illustrated by a straight line on the chromaticity diagram, simple two-white blends will have a pink bias, becoming most severe in the middle. A small amount of green light, provided by another LED, could correct the problem.[38] Some products are RGBWW, i.e. RGBW with tunable white.[39]
A final class of white LED with mixed light is dim-to-warm. These are ordinary 2700K white LED bulbs with a small red LED that turns on when the bulb is dimmed. Doing so makes the color warmer, emulating an incandescent light bulb.[39]
Another method used to produce experimental white light LEDs used no phosphors at all and was based on homoepitaxially grown zinc selenide (ZnSe) on a ZnSe substrate that simultaneously emitted blue light from its active region and yellow light from the substrate.[40]
In an organic light-emitting diode (OLED), the electroluminescent material composing the emissive layer of the diode is an organic compound. The organic material is electrically conductive due to the delocalization of pi electrons caused by conjugation over all or part of the molecule, and the material therefore functions as an organic semiconductor.[41] The organic materials can be small organic molecules in a crystalline phase, or polymers.[42]
The potential advantages of OLEDs include thin, low-cost displays with a low driving voltage, wide viewing angle, and high contrast and color gamut.[43] Polymer LEDs have the added benefit of printable and flexible displays.[44][45][46] OLEDs have been used to make visual displays for portable electronic devices such as cellphones, digital cameras, lighting and televisions.[42][43]
LEDs are made in different packages for different applications. A single or a few LED junctions may be packed in one miniature device for use as an indicator or pilot lamp. An LED array may include controlling circuits within the same package, which may range from a simple resistor, blinking or color changing control, or an addressable controller for RGB devices. Higher-powered white-emitting devices will be mounted on heat sinks and will be used for illumination. Alphanumeric displays in dot matrix or bar formats are widely available. Special packages permit connection of LEDs to optical fibers for high-speed data communication links.
These are mostly single-die LEDs used as indicators, and they come in various sizes from 1.8 mm to 10 mm, through-hole and surface mount packages.[47] Typical current ratings range from around 1 mA to above 20 mA. LED's can be soldered to a flexible PCB strip to form LED tape popularly used for decoration.
Common package shapes include round, with a domed or flat top, rectangular with a flat top (as used in bar-graph displays), and triangular or square with a flat top. The encapsulation may also be clear or tinted to improve contrast and viewing angle. Infrared devices may have a black tint to block visible light while passing infrared radiation, such as the Osram SFH 4546.[48]
5 V and 12 V LEDs are ordinary miniature LEDs that have a series resistor for direct connection to a 5 V or 12 V supply.[49]
High-power LEDs (HP-LEDs) or high-output LEDs (HO-LEDs) can be driven at currents from hundreds of mA to more than an ampere, compared with the tens of mA for other LEDs. Some can emit over a thousand lumens.[50][51] LED power densities up to 300 W/cm2 have been achieved. Since overheating is destructive, the HP-LEDs must be mounted on a heat sink to allow for heat dissipation. If the heat from an HP-LED is not removed, the device fails in seconds. One HP-LED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp.
Some HP-LEDs in this category are the Nichia 19 series, Lumileds Rebel Led, Osram Opto Semiconductors Golden Dragon, and Cree X-lamp. As of September 2009, some HP-LEDs manufactured by Cree exceed 105 lm/W.[52]
Examples for Haitz's law—which predicts an exponential rise in light output and efficacy of LEDs over time—are the CREE XP-G series LED, which achieved 105 lm/W in 2009[52] and the Nichia 19 series with a typical efficacy of 140 lm/W, released in 2010.[53]
LEDs developed by Seoul Semiconductor can operate on AC power without a DC converter. For each half-cycle, part of the LED emits light and part is dark, and this is reversed during the next half-cycle. The efficiency of this type of HP-LED is typically 40 lm/W.[54] A large number of LED elements in series may be able to operate directly from line voltage. In 2009, Seoul Semiconductor released a high DC voltage LED, named 'Acrich MJT', capable of being driven from AC power with a simple controlling circuit. The low-power dissipation of these LEDs affords them more flexibility than the original AC LED design.[55]
An LED strip, tape, or ribbon light is a flexible circuit board populated by surface-mount light-emitting diodes (SMD LEDs) and other components that usually comes with an adhesive backing. Traditionally, strip lights had been used solely in accent lighting, backlighting, task lighting, and decorative lighting applications, such as cove lighting.
LED strip lights originated in the early 2000s. Since then, increased luminous efficacy and higher-power SMDs have allowed them to be used in applications such as high brightness task lighting, fluorescent and halogen lighting fixture replacements, indirect lighting applications, ultraviolet inspection during manufacturing processes, set and costume design, and growing plants.
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The current in an LED or other diodes rises exponentially with the applied voltage (see Shockley diode equation), so a small change in voltage can cause a large change in current. Current through the LED must be regulated by an external circuit such as a constant current source to prevent damage. Since most common power supplies are (nearly) constant-voltage sources, LED fixtures must include a power converter, or at least a current-limiting resistor. In some applications, the internal resistance of small batteries is sufficient to keep current within the LED rating.[citation needed]
LEDs are sensitive to voltage. They must be supplied with a voltage above their threshold voltage and a current below their rating. Current and lifetime change greatly with a small change in applied voltage. They thus require a current-regulated supply (usually just a series resistor for indicator LEDs).[65]
Efficiency droop: The efficiency of LEDs decreases as the electric current increases. Heating also increases with higher currents, which compromises LED lifetime. These effects put practical limits on the current through an LED in high power applications.[66]
Unlike a traditional incandescent lamp, an LED will light only when voltage is applied in the forward direction of the diode. No current flows and no light is emitted if voltage is applied in the reverse direction. If the reverse voltage exceeds the breakdown voltage, which is typically about five volts, a large current flows and the LED will be damaged. If the reverse current is sufficiently limited to avoid damage, the reverse-conducting LED is a useful noise diode.[citation needed]
By definition, the energy band gap of any diode is higher when reverse-biased than when forward-biased. Because the band gap energy determines the wavelength of the light emitted, the color cannot be the same when reverse-biased. The reverse breakdown voltage is sufficiently high that the emitted wavelength cannot be similar enough to still be visible. Though dual-LED packages exist that contain a different color LED in each direction, it is not expected that any single LED element can emit visible light when reverse-biased.[citation needed]
It is not known if any zener diode could exist that emits light only in reverse-bias mode. Uniquely, this type of LED would conduct when connected backwards.
LED manufacturing involves multiple steps, including epitaxy, chip processing, chip separation, and packaging.[76]
In a typical LED manufacturing process, encapsulation is performed after probing, dicing, die transfer from wafer to package, and wire bonding or flip chip mounting,[77] perhaps using indium tin oxide, a transparent electrical conductor. In this case, the bond wire(s) are attached to the ITO film that has been deposited in the LEDs.
Flip chip circuit on board (COB) is a technique that can be used to manufacture LEDs.[78]
Conventional LEDs are made from a variety of inorganic semiconductor materials. The following table shows the available colors with wavelength range, voltage drop and material:
Color | Wavelength (nm) | Voltage (V) | Semiconductor material | |
---|---|---|---|---|
Infrared | λ > 760 | ΔV < 1.9 | Gallium arsenide (GaAs)
Aluminium gallium arsenide (AlGaAs) |
|
Red | 610 < λ < 760 | 1.63 < ΔV < 2.03 | Aluminium gallium arsenide (AlGaAs)
Gallium arsenide phosphide (GaAsP) Aluminium gallium indium phosphide (AlGaInP) Gallium(III) phosphide (GaP) |
|
Orange | 590 < λ < 610 | 2.03 < ΔV < 2.10 | Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP) Gallium(III) phosphide (GaP) |
|
Yellow | 570 < λ < 590 | 2.10 < ΔV < 2.18 | Gallium arsenide phosphide (GaAsP)
Aluminium gallium indium phosphide (AlGaInP) Gallium(III) phosphide (GaP) |
|
Green | 500 < λ < 570 | 1.9[79] < ΔV < 4.0 | Indium gallium nitride (InGaN) / Gallium(III) nitride (GaN)
Gallium(III) phosphide (GaP) Aluminium gallium indium phosphide (AlGaInP) Aluminium gallium phosphide (AlGaP) |
|
Blue | 450 < λ < 500 | 2.48 < ΔV < 3.7 | Zinc selenide (ZnSe)
Indium gallium nitride (InGaN) Silicon carbide (SiC) as substrate Silicon (Si) as substrate — (under development) |
|
Violet | 400 < λ < 450 | 2.76 < ΔV < 4.0 | Indium gallium nitride (InGaN) | |
Purple | multiple types | 2.48 < ΔV < 3.7 | Dual blue/red LEDs,
blue with red phosphor, or white with purple plastic |
|
Ultraviolet | λ < 400 | 3.1 < ΔV < 4.4 | Diamond (235 nm)[80]
Boron nitride (215 nm)[81][82] Aluminium nitride (AlN) (210 nm)[16] Aluminium gallium nitride (AlGaN) Aluminium gallium indium nitride (AlGaInN) — (down to 210 nm)[83] |
|
White | Broad spectrum | 2.7 < ΔV < 3.5 | Blue diode with yellow phosphor or violet/UV diode with multi-color phosphor |
LED uses fall into five major categories:
The application of LEDs in horticulture has revolutionized plant cultivation by providing energy-efficient, customizable lighting solutions that optimize plant growth and development.[90] LEDs offer precise control over light spectra, intensity, and photoperiods, enabling growers to tailor lighting conditions to the specific needs of different plant species and growth stages. This technology enhances photosynthesis, improves crop yields, and reduces energy costs compared to traditional lighting systems. Additionally, LEDs generate less heat, allowing closer placement to plants without risking thermal damage, and contribute to sustainable farming practices by lowering carbon footprints and extending growing seasons in controlled environments.[91] Light spectrum affects growth, metabolite profile, and resistance against fungal phytopathogens of Solanum lycopersicum seedlings.[92] LEDs can also be used in micropropagation.[93]
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The low energy consumption, low maintenance and small size of LEDs has led to uses as status indicators and displays on a variety of equipment and installations. Large-area LED displays are used as stadium displays, dynamic decorative displays, and dynamic message signs on freeways. Thin, lightweight message displays are used at airports and railway stations, and as destination displays for trains, buses, trams, and ferries.
One-color light is well suited for traffic lights and signals, exit signs, emergency vehicle lighting, ships' navigation lights, and LED-based Christmas lights
Because of their long life, fast switching times, and visibility in broad daylight due to their high output and focus, LEDs have been used in automotive brake lights and turn signals. The use in brakes improves safety, due to a great reduction in the time needed to light fully, or faster rise time, about 0.1 second faster[citation needed] than an incandescent bulb. This gives drivers behind more time to react. In a dual intensity circuit (rear markers and brakes) if the LEDs are not pulsed at a fast enough frequency, they can create a phantom array, where ghost images of the LED appear if the eyes quickly scan across the array. White LED headlamps are beginning to appear. Using LEDs has styling advantages because LEDs can form much thinner lights than incandescent lamps with parabolic reflectors.
Due to the relative cheapness of low output LEDs, they are also used in many temporary uses such as glowsticks and throwies. Artists have also used LEDs for LED art.
With the development of high-efficiency and high-power LEDs, it has become possible to use LEDs in lighting and illumination. To encourage the shift to LED lamps and other high-efficiency lighting, in 2008 the US Department of Energy created the L Prize competition. The Philips Lighting North America LED bulb won the first competition on August 3, 2011, after successfully completing 18 months of intensive field, lab, and product testing.[94]
Efficient lighting is needed for sustainable architecture. As of 2011, some LED bulbs provide up to 150 lm/W and even inexpensive low-end models typically exceed 50 lm/W, so that a 6-watt LED could achieve the same results as a standard 40-watt incandescent bulb. The lower heat output of LEDs also reduces demand on air conditioning systems. Worldwide, LEDs are rapidly adopted to displace less effective sources such as incandescent lamps and CFLs and reduce electrical energy consumption and its associated emissions. Solar powered LEDs are used as street lights and in architectural lighting.
The mechanical robustness and long lifetime are used in automotive lighting on cars, motorcycles, and bicycle lights. LED street lights are employed on poles and in parking garages. In 2007, the Italian village of Torraca was the first place to convert its street lighting to LEDs.[95]
Cabin lighting on recent[when?] Airbus and Boeing jetliners uses LED lighting. LEDs are also being used in airport and heliport lighting. LED airport fixtures currently include medium-intensity runway lights, runway centerline lights, taxiway centerline and edge lights, guidance signs, and obstruction lighting.
LEDs are also used as a light source for DLP projectors, and to backlight newer LCD television (referred to as LED TV), computer monitor (including laptop) and handheld device LCDs, succeeding older CCFL-backlit LCDs although being superseded by OLED screens. RGB LEDs raise the color gamut by as much as 45%. Screens for TV and computer displays can be made thinner using LEDs for backlighting.[96]
LEDs are small, durable and need little power, so they are used in handheld devices such as flashlights. LED strobe lights or camera flashes operate at a safe, low voltage, instead of the 250+ volts commonly found in xenon flashlamp-based lighting. This is especially useful in cameras on mobile phones, where space is at a premium and bulky voltage-raising circuitry is undesirable.
LEDs are used for infrared illumination in night vision uses including security cameras. A ring of LEDs around a video camera, aimed forward into a retroreflective background, allows chroma keying in video productions.
LEDs are used in mining operations, as cap lamps to provide light for miners. Research has been done to improve LEDs for mining, to reduce glare and to increase illumination, reducing risk of injury to the miners.[97]
LEDs are increasingly finding uses in medical and educational applications, for example as mood enhancement.[98] NASA has even sponsored research for the use of LEDs to promote health for astronauts.[99]
Light can be used to transmit data and analog signals. For example, lighting white LEDs can be used in systems assisting people to navigate in closed spaces while searching necessary rooms or objects.[100]
Assistive listening devices in many theaters and similar spaces use arrays of infrared LEDs to send sound to listeners' receivers. Light-emitting diodes (as well as semiconductor lasers) are used to send data over many types of fiber optic cable, from digital audio over TOSLINK cables to the very high bandwidth fiber links that form the Internet backbone. For some time, computers were commonly equipped with IrDA interfaces, which allowed them to send and receive data to nearby machines via infrared.
Because LEDs can cycle on and off millions of times per second, very high data bandwidth can be achieved.[101] For that reason, visible light communication (VLC) has been proposed as an alternative to the increasingly competitive radio bandwidth.[102] VLC operates in the visible part of the electromagnetic spectrum, so data can be transmitted without occupying the frequencies of radio communications.
Machine vision systems often require bright and homogeneous illumination, so features of interest are easier to process. LEDs are often used.
Barcode scanners are the most common example of machine vision applications, and many of those scanners use red LEDs instead of lasers. Optical computer mice use LEDs as a light source for the miniature camera within the mouse.
LEDs are useful for machine vision because they provide a compact, reliable source of light. LED lamps can be turned on and off to suit the needs of the vision system, and the shape of the beam produced can be tailored to match the system's requirements.
The discovery of radiative recombination in aluminum gallium nitride (AlGaN) alloys by U.S. Army Research Laboratory (ARL) led to the conceptualization of UV light-emitting diodes (LEDs) to be incorporated in light-induced fluorescence sensors used for biological agent detection.[103][104][105] In 2004, the Edgewood Chemical Biological Center (ECBC) initiated the effort to create a biological detector named TAC-BIO. The program capitalized on semiconductor UV optical sources (SUVOS) developed by the Defense Advanced Research Projects Agency (DARPA).[105]
UV-induced fluorescence is one of the most robust techniques used for rapid real-time detection of biological aerosols.[105] The first UV sensors were lasers lacking in-field-use practicality. In order to address this, DARPA incorporated SUVOS technology to create a low-cost, small, lightweight, low-power device. The TAC-BIO detector's response time was one minute from when it sensed a biological agent. It was also demonstrated that the detector could be operated unattended indoors and outdoors for weeks at a time.[105]
Aerosolized biological particles fluoresce and scatter light under a UV light beam. Observed fluorescence is dependent on the applied wavelength and the biochemical fluorophores within the biological agent. UV induced fluorescence offers a rapid, accurate, efficient and logistically practical way for biological agent detection. This is because the use of UV fluorescence is reagentless, or a process that does not require an added chemical to produce a reaction, with no consumables, or produces no chemical byproducts.[105]
Additionally, TAC-BIO can reliably discriminate between threat and non-threat aerosols. It was claimed to be sensitive enough to detect low concentrations, but not so sensitive that it would cause false positives. The particle-counting algorithm used in the device converted raw data into information by counting the photon pulses per unit of time from the fluorescence and scattering detectors, and comparing the value to a set threshold.[106]
The original TAC-BIO was introduced in 2010, while the second-generation TAC-BIO GEN II, was designed in 2015 to be more cost-efficient, as plastic parts were used. Its small, light-weight design allows it to be mounted to vehicles, robots, and unmanned aerial vehicles. The second-generation device could also be utilized as an environmental detector to monitor air quality in hospitals, airplanes, or even in households to detect fungus and mold.[107][108]
The light from LEDs can be modulated very quickly so they are used extensively in optical fiber and free space optics communications. This includes remote controls, such as for television sets, where infrared LEDs are often used. Opto-isolators use an LED combined with a photodiode or phototransistor to provide a signal path with electrical isolation between two circuits. This is especially useful in medical equipment where the signals from a low-voltage sensor circuit (usually battery-powered) in contact with a living organism must be electrically isolated from any possible electrical failure in a recording or monitoring device operating at potentially dangerous voltages. An optoisolator also lets information be transferred between circuits that do not share a common ground potential.
Many sensor systems rely on light as the signal source. LEDs are often ideal as a light source due to the requirements of the sensors. The Nintendo Wii's sensor bar uses infrared LEDs. Pulse oximeters use them for measuring oxygen saturation. Some flatbed scanners use arrays of RGB LEDs rather than the typical cold-cathode fluorescent lamp as the light source. Having independent control of three illuminated colors allows the scanner to calibrate itself for more accurate color balance, and there is no need for warm-up. Further, its sensors only need be monochromatic, since at any one time the page being scanned is only lit by one color of light.
Since LEDs can also be used as photodiodes, they can be used for both photo emission and detection. This could be used, for example, in a touchscreen that registers reflected light from a finger or stylus.[109] Many materials and biological systems are sensitive to, or dependent on, light. Grow lights use LEDs to increase photosynthesis in plants,[110] and bacteria and viruses can be removed from water and other substances using UV LEDs for sterilization.[15] LEDs of certain wavelengths have also been used for light therapy treatment of neonatal jaundice and acne.[111]
UV LEDs, with spectra range of 220 nm to 395 nm, have other applications, such as water/air purification, surface disinfection, glue curing, free-space non-line-of-sight communication, high performance liquid chromatography, UV curing dye printing, phototherapy (295nm Vitamin D, 308nm Excimer lamp or laser replacement), medical/ analytical instrumentation, and DNA absorption.[104][112]
LEDs have also been used as a medium-quality voltage reference in electronic circuits. The forward voltage drop (about 1.7 V for a red LED or 1.2V for an infrared) can be used instead of a Zener diode in low-voltage regulators. Red LEDs have the flattest I/V curve above the knee. Nitride-based LEDs have a fairly steep I/V curve and are useless for this purpose. Although LED forward voltage is far more current-dependent than a Zener diode, Zener diodes with breakdown voltages below 3 V are not widely available.
The progressive miniaturization of low-voltage lighting technology, such as LEDs and OLEDs, suitable to incorporate into low-thickness materials has fostered experimentation in combining light sources and wall covering surfaces for interior walls in the form of LED wallpaper.
LEDs require optimized efficiency to hinge on ongoing improvements such as phosphor materials and quantum dots.[113]
The process of down-conversion (the method by which materials convert more-energetic photons to different, less energetic colors) also needs improvement. For example, the red phosphors that are used today are thermally sensitive and need to be improved in that aspect so that they do not color shift and experience efficiency drop-off with temperature. Red phosphors could also benefit from a narrower spectral width to emit more lumens and becoming more efficient at converting photons.[114]
In addition, work remains to be done in the realms of current efficiency droop, color shift, system reliability, light distribution, dimming, thermal management, and power supply performance.[113]
Early suspicions were that the LED droop was caused by elevated temperatures. Scientists showed that temperature was not the root cause of efficiency droop.[115] The mechanism causing efficiency droop was identified in 2007 as Auger recombination, which was taken with mixed reaction.[66] A 2013 study conclusively identified Auger recombination as the cause.[116]
A new family of LEDs are based on the semiconductors called perovskites. In 2018, less than four years after their discovery, the ability of perovskite LEDs (PLEDs) to produce light from electrons already rivaled those of the best performing OLEDs.[117] They have a potential for cost-effectiveness as they can be processed from solution, a low-cost and low-tech method, which might allow perovskite-based devices that have large areas to be made with extremely low cost. Their efficiency is superior by eliminating non-radiative losses, in other words, elimination of recombination pathways that do not produce photons; or by solving outcoupling problem (prevalent for thin-film LEDs) or balancing charge carrier injection to increase the EQE (external quantum efficiency). The most up-to-date PLED devices have broken the performance barrier by shooting the EQE above 20%.[118]
In 2018, Cao et al. and Lin et al. independently published two papers on developing perovskite LEDs with EQE greater than 20%, which made these two papers a mile-stone in PLED development. Their device have similar planar structure, i.e. the active layer (perovskite) is sandwiched between two electrodes. To achieve a high EQE, they not only reduced non-radiative recombination, but also utilized their own, subtly different methods to improve the EQE.[118]
In the work of Cao et al.,[119] researchers targeted the outcoupling problem, which is that the optical physics of thin-film LEDs causes the majority of light generated by the semiconductor to be trapped in the device.[120] To achieve this goal, they demonstrated that solution-processed perovskites can spontaneously form submicrometre-scale crystal platelets, which can efficiently extract light from the device. These perovskites are formed via the introduction of amino acid additives into the perovskite precursor solutions. In addition, their method is able to passivate perovskite surface defects and reduce nonradiative recombination. Therefore, by improving the light outcoupling and reducing nonradiative losses, Cao and his colleagues successfully achieved PLED with EQE up to 20.7%.[119]
Lin and his colleague used a different approach to generate high EQE. Instead of modifying the microstructure of perovskite layer, they chose to adopt a new strategy for managing the compositional distribution in the device—an approach that simultaneously provides high luminescence and balanced charge injection. In other words, they still used flat emissive layer, but tried to optimize the balance of electrons and holes injected into the perovskite, so as to make the most efficient use of the charge carriers. Moreover, in the perovskite layer, the crystals are perfectly enclosed by MABr additive (where MA is CH3NH3). The MABr shell passivates the nonradiative defects that would otherwise be present perovskite crystals, resulting in reduction of the nonradiative recombination. Therefore, by balancing charge injection and decreasing nonradiative losses, Lin and his colleagues developed PLED with EQE up to 20.3%.[121]
Certain blue LEDs and cool-white LEDs can exceed safe limits of the so-called blue-light hazard as defined in eye safety specifications such as "ANSI/IESNA RP-27.1–05: Recommended Practice for Photobiological Safety for Lamp and Lamp Systems".[122] One study showed no evidence of a risk in normal use at domestic illuminance,[123] and that caution is only needed for particular occupational situations or for specific populations.[124] In 2006, the International Electrotechnical Commission published IEC 62471 Photobiological safety of lamps and lamp systems, replacing the application of early laser-oriented standards for classification of LED sources.[125]
While LEDs have the advantage over fluorescent lamps, in that they do not contain mercury, they may contain other hazardous metals such as lead and arsenic.[126]
In 2016 the American Medical Association (AMA) issued a statement concerning the possible adverse influence of blueish street lighting on the sleep-wake cycle of city-dwellers. Critics in the industry claim exposure levels are not high enough to have a noticeable effect.[127]
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