Five concepts that high-power LED lighting designers should understand

        High-power LEDs, which usually refer to LEDs above 1W, are the hottest technology in the market. Since the birth of this technology, high-power LEDs have attracted widespread attention from the lighting industry and consumers around the world for their wide range of uses and full functions. High-power LEDs

        are a major breakthrough in the development of lighting technology, with unparalleled advantages in energy efficiency, cost savings and lighting. High-power LEDs can reach 80 lumens per watt (note: the brightness of ordinary incandescent lamps is 15 lumens/watt, and the brightness of CFLs is 70 lumens/watt), providing unlimited energy saving possibilities. In addition, the life of high-power LEDs is 10-15 times that of traditional incandescent bulbs and 3-10 times longer than that of CFLs. In fact, in addition to this, the durability of LED technology greatly saves lighting maintenance expenses. LEDs have better design flexibility than other lighting. LED systems are compact and can be used with sensors or other lighting controllers such as dimmers, daylight control devices, and color dynamic regulators.

        As regions, countries and city agencies pave the way for the transition from traditional incandescent lighting to newer technologies, high-power LEDs will become more popular in the coming years. Countries around the world (including EU member states such as Japan, Australia, Brazil and Canada) will strictly ban the use of incandescent bulbs in 2012. In the United States, some cities have begun to use LED technology in traffic signals and street lights. With the implementation of state laws in the United States (such as California Law Article 24) requiring the use of energy-saving lighting in buildings, it is believed that the speed at which LED devices replace traditional lighting equipment in the United States will double in the next few years. Although lighting equipment using LED technology and traditional energy-saving lamps can both achieve energy-saving effects, LED lighting equipment also has environmental protection functions. Energy-saving lamps contain mercury elements that cause environmental pollution. At present, more than twenty states in the United States have enacted laws to restrict the use of mercury-containing lamps.

        Today, we stand on the cusp of a new era of lighting led by high-power LEDs. Interestingly, however, there are still some widespread misunderstandings about this technology. In order to make this developing technology more powerful and effective in future technology products, design engineers need to correctly understand the performance of high-power LEDs and all aspects of design integration. Here are 5 concepts that high-power LED lighting designers often confuse, and test how much you know about high-power LEDs.

Concept 1: High-power LEDs consume high energy 

        . Wrong. A key benefit of high-power LED technology is low energy consumption. Although high-power LEDs consume more energy than standard LEDs, some comparative values ​​in surveys show that high-power LEDs are the lowest energy on the market. A regular LED lamp consumes 75-15mW, while a high-power LED consumes between 1W and 10W (no upper limit is required, 10W is the upper limit of the current standard size, which can be compared with a finished device with many components). When compared with a 40W low-power household bulb and a 60W standard fluorescent lamp, these are considered low energy values. In some cases, the energy consumption of a 60W incandescent lamp is equivalent to that of a 15W CFL, while the energy consumption of CFL is closer to that of high-power LEDs. However, LEDs do not contain mercury and have a long life, making them the first choice for low-energy light sources.

        In response to the common misconception that high-power LEDs consume a lot of energy, many groups in the industry have begun to refer to high-power LEDs as high-brightness (HB) LEDs.

Concept 2: For household appliances where color rendering is critical, it is not advisable to choose high-power LEDs to replace incandescent lamps

        because the special phosphor blue chip device of white high-power LEDs will make the color performance inconsistent. 
   
        Wrong. The color rendering level is from 1 to 100, and 100 is exactly the same as sunlight on the visible spectrum. When the color rendering index (CRI) rating drops below 80, the color under the light will not match the true color of the object. Research shows that from the perspective of the true color of the object, color matching is more important than light brightness. The human eye is not as sensitive to subtle changes in color matching as it is to changes in light brightness. This makes color rendering extremely important, especially in practical applications - such as lighting food in refrigerators, lighting clothing changing rooms, or lighting paintings in exhibition halls where color perception is extremely important. Both white and colored high-power LEDs continue to provide high color rendering scores. This has not always been the case, but is due to recent technological breakthroughs.

        The first white LEDs were made from blue indium gallium (InGaN) LED chips with phosphors. Until about three years ago, the color rendering of white high-power LEDs was not enough to meet practical needs. "Cold" light is usually used in installation applications, office spaces or sidewalks, but phosphors cannot produce satisfactory "warm" white light, which is needed for kitchen and bedroom lighting to create a warm atmosphere. In the

        past two years, especially, technological advances have made it possible to use white phosphor LED lighting with consistent cool and warm tones. Advances in phosphors and accumulated experience in mass production have made it possible to create automated systems. This automated system can automatically classify and measure the radiation spectrum of cool and warm white LED lights. However, in the past, LEDs were limited to the two options of "white" or "non-white", but now some manufacturers can divide white into 50 different "hues".

        Further developments in LED color rendering may come from the progress of three-primary color (RGB) LEDs. RGB LEDs are characterized by chips of three colors, red, green and blue, packaged together. These chips can be used to produce white light or other colors of light. RGB technology has made great progress in recent years. Before this, RGB technology strived to achieve color stability, especially the color stability of LED red chips as a function of wavelength and conversion temperature intensity. The new generation of RGB LED controllers challenged this technology by derating the color and modulating the pulse width.

        In 2008, high-power RGB LEDs, such as Lumex's AstraLED, became available. High-power RGB LEDs are extremely useful for a wide variety of applications that require bright light and low energy consumption. A

        good CRI score is usually greater than 90. Most energy-saving bulbs have a CRI between 75-90, while incandescent bulbs reach 100. LEDs can reach a CRI of 90 or more, which was unattainable when LED technology was first introduced six years ago. CRI systems do not translate well to RGB LEDs. But if you look at the phosphor spectra of white LEDs and RGB LED conversions, you will see how much usable light there is in the emitted spectrum. It makes sense that the more wavelengths of light there are, the easier it is to get true white light. 
         In addition to providing excellent color rendering, high-power RGB LEDs have other key advantages. Packaging the red, green and blue chips together saves 30% in cost and 67% in real estate expenses compared to using high-power red, green and blue packaging separately. In addition, the sorting and storage process can be simplified to a single part number instead of three completely different parts.

Concept 3: One advantage of high power LEDs is that they are not hot to the touch 

        . High power LEDs do emit heat. Heat from a solid core cannot be dissipated in the form of infrared radiation and needs to be dissipated from the LED device. Thermal management is an important factor to consider when creating an LED system.

        The type of thermal management required for an LED system varies from device to device. A 1W high power LED system can remove heat through a special PCB (printed circuit board) with extra copper. A higher power LED system will require heat sinking technology to remove heat.

        The cost of thermal management is increasing, so the question is how to choose high power LEDs for generally cheaper non-LED technologies. First, properly thermally managed HP LEDs have a longer lifespan than other products on the market. They are virtually unaffected by vibration and shock. There is a wide operating temperature range, which can provide fine-tuning of output and color tone, which is simply not available with other general lighting. At the same time, their inherent lifespan is longer than that of current non-LED technologies. All of these factors save costs, greatly reducing the investment required for thermal management.

Concept 4: Top LED suppliers now offer customized high-power LED solutions

        . Not only has high-power LED technology advanced in recent years, but the services provided by LED suppliers have also developed rapidly. Truly excellent LED suppliers not only provide superior product quality, but also provide in-depth services. Excellent LED suppliers will have expert insight into the application of LED technology to a wider range of lighting systems. Excellent LED suppliers should have expertise in optical, thermal and electronic systems to help you find the best LED solution for your specific application.

One way to judge the quality of technical support provided by suppliers is to pay more attention to them during the first interaction. Excellent suppliers should ask a wide range of questions, such as the system you are creating, to confirm whether the technology they have identified is basically a match for your actual needs. They may ask you questions about design aspects or environmental and performance prerequisites. Suppliers will not only tell you which LED is more suitable for your actual needs, but also provide information on how to integrate this technology with other system components such as lenses, printed circuit boards, wiring harnesses, and switchboard device technology in a "plug and play template".

Concept 5: High-power LEDs are mainly used for general lighting

        . With general lighting accounting for about 20% of electricity bills in many developed countries, it is no surprise that the focus on high-power LEDs has been on general lighting applications. Cities are committed to reducing energy, maintenance and replacement costs every year by switching to high-power LED technology, such as in traffic lights, street lights, parking structure lighting, etc. However,

        new applications for high-power LED technology are constantly emerging, and many of them are quickly becoming popular with the public. Some of the more popular applications include: Automotive – turn signals, headlights, backlighting for car dashboards, map lights, overhead lighting, continuous lighting, license plate lighting, decorative accent lighting, and signal lighting; Home appliances – refrigerators, cookers, washers and dryers, and freezer lighting; Backlighting – consumer electronics, such as company logos on computers; Communications equipment – ​​servers, gateways, network hubs, cell phone base stations; Consumer electronics – LCD monitors or LCD TVs; Medical equipment – ​​sensor systems, diagnostic equipment, gadgets, and digital scales and monitors; Security lighting – spotlights, deterrent lighting, access control lighting, indoor and outdoor cameras; Signage – jumbotrons, emergency exit lighting, large billboards, decorative or architectural lighting; Military – lighting for weapon systems, submarines, and aerial target identifiers.

        Some of the exciting applications of high-power LEDs in the coming years will incorporate sensors, such as lighting that turns on when you enter a driveway or approach a refrigerator in a grocery store. Infrared LED technology is also a rapidly developing area, including innovative applications such as nighttime urban combat lighting, long-range (greater than 2,500 feet) transmitters and detectors, and ultra-high-speed agricultural sorting equipment. In the future, we will see high-performance IR LEDs driving communication capabilities between home appliances, between vehicles and homes, and changing the way we use night vision systems.

Author Bio

        Mr. Coates is the High Power Technology Manager at Lumex and a leader in LED and LCD technology. During his ten years in the optoelectronics field, he has been involved in the design of LEDs and LCDs for industry-leading brands in applications ranging from small appliances to large aircraft, with a specialization in high-power LED lighting. Mr. Coates has a degree in electrical engineering from Northern Illinois University and can be reached at engineering@lumex.com .

        Lumex, an ITW company, is a leading designer and manufacturer of components, devices, and displays for optoelectronic applications. Their products are widely used in human-machine interfaces, sometimes in detectors, short-range signals, and fiber optic communications. Lumex Corporation manufactures thousands of state-of-the-art, high-efficiency optoelectronic components, devices and displays, targeting specific application and customer markets in South America, Asia and Europe.

        The company is headquartered in Dongzhen, Hsinchu County, Taiwan and Palatine, Illinois, with operations located near Frankfurt, Germany. Manufacturing facilities are located in Illinois, Taiwan and China, and its distributors are located in North America, Europe and the Pacific Rim. Since its founding in 1980, Lumex has become a global company specializing in providing application solutions - with production efficiency usually only associated with high-volume operations. Lumex first achieved ISO 9001 certification in 1996. By

Brian Coates,

Manager, High Power Technology

, Lumex