Efficiency and Long Life only Part of LED Lighting Benefits|
Article- January 2012 By Larson Electronics.com
Larson Electronics High Intensity LED Boat Light
Among the top cited benefits of LEDs are their extreme long life and very high efficiency. While these are excellent points to consider, LEDs offer a host of other advantages over traditional incandescent and fluorescent lights that only serve to further add to their desirability over traditional light sources.
LEDs hold several distinct traits that give them an inherent advantage over other light sources due to their unique design. Rather than heating a filament to create light, which is highly wasteful and inefficient, LEDs pass electrical energy through a small piece of semi-conductor coated with materials designed to alter the wavelength of energy radiated from the semi-conductor. As energy passes through this chip, a process called electroluminescence takes place which results in light energy being radiated from the materials surface. The type of material applied or “doped” to the semi-conductor determines the wavelength of the light energy being radiated, in effect allowing LED designers to control the color of the light being produced without the need for filters or colored lenses. This process is highly efficient as much less energy is wasted as heat or blocked by an inefficient lens, and has the benefit of allowing designers to produce light tailored to narrow parts of the light spectrum.
This unique design makes LEDs ideal for specialty applications as well as general illumination as they can be designed to produce very “clean” light. By “clean” we mean light that covers only a narrow band of the electromagnetic spectrum, which means that a blue LED will produce blue light only and little or no red or orange light, and so on with LEDs of other colors. This narrow band emission was initially a problem for designers of LEDs looking to produce LEDs that could be applied to general illumination applications, because white light includes a wide part of the electromagnetic spectrum. For instance, if you direct a focused beam of white light at a prism, you’ll see a rainbow effect, with the white light split into its several color wavelengths. In order to produce LEDs that could radiate white, developers found they could either combine tiny red, green, and blue LED chips onto one small square to create a white light emitting LED, or they could coat the semi-conducting material with materials such as phosphorous which acts to alter the wavelength of the light energy emitted. LEDs can also be designed to produce invisible ultraviolet and infrared light, making them excellent for covert applications such as security cameras and military night vision devices. Regardless of how it is done, LEDs now rival all other forms of lighting for light quality and intensity, and surpass most in efficiency and longevity, all while offering even more advantages which we’ll go over next.
With all other forms of lighting, be it incandescent, fluorescent, or HID, the bulbs emit light in all directions from the bulbs surface. The result is that a lot of light is lost radiating away from where we want it to go. If you put a four foot long fluorescent tube by itself over your workspace, you’re only going to get a fraction the light it produces reaching the area you want illuminated. Designers try to overcome this problem by adding reflectors and housings that attempt to redirect all of the light towards where it is needed, but a good portion of light is still lost due to inefficient reflector properties and diffusion. LEDs however, radiate light in a much more directional nature. LEDs are basically flat in shape, and while the surface of the LED radiates, its reverse side does not. For most practical intents, LEDs thus radiate light energy perpendicular to the emitting surface. As a result, more of the total amount of light produced by an LED reaches the task area rather than radiating off in unwanted directions. Developers can also modify the surface shape of the LED, making it somewhat concave or convex, as well as add reflectors and special lenses, which then allows them to even more tightly control the radiation pattern, spreading it or narrowing it as needed. The end result is that where a fluorescent tube of 1,000 lumens was once needed to illuminated a task space, an LED fixture of 700 lumens can put the same amount of light on that same area simply because it radiates more efficiently even though it produces less over all lumen output. This means that combined with the already high energy efficiency of the LED, efficiency is even more greatly improved simply getting more of the light produced reaching where it is needed.
LEDs are very small, averaging only 3-5 millimeters across. Larger or smaller LEDs are available, but for most applications these sizes are used. Since LEDs are so small, yet produce so many lumens per watt, they can be installed into a huge variety of fixtures that would be impractical for a normal incandescent bulb. They can be set up in clusters as a replacement for incandescent bulbs, arrayed in strips, mounted in rows as is common with LED light bars for boats, and even mounted singly in tiny fixtures for specialty applications. This compact size and versatile installation capability makes LEDs ideal for recessed and hidden lighting, task lighting, and installation in unusual areas such as under cabinets or along railings. The small size of LEDs comes with a price however as although LEDS run much cooler than other lamps, they still produce heat which must be removed in order to maintain LED longevity. Developers address this heat by mounting the LEDs to fixtures either designed to act as heat sinks, or including dedicated heat sinks into fixtures, both of which methods work to radiate the heat produced away from the LED.
Although they aren’t indestructible, when it comes to lighting, LEDs are about as close as you can get. LEDs resemble the circuitry you’d find in a television or computer more than they do a light bulb. They have no glass, no gases or vapors, and have no flimsy wire filaments. They are usually either encased within a hard clear resin, or housed within a sealed fixture, all of which makes them highly resistant to vibrations, impacts and shocks. You could literally drop an LED fixture on the floor (provided the housing has no glass or cheap plastic) then pick it up and install it and find no reduction in effectiveness. The same cannot be said of traditional lamps, which either shatter on impact or are prone to having the filament break.
One more attractive aspect of LEDs is their ability to provide instant full power illumination and resist the negative effects of repeated on and off cycling. Most HID lamps require a warm up and cool down period between on and off cycles. When an HID lamp is switched on, it takes up to 3 minutes for it to reach full output. If it is switched off after reaching full operating temperature, it must cool down before it can again be switched back on. Fluorescent lights on the other hand are subject to a greatly reduced life-span through frequent on and off cycling. If a fluorescent lamp is only run for brief periods, much as you would use a light in your closet, its operational life can easily be reduced by half or more. Fluorescent lights must thus be operated for prolonged periods in order to achieve their greatest efficiency and operational life. LEDs however, are an instant on light source that requires no cool down or warm up period, and is not subject to degradation or reduced life-span from frequent cycling.
Although LEDs are more efficient and long lived, many still have some difficulty justifying their higher price. As outlined here, the benefits offered by LEDs go far beyond simple efficiency, and offer practical uses that other light source simply cannot practically match. By switching or upgrading to LEDs, you not only reduce the costs associated with lighting, you also improved the durability, longevity and overall effectiveness of your lighting as well.