The LED (Light Emitting Diode) market is the hottest segment of the lighting market, growing at a compound annual growth rate of approximately 40% per year over the past 5 years. There have been significant strides over the past several years, making LEDs cheaper and more efficient. Most major lighting manufacturers, including GE, Philips, Samsung and a host of lesser known brands, are competing to come out with the first commercially acceptable products for home and office use. LEDs now dominate the automotive market, replacing their incandescent predecessors in almost every new vehicle. They are replacing traffic lights throughout the nation. LEDs are appearing in more and more applications and are seen as the replacement for both incandescent and fluorescent lighting because they last far longer, their efficiencies are surpassing the best of all other lighting sources, their pricing is dropping rapidly, they pose no environmental threat, they are far less delicate than either incandescent or fluorescent lamps, their form factor is tiny, allowing many alternative shapes and sizes, and their unique color adaptability enables them to be independently tunable both in color and intensity. The U.S. & Canada have outlawed the incandescent lamp as of 2012 and Ireland has done so as of January 2009. Doubtless all industrialized countries will outlaw them eventually. It has been projected that within 10 years, LEDs will become the norm of the industry, replacing all incandescent and fluorescent lamps.
How It All Started
Historians of technology agree there have already been two major revolutions in lighting technology, in the 19th century and again in the 20th. In the dim era of oil lanterns and gas- lights, the incandescent light bulb began an astonishing revolution that amazed the first World’s Fair in Chicago in 1893. From the early 1870s through Thomas Edison’s commercialization of the technology in 1880 (and his founding of GE), the incandescent light was the pinnacle of 19th-century marvels, though its final form wasn’t achieved until 1910, when the tungsten filament brought the cost of incandescent lamps down to the average man’s price level. Only a generation later came the second revolution in lighting, when in 1938 GE engineers invented the fluorescent lamp, with twice the energy efficiency of the incandescent lamp as well as twice its lifetime. Only the compactness and high brightness of the incandescent filament kept it in widespread use, in spite of the continued refinements of the fluorescent lamp over the past 65 years, raising its efficiency growing to six times that of the incandescent lamp (80 lumens per watt [lm/W]) and its lifetime to 10 times (15,000hours). Thus, the fluorescent lamp became the lamp of choice for most commercial, government, and institutional facilities. On the other hand, the incandescent lamp and its halogen offspring continue as the lamp of choice for most residential lighting, as well as much commercial down-lighting, because of its compactness, perceived warm hue, and high color rendering index.
The Third Revolution in Lighting
The third revolution in lighting began very quietly in 1962, (again, at GE) with the first practical demonstration of the light emitting diode (LED) by Nick Holonyak. Quietly because LEDs were good only as modest indicator-lights, since early devices emitted only 0.1 lumens per Watt, 1/20th the luminous efficacy of Edison’s very first electric light bulb (0.5% of today’s), and they came only in red and yellow colors.
This all changed in 1992 with a factor-of-ten increase in red and amber output, from a new quaternary solid-state material, AlInGaP, supplanting the previous GaAsP and GaP materials. LED efficacies jumped from 1-2 lm/W to 10-20lm/W. Thus LEDs became superior to red-filtered incandescent lamps, so that as their costs fell, red-LEDs appeared first in automobile taillights and then in red traffic signals.
For the missing colors of blue and green LEDs, a similar materials-shift began in 1993, when in Japan Nichia’s Shuji Nakamura producing very bright blue and green GaN LEDs, with a hundred times the luminosity of previous materials. This made RGB packages possible, and with a full color gamut finally available, LEDs entered the general lighting marketplace. Also, Nichia introduced the first white LED, by covering a blue LED with layer of yellow YAG (yttrium aluminum garnet) phosphor. While RGB packages require controls, white LEDs have a color temperature fixed by the specification of phosphor thickness. In the past fifteen years, both types have grown in output as fast as they have dropped in price, making their market penetration even faster than either incandescent or fluorescent lamps. For example, the average automobile now contains in excess of 200LEDs in its dashboard assembly and tail/stoplights. And one only has to look closely at our stop lights at major intersections to realize that almost all of these have been converted to LEDs over the past 5 years. General lighting is next.
The magnitude and scale of the coming LED boom have yet to be fully appreciated, except by those working in LED illumination or those who pay close attention to the technology sections of the WSJ or Business Week. The remarkable energy savings and superior lifetime of LED lighting have engendered burgeoning government and utility incentives for their widespread adoption, adding further economic impetus to their future market penetration.
- White LEDs just now in production have efficacies over 100 lm/W (equivalent to sunlight), and are expected to reach 130 lm/W over the next 12 to 18 months (as compared to tungsten-halogen incandescent lamps with 15 to 20 lm/W, or to compact fluorescent lamps of 40 to 60 lm/W, and long tube fluorescent lamps of 80-100 lm/W).
- LEDs produce much less waste heat than incandescent light bulbs of the same luminosity, and no infrared or ultraviolet accompanies their visible output.
- LEDs have an extremely long lifespan: typically 60,000hours (continuous on), four times as long as the best fluorescent bulbs and 40 times longer than the best incandescent bulbs. Unlike mercury-laden fluorescent lamps, LEDs are quite disposable, with no toxic waste problems.
- Rather than the abrupt and unpredictable burnout of incandescent bulbs, LEDs degrade (but rarely fail outright) by dimming over time, in a manner that is very predictable.
- LEDs don’t need the color filters that traditional lighting methods require. The addition of the filters greatly reduce the efficiency of other methods of lighting.
- LEDs are insensitive to vibration and shock, and are extremely tough, without glass envelopes to shatter or filaments to break, unlike incandescent and fluorescent lamps.
- LEDs love cold temperature, in fact, the colder the ambient temperature is, the better the LED operates. In contrast, the luminosity of fluorescent lamps drops dramatically at temperatures near or below freezing. This factor is especially important for one of the intended markets of the Company, illumination of refrigerator compartments in supermarkets.
- LEDs can be dimmed (unlike fluorescents), and without changing color temperature, unlike incandescent lamps, which grow redder. Dimming can be under the control of occupancy sensors or demand-response radio receivers (as the Company’s refrigerator lighting will be). Also, RGB LEDs can tailor the color temperature for time of day effects or to complement day-lighting.
LED lamps, however, do have some shortcomings, ones that have so far precluded them from more rapid penetration into the general lighting market. In the coming LED boom these factors will become less and less important:
- So far, the price per lumen of LED light flux has been much higher than for conventional light sources, but the prices of LED lamps have been falling historically at 30% per year. Although to be price-comparable with conventional light sources, LED prices still need to fall another ten fold before retail buyers won’t need life-cycle costing arguments.
- Individual LED lamps have not been as powerful as incandescent sources. Therefore, most LED powered lights require an array of LEDs to match the luminosity of conventional lamps, making the light source more complex and costly. Optics alleviates this factor by efficiently putting the light only where it is needed. The newest multi-chip lamps, however, are nearing a thousand lumens from a single package, a key breakthrough towards displacing old-technology light sources.
- LEDs are current-driven devices, not, as were previous sources, voltage driven. Although the drive-current and light output are directly related, exceeding an LEDs maximum current rating leads to an over-temperature condition that reduces operating lifetime, unless special attention is paid to the transfer of heat out of the LED.
Why Use InteLED?
InteLED’s non-imaging optical technologies and LED integration know-how can combat some of the shortcoming of using LEDs.
What markets can benefit from optically enhanced LED products? InteLED teams have over 50 years experience in designing and providing LED lighting solutions for multiple markets.
Here are some of them:
- Transportation – Automotive, Air and Sea
- Signage / Channel Letters
- Backlight / LED Displays
- Theatrical / Entertainment
- Architectural / Interior Mood Lighting
- General Lighting –
- Incandescent Light Bulb Replacement
- Fluorescent Replacement
- Downlight System
- Exterior / Landscape Lighting