ANALYSIS
Edison to LED: Advancements in Lighting Technology
By Brandon Billingsley Technological advancements have greatly influenced human existence over the past 130
years since Tomas Edison worked to combine a carbon filament, which would enable a light bulb to glow for over 1500 hours. Fast-forward to 2012 and that technology has evolved to the light-emitting diode, or LED, and the school bus industry is among those that stand to benefit. British experimenter H.J Rounds discovered electro-luminescence, an optical and electri-
cal phenomenon in which a material emits light in response to the passage of an electric current or to a strong electric field, in 1907, less than 40 years after the invention of Edison’s light bulb. However, it would take another 55 years until Nick Holonyak, Jr., the so-called father of the LED, would develop the first practical visible spectrum (red) LED while work- ing at General Electric in 1962. LED light technology has evolved from the early days of the first-generation 5 millimeter
LED, with its inherent heat management problems, to today’s high-output LED technology. Practically everyone is familiar with LEDs encapsulated in a 5 mm (or smaller) plastic-like, bul- let-shaped case. Tese early LED designs are the most commonly recognized with their long metal connectors protruding for easy solder connections. Far from being outdated, these arrays of LEDs are still used today because of their high brightness and long lifespan. In the mid-1990s, high-brightness blue LEDs were developed. Ten, the addition of a
phosphor coating to “yellow-down” the blue light to appear white earned the Millinium Technology Prize in 2006, yielding the high-intensity white LED. Tis is important as it be- gins the transition of LED lamps from a signal lamp to become a primary light that can illuminate for the human eye to see with, while offering the low power consumption and long lifespan advantages LED is known for. Enter SMD, or Surface Mount Device, which employs surface-mount diodes, further ad-
vancing LED technology for everyday use. As the SMD LED light source is a very small and lightweight chip enveloped by an epoxy resin, it reduces power consumption further and produces less heat. Tis results in as much as three times less optical decay than the 5 mm LEDs used only a few years ago. Among the many advatages of the SMD LED is the miniaturized components, which
are mounted directly to the board. Tey can be placed very close together and maintain the capability to produce the MCCOB or Multi-Color Chip On Board. Just when we think we’ve ehausted all acronyms, the multi-color chips provide for what is called RGB for “red, green, blue,” the three primary lighting colors that can be mixed in various intensities and combined to form most perceivable colors. Tese are the chips used in our laptops, tablet computers and smartphones. Currently, we’re witnessing a revolution in energy-efficient lighting that provides a long
lifespan. New products, from personal communication devices to household LED lights, are possible as a result of chip on-board and surface-mount technology, which has inte- grated solid-state lighting into the computer age. Now evident is that colored lenses are no longer necessary for various colors of light. As
LED technology is adopted and employed by modern socket/base lamps, changing light bulbs may become something of the past in our homes, offices and on the school bus. ■
Brandon Billingsley is president of Heavy Duty Bus Parts, a manufacturer and supplier of OEM and aftermarket parts based in Willis, Texas. Billingsley can be contacted at
lbrandon@directbus.com.
64 School Transportation News Magazine September 2012
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