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What Is An LED?

The most efficient light fixtures of the 21st century will be made from Light Emitting Diodes, aka LEDs, small pieces of semiconductor that glow intensely when electricity runs through them in the right direction. LEDs are the light of the future.

LED is the acronym for Light Emitting Diode. This is a tiny "solid state" semiconductor device much like a transistor. An LED has the property that when an electrical current flows between its conducting plates, almost all of the power dissipated by the current flow over the voltage drop is converted into visible light.

As a diode, the device will not permit current to flow in the opposite direction, thus the electrical connections must be of the correct polarity for the LED to function. With special circuitry LEDs can operate with AC (alternating current), emitting light the half-the-time when the polarity is correct.

Typically, over 85% of the energy of the electrical current flowing through an LED lamp is converted into visible light. Very little of the energy is used to create heat. However, if a resistor must be used in series with the LED to reduce the DC voltage to match that required by the LED, the voltage drop across the resistor will create heat that must be dissipated.

The average lifetime of an LED that has been burned in (operated past the time when "infant mortalities" occur) is typically 100,000 hours of continuous operation. That amounts to over 11 years. Shocking an LED with over-voltage or with excess heat will lower the lifetime of the device.

Since the LED is a solid state device, if it is securely mounted, it is quite resistant to physical damage.

The color of the light created by an LED is determined by the chemical composition of the semiconducting material. The most common LEDs available today produce light that is ultraviolet (400nm: a wavelength of 400 nanometers), pink (420nm), blue (470nm), aqua (505 nanometers), green (525nm), yellow (590nm), red (605-660nm), and infrared (880-945nm). Prices of LEDs depend upon their color; for example, pink is more than twice as expensive as red.

Energy Distribution for a Blue LED

The spectrum of colored LEDs is very sharp. An LED resonates at a single optical wavelength, and produces one and only one color. As you can see in the figure above, there is no light energy produced in the other wavelengths. If you look at a red, green, or yellow LED through a blue filter (which blots out all light except blue), you will see no light coming through the filter.

What we recognize as white light is a "spread spectrum," energy in wavelengths ranging from ultraviolet to infrared. White light has a mix of all colors in it. LEDs that produce white light are hybrids: the light from an ultraviolet or blue LED shines through a special phosphorescent material that absorbs much of that light energy and re-emits it at a lower energy to produce a spread white spectrum. However, you will still see a peak of light energy at the wavelength of the exciting LED.

Energy Distribution for a White LED

Though the light from white LEDs appears bluish, it is suitable for much of the lighting in RVs. As improvements are made in the phosphorescent materials, white LEDs will become "warmer," meaning less of the excitation color will come through and more of the longer wavelength colors will be mixed in.

White LEDs are not recommended for use as vehicle brake and turn-signal lights. There is little energy in the spectrum between 600nm and 700nm, the colors that can be seen through the red lens covers. Use the native red-colored LEDs instead.

LEDs have been in use for over twenty years, and the technology has improved over that time. However, up to now the suitability of LEDs for interior RV lighting has been inadequate. Though the prices have been pushed low, the quality and applicability of the existing products has been marginal at best.

Recent advances in technology have changed that picture. LightBlasters uses the latest nexLED™ LED technology to design intense, high-performance devices for RV lighting applications. This new technology, coupled with strict attention to product quality and applicability, are key to providing the Prudent RVer with adequate LED lighting for their RV.