Beyond the Bulb

Light Emitting Diodes (LEDs)

Since their introduction in the early 1960s, LEDs have evolved from simple indicator lights and alphanumeric displays to an exciting new source for general lighting. LEDs differ radically from traditional light sources in that there are no glass bulbs or filaments to break, or electrodes to decay. Instead, LEDs are solid state light sources,basically a chemical chip embedded in a plastic capsule. When the chip is energized by applying a voltage, it emits visible light, the color depending on the chips chemical composition. The light can then be focused, routed, or scattered using lenses, wave guides or diffusers. Because LEDs run on direct current, they must be operated with a transformer- type power supply.

Run Long, Run Strong

With the LEDs solid state construction comes durability and exceptionally long life. For example, a properly operated red or yellow LED can maintain up to 50% of its initial brightness after 100,000 hours. The classic LED,a radial design with its characteristic wire leads, set the standard for miniature light sources. However, new surface mount technologies (SMT) have eliminated external wiring, allowing even smaller LEDs to be mounted directly to printed circuit boards, and resulting in more durable modular systems. System durability is critical for taking advantage of LEDs long service life, and becomes important in demanding applications like traffic and automotive signal or situations where lamp replacement costs are high.

Advances in Light Output and Color Quality

Due to the tremendous pace of technical developments, LED efficacy now rivals or surpasses that of standard incandescent lamps. For example, white LEDs are now producing more than 20 lumens per watt, compared to 8 to 15 lumens per watt for incandescent lamps. White LEDs are actually blue LEDs with a phosphor coating, which converts a portion of the blue light to yellow, the combination resulting in white light. First available in cool white (e.g., 6000 K), white LEDs are now available in neutral and warm white, quite often demanded in architectural applications. LEDs are even more efficient at producing pure colored light, as their entire light output is channeled into single wavelengths. With traditional light sources, colored filters have to be used to create colored light, absorbing and wasting much of the lamps light output. LEDs small size and minimal power draw make them ideal for situations where storage batteries are used as in RVs and marine.  LEDs are also ideal for low-profile signage and architectural accent applications.

Innovative Applications

Flexible strips. light bars, light panels, light bricks  and linear LED modules (fluorescent tubes) can provide uniform back for signs and contour for architecture, while occupying a fraction of the space and consuming a fraction of the energy required by traditional light sources. Similarly, low-profile marker lights can highlight steps or edges, guiding or alerting users to hazards in areas like auditoriums, stairways and subway platforms. Effect lights combine an array of a number of LEDs with individual lenses in a single compact module, focusing the combined light output into an intense (approximately 1000 cd) and narrow (four degree) beam, which can provide colorful accent for architectural features. LEDs invite designers and manufacturers to "think beyond the bulb," and ponder a more seamless integration of an effective and efficient light source.