What is an LED?
LED stands for Light Emitting Diode. It is a semiconductor device which converts electrical energy directly into light. Compare this to the incandescent lamp which converts energy into light by heating a thin wire filament until it glows and gives off light.
LEDs are made from a semiconductor material that has impurities called "dopants" that are added to the crystal. Two types of dopants are added to create "N" and "P" regions. "N" regions are parts of the crystal that are electron rich (free electrons) and "P" regions that are deficient in electrons (free holes). When the "P" region is connected to a positive voltage and the "N" region is connected to a negative voltage a current flows. When an excited electron from the "N" region meets with a hole from the "P" region, they combine where the two regions meet. This liberates energy of a discrete amount (the sum of electron and hole energy) in the form of light of a particular color.
White LEDs are formed by covering a blue LED with a yellow phosphor. This phosphor converts the blue light to a range of colors in the yellow part of the spectrum. This combination of blue and yellow light gives the appearance of white. Compare the color spectrums of white LEDs and incandescent lights.
We pioneered the use of LED optimized optics as well as custom electronic drivers for use in flashlights. The LED is the most significant innovation in portable lighting since the advent of the incandescent lamp. It is more efficient, less fragile, runs cooler, and has a 50-100 times improvement in life expectancy. The quality of light is quite different from that of an incandescent lamp. Like HID, it appears much whiter and shines farther underwater. Despite all of the positives there are also some challenges. Red and purple objects do not appear as vibrant under white LED light. Brightness decreases slightly as the LED heats up. Because power is limited to a few watts per LED, large arrays must be clustered to reach the illumination of a high wattage incandescent lamp.
The unique electrical properties of the LED make it possible to attach it to an electronic circuit which controls power from the batteries in a flashlight in such a way that brightness and color of the beam remain constant as the batteries drain. Contrast this to a conventional flashlight with an incandescent bulb. With fresh batteries the light is extremely bright. As the batteries are consumed the light grows dim and the color turns more yellow. This feature is represented by the "e" used in naming UK eLED lights.
Another unique feature of LEDs is that they continue to give light when there is very little power left in the batteries. The benefit is that even though the batteries are considered dead in any other type of flashlight, the LED continues to give light for hours or even days after the high brightness mode is past. For emergency situations this could make the difference.
UK is unique among light manufacturers in that we have many of our LEDs custom designed and manufactured for us. Like our incandescent lamps we found that the optimum light source/optics configurations were often not possible with standard products. Rather than compromise, we spend the extra effort to produce what is optimum, not what is easy.
UK is also unique in light manufacturers in that we custom design analog discrete component drivers for each of our lights. This means that our lights have drivers which produce 90% efficiency versus the 60 to 80% efficiency produced by competitors IC driven LEDs. Our circuit boards will often have 10 to 30 components versus the 3 to 5 components used in other brands.
For any light which uses LEDs it is extremely important to keep the LED from getting too hot (less than 100°C). Heat shortens the life of the LED and reduces the brightness. At UK, we have developed circuitry which monitors the temperature of the LED and cuts back power when used in conditions which allow it to get too hot. We have also developed specialized metal heat sinks which either carry the heat to the batteries (helpful in sub-freezing temperatures) or into the water (in our dive lights). For our underwater lights, this affect allows our lights to burn much brighter as the water acts as a an excellent coolant for the LEDs.
At UK, we work to find innovative ways to cluster several LEDs chips in a single package. This provide a uniform narrow beam of light which appears like it was made from central lamp and facilitates removal of the heat from the LEDs.