Why the White LED Shows White

The ‘white’ of white LEDs comes from the narrow-band blue naturally emitted by GaN LEDs, plus a broad spectrum yellow generated by a phosphor coating on the die which absorbs a proportion of the blue and converts it to yellow.

‘GaN’ die are actually InGaN heterostructures, which can produce operational wavelengths from green to ultra-violet by varying the relative amounts of indium and gallium during production.

Although this blue die + yellow phosphor approach yields light which appears white, it has little green and almost no red content leading to inferior colour rendering compared with incandescent bulbs and even ‘tri-phosphor’ florescent tubes. ‘Warm white’ LEDs, which include a red-producing phosphor, are an attempt to improve this situation as well as make LEDs illumination more acceptable in living spaces.

LEDtronics has the largest variety of White LEDs and LED lamps on the market from White SMT LEDs, 3mm, 5mm White LEDs, to Direct Incandescent Replacement White Based LED lamps in standard electrical bases and voltages from 6 Volts to 270 Volts. Base styles such as T1-3/4 (5mm) Midget-Flanged White based LED lamps, Telephone-Slide based White LED Lamps, T3-3/4 (9mm) Miniature based White LED lamps, 15mm DC Bayonet based White LED lamps, 15mm SC Bayonet based White LED lamps, A19, R20, PAR20, R30, S11, S14L, G30, Candelabra Screw based, Panel-Mount and MR16-style based White LED lamps. And durable White LED Torches and Flashlights.

White LED

LED technology is driving the future of lighting with the developments made in the efficacy of white LEDs in the past few years,

As white light is the main driver for general illumination, there is a particularly strong focus on improving the efficiency of white LEDs, which currently outperform tungsten halogen lamps with efficacies from 45-55lm.

Manufacturing methods have allowed for significant progress to be made in increasing the efficiency of LEDs. Previously, the only way to produce white LED light was by the additive colour mixing of the three basic colours using so-called “multi-LED”, ie, three semiconductor chips (red, green and blue LEDs) had to be combined.

Today it is possible to produce white LED light with a single chip.

In luminescence conversion, only a blue LED is used, whose light stimulates a luminescent substance that emits yellow light. With interaction, the system produces the colour white.

White light is generated on the basis of a principle similar to that used in luminescent substance lighting. Depending on the composition of the luminescent substance, various white tones can be realised.

White LED versions of traditional luminaires are already available from several manufacturers, particularly in the MR11 spotlight  style.

LED headlights for cars are in the pipeline is producing a range of multi-die packages that are close to producing enough light for road illumination. LED bicycle headlights are already available.

Let’s Switch to LED Lighting

Studies suggest that a complete conversion to the lights could decrease carbon dioxide emissions from electric power use for lighting by up to 50 percent in just over 20 years; in the United States, lighting accounts for about 6 percent of all energy use. A recent report by McKinsey & Company cited conversion to LED lighting as potentially the most cost effective of a number of simple approaches to tackling global warming using existing technology.

LED lighting was once relegated to basketball scoreboards, cellphone consoles, traffic lights and colored Christmas lights. But as a result of rapid developments in the technology, it is now poised to become common on streets and in buildings, as well as in homes and offices. Some American cities, including Ann Arbor, Mich., and Raleigh, N.C., are using the lights to illuminate streets and parking garages, and dozens more are exploring the technology. And the lighting now adorns the conference rooms and bars of some Renaissance hotels, a corridor in the Pentagon and a new green building at Stanford.

LEDs are more than twice as efficient as compact fluorescent bulbs, currently the standard for greener lighting. Unlike compact fluorescents, LEDs turn on quickly and are compatible with dimmer switches. And while fluorescent bulbs contain mercury, which requires special disposal, LED bulbs contain no toxic elements, and last so long that disposal is not much of an issue.

Another issue is that current LEDs generally provide only “directional light” rather than a 360-degree glow, meaning they are better suited to downward facing streetlights and ceiling lights than to many lamp-type settings.

And in the rush to make cheaper LED lights, poorly made products could erase the technology’s natural advantage, experts warn. LEDs are tiny sandwiches of two different materials that release light as electrons jump from one to the other. The lights must be carefully designed so heat does not damage them, reducing their lifespan to months from decades. And technological advances that receive rave reviews in a university laboratory may not perform as well when mass produced for the real world.

The lights are also rapidly moving indoors, where they could have an enormous effect on climate change. About 20 percent of carbon dioxide emissions associated with buildings in the United States and the United Kingdom are related to indoor lighting; in some houses the number is as high as 40 percent.

This month, LED lights were for the first time the centerpiece at two of the world’s major trade shows for lighting, Lightfare International in New York and EuroLuce in Milan. A growing number of builders are starting to fit them into public buildings, offices and homes.