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Tech Thursday: Lighting Nirvana

09/02/04

Sometimes, the old standard tube fluorescent or bulb incandescent is just what the doctor ordered. Sometimes, you've even been adventurous enough to try out a compact fluorescent, halogen, or even an LED lighting solution in your designs. But this week, we want to turn your world on it's head. That's right, alternative lighting (get it... Nirvana... Man, we are hilarious) is going to rock you like nothing else!
Electroluminescent Wire

We got a great response from the LED tech Thursday, but LEDs are only the most publicly hyped member of what can only be described as a lighting revolution. Fueled by the need for better small light sources for things like laptops, cellphones, watches, and PDAs, the number of light sources available to designers has increased by leaps and bounds.

In order to meet the needs of the display industry, these new lights had to be small, white(which is easier said than done), low-power, and run cold, to prevent fire hazards and not waste energy. Currently, there are three major types of display lighting used. We'll cover them in the order that they've come into power, so they pretty much go from least potential to most potential.

Cold Cathode Fluorescents

Your current laptop, flatscreen monitor, and if your lucky, iMac G5, all can thank these little babies for their screen's brightness. Cold Cathodes allow a large amount of white light to be produced with almost no heat. They operate on the same principle as standard fluorescents, using an excited mercury vapor to generate UV light which is then converted to white light with a phosphor.

Despite it's major advantages, these guys have some drawbacks. In order to allow for cold operation, and to manage the starting up of the lamps, a special electronic ballast circuit is usually used. Additionally, the system needs AC power, so if a battery is used, an inverter is necessary. Finally, being glass bulbs, the lights are not flexible, and can break if hit smartly, as many a sad laptop-dropper can tell you.

Since their introduction, the production of flat LCD screens has become so big, that there are extra factories in Asia kicking these CCF tubes out. In order to keep demand up, they have branched out into other markets. The most visible application has been user-customizable "Neon" in car interiors. The tube's small size is perfect to squeeze into the underside of a dashboard, or recess into an outer panel. Because of this, designers now have access to custom colors.

Electroluminescent Film

EL technology also came to be as a method for lighting LCD displays, but because of it's higher cost, it only found use in watches and PDAs. Timex had the Indiglo watch first, but soon others came up with their own EL materials; other watches soon followed, and even the Palm V had a eerie blue backlight. These days, the technology has matured, and all different colors are available. Most backlights, like those in newer phones and PDAs use a white phosphor, in order to allow color. The light is created by a high voltage signal exciting atoms in a special phosphor in much the same way that UV glows the phosphor in a fluorescent tube. The material comes in rope, sheet, and strips, and it is printed on flexible plastic, which allows it to be used in some amazing ways.

As far as disadvantages go, the major one is the extremely high voltages needed to drive the EL material. Since the material does not actually conduct electricity, there is hardly any current needed, so the material can be made to run off of a watch battery. But in order to generate the high voltages and need for alternating current (around 50-130 volts AC), a special inverter and voltage raising circuit must be included in the design. The material also puts out a lower level of light than Cold Cathode tubes would, so it is most useful in quite low light.

Recently, EL film and wire has made design headlines in a number of places. Forget about the thousands of uses in custom cars, and casemods, Voon Wong and Benson Saw produced these woven EL lamps to light your house. Yves Béhar created the Nest Chandelier using a vast sheet of EL film and Swarovski crystals. Rachel Wingfield of Loop created a whole series of EL textile goods. There are clearly opportunities open to this new material.

Organic LEDs

Now at the bottom of this list, we have reached the future of lighting as some people see it. Not just the future of displays, but the future of all lighting. Don't believe us? Hey, it was GE's idea. Since the first organic molecules were produced with semiconductor properties, creating an organic counterpart to LEDs, which are one of the simpler, but most useful semiconducting components, has been a priority. OLEDs are basically this; an LED made of hydrocarbon molecules. The biggest carrot that is driving companies after this technology is that hydrocarbons (plastics) are moldable, flexible, emit their own light (no backlight needed) and are printable. Most importantly, since they are easily mass-produced using low-tech methods, they would be cheap. At least that's the hope.

Current formulations have a number of drawbacks. They are inefficient, and don't put out much light, unless you drive them with way too much voltage. If you drive them too hard, they break down very fast, some on the order of hundreds of hours, which is nowhere near long enough to compete with any current light source. Not many companies have been successful at printing them in flexible form either; most current applications are printed on glass, which has the same non-flexible drawbacks as conventional LCDs.

Hopefully, with time, these problems will be overcome. In any case, OLEDs are worth experimenting with, and definitely worth keeping an eye on.

The Wrap Up:

None of these technologies replaces compact fluorescents or incandescents. Yet. But each one has its unique abilities. And each one could find a happy home in your designs.

Where to Buy:

Manufacturers

Metromark EL lamps
Elam makes Lytec brand EL wire
Surelight supplies Benson Saw with his material

Resellers

Laservision's EL sheet can be screenprinted on for large, luminous signs
Beingseen carries a variety of sheet and rope EL material
EL Wire Cheap has a pretty self explanatory name
GloWire sells a kit to make inkjet-printable EL signage, but it's a little spendy

Do it yourself

Make your own inverter circuit
Install a cold cathode tube
Solder to an EL wire

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Tech Thursday: Lighting Nirvana

09/02/04

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