I wonder if they have addressed the issue of light spread. It's major failing is that LEDs are more like flashlights in that they are directional. Getting them to spread the light out like fluorescent, incandescent or metal halide has been difficult.

Many of the LED manufacturers will measure the lumens per watt directly under the LED but when you move the meter a few feet to the side the lumens per watt drop dramatically.

I know they will eventually solve the problems but for now fluorescents are king for general lighting.

So the best applications for LEDs are signals (exit signs, traffic lights, neon light replacements), and spotlights such as for retail stores.

yeah, that and Color. LEDs are still too 'cool' in color. 'Warm' lights sell better.

One of the best features of LEDs is that they are dim-able. Compact fluorescent bulbs are a convenient swap-out replacement for incandescent, but they lack dim-ability. LEDs bulbs will solve that problem.

Another benefit is that LEDs can be strobed with electronics up to 10,000 Hertz. Someone may find an interesting application for this feature, perhaps an alternative way of mixing color, or subliminally suggesting mood.

One last suggestion. Is it possible to use UV LEDs to excite phosphorus? The question of number of lumens per watt power would have to be evaluated.

@Johann:

LED's send out a beam rather than a spread largely due to the way they are shaped. The plastic LED units that we are used to uave dome-shaped tops, which acts like a magnifying glass and sends the light out in a narrow beam. If LED makers would simply shape the tops of LEDs differently and frost the plastic, the light spread would be a lot better, though it would still be somewhat narrow compared to incandescents and flourescents. For the best spread, LED's should be arranged to point in all directions, and be put under a diffusing shroud or have their light reflected off of soft white reflectors.

@Jack Kayser:

Current white LEDs do exactly as you suggest: they use short-wavelength LEDs to excite a white phosphor-blend dot that is placed right above the LED emitter.

LEDs are actually more efficient than flourescents; the article should rather say that they are less intense than flourescents. They are actually significantly more efficient than flourescents right now, it's just not affordable to get enough of them together to put out enough light to use as conventional lighting.

The spot/flood phenomenon is not so much a problem as a feature usable in different applications.

Something like the Cree LED is actually intended for use in flashlights first and foremost. They're designed for a narrow beam.

This doesn't mean you can't put multiple LEDs in a fixture arranged across an arc, maybe even using a reflector that is wavy and bumpy to spread the light out even more, and/or mount the LED array behind a frosted glass pane to diffuse the light.

Getting usable bright and efficient LEDs was the hard part. Creating fixtures to use them effectively will be relatively simple.

I just purchased some LED floods from www.besthomeledlighting.com and they are great. They have the full round bulbs that your were talking about. The floods I purchased are the PAR-20 36-LED spot floods. I use them outside to illuminate landscaping and the house. The LED's are replacing 5-50watt incandescent PAR-20 spot lights. Here is the kicker. The LED bulbs use 3watts, yes 3, of power. They are cool to the touch, even after hours of operation. They also are rated to last over 30,000 hours. I believe the incandescents I was using lasted maybe 6000-8000 hours and are $8 a piece. The LED spots were only $20. The cost savings is in the replacement alone, let alone the tremendous energy savings. I am about to order some the the globes for my ceiling fixtures and lamps. Some of the globes are available in warm white, similar in color to an incandescent. I will let you know how it goes.

@Jack Kayser -

LEDs in general do not necessarily send out a (tightly focused) beam rather than spread largely, you are only considering a deliberately shaped hobbyist type (probably 5mm) encapsulated LED. Look at most LEDs in consumer electronics for examples.

You don't want the plastic frosted! That would ruin their efficiency. For the best spread all one has to do is not choose LEDs deliberated focused (why is this not obvious?) and overlap the output from two properly designed reflector systems.

-----------------

@Berkana -

Cree LEDs (not their efficient higher powered types at least) are not designed for narrow beam like in a flashlight. While they are not as wide as some, they still absolutely require the reflector or collimator secondary optics, are unusable (for a flashlight, which was the context) in their typical packaging without it.

LEDs were not (at the time you wrote that) more efficient than fluorescents. They challenged CFL if you had high grade (binned) LEDs from Cree (XR-E)/etc, but this would be an inappropriate comparison, in contrasting only cutting edge premium LEDs versus the cheapest consumer grade CFL.

LEDs are MORE intense than fluorescents as a fluorescent spreads light 360' which is the least intensity possible per any lumen level. Thus, some LED sellers will spec a high intensity MCD value from a dead-center spot measurement that fluorescent can't match at even 2X the power consumption, but the lumen output of the fluorescent is still much higher (if comparing optimal types of each technology).

One of the most practical differences in LED lighting is that while they aren't a true point-source light, for implementation purposes they can be considered that, allowing either a broad beam or a reasonably well engineered optics to shape the light as desired which cannot be done with fluorescent without a far larger penalty in reflector system inefficiencies (and reflectors several orders of magnitude larger and more expensive in many cases).

Actually, one of the big advantages of LEDs is that they send light in a hemispherical direction instead of everywhere. After all, most tasks require light on a place, not all over the place. STarting with an omnidirectional source requires reflectors to put the light where you need it. Since reflectors are usually very inefficient (30%-50%), it just adds to the inefficiency of the lamp.

The apparent exception to this is room lighting. But think about it... would you rather take up table, desk, or floor space to light a room, or would you rather put a hemispherical light source on the ceiling or wall? LEDs are actually inherently MORE efficient in most circumstances than omnidirectional sources.

In answer to the comment about phosphors -- yes! ALL white LEDs use phosphors to convert blue light to white. There is some loss of efficiency in doing this, but it works, and the industry is getting better at it every day. You can now purchase LEDs with equivalent efficiency to fluorescent - but without the mercury!

I have worked with LEDs for the past 10 years. They have made tremendous improvements in the recent years. They are making high powered LEDs with wide angle views.

Right now you can get a 5Watt, 120 degree single LED with LUMENS in 100's! If you put 10 of these together you have a brighter bulb than floro and incando lightsbulbs with a fraction of usage. Also remeber lights do not always have to be high above and they can be close to the task you are working on!

Additionally. with all due respect, Cree is not the only manufacturer of LEDs. There are tons of mnufacturing of fine LED (and specialized) in Germany, China, and USA that have come a long way and it would be matter of time USA catches up with countries like China in switching over signs, displays, home lighting, street lighting all to LEDs.

The limit in technology is only the imagination.

By the way average durability of incando lights are about 2000 hours and average durability of LEDs are about 10000 hours. With incando lights switching the bulb will shorten the life of the bulb exponentially while with LED switching of the bulb shortens the brightness of the bulb over the lifetime and you still can expenct 8000-10000 hours of heavy use out of LEDs.

Actually, I see much much longer-life claims on LED lighting than 10,000 hours. The first ones I began learning about today claim 50,000 hour longevity.

Please provide me with more info on led lighting in offices