Luxeon Desk Lamps

Hi this is Dean I would like to first start off by saying what a fantastic forum this is. I am a lighting designer and I want to bring out a new series of task lights (desk lamps) and the style is going to be ultra modern. I believe the lumileds LED's would make a great choice for their compact size and light output. So I will get right to the point; I am concerned about light quality, will one 1 watt luxeon be sufficient? Or will the Luxeon lll be better? Is the white really white , or should I consider the new warm white Luxeon? I am sorry that these questions sound elementary but I need as much feedback and information as I can get, so I can get this project off the ground. /ubbthreads/images/graemlins/help.gif

For me with my bad eyes, I'd need a Luxeon III for enough light to be practically usable in a desklamp application.

oO

Welcome to CPF, deano.

All the white luxeon emitters I have ever seen (nowhere near as many as many of the regulars) have a good, relatively neutral white to them - unlike commodity white LEDs, which almost always have a visible blue tint and hotspot. It seems that the tint variations amongst luxeons are relatively minor relative to commodity LEDs. Any decent white luxeon will put out white light similar to a florescent tube.

I understand that Luxeon IIIs have much less tint variation than 1-watt emitters.

Ah, here comes the point where I offer armchair advice (sort of) to the light designer... I've evaluated LEDs to replace the florescent tubes in my company's interior architectural lighting applications. Regrettably, I couldn't justify the concept 12 months ago, but perhaps that will change as high-power LEDs get cheaper and more readily available.

One thing to keep in mind about LEDs is that they're point-sources - if you look at even a 1-watt emitter directly, you will get a memorable, lasting afterimage. You'll probably need some sort of diffuser to counter this effect and distribute the light from the point-source.

Another point: while a 1-watt LED looks amazingly bright, the light output is less than it might seem - 1-watt emitters usually top out around 30 lumens.

First of all, get a Luxeon datasheet, if you haven't already. Second, your average desk lamp puts out between 300 (20w halogen) and 900 (60w lightbulb) lumens. Some desk lamps put out even more.

A 1W luxeon has a "typical" output of 25 lumens, with a CCT of 5500K, and a CRI of 70. Warm White luxeons have a "typical" output of 20 lumens, with a CCT of 3300K and a CRI of 90. The Luxeon III is rated for up to 80 lumens, with the same output characteristics as the luxeon 1. I don't think that a single LED will have enough output for a desk lamp, and, from the point of view of light quality, I'd rather see a warm white luxeon in the desk lamp, unless you're going for the whole "cool metallic productivity" look.

Hm - when I said Any decent white luxeon will put out white light similar to a florescent tube, I meant that it's a cool white light, but doesn't have a CRI as good as decent florescent tubes - and can't touch full-spectrum tubes.

I imagine that most general-purpose task/desk lights aren't used in applications where accurate color rendition is critical - ie offices, etc. Most users that need tight color rendition know to look for a light with "full spectrum" light, or a CRI figure for the light source.

I have a GE Warm White 14W CFL bulb in my desk lamp (Bankers Style). It puts out plenty of light. Color rendition looks just peachy to me.

I am not sure I could even afford a luxeon desk lamp!

Good luck in your venture however!

Re: Luxeon vs Fluorescent

I know that this is tangential, but it should provide some insight for other forumites.

White LEDs can't touch flourescents right now. A Lux III (one of the more efficient LEDs) is pushing about 25 lumens/watt; your average flourescent is at over 80 lumens/watt, although compact flourescents and high (>90) CRI lamps are down around 50. A typical "cool white" flourescent has a CRI of around 65; more efficient flourescents and compact flourescents have CRIs around 85, with the highest I've seen around 95. Compare that with Luxeons, with a CRI of 70, or 90 with an efficiency loss.

Given that the largest cost of light is the energy used, and flourescent lamps have life spans in excess of 20000 hours, I don't see LEDs replacing flourescents anytime soon.

That said, in certain applications, an LED is the right choice. They are the highest efficiency low wattage lamps available. They are shockproof, and they naturally emit colored light. If you need color, LED is the way to go; they are more efficient than any other source with a filter on it. But aside from the "cool" factor, I don't think that LEDs are the right choice for a desk lamp at this time.

Re: Luxeon vs Fluorescent

I'd be interested in a Luxeon Desk Lamp. Fluorescent is not an option for me: the 60Hz flicker bothers my eyes. If you don't believe me, I can see my Arc4+ Rev.1 flicker at all levels! /ubbthreads/images/graemlins/blush.gif

Re: Luxeon vs Fluorescent

[ QUOTE ]
Skyline said:
I'd be interested in a Luxeon Desk Lamp. Fluorescent is not an option for me: the 60Hz flicker bothers my eyes. If you don't believe me, I can see my Arc4+ Rev.1 flicker at all levels! /ubbthreads/images/graemlins/blush.gif

[/ QUOTE ]

I have one word for you: Electronic ballast! OK, two words. /ubbthreads/images/graemlins/grin.gif
Better ones run around 44,000 Hz.

I'd like to understand your idea better. Offhand, LEDs don't have a lot to offer right now for a desk light, as I see it. Namely, their efficacy is about the same as a halogen, (and much less than a fluorescent) their CRI is (at best) on par with a good fluorescent, they are very expensive on a per lumen basis. They do have a long life, but that doesn't seem to justify their expense IMO. And I suppose their high CCT may be an advantage for some, but it's not obvious that the average consumer would prefer that.

So, outside of their 'high tech' appeal, why use an LED in a desk light?

Re: Luxeon vs Fluorescent

I'm wired in a similar way, Skyline. 60hz on a monitor is awful, 72hz is better but not good, 75 is OK and I can even see 85hz but Its' alright. Flat panels are no problem at all because, as someone on CPF explained, the media stays lit well enough that I see no flicker at 60hz.

So I would be interested in a Luxeon Desk Lamp too. Looked at a couple on line. Kinda expernsive.

I don't know if the pictures still show up (sometimes they do, sometimes they don't) but HERE is one I did last year.

It puts out about 100 Lumens into a diffused rectangular reflector and at about 15in above the work covers about 15in by 20in. I am working on an eight led (over driven a bit, total about 250 Lumens) with a grid refector to cover the same area but from about 20in.

If the pics don't show up, ask, and I can e-mail them later.

Re: Luxeon vs Fluorescent

[ QUOTE ]
Skyline said:
I'd be interested in a Luxeon Desk Lamp. Fluorescent is not an option for me: the 60Hz flicker bothers my eyes. If you don't believe me, I can see my Arc4+ Rev.1 flicker at all levels!

[/ QUOTE ]

Perhaps the 12 VDC version, which is high audio, even ultrasonic?

Doug Owen

I'd like to thank everyone for replying to my initial post. All the concerns are justified. Now to answer Brickbat's question my designs are not something you are going to find at Wal-Mart. All of my designs and projects are of the one off and low quantity variety. I have a small cliental and fan base of highly intense individuals, these people have the gulf stream five private jets the 30,000 square foot homes in Malibu and Villas in Italy and they want the newest now. My designs could be best described as ultra modern and very close in style to that of the famous lighting design Ingo Maurer www.ingo-maurer.com although I am nowhere near as talented or famous as Ingo, I do make a living with no advertising or Web Sites. Like I stated above these individuals demand the latest technologies from my work. I thought maybe the new high output luxeon series of LED's might be worth a closer look. I hear so many people on the net talking about how brilliant and how white and how intense the light output is. I know it's not perfect but I thought for this series it wouldn't be too bad, but if not I will go with Xenon. One more interesting note if you go to Ingo Maurer's site, go to products then to LED lights and you will see a very interesting desk light made up with a large circuit board with about fifty low powered white LED's and it's clamped to the main arm pole with a pair of vice grips (yes you heard me right VICE GRIPS)I personnally think it's ugly but who am I to say. I think the retail on that light is $5,600. I was told they were all presold in four days. Thanks again,

Deano

Funny that this thread popped up.

I'm in the process of making a small Lux based task light for use on my lathe. I decided to use a lux because I can make the head miniscule (compared to halogen) so it won't be in the way when I'm working. There should not be worries about accidently hitting it with shavings and such. It will be about a foot from the piece I'm working on, so it should not need to be too bright.


Daniel

Greetings, deano and welcome to CPF /ubbthreads/images/graemlins/buttrock.gif

LEDs are wonderful, of that there is no doubt. They offer many advantages over tungsten/fluorescent/discharge sources, in terms of energy efficiency/longevity/indestuctibility but at the moment brightness isn't really on the list, although it will be in the not too distant future. Luxeon is a bit of a buzz word at the moment and although they certainly represent a big step forward in LED technology they are by no means the final statement.

For an alternative LED source, have a look at Lamina Ceramics There have already been a few discussions on them in here, just do a forum search for "Lamina" to see them.

[ QUOTE ]
lightnix said:
They offer many advantages over tungsten/fluorescent/discharge sources, in terms of energy efficiency/longevity/indestuctibility

[/ QUOTE ]

Seems to me that we should be careful making statements like this. Some people might read this and think (wrongly) that LEDs are generally more efficient than other light sources. In fact, the opposite is true. In most cases LEDs are LESS efficient. Of course there are some niches where LEDs are great, and if you need colored light, or a very small amount of light (say, less than 100 lumens or so) they MAY even be more efficient. But in general, at this point in their development, energy efficiency isn't their strong suit.

Back to the original desk lamp idea, though. If you want to dream up a super unique lamp, why not have one where the user can adjust the color, saturation, and intensity - That's something no 'Wal-mart' lamp has - and maybe some folks might pay big $ for that. It would be a fairly straightforward design - Just need a cluster of red, green, and blue LED's with variable PWM drive to each, and some sort of intuitive user interface to adjust it...

/ubbthreads/images/graemlins/bowdown.gifWOW! brickbat I thought I was the creative one good idea.I'm flying to LA. I'll be in touch...................OH YA ARE YOU OFFERING TO DRAW ME UP SOME BLUEPRINTS?....IN YOUR SPARE TIME OFCOURSE. /ubbthreads/images/graemlins/smile.gif

Uh, well I wasn't really offering THAT. I'm an EE - this project would probably have more development effort in the firmware than the hardware. And the industrial design and mechanical design would be pretty big pieces of the development, too. And besides, my company generally charges $$$/Hr for all of my 'spare time'. /ubbthreads/images/graemlins/smirk.gif

[ QUOTE ]
deano said:
/ubbthreads/images/graemlins/bowdown.gifWOW! brickbat I thought I was the creative one good idea.I'm flying to LA. I'll be in touch...................OH YA ARE YOU OFFERING TO DRAW ME UP SOME BLUEPRINTS?....IN YOUR SPARE TIME OFCOURSE. /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]

Why stop there? How about having it responsive to the sound in the room. Maybe senses the user and switches back to 'white desk light' automatically? Otherwise when not in use as a desk lamp for a give time, it reverts to background mode. Maybe returns the light to the color themes programed into it?

A prototype and drivers should be fairly easy, the rub is deciding what to make it do (artist stuff) and programing it (softhead stuff).

I kind of like the idea of a desk that shuts down to tranquil background colors (maybe a shifting pattern to make it interesting) on it's own.

Doug Owen