Why are there not more mass-produced undomed leds?

[easilyled]

I realize that the majority of leds are produced for fixed lighting applications .... BUT .... there is still quite a sizable niche market for flashlights and within that flashlights with the need to project a throwy beam.

So, why is Luminus Devices the only manufacturer who has so far produced dedicated dedomed leds?

 

[Testpostaccess]

Re: Why are there not more mass-produced dedomed leds?

I suspect it is due to the dome providing protection to the phosphor coating. If it is removed (or not put on) the LED is more fragile. That would be my guess.

 

[Harold_B]

Re: Why are there not more mass-produced dedomed leds?

I believe it's been mentioned in other threads but the dome is not there to protect the die or phosphor but to improve out coupling of the light from the die and/or phosphor layer. The phosphor is sensitive to moisture but will simply degrade not fail. The wire bonds are the most delicate part in the structure and like the die and phosphor layer are protected by an encapsulant, typically silicone.

There are several LEDs available without domes. The ones I have used the most are the Luxeon Z and Z ES. There is also the Luxeon C.

 

[DIWdiver]

Re: Why are there not more mass-produced dedomed leds?

LEDs produced without domes should be called undomed, not dedomed. The difference is that an undomed LED will still have a protective coating over the die, applied by the manufacturer, it's just flat instead of spherical (or approximately so). A dedomed LED may have no protection, and so may degrade (much?) more quickly.

The reason LEDs are domed is that the shape of the dome allows more of the light to be passed through the dome/air interface than is possible with a flat surface. With an undomed LED, more of the light is reflected internally and thus (at least partly) lost. So the same die will have higher output with a dome than without. Since domed LEDs work as well as undomed in most lighting fixtures, and lighting accounts for the vast majority of sales, that's what the big guys go after.

If you think that throwy flashlights represent a market that LED makers, including Luminus, even NOTICE much less care about, then you have no grasp of the numbers involved. A few years ago, I was involved with a lighting project for military use. The LED we were using for prototypes was made obsolete by a major manufacturer. We offered to buy a million LEDs (yes, really a million, not an exaggeration), and they didn't even bother to reply to our requests. Do you think the throwy flashlight market has anything like that kind of clout?

Throwy flashlight makers aren't even begging for table scraps, they are digging in dumpsters. They take what they can get and use their ingenuity to create wonders. We marvel. LED makers don't.

 

[saabluster]

Re: Why are there not more mass-produced dedomed leds?

Throwy flashlight makers aren't even begging for table scraps, they are digging in dumpsters.

That's kind of creepy DIWdiver. You spying on me?

 

[LEDninja]

Re: Why are there not more mass-produced dedomed leds?

Why are there not more mass-produced dedomed leds?

Do you know how much it costs to make a car?
Do you know how much it costs to make a car FACTORY?
Do you know how much it costs to make an LED?
Do you know how much it costs to make an LED FACTORY?
Without a guaranteed customer base it is too risky to spend a fortune building a factory.
All the Chinese flashlight manufacturers would go with the cheapest LEDs available. There goes your main customers. The few supplying CPF simply can not buy 10 million LEDs. (foursevens buys 2 rolls at a time (2000 LEDs). Favourlight one of the better Hong Kong manufacturers have a minimum order of 100,000. They sell several million a year.)

The best throw flashlights use aspherical lenses. Aspherical lenses like domed LEDs.

 

[mesa232323]

Re: Why are there not more mass-produced dedomed leds?

So, why is Luminus Devices the only manufacturer who has so far produced dedicated dedomed leds?

Sunlite engineers flashlights and un-domed emmiters for their lights.

 

[easilyled]

LEDs produced without domes should be called undomed, not dedomed. The difference is that an undomed LED will still have a protective coating over the die, applied by the manufacturer, it's just flat instead of spherical (or approximately so). A dedomed LED may have no protection, and so may degrade (much?) more quickly.

The reason LEDs are domed is that the shape of the dome allows more of the light to be passed through the dome/air interface than is possible with a flat surface. With an undomed LED, more of the light is reflected internally and thus (at least partly) lost. So the same die will have higher output with a dome than without. Since domed LEDs work as well as undomed in most lighting fixtures, and lighting accounts for the vast majority of sales, that's what the big guys go after.

This is the best answer so far. :thumbsup:

If you think that throwy flashlights represent a market that LED makers, including Luminus, even NOTICE much less care about, then you have no grasp of the numbers involved. A few years ago, I was involved with a lighting project for military use. The LED we were using for prototypes was made obsolete by a major manufacturer. We offered to buy a million LEDs (yes, really a million, not an exaggeration), and they didn't even bother to reply to our requests. Do you think the throwy flashlight market has anything like that kind of clout?

Throwy flashlight makers aren't even begging for table scraps, they are digging in dumpsters. They take what they can get and use their ingenuity to create wonders. We marvel. LED makers don't.

Well, there are some LED Manufacturers that are making undomed leds. (Luminus Devices, Sunlite, and Phillips lumileds) So if its not for the purpose of increasing throw in flashlights, it must be for some other reason, no?

 

[Harold_B]

This is the best answer so far. :thumbsup:



Well, there are some Flashlight Manufacturers that are making undomed leds. (Luminus Devices, Sunlite, and Phillips lumileds) So if its not for the purpose of increasing throw in flashlights, it must be for some other reason, no?

I assume you meant to say LED Manufacturers? I'm not sure who Luminus Devices is targeting. It's been a while since I've talked with them but the rep at the time had said they were responding to customer requests. The Philips products however are intended for users that plan to have optics in close proximity to the die surface. Another benefit of the Z package that we've taken advantage of is that the parts can be packed really tight without optical crosstalk.

 

[easilyled]

I assume you meant to say LED Manufacturers? I'm not sure who Luminus Devices is targeting. It's been a while since I've talked with them but the rep at the time had said they were responding to customer requests. The Philips products however are intended for users that plan to have optics in close proximity to the die surface. Another benefit of the Z package that we've taken advantage of is that the parts can be packed really tight without optical crosstalk.

Yes, I did mean LED Manufacturers. I've corrected that sentence now. Thanks.

 

[bshanahan14rulz]

MagLite has the Luxeon C in their Solitaire. It takes advantage of the small die, combined with lack of dome for an even smaller image for projection using smooth reflector. Because of the reduced apparent size of the LED, it is able to make a fairly tight hotspot.

Luminus is targeting projection engines, where a large, luminous surface with high flux is better than a large COB LED with discreet hotspots.

 

[easilyled]

MagLite has the Luxeon C in their Solitaire. It takes advantage of the small die, combined with lack of dome for an even smaller image for projection using smooth reflector. Because of the reduced apparent size of the LED, it is able to make a fairly tight hotspot.

So, if Maglite inquired if they could utilise undomed leds for more throw into their C and D-cell flashlights, would they have enough influence to persuade mainstream manufacturers like Cree to produce a series of undomed high-power leds such as XP-G2s or XM-L2s?

Luminus is targeting projection engines, where a large, luminous surface with high flux is better than a large COB LED with discreet hotspots.

They're not using the SBT70 or SBT80 for these though, rather the Blue/Red/Green Phlatlights.
So, it still doesn't explain for what purpose the SBT70 and SBT80 is intended.

 

[alpg88]

Re: Why are there not more mass-produced dedomed leds?

there are undomed leds made, cxa series from cree, bridgelux leds don't have domes.

 

[bshanahan14rulz]

They're not using the SBT70 or SBT80 for these though, rather the Blue/Red/Green Phlatlights.
So, it still doesn't explain for what purpose the SBT70 and SBT80 is intended.

Some projection engines use RGB and DLP to create a projection of a computer generated image. Other projection engines use white LED and RGB LCDs to project the image. Still other projection engines are for things like pattern projectors and stage lights that make beams. These are a few of my favor-- oh, wait, what?

The SBT-70 I do believe Luminus actually tried to market a flashlight based on the SBT-70, or worked in conjunction to produce a flashlight to be the first to use the SBT-70, or something. http://www.luminus.com/news/050912%20Ruijia%20Flashlight%20PR.pdf

I think the main thing is that LEDs, people think, "ah, those super-efficient things? cool!" So, it would behoove the manufacturers to focus on efficacy including extraction efficiency, more than, say, color rendering or beam uniformity. Those things can be modified by using more/different LEDs and using different combinations of optics.

 

[stevethumb21]

I realize that the majority of leds are produced for fixed lighting applications .... BUT .... there is still quite a sizable niche market for flashlights and within that flashlights with the need to project a throwy beam.

So, why is Luminus Devices the only manufacturer who has so far produced dedicated dedomed leds?

In my view, the domed shape solves two purposes :

Firsly, it provides an added protection layer.
Secondly, the light emitted by LED's posses an angle...in planar LEDs the reflection is more for this reason only. The light should not be totally internally reflected otherwise it will not come out. hence, the shape of LED's have their importance.