Single-emitter vehicle signal lamps — finally

[-Virgil-]

It was only a matter of time; I was curious which of the majors would come up with them first. Looks like Truck-Lite:

single-emitter 4" round turn and stop/tail lamps — the stop function takes 3.5w, which is roughly 1/8 the power consumed by an ordinary P21W incandescent stop lamp bulb.

(also 2-emitter 4" round rear fog lamps)

These meet ECE regulations; doesn't look like they're SAE/DOT certified. Minimum intensity is higher for the stop and turn functions in SAE/DOT, but visibility angles are wider in ECE. So it's probably only a matter of a little more time before DOT versions of these become available. There's been a great deal of hand-wringing about LED 4" round lamps not meeting the DOT's minimum requirements for effective projected luminous lens area, because of the dark gaps in amongst the emitters. This single-emitter device, depending on optic design, may solve this problem (or may aggravate it). I want to see them all in person, but I'll be especially interested to look at the rear fog, which would meet DOT stop lamp photometrics. I can't tell from the images on the site whether EPLLA would be a problem or not.

 

[LukeA]

Is that an Edison in the singles?

 

[-Virgil-]

Good question. Can't tell which emitter it is. I want to get my hands on some of these.

 

[bshanahan14rulz]

psh, can't be that hard to make a single-emitter signal lamp if it's round!

And from the pictures, the emitter looks funky! almost like 2 large dice side-by-side. Must be some kind of optical artifact... although DX does have a strange LED that has 3 chips in a triangle arrangement... let me dig up the link. It's very generic-looking and I can't really tell what color it is

Ah, here it is: http://kaidomain.com/ProductDetails.aspx?ProductId=7517

The color is chrysoidine, whatever that is... best guess from googling is orange.

 

[-Virgil-]

Well, define "not hard"...remember, there are a whackload of fairly challenging regulated aspects of signal lamp performance. Illuminated area, minimum and maximum intensity, bright/dim intensity ratio, etc. If it were so simple, most of the standard-sized truck/bus lights on the road would be single-emitter devices, but they're not; most of the 4" round units use between 6 and 40 emitters.

 

[TorchBoy]

Interesting. I worked out just a couple of days ago that a single white XP-G R2 at 650-800 mA would produce about the same lumens as a P21W bulb (I think that's the right number), so the technology is definitely getting there.

Also interesting:

Common name	C.I. generic name	C.I. number
Chrysoidine R	Basic orange 1		11320
Chrysoidine Y	Basic orange 2		11270

So "basic" I'd never heard of it before. But then again, there were several "acid orange"s listed.

 

[-Virgil-]

Interesting. I worked out just a couple of days ago that a single white XP-G R2 at 650-800 mA would produce about the same lumens as a P21W bulb

H'mm. You sure? A P21W bulb, commonly used in bulb-type brake lamps, produces 460 lm @ 13.5v. The XP-G spec sheet says the R2 produces 114 lm at about 350mA. 460 lm is 404% of 114 lm, and the table of relative flux vs. current doesn't go that high. It tops out at 250% relative flux (285 lm) at 1000mA.

 

[TorchBoy]

460 lumens?!? I found figures that indicated 250-300 lumens, hence my calculation result. That's a lot of lumens for a single LED to aspire to. BTW, do you know of a table anywhere on the web that lists that sort of info?

 

[-Virgil-]

460 lumens?!? I found figures that indicated 250-300 lumens, hence my calculation result. That's a lot of lumens for a single LED to aspire to. BTW, do you know of a table anywhere on the web that lists that sort of info?

You can get the rated output info for all the European-code bulbs from ECE R37. All these bulbs are used worldwide; there are other types used in the US and/or Japan for which accurate ratings are tougher to come by, but you can get approximations from donsbulbs.com . Multiply MSCP by 12.57 to get lumens, and remember to apply a correction factor (use an exponent of 3.4) if you're comparing filaments rated at different voltages.

But really, the Euro-code bulb info is pretty much all you need until you get to the design-to-conform stage. Use P21/5W to approximate the American 1157, use P21/4W to approximate the 2057, W3W approximates the 194, W5W approximates the 168, P27/7W is the same as 3157, W21/5W is the same as 7443, use PY21W to approximate 1156NA and get the filter factor for approximating an amber version of any of the other bulbs, etc.

 

[TorchBoy]

Awesome. Thank you!

I see that the amber version of that bulb is "only" 280 lumens. Now what on Earth did I do with the spreadsheet where I was figuring everything out?

 

[lonesouth]

What is your take on THESE bulb replacements? They are single emitter and have been out for about a year

 

[TorchBoy]

What is your take on THESE bulb replacements?

Red Luxeon K2? 75 lumens at 700 mA. Compares to 110 lumens for a 21 watt red incandescent bulb in the PDF linked above.

 

[-Virgil-]

What is your take on THESE bulb replacements?

Same as every other "LED bulb" that has ever been hawked by anyone, and every other "LED bulb" that will ever be hawked by anyone. They do not work safely or effectively. Period.

 

[jtr1962]

Re: Single-emitter vehicle signal lamps — finally

Red Luxeon K2? 75 lumens at 700 mA. Compares to 110 lumens for a 21 watt red incandescent bulb in the PDF linked above.

The LED still might produce enough light despite the difference in raw output given that there are greater losses trying to direct the omnidirectional light from the incandescent to where you want it to go. That being said, I tend to agree with Scheinwerfermann regarding LED bulb replacements-they'll be suboptimal in a system designed for incandescents. Rather, it makes more sense to have the entire taillight assembly system specifically designed for whatever LEDs are used.