The LED Technology that Makes Fiilex Lights Unique

The LED Technology that Makes Fiilex Lights Unique

Today we’re interviewing Jeff Lee, Ph.D. and head of product development at Fiilex. In this segment, the third in a series of four, Jeff provides an overview of Fiilex’s LED technology, and how it differs from the tech used by other lighting manufacturers.

When it comes to LEDs, what does the industry generally do, and what does Fiilex do differently?

Jeff Lee:
In addition to just the properties of the LED chips themselves, these have to placed in packages which, because they’re selling off the shelf are somewhat universal. What this means from a mechanical design point of view, is that there’s a limitation to how they can put things together. Our mechanicals and optics work together, and so, in their case, the chips may be small, but the way they route the wires, the platform on which they’re built can be large and unusual in shape. And because of that they have to design their fixtures to be large, to work around that.

Jeff Lee, Ph.D.

From a more optical point of a view it’s more – the light coming out of the chips has a certain distribution. You basically – what you get from that distribution is what you need to do to shape the light to shoot on a subject and whatnot. In our case we actually can shape that distribution at the LED level, so we get a lot more control from the source.

What’s the big deal with Fiilex’s cooling technology? Why does that matter?

Jeff Lee:
I like to draw analogies between LED chips and CPU processing technology. Everyone’s wanted to make things smaller smaller smaller more compact—fit more into a smaller package, but what happens as you get smaller and smaller you start getting multiple heat sources closer and closer together, and that creates a thermal issue, and that’s what happened during the whole Pentium craze, you know Pentium 2 – 3 – 4—they made it smaller, but then they realized it’s creating too much heat in a small area, and so then they went to multiple cores—part of that was because they wanted to spread the heat out. In the case of our LEDs—same thing: as you make them smaller, which gives you better mechanical and optical performance, you have to start dealing with heat. Fortunately, our core technology, is that our electronic board on which the chips are placed is a really good conductor. And so that same board that routes the electricity—is also what does a really good job of conducting heat away from the source. And that’s how we’re able to pack so much power in such a small package.

What’s good about a point source?

Jeff Lee:
So if you want to create a hard light—for instance a really good hard light we like to use is the sun—and the reason why the sun is so darn good is because it is a point source. It’s huge, but it’s so far away that it’s a little point in the sky, and the rays that travel so far, are basically straight on, and so that’s what gives us that hard shadow, that hard light. Same idea with the LED source. If you have a very small source, the rays coming out of that object are also very straight. And so in many ways if you’re looking for a hard source, then you do want to start with the point source. And I think traditionally that’s what the industry’s been—light bulbs and small filaments, or HMIs, those are more like point sources. And we’re also really comfortable with that because we’re so used to looking at things illuminated by the sun and the shadows from the sun. That’s why this whole thing with multiple shadows it’s really unnatural because when in our history have we seen multiple shadows?

What is a Dense Matrix array?

Jeff Lee:
Ultimately what we want do is illuminate a subject, which in space has some dimensions, with a light that’s tunable, and so the idea of the Dense Matrix is that we can pack strings—or LEDs of different colors in a really tight package such that spatially they look like one source. Our goal is to illuminate a subject in space with a uniform color. You don’t want to be red in some area, green in some area, and blue in some other area, and that’s what would happen if you started with a source which is like red, green, and blue like that.

What we do is we take the chips and we squeeze them together into what we call the Dense Matrix array, and by squeezing them together in a small package, they mix together better so it’s more like white light. This is more of an issue with LEDs because in the past LEDs—what they’ve allowed you to do is have different color chips, but because of the packaging and electronics around them they can’t be packed so tightly together, and so that’s really where the Dense Matrix array comes in and our technology is that, we’re able to pack them so close together that they mix well and look like a white source.

And it also helps when you’re trying to create a color-tunable source you want to have a lot of control over what color each individual chip is. Traditionally there’s RGB, and yes, that mixes together to make white light, but if you want a really high CRI, then you can’t have these sharp peaks in the spectral space which is what you would get from a blue, a green, and a red—instead what you want to use are phosphors, which sit on top of the chips and re-emit a broader spectrum, and each phosphor has a slightly different spectrum, so at Fiilex, not only can we tune the chips to be different intensities but each of these chips can have a separate phosphor. In fact we keep about 40 different phosphor recipes in house, and we adjust those specifically for each fixture.

Wait, phosphor “recipes” are a thing? Why is that necessary?

Jeff Lee:
Fiilex uses different mixtures of phosphors to get us a tunable full spectrum. What full spectrum means is basically as you look through the wavelength spectrum of our LEDs, there aren’t too many peaks—it’s pretty smooth and broad across, and the different phosphors we use have different spectrums, and as we tune between them we can get different mixtures of these spectrums. So as we mix them we still maintain that broad continuity—that smooth spectrum.

So Fiilex uses that full spectrum in Fresnels right? Is that easy?

Jeff Lee:
Doing a full spectrum that’s tunable is really difficult to make cause essentially you need different mixtures of phosphors and having different chips turn at – with different intensities. What that means is that your color mixing has to be good or else you’ll see certain color temperature in this part of your light source and different in this part. And this problem is made even more difficult or challenging in fresnels because what fresnels do is they essentially act like a lens – and the lens is what they do is the image. So they’re taking a pattern and trying to project that pattern somewhere else. And so if you’re pattern – if you start off with something that’s not uniformly mixed, has different color temperatures in different parts of the array – like a bi-color for instance then as you image that, if you project it across the room you’ll get that same pattern over there. And so this has been a much more challenging thing to do with a fresnel and lenses than it has been with, for instance panels, or kind of wider angle softer sources.

Wait, phosphor “recipes” are a thing? Why is that necessary?

Jeff Lee:
Fiilex uses different mixtures of phosphors to get us a tunable full spectrum. What full spectrum means is basically as you look through the wavelength spectrum of our LEDs, there aren’t too many peaks—it’s pretty smooth and broad across, and the different phosphors we use have different spectrums, and as we tune between them we can get different mixtures of these spectrums. So as we mix them we still maintain that broad continuity—that smooth spectrum.

So Fiilex uses that full spectrum in Fresnels right? Is that easy?

Jeff Lee:
Doing a full spectrum that’s tunable is really difficult to make cause essentially you need different mixtures of phosphors and having different chips turn at – with different intensities. What that means is that your color mixing has to be good or else you’ll see certain color temperature in this part of your light source and different in this part. And this problem is made even more difficult or challenging in fresnels because what fresnels do is they essentially act like a lens – and the lens is what they do is the image. So they’re taking a pattern and trying to project that pattern somewhere else. And so if you’re pattern – if you start off with something that’s not uniformly mixed, has different color temperatures in different parts of the array – like a bi-color for instance then as you image that, if you project it across the room you’ll get that same pattern over there. And so this has been a much more challenging thing to do with a fresnel and lenses than it has been with, for instance panels, or kind of wider angle softer sources.

So it’s just the phosphor that’s important, or is there more to it?

Jeff Lee:
The phosphors tell you what color the chips are, or what kind of colors your light source has, but the way you arrange that on the array is really important too. Let’s say, for example, I have two different phosphors—half of them on one side and half of them on the other—then you’d get a really clear left and right, and that same pattern would be then projected by your Fresnel lens onto your subject.

And so what you want to do to get uniformity is to mix them together so you don’t have all of them on one side. You want to mix them so that they’re more uniformly distributed. And so the way we designed our array, is that we tried to kind of almost scramble the chips so that it looks more like a well-mixed source.

Are the arrays and Fresnels optimized to work together?

Jeff Lee:
Typically what we do is we start with our light source, which is our LED array, and then using computer simulations we kind of build an optical assembly around that, and then we actually build a real model and then try it out, and then we go back and retune the Fresnel until it works perfectly. So we believe that every component in the system has to work well together, and so in the case of our Fresnel, we think that you need a specific Fresnel to be optimized for a certain array, and every time we make a small adjustment to an array, we typically have to adjust the Fresnel as well, and that’s why we do a lot of computer simulation and modeling so that we can get this mixture or combination correct.

Ok, just to be clear, what is the key benefit of using a dense matrix?

Jeff Lee:
Because it’s so small in a small area it looks like a point source. And so if you’re trying to make a hard light we make a good source to start with. Also because of that good color mixing, we also have a very uniform and smooth profile. You don’t get weird colors on the fringe, weird colors on the rings, you don’t get hot spots—things like that. And because we have so many different phosphors, and so much phosphor technology as well as the ability to mix them we have a wide range of tunable spectrums.

This has been part three of our series on the tech behind Fiilex. Stay tuned for future installments!

2018-05-24T16:57:52+00:00 May 5th, 2018|Tech|