Recent Patent: Directing the Beam

A new patent may describe a technically workable way to get directional light without optics or reflectors, but its economic practicality is another matter.

In the press release for its patent, Evolucia CEO Mel Interiano was quoted:

We don't need to redirect the light path with optics, which creates inefficiencies. We aim the LEDs exactly where we want the light to shine, which uses less energy to create more light... The more our technology is examined by people who understand LED, the more it is demonstrated that Evolucia's products are among the most energy-efficient available... It's original, proprietary, and delivers on the promise of LEDs changing the way we light our world...

The title of this patent is "Light unit with light output pattern synthesized from multiple light sources." The patent was issued to R. Kauffman, D. Sipes, D. VanderSluis, and R. Fugerer, and assigned to Evolucia (the former Sunovia). In this blog, I am going to look at: 1) What problem the patent is addressing; 2) How the invention works; and 3) Problems vs. benefits of the design.

The problem

Here's the problem I think this patent is trying to address. LEDs are very directional -- if what you're trying to build is an omnidirectional light bulb like an A19. But if you're trying to build, say, a spotlight, they're not directional enough. They emit some degree of light as far out as 90 degrees from perpendicular. Of course, incandescents and fluorescents do that even more so, emitting light in all directions. The workaround for incandescents and fluorescents has been to bend metal: You put an aluminum reflector around the light, and with the appropriate design, that focuses the light into the beam angle you desire.

LED designers want to do the same thing. But since so much of an LED beam is forward, it ends up non-uniform if you just use a reflector: It's brighter in the middle than on the edges. So what people actually do is add optics on top of the LEDs to move the light around, and then a reflector to get the desired beam and beam angle.

The method

What Evolucia wanted, apparently, was to do away with the reflector and the optics. Its idea was to stick LEDs in all sorts of different directions, so that their light would add up to give approximately uniform illumination with the right beam angle. If you take a look at the figure from the patent, reproduced below, you can see that that's what was patented.

Issues with the design

I suppose it probably works, if you have enough LEDs. Of course, LEDs are getting brighter every day, so you need fewer of them to get the right amount of light. The picture shows more than 100 LEDs; if they were each (say) 200 lumens, that would be more than 20,000 lumens -- definitely too much for a normal spotlight.

A more serious problem it seems to me is that this arrangement apparently has 10 different planes. That sounds a lot like 10 PC boards, and 10 interconnects between the boards. That's a lot of (presumably) hand-wiring, and translates to a fair amount of cost. The figure also apparently shows each of the LEDs with its own optics -- there goes the point of the thing! If you still need optics after all the business of arranging every LED just so, then the cost has been wasted.

Finally, let me note that there are a whole lot of patents out there dealing with the such an arrangement of LEDs. The patent office says that this one is novel -- great. Maybe it even has slightly higher efficacy. But would it hold up in a court contest? It seems to me that we're unlikely to find out, because this design costs too much money to be practical.