There’s an old saying from the nineteenth century “Build a better mousetrap, and the world will beat a path to your door …” and it’s no less relevant now. The trouble is, especially in the lighting industry, how much more genuine innovation is possible? How many more ways are there to direct light to good purpose? Surely the fundamentals of luminaire design have all been exploited?
Well, that’s what we thought when we were challenged to invent a square-illuminating downlight for optimised installation efficiency, because the requirements conflict:
When you start to look at this you find that you can design for high efficiency with square illumination but at the cost of glare, depth and aesthetics.
So we put our thinking caps on and looked carefully at the many preceding luminaire designs that have successfully produced square illumination over the years. We found that most designs utilise baffles or reflectors to create square illumination. Baffles lead to very low efficiency as they just block light and square reflectors concentrate light at their corners resulting in high glare. Some of these issues can be mitigated by extending the depth of the luminaire and moving the light source far into the ceiling but this limits application in shallow ceilings and adds cost and complexity.
Our approach to the innovation challenge was to apply a bit of lateral thinking and invert the logic. We retained the traditional symmetrical spherical reflector that all standard circular-illumination downlights have but instead created square illumination by means of a squared LED secondary optic. And by employing a diffusing reflector rather than a specular (mirrored) reflector we minimised glare & retained a covert aesthetic – it’s not at all obvious that the downlight produces square illumination! This design philosophy resulted in exceptional efficiency because the reflector could be made highly reflective, and the squared optic could be designed for minimal light losses by utilising total internal reflection.
The resulting technology has proven to be able to provide class-leading efficiency in a world where there are many impressively efficient downlights!
For example, a 195mm diameter downlight less than 100mm deep operating at 145lm/w at 2850lm, or 154lm/w at 1220lm with over 4000lm capability and with UGR < 19 at 3000K or 4000K CCT, CRI 80 with lifetime > 100Khrs (L90 B10). Smashed it!
And this tech is entirely scalable from small luminaires producing a few hundreds of lumens to large luminaires producing many thousands of lumens.
Forge hold granted patents for this tech in the United Kingdom, the United States and Germany. If you’d like to exploit this in your luminaires we will be very happy to discuss your requirements.
United Kingdom: GB 2590433 B https://patentimages.storage.googleapis.com/06/fd/17/1517cd430fd950/GB2590433B.pdf
United States: US 11761609 B2 https://patentimages.storage.googleapis.com/22/4e/74/b11a5b205ea4f9/US11761609.pdf
Germany: DE 112020006165 B4 https://patentimages.storage.googleapis.com/62/d9/7a/4bb25f93fec191/DE112020006165B4.pdf
This article was written by our Director, David Scott-Maxwell
