Andy Douglas, MD at Timeguard, looks at why LEDs are stepping up to the plate when it comes to meeting your floodlighting needs.
Do you really understand the “halogen ban” deadlines? Actually, you don’t really need to, because the market has basically overtaken the EU and voted for LED.
While there are some great bargains to be had when buying halogen floodlights, LEDs are winning hearts and minds for floodlighting too because the better manufacturers (the ones who are prepared to invest in R&D) have solved the light quality issues.
It isn’t so long ago that the switch to C-class halogen lamps was hailed as a big leap in energy saving for floodlights, and Timeguard enjoyed market leadership in this area for many years. Those energy savings are relatively low by today’s standards, but halogens look the part and still do a great job of totally flooding an area with light.
In contrast, even though some low-end designs for LED floodlighting simply replaced halogen bulbs with a row of diodes, this had the effect that the light distribution felt poor in comparison by users. The solution came with the design of prismatic lenses covering the diodes and better diffusive reflector plates.
Secondary optics
Older lamps blast light in all directions over 360˚. LEDs are, however, far more directional in their light distribution and their light can lack intensity over a wide range/distance, so secondary optics are used to create better floodlighting.
An LED unit typically comprises one or more semiconductor chips mounted on a heat-conducting material, a primary lens or encapsulant that encloses the chips, and other components to regulate heat and power.
Secondary optics, which can consist of lenses, reflectors, total internal reflection (TIR) optics and diffusers will collect, magnify and direct light and enhance beam and colour uniformity. For exterior outdoor floodlighting, the logical and economical choices are lenses and reflectors.
You’ll be familiar with prismatic lenses as covers for bulkhead lights, for instance, usually made of polycarbonate instead of the older-style heavy borosilicate glass. The square-hatched patterns of these covers are akin to what you should be looking for on top of the LEDs in a floodlight. If you can see naked rows of diodes, then the light field may not be as good.
Reflector plates have a key part to play in amplifying the diffusion effect and the degree to which an area will be flooded with light. Lining a traditionally-shaped floodlight casing with reflective silver was great for halogens, but was never going to work as well with LEDs.
Engineers have come up with many solutions, and a consensus on faceting and segmenting the surface is emerging. We, of course, prefer to think of it as imitation of Timeguard’s early ideas and the sincerest form of flattery.
Having put so much effort into designing reflector plates, we decided to make it a cosmetic design feature of them as well. We make them from the toughest polycarbonate so we can do away with the front window that did little more than protect the lamp in halogen floods.
So, the fundamental engineering problems have been solved – you can use LED floodlighting with confidence, but do heed all the usual warnings about the need to choose branded quality.
