52 in 52 – Design(s) Sixteen Complete

Posted: May 7, 2010 in 52 in 52 for 2010
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Teaching new dogs old tricks.

While LEDs are great stuff for optimizing the use of energy for generation of light, they are not immune to the issues of brightness and glare. In application, some of the newer LED products are downright glare bombs. In the over-zeolous pursuit of maxing out efficacy many of the most efficient products get that from lack of optical control. This is great for by-the-numbers evaluation, but can result in some pretty ugly field conditions. Other source using LEDs, have small luminous source areas delivering high light output. The result is an offending brilliance for those unfortunate to be in their focal path.

This is an exercise in taking a couple of these new LED dogs to training camp and applying some old tricks to resolve their issues. Since most LED lights and retrofit lamps are configured differently than the conventional sources they replace, grabbing off-the-shelf parts to apply is rarely possible. The combination of luminaos source area, orientation, and package dimensions means fixing any glare issues requires an equally unique approach. This is but the start of a process I intend to pursue, one source at a time if necessary.

The Cree LR6

For those sensitive to source brightness and in many applications where the proximity of the occupants is such that the aperture of the LR6 is close in hand, their can be a serious issue of glare and brightness. This is the result of this products overly wide distribution and field angles, often promoted as an attribute in generating high vertical surface illuminance. I appreciate the product, and the pitch, but… after living with the LR6 for two years now, it became so much an issue that we stopped turning them on to avoid them. The issue is that any time the viewing angles are shallow, the apparent brightness of the lens in the LR6 is, to put it bluntly, offensive. Even with the Cree accessory lower trims, the brightness from the too-shallow trim and exposed lens is unattractive.

The approach taken was simple. First, by encroaching on the lens perimeter a very small amount (about 3/16″), and increasing the depth of the baffle itself, I eliminated the high angle brightness. All light above 25 degrees is simply blocked off. The effect on illuminance in the desired lighting zones below was imperceptible, and measured less than 3% less than no trim at all. I feel the result is a much more comfortable and attractive lighting effect.

The LR6 without trim or baffles produces very high angle brightness than can be offensive at many viewing angles.

With a simple snap-in baffle that reduces the aperture slightly and increases the shielding depth, the high angle brightness is eliminated, resulting in a more attractive and comfortable application

Several LR6 Approaches

In the process of experimenting with various approaches to control the brightness from the large source area of the LR6, I also tried some louver designs, like were once used on big R40 lamps, which have the same problem in shallow housings. While these were even more effective in controlling brightness, the loss of total light output was more than I felt necessary. However, in some applications, these may be an even better solution.

The baffle is 1 1/2″ deep, snaps onto a lip on the LR6 lens

These louvers will be familiar to anyone who has done a church using R40 or R56 lamps. They do a great job of brightness and glare control, but impose a loss of light that is not always desirable.

The MR16 Retrofit Lamp

The MR16 lamp has always been a little glare grenade. LED versions that make enough light to be considered viable replacements, like the ones here from LEDengine, are just like their halogen forbearers in this regard, and worse. With an optical source size of just 1″, the brightness of the source is really offensive.

To avoid cutting into the light pattern, while creating a reasonable cutoff takes a little effort in working out the geometry of a very simple and familiar snoot. Further, since most all retrofit lamps have their own geometry and rarely match conventional lamps, mounting standard MR16 accessories is not an option.

The snoot here cuts off all light outside 45 degrees from the furthest edge of the light source. However, the design is also wide enough not to cut into the beam pattern, so applied light levels are not effected. The result is an elimination of glare from most vieing angles, just as this approach has done for halogen lamps of the past.

The brilliance of an efficient LED optic can be offensive and distracting if left uncontrolled.

The snoot cuts off light outside 45 degrees, eliminating the visibility of the optic, yet retains the main beam angle and most of the field distribution, so lighting effect is the same, just more comfortable to live with.

Not a new approach, just one designed specifically to this lamp. Unlike the standard halogen lamp, every LED retrofit lamp will need tweaks to the design to suit its unique geometry and optics.

  1. Soheb V. says:

    Under your section labeled “Several LR6 Approaches” there are two images of a baffle and a louver. Do you have any idea when these were manufactured? Or a date for when they were first introduced into the industry?



    • kwillmorth says:

      I manufactured all of the products in the 52 in 52 project, including the louvers and baffles you referenced. They were not introduced commercially, although they can be made easily enough. We produce all of our products to order using rapid production techniques, such as plastic modeling, or CNC machining, to facilitate customization to suit specific project or customer needs.

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