Lighting, as an industry, has seen very few significant innovations in the basic technology of light production in the past century. As a result of this static situation, lighting companies have largely been concerned with novel ways to bend metal and shape glass. Current mature technologies such as incandescent and fluorescent have given rise to a lighting infrastructure that is inefficient, overbuilt, and mostly focused on mitigating the overproduction of light from highly inefficient sources.

A Soraa lamp with thermocouples attached.

LEDs—only the fourth manmade lighting technology in the history of humanity—have become a truly disruptive technology. The significant increase in efficiency and longevity of LED lighting versus other lighting technologies is causing a fundamental disruption of the lighting industry along the entire value chain. Standard lighting approaches are now being challenged by entirely new possibilities enabled by LEDs, such as design flexibility.

The Problem

Quality of light is the crucial factor in the adoption of LED light sources to replace incandescent and fluorescent sources. Until now, customers whose revenue is directly impacted by the quality of light in their retail establishments have held back from upgrading to LED lamps in spite of an attractive ROI, because the quality of light in the first generation of LEDs wasn’t up to par. With a Soraa GaN on GaN™ LED MR16 lamp, customers get a no-compromise, “beyond halogen” replacement that has full visible spectrum light, high CRI (color rendering index) & R9 (an indication of how well the light shows deep, saturated shades of red), and no harmful UV & wasteful IR.

The first waves of LED adoption have necessarily involved a high degree of “plug and play” retrofitting, where replacement lamps simply plug into fixtures and systems that were designed for very different light sources. Naturally, this gives rise to many types of incompatibilities that threaten more widespread adoption of LED lighting. Manufacturers need to address issues of plug and play compatibility while simultaneously developing the new fixtures and infrastructure necessary for full adoption of LED lighting. This is challenging because innovation in light source development now follows a semiconductor innovation pattern, while fixture innovation has up until now maintained a slower pace.

Soraa lamp in a fixture being tested with a digital handheld thermometer.

Compatibility problems with LED lamps and fixtures fall into three categories: mechanical, thermal, and electrical.

Mechanical incompatibility problems are encountered when LED lamps do not match the mechanical dimensions of traditional lamps and, therefore, do not fit in the fixtures. In the case of the MR16 form factor, some LED MR16 lamps exceed the height or width of standard halogen MR16 lamps, and do not fit into many fixtures that were specifically designed for the halogen lamps.

With thermal incompatibility, problems arise from the different thermal management needs of incandescent sources and LEDs. For instance, halogen lamps can operate at very high temperatures (over 200°C in many cases), and therefore no special consideration is paid to heat dissipation in the design of fixtures used for these lamps. LEDs must operate within a certain thermal envelope to ensure a long, reliable life, and they must also meet safety standards. Soraa's GaN on GaN LED MR16 lamps, for example, can operate at much higher temperatures than other LED lamps, but still need to stay under 120°C at the base. Even though LEDs do not produce anywhere near as much heat as incandescent sources, many LEDs will not operate properly in fixtures designed for incandescent lamps.

Electrical incompatibility problems also arise from very different requirements of LEDs compared to incandescent sources. Most currently installed transformers and dimmers were designed to work with the purely resistive loads of filament-based halogen/incandescent lamps, and in many cases, at much higher power levels (50W being the most common power level for halogen MR16 lamps, for instance). LEDs are very different – they do not appear as resistive loads, and they operate at much lower power levels, often at 75% or less than incandescent sources (9-12W in the case of Soraa LED MR16 lamps). The dramatically lower power requirements of LEDs lead to many performance problems when they are used with the wrong kind of dimmers and transformers (or dimmer/transformer combinations) including flickering, inconsistent dimming, or not powering up at all.

The Solution

Temperature vs time test results for a 9.5W Soraa lamp inside a tight fixture in the horizontal position.

Addressing these incompatibility issues benefits many stakeholders: end-users, specifiers, manufacturers, utilities, and regulatory agencies. The Works with Soraa fixture program is designed to foster strong collaboration between Soraa and fixture manufacturers, so fixture and lamp combinations can be validated and approved for mechanical, thermal, and electrical compatibility.

End-users have many reasons to replace their current incandescent/ halogen lighting with LED lighting. They want longer lamp life and lower energy bills, but they refuse to compromise on quality of light. They also are motivated in part by governmental mandates that phase out incandescent lamps. First generation LED lamps, like early versions of CFLs, may have mechanical & thermal compatibility problems with fixtures, dimming systems and transformers designed for incandescent and flourescent sources. End users need to know that LED lamp/fixtures combinations are fully compatible and that they will perform as desired. They also need affordable, flexible solutions that are easy to install.

Specifiers, who routinely make design and specification decisions that affect large buildings, many people, and long term energy use, need confidence that the LED lamps they specify will perform as expected while providing a high quality of light, low maintenance costs, and significant energy savings. In addition to dependability, they also want the design flexibility and affordability that LED lighting promises.

Most fixture manufacturers in the lighting industry tend to be medium to small sized companies, and lack the skills or resources to develop their own LED solutions profitably. They need to adapt to the disruptive wave of LED technology in a way that allows them to evolve new solutions affordably and with much greater agility, as the pace of technological development is now much faster. The Works with Soraa compatibility program allows them to stay focused on their fixture innovations, partner with Soraa to enable complete solutions, get products to market faster, give customers more product choices, and stay on the leading edge of LED lighting.

The official “Works with Soraa” logo.

The Works with Soraa program is built to be efficient — fixture manufacturers signing up for the program receive lamps with thermocouples attached. These are used to test with as many of their fixtures as possible for thermal and mechanical compatibility, using testing protocols developed by Soraa.

Each lamp is wired with three thermocouples, one attached at the lamp base (which contains the driver electronics), and two on the heatsink. The fixture manufacturer installs the lamp in each fixture they want to test. The fixture/lamp combination is then placed in an environment that matches its most challenging real-world application in terms of ambient temperature, vertical and horizontal fixture mounting angle, humidity, and other conditions. One thermocouple measures base temperature, the other two on the heatsink are monitored to characterize the thermal resistance across the lamp when operating in the fixture. Data is captured from the three thermocouples over a period of one hour, during which the lamp base temperature must stay below 120° C. If the fixture performs to specification, it is validated as a “Works with Soraa” fixture. Soraa and the OEM then jointly promote the fixture/lamp combinations, so specifiers can then specify, and customers can purchase and install, these validated combinations with confidence.

The program launched in December 2012 with four fixture manufacturers—Tech Lighting, Focal Point, Hevilite, and Dreamscape. Soraa plans to add another ten to fifteen selected manufacturers in Q1, and then open the program up to all manufacturers in April of 2013.

Industry response to the program so far has been very positive. Chip Israel, current president of the IES and president of the prominent Los Angeles design firm Lighting Design Alliance, said “For LED lighting to gain greater acceptance in the lighting design community, it is critical that we solve the LED lamp and fixture compatibility issue. I commend Soraa and its fixture manufacturer partners for tackling this important issue and encourage other fixture manufacturers to join this program, as we are desperate for this information.” And according to internationally recognized lighting designer Jan Moyer, "Soraa LED replacement lamps give us the ability to retrofit existing recessed lighting in homes so that owners can benefit from the energy savings this new technology has brought to the table. We are able to retrofit with confidence knowing that Soraa lamps have been tested and validated with the fixtures.”

Soraa’s GaN on GaN technology is a “native substrate” approach, where Gallium Nitride is deposited in epitaxal layers on a native Gallium Nitride substrate, rather than on cheaper foreign substrates like sapphire, silicon carbide or silicon, as with first generation LEDs. This enables LEDs that can handle significantly more current, and emit ten times more light, per unit area of LED wafer material than first generation LEDs. GaN on GaN technology leverages the advantages of the native substrate, including over a thousand times lower crystal defect densities that allow reliable operation at very high current densities (the same principle that enabled Blu-ray laser diodes) and temperatures. In addition to superior crystal quality, the native substrate’s optical transparency and high electrical and thermal conductivity produce very high levels of light extraction and enable a very robust, simple LED design that delivers maximum performance.

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Lighting Technology Magazine

This article first appeared in the May, 2013 issue of Lighting Technology Magazine.

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