LED Lighting: A Bright Future That Is Now Enlightening the Past
By Paul Golata, Mouser Electronics
Over several years now, high-power LEDs have made rapid advances as far as power and raw luminous output are
concerned. Much to Edison's discontent, solid-state is now firmly established as the technology of choice for
ambitious indoor and outdoor lighting applications-leading to greater engineering light-bulb moments. The conversion
includes even the popular location of St. Peter's Square in Rome,
which is now lit by over 130 luminaires containing Osram neutral white LEDs. Could this be the ultimate blessing for
LED lighting?
Figure 1: Osram now provides a unique lighting experience to St. Peter's
Square in Rome. (Source: Governatorato S.C.V. - Direzione dei Musei)
Device-Level Advances
Engineers can expect ever more powerful emitters to continue emerging from the laboratories of the leading
manufacturers, if for no other reason than to claim kudos as King of the Hill. For some time now, however, the
emphasis has been shifting towards optimizing device performance to meet other practical economic and aesthetic
considerations.
The continued focus on improvements in efficiency regarding lumens per square millimeter (lm/mm2), as
well as lumens per Watt (lm/W). This is important, as lighting manufacturers now look to improve subsequent
generations of currently successful products: newer, better devices within the same footprint as their predecessors
allow new products to be introduced quickly and cost-effectively without requiring a major redesign. Cree introduced
the latest generation of its benchmark high-power XP-L emitter in September, raising lumen output and efficacy
(lumens per Watt) by 7% and 15% respectively. Reflecting the value placed by industry on area efficiency, the
Illuminating Engineering Society of North America Progress Committee praised three LEDs from Osram's Oslon and
Durius families for delivering a combination of high output and small footprint.
The latest generations of packaged LEDs, such as Cree's XP-L and Lumileds'
Luxeon Core
and Compact Chip On Board (COB), a variety of new devices arrived to help designers take their products to the next
level quickly while bringing significant advances in the development of package-less LEDs. Seoul Semiconductor has become the first supplier to enter
mass production of
package-less devices with its WICOP family. These devices promise to save cost and footprint by eliminating package
components such as a lead frame and bond wires. With WICOP, Seoul Semiconductor has perfected a way of enhancing the
luminous efficacy of package-less emitters: the devices achieve higher lumens per Watt than either conventional
packaged high-power LEDs or alternative chip-scale package devices.
Focus on Quality and Color
With growing confidence in the ability to illuminate large areas, either indoors or outdoors, engineers and
designers are increasingly directing their attentions towards the quality of illumination. The IES has published the
TM30-15 color-quality metric, which helps designers assess the rendering of a wider range of colors more accurately
than is possible using the traditional Color Rendering Index (CRI) that expresses average color fidelity in
comparison with an ideal light source.
Although CRI can be manipulated to achieve an artificially high score, its strength lies in its simplicity. It is
still not clear whether the significantly more complex TM30-15 will be widely used, or even well understood,
throughout the industry. However, component producers and lighting designers are coming to terms with the ability to
customize light in ways that have not been possible in the past, and this is creating new opportunities.
One of these is horticultural lighting, and in recent months, major LED manufacturers have introduced products
aimed directly at this sector, including the Lumileds Luxeon
SunPlus and Cree XQ-E and XP-E families. These new LED devices are optimized to
produce spectra that are
known to maximize photosynthesis which enables growers to combine excellent, LED-optimized lighting with existing
indoor-farming expertise, covering aspects such as temperature and atmospheric carbon dioxide to shorten the
crop-growing season further while also optimizing flavor and yield. Moreover, of course, there is the added
attraction of lower utility bills thanks to the known efficiency advantages of LED lighting. As global food demand
continues to increase with rising population, here is one-way technology can help to meet the critical challenges
facing future generations.
The success of horticultural LED lighting is one example of how the controllability of LEDs can deliver extra value
in specific applications. A tougher challenge, and potentially an even greater opportunity, is to increase
understanding of human-centric lighting and provide new products that fully exploit the controllability of LEDs to
benefit human health, well-being, and productivity.
Still Waiting for Bluetooth® Mesh
LED light is closely associated with the smart lighting revolution, and for much of the year, the industry has been
excited by the promise of the new Bluetooth® mesh profiles. These should enable end-users to
control lights throughout a large area, such as an entire house or even an office or factory, directly from their
smartphone when in Bluetooth range of any node in the network. The Bluetooth SIG has assigned a
working group to look at various proposals; its publication is expected but has not yet been announced. When it
arrives, the official Bluetooth mesh standard may not contain many surprises, as it is widely projected to
be
based on the CSRmesh™ technology currently powering networkable Bluetooth radios such as
CEL's MeshConnect™ modules.
New Standard for Efficient Power?
If integration of LED lighting within smart networks is to become easier, integration with the building's power
infrastructure could also benefit from some simplification. Implementing circuitry for AC/DC and voltage conversion
in each fitting adds expense and wastes energy. Power over Ethernet (PoE) is one option that could help minimize
power-conversion losses and save costs, which has the additional benefit of carrying power as well as control
signaling over the same network cable.
Distributed Low-Voltage Power (DVLP) has arrived. Like PoE, DLVP comes within the class 2 power limits of 100 Watts
and 60V. While PoE is arguably better able to service smart lighting as a part of the IoT, DLVP-provided it becomes
an open standard-could help significantly reduce lighting installation costs while maximizing the inherent
energy-saving advantages of LED lighting; which, if we can all cast our minds back far enough, was the reason the
technology first gained widespread attention.
Paul Golata joined
Mouser Electronics in 2011. As a Senior Technical Content Specialist, Mr. Golata is accountable for contributing to
the success in driving the strategic leadership, tactical execution, and overall product line and marketing
direction for advanced technology-related products. Mr. Golata provides design engineers with the newest and latest
information delivered through the creation of unique and valuable technical content that facilitates and enhances
Mouser Electronics as the preferred distributor of choice. Before Mouser Electronics, he served in various
manufacturing-, marketing-, and sales-related roles for Hughes Aircraft Company, Melles Griot, Piper Jaffray,
Balzers Optics, JDSU, and Arrow Electronics. Mr. Golata holds a BSEET from DeVry Institute of Technology - Chicago,
IL; an MBA from Pepperdine University - Malibu, CA; an MDiv w/BL from Southwestern Baptist Theological Seminary -
Fort Worth, TX; and a PhD from Southwestern Baptist Theological Seminary - Fort Worth, TX. Mr. Golata may be reached
at paul.golata@mouser.com
