LED arrays light the way

The real advantages of solid-state lighting are realised when lamp designers shake off limitations imposed by traditional lamps and take advantage of the low power, low heat and low profiles of LED light sources, as LED arrays light the way.

Alternatives to the incandescent light bulb have come a long way over the past 10 years. Demand from both government agencies as well as consumers for improved energy efficiency drove development of the compact fluorescent bulb but raised concerns about the quality of the light, dimming limitations and mercury contamination.

LEDs entered the general lighting market as individual lamps, often mounted on a PCB substrate to form a matrix of lamps necessary to provide the required light output. Major advances in the materials and fabrication of LEDs have dramatically increased their performance while the price per lumen has dropped. LEDs packaged in bulb and tube form factors that are designed to retrofit standard light bulbs and fluorescent tubes have simplified consumer adoption of solid-state lighting.

The real advantages of solid-state lighting are realised when lamp designers shake off limitations imposed by traditional lamps and take advantage of the low power, low heat and low profiles of LED light sources. The abilities to dim, operate in temperature extremes and dynamically adjust colour hue introduce attractive options to the designer and consumer.

Entirely new light fixture designs are possible using LEDs. Manufacturers now provide LED light sources as individual emitters, LED modules that may include current-limiting resistors and light engines with integrated drivers. The chip-on-board (COB) module has emerged as the most effective package for commercial and residential lighting fixtures.

Leading COB module suppliers, including Bridgelux, Citizen, Cree, Osram, Philips and Sharp, have introduced multiple series of packaged LED arrays that combine ease of manufacture, lower cost per lumen and higher efficiency. Many of these modules feature solder pads that allow permanent wire attachment, while others are designed for socketing.

The ability to replace an LED module that claims an operational lifetime of up to 20 years may seem unnecessary, but this feature is not for the consumer’s benefit. Luminaire manufacturers want design flexibility to take advantage of fixture platforms that may extend over many models.

Pluggable LED modules allow manufacturers to select from a variety of photometric, mechanical, thermal and electrical variables in order to match the requirements of a specific application. A common LED platform also provides an upgrade path as LED technology continues to evolve.

To minimise the risks of hand soldering, such as poor solder joints and damage to the COB, skilled labour must be used, increasing assembly time and cost.

Connector manufacturers such as BJB, Molex, Ideal Industries and TE Connectivity have solved this problem with a series of low-profile, solder-less LED array sockets that enable simple snap-in pluggability. Also known as LED holders, these connectors provide mechanical support, thermal mitigation, optical attachment and electrical interconnection.

Up to this point, there has been little standardisation among solid-state lighting manufacturers. Each supplier has gone its own way in establishing the shape, mechanical dimensions and performance of its lighting products. The Zhaga Consortium focuses on a series of global specifications that will make LED lighting components interchangeable between manufacturers. Several module, holder, electronic controller and luminaire manufacturers now offer Zhaga-compliant products, which require testing by a Zhaga-certified laboratory. Creating an ecosystem of interchangeable SSL components is expected to lower the cost and accelerate the mass adoption of LED lighting.

As rapid as the development of solid-state lighting has been, we may still be in the early stages of a revolution in general lighting. Cost is still relatively high as compared to the incandescent bulb but is becoming more competitive. New materials used in the fabrication of LEDs continue to increase the lumens per watt, quality of light and power efficiency. Solid-state lighting fixtures that have their own IP address can be remotely controlled by a smartphone. Low-voltage DC power generated by solar panels is an ideal energy source for solid-state lighting devices. Organic LEDs (OLEDs) and quantum dot technology are providing a roadmap to the future of lighting. Connectors will continue to play a key role in this burgeoning new market.

Further information, please contact Robin S Pearce, Bishop and Assoc - ANZ, apearce4@bigpond.net.au.