Conference Brings Together Solid-State Lighting Suppliers

Richard Gaughan

For six years, Intertech Corp. of Portland, Maine, has sponsored a conference for representatives from all levels of the LED industry supply chain. This year’s event, held in October in San Diego, showcased a rapidly maturing industry facing challenges on several levels: technological barriers to overcome, profit margins with which to struggle and standardization issues to address.

An AC-coupled configuration with the current controlled by the selection of a capacitor in the LED package enables various types of LEDs to be driven by a single power source. Courtesy of Lynk Labs Inc.

LEDs are finding a place in giant billboard displays and mobile handset backlighting, but incursions into the general lighting market have barely begun. The potential market for solid-state general illumination is huge — billions or even tens of billions of dollars per year. The energy efficiency and reliability of solid-state emitters are advantages for general lighting, but ways must be found to enable these devices to best work with the existing infrastructure if they are to be adopted for this application.

Several conference participants noted that the line engineers who specify lighting for architectural projects are not being informed about what is available from the industry. But Makarand Chipalkatti of Osram Sylvania in Beverly, Mass., questioned whether LED manufacturers had credible information to provide specifiers.

To develop such information, a degree of standardization is necessary. For example, the quality of white light conventionally is measured in terms of the color-rendering index. However, Jan-Willem Andriesse of Philips Lighting in Eindhoven, the Netherlands, explained that LEDs may display a high color-rendering index but exhibit poor true-color rendering.

Bill Kennedy of Toyoda Gosei North America Corp.’s optoelectronics office in Irvine, Calif., further noted that the existing range of warm and cool white phosphor devices available to the lighting industry can more or less achieve any desired color, but each company has its own definition of color quality, so designers cannot compare the relative quality of the various sources.

These engineers are not the only ones put at a disadvantage. Kathryn M. Conway, the conference co-chairwoman and an LED consultant, believes that the industry must develop standard measures of efficiency and effectiveness of light delivery so that financial analysts can do their work. Moreover, the industry is searching for a standardized mechanical interface, which would ease the adoption of LED technology by lighting suppliers.

Of course, it does not matter how good the standards are if the products cannot do the job, so LED developers are pushing device performance. A notable introduction at this year’s conference was Kirameki from Nichia Corp. of Tokyo, a compact package that will be available in 5.5- and 11-W white-light versions. For integrators such as decorative crystal manufacturer Swarovski AG of Wattens, Austria, the small size and straightforward mechanical interface of Kirameki are welcome.

A couple of companies are working on AC-driven LED devices that they hope will be embraced for their potential to reduce cost and size and to improve system reliability over traditional, DC-driven solutions. III-N Technology Inc. of Manhattan, Kan., uses a single die with two parallel strings of several micro-LEDs, which together provide enough voltage drop to be connected directly to the AC power main. Lynk Labs Inc. of Elgin, Ill., uses a higher-frequency AC supply and controls the current to each LED by coupling it through a resonant capacitor.

From die manufacturers to suppliers of solar-powered marine lighting, the participants in the conference showed a businesslike attitude because, Conway said, they recognize that solid-state lighting is a real business with real milestones.