What's New in Lighting Technology & Design【Tsutomu Ochiai】
Lighting Fair 2007 Review--Part 1: OLED
Jun 19, 2007
Tsutomu Ochiai, lighting designer (M&O Design Office)
1. Introduction
East Hall 3 of the Tokyo International Exhibition Center (Tokyo Big Sight) was the venue of the Lighting Fair 2007 from March 6 through 9. The event, held under the theme "Lighting - Friendly to People and the Earth," hosted an exhibition of lighting appliances running the gamut from illuminants to materials and components from both inside and outside of Japan. Marking its 8th anniversary, the comprehensive fair proved its growing popularity with the exhibiting companies and visitors numbering 121 (21% increase from the previous event in 2005) and 96,948 (17% increase), respectively. Of particular note among the exhibits were LEDs and OLEDs, next-generation illuminants for which Japan has led the world in the area of application. In keeping with the growing importance of energy conservation and ecological requirements felt in the market, they had attracted a great deal of interest not only from those in the lighting industry, but also from those in the furniture, interior, construction and automobile industries as well as in the home appliance and cell phone business. The site was practically replete with manifestations of leading-edge lighting technology. The 4-day event kept the visitors simply wowing at the high quality of the competing appliances on exhibition. In this article, I will be reporting on my visit in 3 parts, starting with booths proudly exhibiting their OLED lighting appliances that have attained world-class brightness.
2. Five Booths Exhibiting OLED Lighting Appliances
There was a booth literally overflowing with visitors, and it belonged to the Research Institute for Organic Electronics of Yonezawa, Yamagata prefecture. Drawing upon one of the features of OLEDs, the institute came up with pendants having a distinctively thin design whose 4 variable panels are made to control the spread of light. The OLEDs used in the exhibited lighting appliances have an intensity of 5000 Cd, and the color appearance (color temperature) is tuned to that of a fluorescent lamp while the luminance level is set somewhat lower than that of a fluorescent lamp - in other words, they are more or less glare-free. Their light-emitting efficiency reportedly stands at 20 to 30 lm/W, which is better than an incandescent lamp although not as good as a fluorescent lamp. (The news is that there could well be a practical OLED lamp with an efficiency of 100 lm/Watt or higher within a few years, exceeding that of fluorescent lamps.) Being told the lighting intensity directly under each of the exhibited pendants is 300 lx (1-m distance), I readily joined others in seeing a bright future for them. In a general household, any one of them may be hung above a dining table to obtain the necessary brightness. Moreover, OLEDs have already been tested and have proved their adaptability in regard to color appearance and Ra (color rendition), paving the way to a new market for flat-surface light sources.
Figures 1, 2, 3 Winner of the top award at the Yamagata OLED Design Competition.
It consists of a total of 5 14-cm square panels, the surrounding 4 of which move up
and down like wings to freely light the entire area or shine in a particular direction.
Figure 4 Booth of the Research Institute for Organic Electronics overflowing with visitors.
Figure 5 Junji Kido, professor at Yamagagata University and father of the white OLED,
busily working to spread the good news of OLEDs in the booth.
People waited in line for the Matsushita booth (Matsushita Electric Works + Lighting Company of Matsushita Electric Industrial). They were there for OLEDs in action. The booth provided a room exclusively for first-hand experience with OLEDs, designed to shut out light from other exhibits, and the OLED lighting appliances on exhibit were made to low-volt wiring specifications so as to bring the low-voltage activation feature of OLEDs to the fore.
Figure 6 OLED exhibits inside the Matsushita booth.
Figure 7 People waiting for first-hand experience with OLEDs.
The next stops on our tour will be the booths of NEC Lighting, and Koizumi Lighting Technology, both of which offered specific and easy-to-understand exhibits of OLED uses. The OLED features NEC Lighting focused on were "thin-flat and light-weight," and their booth had wire-suspended appliances on display. Though hanging from above, they were virtually free of any oppressive feeling. OLEDs are sandwiched by transparent acrylic plates for downward lighting and, with the help of (ceiling) indirect upward lighting, the exhibitor successfully created the illusion of there being a thin OLED sheet floating in the air. The rendition was quite impressive in that it pointed to a new use of OLEDs in creating a calm, magically beautiful lighting atmosphere.
Figure 8 OLED pendant from NEC Lighting.
A total of 6 panels are used, one for indirectly lighting the ceiling.
Koizumi, meanwhile, presented a unique "full-length mirror." An OLED is finished smooth by vapor deposition of aluminum, reflecting light while remaining de-energized to mirror its surroundings. Playing on its mirror effect, the company was suggesting its uses as full-length mirrors, placing them in front of a wall so that they might concurrently serve as standing interior accessories.
The suggestion, in passing, reminded me of something. The recent advances in mirror technology are simply amazing, born out of the need for better insulation of building windows. Called "light-modifying glass technology," a pane of glass can now turn from a clear plate into a mirror and then back. Today, its scope of application is growing wider (e.g., as seen in automobiles) along with the technology used in some new thin alloy membranes. The former can take on or make use of what the latter has to offer, as when coupled with thin membrane technology, OLEDs will most likely bring about yet another round of attractive products.
Figure 9 OLED lamp stand from Koizumi.
No OLED is used for the top segment and the second segment from the bottom,
and the 5 panels in the photo go on and off.
The heart-shaped light-emitting pendant - though not a lighting appliance, but rather an accessory hung on the neck - was from International Manufacturing & Engineering Services (IMES). With its colorfully appealing light-emitting surface glowing red, blue, yellow, and pink, the pendant successfully drew the attention of the visitors. An OLED panel is inherently capable of emitting light in a variety of colors (at any chromaticity and color temperature). Enhanced by the multi-photon emission engineering (described later), its output now provides ever higher light intensity and color saturation, an attribute which made IMES demonstration model stand out together with its unique shape. A small trial model placed as if nonchalantly in the booth also caught my eye. Appreciably small, it was equipped with OLEDs emitting light in vivid colors from both sides. I was told the double-sided light emission came from the full utilization of engineering referred to as "top emission." Although still the size of a postage stamp, it heightened my expectations. Japan has been building an industrial structure based on state-of-the-art production technologies, and we can realistically hope its industrial might will soon add to this diminutive piece the size and light intensity required for general lighting applications. Incidentally, IMES also included among its exhibits models of white OLED lighting appliances. Although introduced as trial samples, the mirror light made of high-rendition OLEDs (with a Ra of 95 or higher) and the ceiling light consisting of 12 built-in OLED panels (each being 100 lm in intensity) both delivered more than I could have expected in terms of the quality and volume of light. While there still remain a few issues to address such as service life and competitive pricing in the market, I felt my expectations grow over the potential of OLEDs as an illuminant for lighting appliances.
Figure 10 Sample exhibit of OLEDs in the shape of a heart from IMES.
Figure 11 High-rendition OLED mirror light from IMES.
Figure 12 High-intensity ceiling light with built-in high-efficiency OLEDs from IMES.
3. Future Developments Expected in the Field of OLED Lighting
In a few years, we are likely to see high-intensity white OLEDs being used in lighting applications emitting light from a super thin surface or, in some, from both sides. In the field of OLED lighting, design concepts quite different from what we have today should spring forth, with a choice of renditions being accordingly wider. These are bound to happen because OLEDs are reportedly compatible with plastic and paper (at present, made from glass) and the resulting sheets will certainly add to the already wide choice of their applications. They could well affect how we create space as well as how we spend time in it. It is undoubtedly a dream come true for any lighting designer looking for a new illuminant. For all the possibilities they offer, there are still factors that need to be dealt with, i.e., efficiency, service life, color of light, ease and quality of rendition, safety, and cost. A good illuminant must satisfy them all, as any of them, if lacking, could limit the marketability and consequently hinder acceptance by the consumers.
Today, the most widely used source of light is said to be the incandescent lamp, followed by the fluorescent lamp. The incandescent lamp has low lighting efficiency, not a good choice from the point of view of energy conservation. The fluorescent lamp, on the other hand, uses mercury, an element giving rise to environmental concerns over its safety. OLEDs are made from, as the name clearly indicates, organic materials found in nature and are recognized as free from safety-related concerns. Their experimental samples have already demonstrated a rate of efficiency on a par with that of a fluorescent lamp. We often hear of the incandescent lamp giving way to power LEDs and the fluorescent lamp to OLEDs, shifting the 21st century's principal sources of light. On the 1st page of the morning issue of the NIKKEI toward the end of March was an article reporting on an arrangement made between Konica Minolta and General Electric for the development of OLEDs in practical lighting uses (in 3 years). We can now look forward to the continuing advancement and early practical application of white OLEDs, which were born and raised in Japan - the next Lighting Fair scheduled for 2009 no doubt will have a great deal in store, demonstrating the upcoming developments in the field of OLED lighting.
