LED Japan/Strategies in Light conference report

The third LED Japan/Strategies in Light Conference and Expo took place in Yokohama on September 29-October 1. The conference was a sold-out event attended by 190 people, with about two-thirds of the audience from Japan and the rest from other parts of Asia, as well as Australia, the US and Europe. Approximately 7,000 people (an increase of 40% from 2009) visited the exhibit area, which featured 90 exhibitors.

The conference was opened by Robert Steele of Strategies Unlimited, who reported that the LED market will reach $9.1 billion in 2010.

Energy savings

Based on several of the presentations from the Japanese speakers, it seems clear that Japan is very serious about the Kyoto Protocol and reducing greenhouse gas emissions. All the Japanese speakers stressed how Japan was doing to reduce carbon footprint, and in particular how LED lighting can aid in this effort. Detailed plans and measurements at national and local levels were presented. Presentations by European speakers also highlighted how LED lighting can help in this regard.

Fig. 1.Both Alfred Felder of Osram Opto Semiconductors (see Fig. 1) and Junichi Nakamura of Shimizu Company discussed how to save 80% of power spent on lighting. Mr. Nakamura gave a detailed breakdown on how this 80% saving can be achieved in a typical office for 48 people at 5.25 m2/person. His calculations are as follows:

• 28% savings by direct 1-1 exchange of overhead fluorescent tubes to LED fixtures
• 27% savings by substituting overhead lights with combination of ambient + task lighting
• 5% savings through reduced lumen depreciation
• 10% savings by introducing day light with variable blinds + sensors to adjust amount of light in different parts of room relative to the windows
• 10% savings by using sensors to control lighting when people are absent from their desk which is about 30% of the time.

On top of the 80% mentioned above, since heat generated by LED is in the ceiling rather than the room, the power consumption of the air conditioning is estimated to go down by 12%.

Jianzhong Jiao of Osram Opto Semiconductors emphasized that the need for standardization is urgent for light engines. IESNA has a proposal on LED light engine measurements. The emergence of Zhaga, a global consortium for standardization of LED light engines, will hopefully speed up the market growth in the area.

Automotive applications

In the area of automotive lighting, Takashi Sato of Stanley Electric had an interesting observation about the cost of 1 kWh of electricity in cars as compared to household use. The former is ¥80 (US$0.97) while the later is ¥18-24 (US$0.22-0.29) in Japan. This makes the value proposition for using energy-efficient LEDs in automobiles relatively more attractive. While concept cars at car shows all have LED headlamps, at present, only about 0.1% of the cars use LEDs in this function. Besides cost, technical challenges such as heat, weight of the heat sinks, alignment of multiple LEDs and fog developing inside lamps are impeding the adoption process.

A member of the audience also commented on the serviceability of LED headlamps. When an exterior lamp goes bad in a car, the police are keen to give tickets and the speed of having that repaired is of the essence. Currently, one just buys a replacement lamp and the car is ready to go. While LED lamps do last the lifetime of the car, if there is a problem, there may be a long lead time to get the right parts for the particular car model and the repair will take longer and the labor cost will be high.

LED manufacturing

The US DOE estimates that a ~10X reduction in $/lumen is required for widespread SSL adoption within the next few years. About ~2X (50%) reduction is possible with better process control enabling:

• Baseline yield improvements,
• Faster excursion detection
• Faster process development and ramp into production

Moving forward, technology changes are resulting in new inspection requirements.

Chip size

One of the ongoing debates in the industry is whether a large chip or multichip package is good for applications that need high lumen SSL products. These applications can include general lighting like PAR38 retrofit lamps, track lights, street lamps, and specialty lighting such as projection display, automotive headlights, entertainment, UV curing, endoscopy, etc.

Fig. 3. Chuck DeMilo of Luminus Devices compared the two types of packages (see Fig. 3). By using a single chip, one can create a single uniform shadow and eliminate “multi-source shadowing”. With the light guide closer to the source, there is better color mixing and uniformity. In the design of light fixtures, the aesthetics is better with one chip vs. multiple chips. Technically, DeMilo claims that a large chip reduces the current density (droop) while enabling high lumen packages with high efficiency. There is also cost savings because the optics used are less complex.

Next year

LED Japan/Strategies in Light 2011 Conference and Expo will take place in Yokohama on September 28-30.

LED Japan/Strategies in Light is part of the global Strategies in Light conference series, which also includes events in the USA, Europe and China.