llumination of Sponsor Billboards at International Stadium Yokohama

Photo 1 Broad view of sponsor billboards (with field lighting + billboard spot lighting)

Outline

This world-class stadium, which seats 70,000 spectators, was selected as the venue for the finals of the 2002 FIFA World Cup Soccer tournament. In addition to soccer competitions, it was constructed and equipped to suit a wide range of events, including international track and field competitions, national athletic meets, and live music concerts.

Sponsor billboards are installed on the front face of the balconies above the spectator seats (Photos 1, 2, 4). Up to now, these billboards were only illuminated by residual light from the field lights, but in response to requests from the sponsors, the stadium installed floodlights on the catwalks on the edges of the ceiling to light up the billboards and show them more clearly and attractively (Photo 3). The floodlights adopt a unique construction that enables adjustment of the lighting range using a mask, so that illumination can be cut in areas where it is not required and minimize light leak.

— Features of the Lighting Facilities —

• Reduced light leak eliminates unwanted light, and is reduces the burden on the global environment.
• Virtually no glare experienced by athletes, administrators, or spectators under the balcony
• Appears similar to internally lit billboards, but more economical

Photo 4 Broad view of sponsor billboards (with billboard spot lighting only)

Lighting Fixtures

(1) Light source

150 W high color rendering metal halide lamps with an average color rendering index (Ra) of 96 were adopted to authentically recreate the original color and design of the billboards. The lamps feature a luminous flux of 12,700 lm, a color temperature of 4,200 K, a lifetime of 6,000 hours, and a ceramic arc tube to ensure that there is virtually no change in color temperature over time. In terms of maintenance, it is extremely difficult to change the fluorescent lamps in internally lit billboards because of their high installation position, but the floodlights can be changed easily because of their convenient installation location. They are also very economical, as only the bulb needs to be replaced.

(2) Features of light fixtures

The floodlights are made up of a light source, a mask, and a convex lens. By adjusting the mask, it is possible to cut illumination in areas where it is not required and minimize light leak. The scope of the floodlights on the back stand is 7.5° up/down and left/right, and on the side stand is 12.5° up/down and left/right.

(3) Luminance

There are a total of 22 sponsor billboards installed at the stadium. Each 9 m × 2 m billboard is illuminated by two floodlights, on the right and left, with an average measured illuminance of between 340 and 400 lx.

Location	Yokohama City, Kanagawa Prefecture
Client	Yokohama Sports Promotion Agency
Design	Kinden Corp.
Completion	March 2000
Materials provided by	Junior Member Yumi Murayama (Koito Industries, Ltd.) © Koito Industries, Ltd.; 2001