Stadiums are moving to LED lighting not only to lower energy and maintenance costs, but also to meet broadcast demands that include a push to high-definition TV and ultra-slow-motion technology, which can cause light flickering. Cree, Inc. is tackling this last holdout for LED lighting adoption with its latest XLamp XP-L High Intensity LED. The new device is touted as the first single-die LED to deliver more than 100,000 candela with a 50-mm diameter optic at 10 watts.
The outdoor LED display market is expected to grow from $4.8 billion in 2013 to $12.5 billion by 2020, growing at a compound annual growth rate of 14.7 percent, according to research from Transparency Market Research. The big drivers: The rising number of sports events, live concerts and corporate exhibitions globally that are using LED boards, LED video walls and LED mobile panels, which includes broadcasting live events at corporate exhibitions, concerts and other shows.
“We envisioned that stadium lights would be the last application to ever adopt LEDs just because of the amount of light needed for those applications is immense,” said Paul Scheidt, leader of product marketing, LED Components, Cree Inc. “In addition, you need to control that light to get it down to the ball field in a very efficient and cost-effective way. It’s very interesting in terms of how it has come about and one of the things that has allowed us to get to this point is the light output and lumens per watt of the LEDs.”
“The first question you have to answer is how many LEDs and how much space will be needed to generate that much raw amount of light that is needed because we’re talking well over 100,000 lumens in light output,” he continued. “A street light might be 10,000 or 20,000 lumens, a track head about 2,000 to 3,000 lumens, and a 60-watt light bulb is only 800 lumens.”
“It’s a large amount of light that has to come out of this luminaire. So that’s one of the key things - just being able to reduce the amount of LEDs required makes it even feasible to talk about this application,” said Scheidt.
Built on Cree’s SC5 Technology Platform, the new XP-L High Intensity LED delivers more than double the candelas of the industry’s previous highest performing single-die XP-L LED through the same optic. The benefits for lighting manufacturers include higher performance, smaller size and lower system cost for applications including stadium, track and other outdoor lighting.
Featuring Cree’s new primary optic design that reduces optical source size by more than 50 percent, the XLamp XP-L High Intensity LED is said to deliver “unprecedented” candela at 185 lumens per watt at one watt. In addition, the LED also uses the existing 3.45 mm x 3.45 mm XP-L package, offering a drop-in ready upgrade for XP-based luminaire designs, while enabling manufacturers to achieve higher luminous intensity with minimal redesign.
“Existing solutions have done a good job of achieving a small size but in achieving that there has been some sacrifices specifically in lumen output and the optical efficiency due to the construction,” Scheidt said.
What’s required to achieve high-intensity light - needed for stadium lighting - is three things: small optical source size, high light output, and an efficient optic design, he added.
Scheidt said some LED products use multiple die and in the middle of the package is a blank space that does not emit light, thus creating inefficiency.
Cree’s new high-intensity LEDs are said to solve these issues by using a small source size coupled with a single-die approach.
When selecting a LED for stadium lighting, there needs to be a discussion around candela and lumens performance. “The difference between candela and lumens is that lumens is your total light output (how much light in all directions) so with a larger LED it can put out more light, which translates into more lumens,” said Scheidt. “Candela is the measure of how much light is going in a specific direction – straight out of the optic – so the smaller one is more efficient at creating candela.”
With stadium lighting you want more intensity coming straight out of the optic and straight down the ball field, explained Scheidt. “It’s not just about the lumens but how you turn those lumens into candelas. The candela per watt is how efficient the LED is in turning electricity into intensity. That is where you see the advantage to using the smaller source versus a larger one.”
The ultimate goal is to reduce system size, power and cost, particularly in stadium lighting applications. The Cree XP-L delivers by providing 120 percent more candela than the XP-L high density parts through secondary optics. In addition, the device achieves a 79 percent reduction in power consumption, while achieving the same level of candela.
“This will be a major breakthrough in enabling stadium lighting,” said Scheidt.
Another benefit is the XP-L is about the same size of the existing XP-G2, which translates into very good optical compatibility with an existing ecosystem of parts. However, the XP-L is more expensive than the XP-G2 but it does offer almost double the lumens in the same optic. “It’s just as efficient in turning lumens into candela as the XP-G2 but it has more lumens to start with so it can achieve more candela,” said Scheidt.
“It’s just another way we’ve optimized our package to go after those new applications to drive faster LED adoption. That is the name of the game - to make that adoption happen as fast as we can.”
Other features of the XP-L LED include color temperatures ranging from 2700 K to 8300 K and up to 90 CRI. The LEDs are characterized and binned at 1050 mA, 85°C. 6,000 hours of LM-80 long-term testing data is available for lighting manufacturers seeking ENERGY STAR qualification, said Cree. Product samples and product quantities are available now.