Lumileds lime green LED for colour-tune lighting
Philips has released the lime green LEDs behind its ‘Hue’ colour tuneable LED replacement light bulbs. Some exceed 200 lm/W.
Branded simply ‘Lime’, it is the newest addition to the firm’s portfolio of colour LEDs.
“Lime enables lighting designers to take the next step in delivering tunable white light in bulbs and fixtures,” said Lumileds, which is part of Philips. “Rebel ES Lime is the proprietary LED technology in the Philips hue bulb, where it combines with Rebel Red-Orange and Rebel Royal Blue emitters to deliver 16 million colour options.”
As well as Rebel ES, there is also a Lime version of Luxeon Z – Lumileds’ un-domed lighting LED with a 2.2mm2 die.
According to Lumileds, lime is closer to the blackbody curve than green LEDs, allowing a “much less inefficient red” to make white light, especially at warmer colour temperatures.
“For instance, colour tuning of 2,250-2,950K can be achieved with an R9>90, CRI>90 and efficacy of 90 lm/W using Luxeon Z combinations. When using a similar combination of red, green and blue LEDs to create 3,000K white light, the CRI is close to 20,” claimed the firm. “Alternatively, tuneable white light with high efficacy can be achieved from 1,800-6,500K along the blackbody curve.”
Lime is the highest efficacy Lumileds LED manufactured to date, some devices hitting 200 lm/W at 350mA and 85°C (Highest bin is 190 lm/W typical). The company tests Rebel ES Lime LEDs at 350mA/85°C, while the equivalent royal blue and blue are tested at 700mA/25°C. All other Rebel Color emitters are tested at 350mA/25°C.
Lumileds attributes high efficacy to lime being close to 555nm, the wavelength that human eye cones are most sensitive to. The data sheet specifies Lime as 567.5nm dominant wavelength (typical, 566nm min, 569nm max) and green as 530nm (520nm min, 540nm max).
The technology inside these LEDs is under investigation in this LED Luminaries blog.