Philips Lumileds has announced formally their new family of chip-on-board (COB) LEDs named CrispWhite after displaying new products featuring this technology at two recent lighting expos.
The new COB family of LEDs is specifically designed to replace ceramic metal halide bulbs in retail applications. Lumileds say “the LED closely mimics the spectral power distribution of a CMH lamp and delivers the combination of vivid saturated colour rendering and daylight-like whites.
Philips has alluded to the capabilities of the CrispWhite LED at both Light+Building and LightFair International (LFI), saying the COB delivered a mix of 3000K and 4000K CCT light for optimal colour and white performance.
Philips-Lumileds have designed the LED to render whites in a more crisp manner, especially with in the presence of brightening agents such as optical or fluorescents that are regularly added to white papers. An article written by Soraa covered the colour science behind these agents, touting the violet emitter of their product has an ability to brighten elements and deliver perfect white appearances of treated paper and fabrics.
For Lumileds new CrispWhite products, there is mixing of some deep blue LED chips in conjunction with the standard blue. Looking at the special power distribution of a typical LED you generally see peaks in the blue region with broader distribution at the greens, yellow and red wavelengths attributable to phosphor. Philips new CrispWhite delivers a second peak at the 410nm blue region that makes the treated whites look best.
They claim their approach is superior to Soraa’s approach for a number of reasons mainly due to efficacy penalties and photo biological safety issues. The advantages are clear while Philips Lumileds deliver 10lm/W more than their counterpart’s product, whilst still providing a very high CRI,
Lumileds also compared the CrispWhite LED with other high-CRI LEDs and light sources. The new LED delivers a CRI of 91 but only an R9 value for saturated reds of 55. The relatively-low R9 value may be in part the reason that the CrispWhite LEDs come in only 1–2% lower than Lumileds standard high-CRI COBs in efficacy. But Senders said the lower R9 value translates to the expected and desired performance in the retail application.
The CrispWhite range is precisely aligned with Lumileds' existing white LEDs in terms of , lumen output, and light emitting area. Manufacturers will be able to use the same design with either a standard COB or one of the CrispWhite models. At typical drive current the maximum lumen output is a huge 3750 lm, but Senders said you can overdrive the LEDs to reach even larger 6000 lm, saying that this will allow designers to reach 100W CMH equivalent products.
Source - By Maury Wright