Compact SSL LEDs feature two separate CCT emitters
The device comprises two different correlated color temperature (CCT) emitters that together produce light output that can be steplessly ‘tuned’ over the range of 2700–6500K.
The LED, which is available from Ismosys, will enable the manufacture of solid-state lighting (SSL) schemes that promise to enhance comfort, productivity and health.
The SMD-based SSL LED complements Sharp’s earlier and larger COB-based Tiger Zenigata tuneable CCTs that feature a 17-mm light-emitting surface (LES) and have visible ‘Tiger’ stripes of different phosphor formulations across the LES. In contrast, the new device comprises two emitters in a conventional discrete LED package measuring a mere 4.2 × 3.0 × 0.9 mm. One of the emitters radiates at 6500K and the other at 2700K. The die are packed closely together to deliver uniform light without shadows.
Sharp has designed the company’s tuneable white, mid-power SMD-based LED to be driven by dual constant-current power supplies with a typical forward voltage of 3.1 V, amounting to a typical combined power output of 0.37 W. The 2700K emitter delivers 32 lm from the 120 mA drive current while the 6500K emitter delivers 38 lm. Colour control is achieved by changing the luminous flux output ratio of the cool- and warm-white areas by independently affecting the drive current to the two circuits. The combined emitters achieve a score of over 80 (minimum) in the colour rendering index (CRI). A DALI (digital addressable lighting interface) would typically be used to achieve maximum tuneable performance and provide ease of connection in a SSL LED installation.
“More and more people are coming to understand the benefits delivered by lighting schemes that that mimic natural daylight in the office and workplace and is able to progress through cool colour tempretures at the beginning of the day to the warm color CCTs needed to maintain personal comfort and well-being in the evening," said Ismosys MD Nigel Watts.
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