An LED that offers high efficiency, good color rendering and a pleasant warm white light has now been developed in the laboratories of OSRAM Opto Semiconductors. The prototype therefore offers three important properties that together are essential for general illumination applications, namely a color temperature of 3000 K, a color rendering index of 82 and an efficiency of 104 lm/W.
The pleasant light from this warm white LED is the result of an advanced conversion process. Not only is the quality of light excellent, the efficiency with which it is produced is also impressive. The combination of these properties is essential for the widespread use of LEDs for general illumination as the warm white light color is targeted specifically at the residential sector. Up to now, efficiencies in excess of 100 lm/W have been achieved only in the cold white spectrum. Dr. Frank Baumann, project manager for the development of warm white LEDs at OSRAM Opto Semiconductors explains: “The successful combination of high quality of light and excellent energy efficiency will bring the commercial breakthrough for LED technology even closer. Efficient feel-good light is no longer just a vision.”
At 3000 K the light color of the LED is similar to that of a halogen lamp. Its color location is precisely on the Planckian curve. The light is exactly white showing no shift to the green spectral region. With an operating current of 350 mA and a chip surface of 1 mm2 the prototype of the new single-chip LED achieves a brightness of 124 lm. This corresponds to an efficiency of 104 lm/W. These record results are based on in-depth OSRAM know-how in providing a new chip architecture in conjunction with improvements in the epitaxial processes, improvements in the converter mix and a highefficiency package. OSRAM will be gradually integrating the new technologies into production.