Color tunable hybrid lamp: LED-incandescent and LED-fluorescent

Abstract

Light-emitting diodes (LEDs) can be chosen to emit light in a wide variety of highly saturated colors. As a consequence, a hybrid lamp assembled with colored LEDs and with one incandescent or fluorescent source easily allows the user to dynamically select the desired color point without additional filters, with high color rendering index, and at a low cost. We measure some properties of a color tunable lamp that uses both colored LEDs and an incandescent or a fluorescent source. For the LED-incandescent type, we assemble an array of blue LEDs with a typical incandescent bulb source, and to assemble a LED-fluorescent type we used an array of red LEDs with a commercially available compact fluorescent lamp. Incandescent and fluorescent sources have a fixed intensity, while LED intensities are adjusted to tune color. For LED-incandescent lamps, our experimental data show that the correlated color temperature (CCT) can be linearly tuned with the electric current of the LED array. The LED-fluorescent lamp exhibits a CCT that exponentially varies with the drive current of red LEDs.