Live and let diode

Interior designers will soon have a new toy: Philips Research Labs in New
Jersey can now light rooms with high-power multicoloured light-emitting diodes
(LEDs). Putting red, green and blue LEDs behind a diffuser panel gives a whitish
light, but the colour changes unpredictably as the LEDs age or the temperature
or drive current change—so dimming the lights tends to make them change
colour. Philips monitors the colours using optical sensors linked to a
controller that adjusts the current to each LED so that the overall colour stays
pure white. Alternatively, a master control can adjust the balance to…