US Patent 8002445 LED luminaire with automatic luminance compensation

An LED luminaire for normal or emergency lighting has a lamp section comprising a least one LED lamp, the LED lamp having an LED chip and a reflector section. The reflector section is formed of silver and is positioned to reflect light from the LED chip. A power section is coupled to supply power to the lamp section. A detector section has a silver-plated detector and is functional to detect sulfuration of the reflector section as a resistance value change. The power section is operable to adjust the power supplied to the lamp section upon detecting an increase in the resistance value at the silver-plated detector of the detector section.