LED light fitting and emergency power supply therefor

摘要

A backup power supply module 10 for an LED light fitting comprises an AC-DC converter 16, a DC-DC converter 50, a battery 40, a controller 100, sensing means 14, 114 to detect whether power is supplied to the AC-DC converter 16, and switching means 20, 22, 24 for switching the module between a passive state and an active state. The module switches from passive state to active state if power supply to the AC-DC converter 16 is lost. In the passive state, the AC-DC converter 16 charges the battery 40 and powers the controller 100, and the DC-DC converter 50 is disconnected from the battery 40 and/or the LEDs 4 of a light fitting 1. In the active state, the battery 40 powers the controller 100 and supplies power to the LEDs 4 via the DC-DC converter 50, and the controller 100 controls the DC-DC converter 50 to supply a substantially constant current to the LEDs 4.