Back-up electrical system for lamps

Abstract

A backup power system is provided for fluorescent lamps which energizes one of the lamps when normal A.C. mains power is not available. The circuit operates with a standard fluorescent fixture which contains two or more fluorescent lamps. When A.C. mains current is available, both lamps are operational so that the lighting fixture produces a maximum brightness. The A.C. mains current also trickle charges a low-voltage battery contained in the lighting fixture. When mains current is not available, the battery maintains only one of the lamps lighted. Consequently, although the lighting fixture produces a reduced output, the battery life is extended. In one embodiment both fluorescent lamps are powered directly from the AC line. When A.C. power is not available, a relay disconnects the A.C. line from both lamps and connects one lamp to a DC/AC inverter which is powered by the internal battery. In another embodiment, one lamp is powered directly from the AC line and the other lamp is powered by a DC/AC inverter which receives power either from a DC power supply operating off the A.C. line or from the internal low-voltage battery. In a third embodiment, during normal operating conditions, both lamps are powered by separate DC/AC inverters driven from a power supply that operates off the AC line. When the A.C. voltage is not present, the DC/AC inverter for one lamp is powered by the internal low-voltage battery.

Dependencies are inferred from the claim text.