Abstract:
The power/switcher module, bi-filament light bulb, and light bulb socket, of this invention are assembled with standard lamp industry hardware and fittings to provide a lamp fixture with conventional utility increased by the addition of an integrated automatic emergency lighting capability. Normal ON/OFF use of the lamp, while connected to household line current, also provides light bulb filament current for maintaining a full charge on a rechargeable storage battery. The loss of charging current through line current power failure, filament burn out, or selective disconnection by removal of the portable cord, immediately switches on the other filament to battery power, extending the emergency use to that of a portable lantern. Restoration of line current and/or a burned out filament automatically reverts the lamp to normal operation. The foregoing capabilities are made available in practical quantitive measure, less than costly and bulky industrial and commercial units, but substantially more than the very limited usefulness available from existing household plug-in, receptacle mounted counterparts.