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.

Abstract: A battery operated emergency lamp is provided for connection to a normally "on" electrical source of power, such as a standard ac line voltage, where such source is subject to occasional power failures. A solid state switching circuit including a single transistor and one diode serves to maintain the lamp in an unenergized condition and to simultaneously generate a low charging current for a re-chargeable battery so long as the power source remains "on." In the event of a power interruption, the solid state switching circuit is immediately responsive to switch to a condition in which the lamp is energized by the battery current. In one embodiment disclosed herein, the emergency lamp takes the form of a relatively small, portable lantern or flashlight equipped with a standard utility plug for connection to a household electrical outlet.