High efficiency incandescent lamp.

摘要

An incandescent lamp has a bidirectional switch 24 in series with a filament 17 of the lamp, the switch being operable to conduct current during a part of each of the positive and negative half cycles of the sinusoidal a.c. voltage applied to the filament. The envelope 10 of the lamp is filled with a mixture of krypton and nitrogen in order to further extend the life of the lamp without reducing its brightness.