초록 ▼

In electric incandescent lamps the efficiency can be increased by surrounding the filament with a light-pervious, infra-red radiation-reflecting filter. It has hitherto always been assumed that the geometry of the filter and that of the filament should be well matched to each other. This, however, r

In electric incandescent lamps the efficiency can be increased by surrounding the filament with a light-pervious, infra-red radiation-reflecting filter. It has hitherto always been assumed that the geometry of the filter and that of the filament should be well matched to each other. This, however, results in a complex filament construction. According to the invention, near the center of a spherical filter, a flat filament consisting of several parts is accommodated, being situated within a square the sides of which are from 0.25 to 0.04 times the diameter of the filter. Such a filament has a relatively simple construction and provides a highly efficient lamp despite the fact that its geometry is very different from that of the filter.

대표청구항 ▼

An electric incandescent lamp having a substantially spherical lamp envelope whose wall is provided with a light pervious, infrared radiation-reflecting filter and in which a filament is accommodated near the center of the lamp envelope, characterized in that the filament is a flat folded filament o

An electric incandescent lamp having a substantially spherical lamp envelope whose wall is provided with a light pervious, infrared radiation-reflecting filter and in which a filament is accommodated near the center of the lamp envelope, characterized in that the filament is a flat folded filament of helically wound wire and is situated within a square having a side length between 0.25 and 0.04 times the inner diameter of the lamp envelope.