Incandescent light bulb with double enclosed filament - has double-walled glass bulb with evacuated wall cavity to reduce energy loss

摘要

The incandescent light bulb has its energy loss due to connection in the gas filling surrounding the filament reduced by enclosing the filament in two glass bulbs. There is a space between the two glass bulbs which are in contact only at the base of the bulb assembly. The first bulb encloses the filament and is filled with the usual inert gas, whilst the second bulb encloses the first and the space between the two is evacuated or contains air at reduced pressure. No heat loss be connection can therefore occur between the inner and outer bulbs.