High voltage incandescent lamp with low-pressure Kr/N2 gas fill

摘要

An incandescent lamp which is operable at about 200-275 V is obtainable by enclosing a filling composition consisting of about 80-95% by volume of krypton gas and about 5-20% by volume of nitrogen gas in a glass envelope bearing a tungsten filament and an inner volume of about 0.2-1.2 ml/operating wattage in an amount of about 0.7-0.9 ml/ml of the inner volume. The incandescent lamp exhibits satisfactory luminous characteristics and an extended life expectancy without causing arc discharge even when operated at a voltage of about 200-275 V. Thus a lighting device which comprises such an incandescent lamp as the luminous source and a power source capable of energizing it at a voltage of about 200-275 V is very useful in general and special illumination.