HIGH PRESSURE SODIUM VAPOR LAMP HAVING UNSATURATED VAPOR PRESSURE TYPE CHARACTERISTICS

摘要

This invention discloses a high pressure sodium vapor lamp having unsaturated vapor pressure type characteristics with sodium and mercury contained in an arc tube. The sodium is enclosed in an amount sufficient to exhibit unsaturated vapor pressure type characteristics while the mercury is enclosed in an amount MHg calculated by the following formula: MHg ? where MHg : the amount of mercury enclosed (mg) D : the internal diameter of the arc tube (cm) L : the electrode-to-electrode distance (cm) Volume: the volume of the arc tube (cc) Vn : the rated lamp voltage (Volt).