HIGH PRESSURE METAL VAPOR DISCHARGING LAMP

摘要

PURPOSE:To start the lamp reliably by employing specific values for the short- circuit current of ballast and the ratio between the diameter of electrode rod and the outer diameter of coil for specific short-circuit current of ballast. CONSTITUTION:Conductive member 9 mainly composed of niobium is provided while penetrating through poly-crystal or single-crystal end cap 8. An electrode 10 filled with oxcide emitter is provided at the tip of condctive member 9, where said electrode 10 is comprised of electrode rod 11 and surrounding 12 and the tip of electrode rod 11 is projected from the coil 12. The ratio between the short-circuit current of ballast and the diameter D of electrode rod is set in the range of 11.7- 17A/mm, while the ratio between said current and the outer diameter d of coil 12 is set in the range of 4.5-15.6A/mm. Consequently it can be started reliably even with kick voltage of 4kv for example.