Discharge lamp operation apparatus.

摘要

A high-pressure sodium lamp is connected to a d.c. power supply (6) through a ballast (8), to operate it with a current containing a d.c. component. The relation between the ratio f/d of the inter-electrode distance f (mm) to the inner diameter d (mm) of the arc tube of the high-pressure sodium lamp and the sodium vapor pressure PNa (kPa) in the arc tube is maintained at PNa ≧ 6.0 (ℓ/d - 5.8), thus making it possible to operate the high-pressure sodium lamp with a current containing a d.c. component without causing a significant color separation which otherwise might be the result of cataphoresis.