Metal halide high-pressure discharge lamp with a fill containing hafnium and/or zirconium

摘要

To generate light output from a metal halide discharge lamp having a fill which includes mercury, at least one noble gas, cesium and a metal halide, such that the color temperature will be between 4000 and 9000 K., and the color rendering index Ra is greater than 90, while, for the red spectral range, the color rendering index R.sub.9 is at least 50, the metal of the metal halides comprises hafnium, preferably present between 0.02 to 6 mg, or zirconium, preferably present between 0.01 to 4 mg, each per milliliter of volume of the discharge vessel (2, 14, 28). Both hafnium and zirconium may also be added.