| 摘要 |
PROBLEM TO BE SOLVED: To improve the lifetime of metal halide lamp not including mercury by using the mixture of arc gas or buffer gas and various metal halide for the sealing gas of a discharge tube. SOLUTION: The sealing gas of a discharge tube includes the rare gas Ar, Kr, Xe working as the buffer gas and at least Hf and/or Zr halide HfX4. X means I, Br, Cl. These material work as the base of a circulating process of tungsten for functioning with the sealing gas, which dose not include mercury. The sealing gas includes at least one additional voltage forming material, and raises the voltage gradient, and hinders the early melting of electrodes because the existence of Hf or Zr raises degree of melting of the tungsten. For this reason, a metal halide for generating the high operating steam pressure at about 900-1000 deg.C of wall temperature is appropriate. Quantity of sealing of the Hf/Zr halide mixture is set at 3μmol/cm3 so as to stabilize the circulating process. |
