| 摘要 |
<p>The purpose of the present invention is to provide a ceramic metal halide lamp with a plurality of light-emitting tubes, wherein other light-emitting tubes light normally when one light-emitting tube is at the end of the life thereof, by setting the gas pressure inside the lamp to a predetermined pressure. The ceramic metal halide lamp (10) comprises: two light-emitting tubes (4-1, 4-2) whereof one light-emitting tube is lit selectively; internal tubes (18H-1, 18H-2) that surround each of the light-emitting tubes; and an outside globe (2) that houses the light-emitting tubes and the internal tubes. The internal tubes are sealed and, when the shortest distance between metal members with different potentials inside the internal tubes is X (mm) and one of the light-emitting tubes has ruptured, the internal tubes are adjusted so as to have an internal gas pressure of Y (kPa) or greater, where Y= -9.44X+72.29, and one atmospheric pressure or lower, and a discharge tube commences discharge without discharge occurring between the metal members with different potentials.</p> |
