High-intensity discharge lamp, system for lighting the lamp and lighting appliance using the lamp

Abstract

The invention provides the high-intensity discharge lamp and the high-intensity discharge lamp lighting system and the lighting system using the high-intensity discharge lamp showing the low enough starting voltage. The high-intensity discharge lamp comprising a lighting-source bulb provided with an enclosure, a light-transmissive ceramic enclosure defining a pair of small-diameter cylinders communicating with the enclosure at both ends thereof, a pair of electrodes and discharge agent, a metallic coil which is wound on the outside surface of at least one small-diameter cylinder and coupled to the other end of the electrode to have the same potential with the electrode, a jacket-bulb which hermetically accommodates therein the lighting-source bulb and the metallic coil, and a pair of outer lead terminals which are coupled to the pair of electrodes and hermetically led outside the jacket-bulb. The metallic coil is preferably wound for four turns or more on the small-diameter cylinder, and placed its one end near the boundary to the enclosure of the light-transmissive ceramic discharge enclosure, and the winding pitch of the metallic coil resides in the range of 100% to 500%. Further, the length L2 of the metallic coil is 0.3 to 1.0 times the length of the small-diameter cylinder. Furthermore, the end of it which is opposite to the enclosure is coupled to have the same potential as the other electrode.

Dependencies are inferred from the claim text.