To provide a discharge lamp, having superior ultraviolet rays radiating efficiency even if power consumption is large and provided with an external electrode capable of stably outputting the light, and to provide a discharge lamp lighting device using this discharge lamp and a lighting system.
At least one of electrodes is arranged as an external electrode 3 in the outer surface of a narrow and long light transmissive discharge container 1 sealed with the discharge medium mainly composed of the rare gas, and a heat radiating means 5 is arranged for heat conduction with respect to the electrodes. Even if the tube wall load is 0.3 W/cm2 or more, the tube wall temperature is maintained at 100°C or less by the heat radiating means, and the relative illuminance is set at 90% or more with respect to that of the lighting initial time. The heat radiating means 5, concurrently can be used functions as a reflecting means and a holder means. Radiation noise can be reduced sharply by using the heat radiating means 5 working as a reflecting means, and grounding the reflecting means for lighting.
WATANABE AKIO
YUASA KUNIO
SHIMOKAWA SADAJI
YAJIMA JUN
AZUMA YUJI
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