PURPOSE: To prevent generation of a crack as well as accidental drop of a bulb by mounting a heat detector on the space where air is stagnant, between the bulb formed by covering an end sealed with an electrode of a fluorescent lamp with a covering member and the covering member.
CONSTITUTION: An end sealed with an electrode of a fluorescent lamp 20 is covered with a covering member 41, so as to form a space 45 where air is stagnant, between a bulb and the covering member 41, and a heat detector 46 is mounted on the space where air is stagnant. When the temperature of a bulb wall near the electrode reaches abnormal level due to half-wave discharge, the temperature of the space 45 surrounded by the covering member is increased, and the abnormal temperature is detected by the heat detector 46, whereby the operation of cutting a power circuit and so on is executed. Electrification is thus stopped, and generation of a crack or accidental drop of the lamp 20 can be prevented thereby.
ITO HIDENORI
HIRAO YOSUKE
TAKAYA MANABU
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