JPS6467857A - Fluorescent lamp - Google Patents

Abstract

PURPOSE:To mitigate the cooling of over-cooled sections and prevent the fluctuation of the tube current and light output caused by the drip of droplets by enveloping the over-cooled sections of bulbs with a globe in a fluorescent lamp having the over-cooled sections at a linear section. CONSTITUTION:In a bulb 1, two linear glass bulbs 11, 11 closed at one end are arranged in parallel, both bulbs 11, 11 are connected via a connection section 13 near the closed end sections 12, 12 to form a continuous discharge path, and the both end sections 14, 14 are closed with stems. The inner face of the closed end section 12 of a bulb 11 near an arc receives the heat of the arc and is kept at a high temperature, but the inner face of the closed end section 12 of a bulb 1 is apart from the arc, the gas pressure is low, and an over-cooled section 6 marked with (x) is formed. Since the bulb 1 is enveloped with a globe 5, the over-cooled section 6 marked with (x) is cooled by the outside air very slightly, and the temperature is not decreased until mercury is condensed. The fluctuation of the lamp current and the light output caused by the quick evaporation of mercury droplets is thereby prevented.