| 摘要 |
PURPOSE:To control mercury vapor pressure optimumly by providing the top of a U-shaped glass bulb for forming a discharge path with an expansion with a specified dimension which serves as the coldest area. CONSTITUTION:The inner surface of a U-shaped glass bulb 1 having an inner diameter of about 14mm. and a thickness of about 1mm. is coated with a rare earth phosphor layer 6. The distance between the legs of the U-shaped glass bulb 1 is adjusted to be 1mm. or less. Electrodes 11 are installed in the ends of the bulb 1 and fused to a ceramic base plate 10, thereby constituting a compact-type fluorescent lamp. The top of the bulb 1 is provided with a hill-like expansion 13 and its inner height is adjusted to be at least 1.5mm.. Owing to the above constitution, even when the temperature of the bulb 1 is increased by locating its legs more adjacent to each other, a temperature for an optimum mercury vapor pressure can be maintained by minimizing the influence of heat on the expansion 13, thereby improving the luminous efficiency of the lamp. |
