| 摘要 |
PURPOSE:To maintain an optimum mercury-vapor pressure within a bulb by bending a straight bulb into a curved bulb with a bent central portion, and curved ends each of which has a U-shpaed curve and is almost perpendicular to the plane that includes the bent center portion, and providing the bent central portion with a pair of tips. CONSTITUTION:A straight bulb is bent into a curved bulb with a bent central portion 10a, and curved ends which has U-shaped curves 10b, 10b and are almost perpendicular to the plane that includes the bent central portion of the curved bulb. An exhaust pipe 21, which is parallel to the opening ends of the bulb, is provided at the bent central portion of the bulb. After evacuating any air remaining in the bulb and charging a gas into the bulb, the pipe 21 is converted into a tip 15. Owing to the above arrangement, the tip 15 provided on the bent central portion 10a of the curved bulb 10 is shielded from the heat of a globe 4, and the tip 15 is cooled by the environmental air flowing into a base 1 through a hole 14. Thus, the temperature of the tip 15 becomes lower than any other part of the wall of the bulb 10. Accordingly, the mercury-vapor pressure within the bulb 10 does not become high since the mercury vapor is condensed at the tip 15 because of the low temperature of the tip 15. |
