| 摘要 |
A low pressure mercury vapour-rare gas discharge fluorescent lamp is provided, at places of relatively low operating temperature such as on a fluorescent coating, with an amalgam in which the atomic ratio of amalgam-forming metal to mercury is not less than 0.5 : 1. The amalgam-forming metals can be those in respect of which the activity coefficient of the mercury (as defined) is less than 1, and can be thallium, cadmium, gold or indium. If cadmium is used the atomic ratio of cadmium to mercury is less than 5 : 1, preferably between 0.5 : 1 and 2 : 1, such as 1 : 1. The amalgam can be in the form of a fine-grained powder, a film or an igniting strip and can be caused to adhere to the desired place in or on the envelope by heat. The amalgam can have an addition of a metal of low melting point, such as gallium or soft solder, which is alloyed or intimately mixed therewith. A hard neutral material such as silicon dioxide can be added to the amalgam and the mixture ground. Free mercury can be present in the lamp envelope as well as the amalgam. |
