| 摘要 |
<p>By surrounding a gas discharge lamp, such as a fluorescent tube (2), with a tubular glass envelope (8), the discharge chamber of the fluorescent tube (2) is thermally insulated. This enables a sufficiently high temperature to be maintained in the fluorescent tube (2) for, e.g., mercury in the discharge chamber to be brought to a partial pressure at which good illuminating efficiency is obtained even at very low ambient temperatures around the lamp. The tubular envelope (8) may be fuzed at the ends thereof to the fluorescent tube (2), or otherwise fixed securely around the tube, in a manner to obtain a tubular space (10) of constant uniform width between the fluorescent tube and the surrounding envelope.</p> |
