| 摘要 |
PURPOSE:To improve color rendition without increasing the load of the wall of a light emission tube and using a high-melting-point metal plate, by making the outside diameter of each end cap portion of the tube larger than that of the central portion thereof. CONSTITUTION:The outside diameter a of each end cap portion 1a of a light emission tube 1 is made larger than that (b) of the central portion thereof. The tube 1 is covered with a cylinder 8 of diffusion glass along the total length of the tube. Infrared rays emitted from the tube 1 are effectively reflected by the cylinder 8 to heighten the temperature of the tube, especially the temperature of the end cap portions 1a which are the lowest temperature of all the portions of the tube. As a result, the pressure of sodium vapor is increased to improve color rendition without heightening the load of the wall of the tube 1 and using a high-melting-point metal plate which would adversely affect the life of the tube.
|
