| 摘要 |
PURPOSE:To improve the luminous efficiency and the life characteristic of a metal vapor electric-discharge lamp by installing an emission tube of below 100W in an outer tube coated with a phosphor and specifying the relationship among the interelectrode distance and the maximum inner diameter of an emission tube bulb and the inner surface area of the outer tube. CONSTITUTION:An emission tube bulb 1a, in which electrodes 2a and 2b are sealed and which is charged with a starting rare gas, mercury and a metal halide, is installed in an outer tube 12 which is charged with an inactive gas and the inner surface of which is coated with a phosphor 13 so as to constitute a small metal vapor electric-discharge lamp of below 100W. Here, when the interelectrode distance of the emission tube bulb 1a and its maximum inner diameter are respectively supposed to be (lcm) and (Dcm) and the inner surface area of the outer tube 12 is supposed to be (S0cm<2>), they are adjusted to satisfy the relationship of S0/lD.>=250. As a result, convection is enhanced by causing the emission tube 1a to have an elliptic spherical shape. Besides, the luminous efficiency and the life of the lamp can be greatly improved by appropriately adjusting the inner surface area of the outer tube 12 relative to the volume of the emission tube 1a.
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