| 摘要 |
PURPOSE:To prevent leakage of sodium from a light emmiting tube and reduce increase of lamp voltage during keeping life by specifying positioning of a light emitting tube and ultraviolet ray shielding body, that is, a cubic angle formed by the tip of electrode of the light emitting tube and the opening of the ultraviolet ray shielding body. CONSTITUTION:In cubic angles formed by each tip 4a and 4Aa of a pair of electrodes 4 and 4A and each opening 2a and 2b of an ultraviolet ray shielding body 2 of a small metal halide lamp having a power of 100W or less, when a cubic angle locating on the upper side from a horizontal surface including the tip of electrode is indicated by omega1 and a cubic angle locating on the lower side is by omega2, positioning of the light emitting tube 1 and the ultraviolet ray shielding body 2 is specified as follows: omega1<=1.3 steradian, and omega2<=2.0 steradian. Thereby, effect of setting of ultraviolet ray shielding body, that is, leakage prevention effect of sodium sealded in the light emitting tube is increased, voltage increase of the lamp during keeping life is reduced, and various troubles relating lighting are suppressed. |
