| 摘要 |
PROBLEM TO BE SOLVED: To improve the temperature characteristic, maintenance factor and illumination factor of a fluorescent lamp for outdoor illumination. SOLUTION: In a fluorescent lamp with a double-tube construction, distribution of luminous intensity on a vertical cross section of the major axis of an arc tube is linearly symmetric on polar coordinates of 0-180[ deg.] and 0--180[ deg.], a reflection material 4 is provided in a range of minimum 180-155[ deg.] and -180--155[ deg.] and maximum 180-80[ deg.] and -180[ deg.]--80[ deg.], and also in a range of 0-25[ deg.] and 0--25[ deg.] with 0[ deg.] as a center, and an aperture 5 is provided in a range of 90[ deg.]-45[ deg.], -90--45[ deg.]. Lamp light flux is reduced by an increase of mutual reflection and absorption arising from an addition of these additional mechanisms in a phosphor layer 6 containing main luminescence a peak of a luminous wavelength of which is in a range of 530-580[nm] and 600-650[nm], a relative temperature of a lamp light color is set to 2500-13000 [k] and Duv is set to 10-70. |
