LAMP BULB, LAMP BULB WITH REFLECTING MIRROR, AND LIGHTING SYSTEM

摘要

A halogen lamp bulb assembled in a reflecting mirror enabling a reduction in the size of a filament and capable of increasing a condensing efficiency. The halogen lamp bulb comprises a bulb and a plurality of filament elements (131-134). Each of the filament elements is formed of a single-wound coil and its axis is in parallel with the optical axis of the reflecting mirror. One (center filament element (131)) of the plurality of filament elements is disposed on the optical axis of the reflecting mirror, and the others (peripheral filament elements (132-134)) are disposed therearound. The profile of each of the filament elements as viewed from its axial direction is formed in an oval shape. When the requirement of 0.2 = Ls/Lc = 0.9 is established where the longitudinal length of the center filament element is (Lc) and the longitudinal length of the peripheral filament elements is (Ls), a center illuminance and a light distribution property are improved. Also, when the requirement of 0.25 = r/R = 0.75 is established where the maximum inner diameter of the bulb is (R) and the maximum outer diameter of the filament body of the filament is (r), the service life of the halogen lamp bulb can be increased.