LOW VOLTAGE INCANDESCENT LAMP WITH VARIABLE PITCH FILAMENT

摘要

Low voltage incandescent lamp has a coiled filament (24) of at least three different segments or sections (26, 28), wherein the center section (26) has less dense winding than the other two sections (28). Alternatively the filament (36) is wound in a coil having a pitch that gradually increases along the length of the coil from one end of the coil towards the center of the coil, and thereafter gradually decreases again towards the other end of the coil, or the coiled filament has more than three sections, one section being the center and having the widest (least dense) pitch of winding, with sections of gradually lesser pitch being located towards the two ends of the coil. Low voltage lamps having these filaments have significantly improved operating life and are significantly brighter than comparable prior art lamps.