| 摘要 |
PROBLEM TO BE SOLVED: To provide an incandescent lamp which restrains halation to be generated by reflecting light from a filament with a base insulator, and reduces light to be leaked at the time of using a spot light as a light source. SOLUTION: The incandescent lamp has: a tube-shaped bulb 11; the tube-shaped base insulator 40 for surrounding a seal section at a part of the bulb 11; and a filament 20 formed into a plane in the bulb 11. When the seal section of the bulb 11 is arranged to face downward, a front face side zone 40a is higher than a back face side zone 40b as a border on a plane F of the filament 20 regarding a peripheral wall of the base insulator 40. An upper end of the back face side zone 40b is located lower than a height level of a reference line A which passes: a point S separating a distance equal to a light center distance in a front face side direction perpendicular to the plane F of the filament 20 from the center O of the filament 20; and an intersection point P of a straight line extending from the plane F of the filament 20 and an outer peripheral edge at an upper end of the front face side zone 40a of the base insulator 40. COPYRIGHT: (C)2011,JPO&INPIT
|
