| 摘要 |
PURPOSE:To eliminate any temperature difference in a bulb, prevent local blackening, and also to improve maintenance of a light flux and a file characteristic by arranging a filament below a lamp shaft while making a front lens a lens having a specific construction. CONSTITUTION:When a lamp 5 is lighted, a fliment 8 emits light, and this light is radiated from the lamp 5 to be reflected on a reflection face 2 to transmit the front lens 3 for irradiating the front. In this vase, by arranging the filament 8 to be displaced to the lower side than a lamp axis 0-0, temperature of the bulb lower side A arranged closer to the filament 8 rises so as to reduce a temperature difference in the bulb wall. Therefore, tungsten vaporized from the filament 8 can be prevented from being concentrated locally, stuck to the upperside bulb wall. Further, in a lens 3, a light distribution characteristic is corrected by changing the segment thickness so as to prevent deflection of light radiated on the front. Thereby, lowering of the flux of light and deterioration in a life characteristic can be provented and a characteristic of light distribution can be improved. |
