| 摘要 |
A bulb 14 is arranged in such a manner that the lower end of a filament 16 of the bulb 14 coincides with an optical axis Ax of a reflector 10. Horizontal cut line forming steps 12aH out of a plurality of light distribution steps 12a constituting a reflecting surface 12 extend over such upper and lower areas as to interpose phantom lines Lh1, Lh2 on the reflecting surface 12 therebetween. The phantom lines will correspond to the horizontal cut lines. Vertical sections of these horizontal cut line forming steps in both upper and lower areas are set to parabolas, each having a short focus, and to parabolas, each having a long focus, respectively. The horizontal cut lines are formed by taking advantage of the luminous fluxes of reflecting light from both areas. Each parabola having a short focus is connected to the corresponding parabola having a long focus at the apex thereof smoothly. As a result, the horizontal cut line forming steps 12aH can be reduced into a single step without steps and bends. |
