| 摘要 |
A method for designing a projection-type headlamp, and a projection-type headlamp produced thereby, that allows the position of a shade member and a light source to be set so that the luminous utilization efficiency is optimized for a given allowable height of the headlamp. Design values of the lens diameter and focal distance of the projection lens are set, and characteristics of the luminous utilization efficiency obtained in a case where the first focal point F1 and second focal point F2 of the reflector are changed are determined, and characteristics of the diffusion angle in the vertical light direction obtained in a case where the first focal point F1 and the second focal point F2 are changed are also determined. Then, the luminous utilization efficiency corresponding to the first focal point and the second focal point for a specified value of the diffusion angle are determined, and the first focal point and the second focal point where the luminous utilization efficiency becomes a maximum are determined. The luminous portion of the light source is placed at the thus-determined first focal point F1, and the upper edge portion of a shade member is located near the second focal point F2. |
