| 摘要 |
PURPOSE:To improve visibility by sectioning a lens surface into sectorial parts with concentric circles and plural radial radii and providing Fresnel prism elements to the respective sectorial parts. CONSTITUTION:A reflector 3 is provided in a lamp housing 2, a light source bulb 4 is provided nearly its focus, and a front lens 1' is mounted covering the front surface opening part of the lamp housing 2. Five concentric circles 1a-0-1a-4 are set on the surface of the front lens 1' and 20 radial radii 1r-1-1r-20 are set, so 80 sectorial parts are formed except in the circle 1a-4 and Fresnel prism elements are provided to the sectorial parts respectively. Further, the part inside the smallest concentric circle 1a-4 is painted out with black opaque paint and the entire shape of a light emission surface is formed in a ring shape. Here, a section E shows an area where one Fresnel prism element is arranged. Consequently, plural parts on the front lens illuminate intensely and the visibility is improved.
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