| 摘要 |
The headlight has a multilayer elongated guide with orientation inclined to vehicle axis and an entry face near a furthest forward end of the guide. The guide comprises several progressively elongated glass layers, stacked under spring compression in a reference frame. A filament or arc light source in an elliptical reflector illuminates the guide's entry face (the coplanar ends of the stacked layers), normally. Light penetrating each layer, axially, is internally reflected at its terminating facet. Opt., a layer may terminate in a stepped facet. Reflected beams exit through the side faces. Each beam is collimated by a Fresnel lens and directed on the illuminated area as the component of a composite beam oriented (E) generally parallel to the vehicle's longitudinal axis, to which the guide is mounted transversely. Where a cut-off beam is required one or more component beams is obstructed by a mask fixed between guide and lens, or on the latter's exit face. The guide is mounted forward of the transverse plane (16) containing the base of the light source reflector (12). The latter's optical axis, parallel to the vehicle's longitudinal axis, intersects an entry face well forward on the guide side; light entering here on the top layer passes through subject only to refraction. In the lower layers the light is reflected back along the guide's major axis, which lies across the rounded corner, diagonally. Light reflected at the end of each layer exits the guide forwards through a Fresnel lens (18) whose optical axis is directed forward at the area to be illuminated. A similar lens is fitted for the directly emitted top layer beam. All facets where reflection is required are made fully reflective eg. by aluminizing. The lenses are mounted in parallel planes between the guide and the curved boundary. Bulk is opt. further reduced by using special lenses with planes inclined to the emitted beam. Additionally, the light guide itself is opt. curved to match the coach work curvature.
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