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US 4,517,630 AGranted
Motor vehicle headlight with condensing lens and diaphragm
AssigneeRobert Bosch GmbH
InventorsRudiger Dieffenbach, Werner Grunwald, Peter Perthus, Friedrich Prinzhausen
Life of this patent
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Abstract
The optic axis of a vehicle headlight comprises a reflector, an incandescent helix and a convergent lens. The reflection surface of the reflector is parabolic in the horizontal midplane section and is elliptical in vertical median section. A narrow band of light spreading out laterally is thus produced without supplementary optical components, particularly the diffusion disk or dispersion lens. A sharp light-to-dark boundary is obtained by a diaphragm having an effective straight edge 18 located below the outer ellipse focus, which is coincident with that one of the principal foci of the converging lens which is the nearer to the reflector.
Claims11
Headlight for a motor vehicle having a filamentary light source and a reflector, wherein;
- the section of the reflector by the vertical median plane thereof is a part of an ellipse and contains a reflector axis which intersects the reflector at the reflector vertex;
- sections of the reflector by planes which intersect the axis of the reflector at right angles are ellipses of which the half-axes are perpendicular to the reflector axis and one of them lies in said vertical median plane;
- said filamentary light source is located at that one of the foci of said vertical median plane section ellipse which is the nearer to said reflector vertex;
- a condensing lens is disposed with its axis on the reflector axis and with its focus towards the reflector coincident with the focus of said ellipse which is the farther from said reflector vertex;
- a diaphragm located in the region of the reflector axis is disposed in the focal plane of said condensing lens nearer said reflector;
- and
- the optically effective edge of said diaphragm lies in the neighborhood of said focus of said lens towards said reflector,
- the section of the reflector by the horizontal median plane thereof being parabolic,
- different radial zones of said condensing lens respectively having different focal lengths, diminishing in magnitude toward the lens rim, while all said zones have a common focus which is said focus coincident with said reflector focus farther from said reflector vertex,
- said condensing lens being constituted as a meniscal Fresnel lens having a convex surface facing away from said reflector and a stepped concave surface facing towards said reflector.
7 more elements
Headlight for a motor vehicle having a filamentary light source and a reflector, wherein:
- the section of the reflector by the vertical median plane thereof is a part of an ellipse and contains a reflector axis which intersects the reflector at the reflector vertex;
- sections of the reflector by planes which intersect the axis of the reflector at right angles are ellipses of which the half-axes are perpendicular to the reflector axis and one of them lies in said vertical median plane;
- said filamentary light source is located at that one of the foci of said vertical median plane section ellipse which is the nearer to said reflector vertex;
- a condensing lens is disposed with on its axis on the reflector axis and with its focus towards the reflector coincident with the focus of said ellipse which is the farther from said reflector vertex;
- a diaphragm located in the region of the reflector axis is disposed in the focal plane of said condensing lens nearer said reflector;
- and
- the optically effective edge of said diaphragm lies in the neighborhood of said focus of said lens towards said reflector,
- the section of the reflector by the horizontal median plane thereof being parabolic,
- an optical system being disposed between said reflector and said condensing lens (16) which system is composed of a dispersing lens (61) and a supplementary condensing lens (62),
- the focus (62') of said supplementary condensing lens (62) and the focus (61') of said dispersing lens (61) nearer said reflector being coincident, the focus of said supplementary converging lens (62') farther from said reflector and a focus (16') of said first-mentioned condensing lens (16) being at least approximately coindicent, and
- the focus (13') of said ellipse (13) farther from said reflector and the focus (61') of said disbursing lens (61) farther from said reflector being coincident.
8 more elements
Headlight for a motor vehicle having a filamentary light source and a reflector, wherein:
- the section of the reflector by the vertical median plane thereof is a part of an ellipse and contains a reflector axis which intersects the reflector at the reflector vertex;
- sections of the reflector by planes which intersect the axis of the reflector at right angles are ellipses of which the half-axes are perpendicular to the reflector axis and one of them lies in said vertical median plane;
- said filamentary light source is located at that one of the foci of said vertical median plane section ellipse which is the nearer to said reflector vertex;
- a condensing lens is disposed with on its axis on the reflector axis and with its focus towards the reflector coincident with the focus of said ellipse which is the farther from said reflector vertex;
- a diaphragm located in the region of the reflector axis is disposed in the focal plane of said condensing lens nearer said reflector;
- and
- the optically effective edge of said diaphragm lies in the neighborhood of said focus of said lens towards said reflector,
- the section of the reflector by the horizontal median plane thereof being parabolic,
- said condensing lens being composed of an upper lens half (77) and a lower lens half (78),
- the focal length (78") of said lower lens half (78) being greater than the focal length (77") of said upper lens half (77) determines the height of the projected light beam and the spacing (60) between said supplementary condensing lens (62) and said dispersing lens (61) determines the width of the projected light beam.
7 more elements
Dependencies are inferred from the claim text.