JPH04233102A - Headlamp for automobile - Google Patents

Abstract

PURPOSE: To avoid disturbance due to a bright-dark boundary for a driver by generating an unclear image overlapping with a clear image of a outer circumference part formed by the circumference region at a predetermined distance as a result of a shorter focal length of the central region. CONSTITUTION: A highly clear image of an outer edge part 14 in a diaphragm 13 is formed in a point Q at a length L by means of a circumferential region 20 of a lens. As a result of a shorter focal length of a center region 19, a clear image of the outer edge part 14 is formed in a point P at a shorter length S. Therefore, light beams 23 cross each other in the point P at the distance S, and by means of these light beams, an unclear image of the outer edge part 14 overlapping its clear image formed by the circumferential region 20 is generated at a distance. In this way, as a whole, a clear image of the outer edge part 14 is generated in the distance L with an unclear band zone over a width defined by a focal length difference between the regions 19, 20 and a size of the central region 19 area.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor vehicle headlamp of the type defined in claim 1.

0002

BACKGROUND OF THE INVENTION Such a headlamp is known from German Patent Application No. 3,602,262. The headlamp has one reflector that generates a bundle of light rays by reflecting the light rays of one light source. In the optical path of the reflected light rays, via an objective lens, a diaphragm is arranged, the diaphragm having an edge having an optical effect, which is imaged as a bright and dark boundary of the light dispersion generated by the headlamp. In this case, the objective has regions with different optical properties.

However, it has been found to be disadvantageous when the edges of the diaphragm are imaged with a high degree of sharpness. This is because the boundary between light and darkness is when driving a car.
This is because it is accompanied by something that is clearly perceptible, and this is perceived as a hindrance by the driver. Furthermore, in order to blur the imaging of the edge of the diaphragm, in the case of the headlamp, a tangerine-textured surface is provided in the area of the objective lens. Due to the tangerine skinning of the surface, an overall smearing of the image is indeed obtained, but the smearing, in terms of intensity and course, cannot be precisely dispersed due to the irregularities of the tangerine skin.

0004

SUMMARY OF THE INVENTION An object of the present invention was to provide a headlamp in which the boundary between brightness and darkness does not become a hindrance.

[0005]

A headlamp according to the invention having the salient features of claim 1 has a high degree of sharpness at distances defined by different focal lengths of the central region and the peripheral region. This results in an imaging of the edge of the diaphragm and an image superimposed on said imaging of the edge of the diaphragm with slight sharpness, in which case the intensity of the blurring depends on the focal length difference as well as the size of the central area. It has the advantage of being defined by the size of the peripheral area.

[0006] Preferred features and further configurations of the headlamp are set out in the dependent claims. The arrangement according to claim 2 provides that the light rays are directed upwards to such an extent that at the transition between two regions an unacceptable increase in the value of the light intensity above the bright/dark boundary occurs. This prevents the object from being refracted toward the object. In a further embodiment according to claim 6, the different imaging produced by the two regions of the edge is
It is only weakly perceptible as a separate image.

Embodiments of the invention are illustrated in the drawings and explained in detail in the following description.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The headlight shown in FIGS.
, in which a light source 11 is used, which may be an incandescent lamp or a gas discharge lamp. The reflector 10 has different ellipses in the vertical and horizontal axes with a common first focus Fe located in the reflector,
However, there are two different focuses, and these two
The two focal points are located at different distances in the exit direction of the light from the reflector. The incandescent spiral or arcuate curve of the light source is arranged, for example, at the first focus of the ellipse and is elongated in the axial direction. A diaphragm 13 with an optically effective outer edge 14 below the optical axis 12 of the reflector 10 in the light exit direction of the light beam reflected by the reflector 10 is provided, for example, vertically in the region of the second focal point of the ellipse. placed in the cross section. Furthermore, in the exit direction of the light, there is an optical axis 12 of the reflecting mirror.
A lens 16 is arranged above the diaphragm 1.
The outer edge 14 of 3 is imaged onto the roadway in front of the motor vehicle as the bright and dark boundary of the light distribution generated by the headlights.

Lens 16 has a flat or slightly curved surface 17 facing mirror 10 and a convex surface 18 facing mirror 10 . The convex surface 18 of the lens is divided into a central region 19 and a peripheral region 20 surrounding the central region. The central region 19 is formed into a spherical shape, and the peripheral region 20 surrounds the central region in an annular shape. The area of the central region 19 is smaller than the area of the peripheral region 20. Furthermore, the focal length of the central region 19 is shorter than the focal length of the peripheral region 20.

The outer edge 14 of the diaphragm 13 is imaged with a high degree of clarity at a point Q at a distance L by the peripheral area 20 of the lens. The distance L is approximately 10 meters in the laboratory during the design of the headlamp, at which distance the measuring screen 22 is arranged. central area 1
As a result of the shorter focal length of 9, by means of the central region the outer edge 14 is already clearly imaged at a point P of a smaller distance S, i.e. the ray 23 intersects at a point P of a distance S, in which case: The light ray produces a blurred image of the outer edge 14 at a distance L, superimposed on the sharp image of the peripheral region 20 . Therefore, overall, at the distance L, the outer edge 14
sharp imaging occurs with a blurred band overlapping the width B defined by the focal length difference between regions 19 and 20 and by the size of the central region, in which case the increasing difference in focal length and The blurred band expands with increasing size of the central region. For a given diameter of the lens, the peripheral area shrinks as the central area expands.

The angle α between the tangent 26 that touches the peripheral region 20 at the transition 25 of the two regions and the tangent 27 that touches the central region 19 at the transition 25 is at most 5° in the case of dimming lights. This causes the blurred band B to widen, thus resulting in unacceptably high light intensity values above the bright/dark boundary. The transition between regions 19 and 20 may not run with the corner 25, but may be rounded, as marked with diagonal lines in FIG.

Advantageously, the central region 19 corresponds to the convex surface 1 of the lens 16.
Above 8, it has tangerine skin or orange skin structure. Tangerine skin has many fine ridges in the central area 19.
is formed on the surface of Depending on the tangerine skin, aperture 1
3 is additionally blurred, so that the edge 14 at distance S is also not sharply imaged. As a result of the tangerine skin, it is no longer possible to recognize the two differently focused images of the edge 14 of the diaphragm 13, and essentially only the image of the edge becomes a superimposed blurred band at a distance L. can be recognized by

The central region 19 and the peripheral region 20 are formed into aspherical shapes and have different aspherical surfaces. For enhanced blurring of the light-dark border in one direction, the central and/or peripheral regions of the lens are
It may be formed into a rick lens shape. In the case of a toric lens-like configuration, the region contains different aspheric surfaces in different axial sections, resulting in a continuous, rotationally asymmetric surface.

In contrast to the embodiments described above, the central region 1
The focal length of 9 may be longer than the focal length of peripheral region 20 . Furthermore, the edge 14 of the diaphragm 13 is sharply imaged on the screen 22 by the central region, with blurring occurring by the peripheral region. In principle, the different focal lengths of regions 19 and 20 result in superimposed imaging of edge 14 and blurring with a constant width.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a headlamp.

2 is an enlarged view of the part of the objective lens of the headlamp of FIG. 1, marked II in FIG. 1;

FIG. 3 is the front surface of the objective lens seen from the direction of arrow III in FIG. 1;

[Explanation of symbols]

10 reflecting mirror, 11 light source, 13 aperture, 14 edge, 16 objective lens, 1
7 curved surface, 18 convex surface, 19 central region, 20 peripheral region, 26 tangent to central region 19, 27 tangent to peripheral region 20

Claims (6)

[Claims] 1. One light beam is generated by reflection of the light beam of one light source (11), and the optical path of the light beam is provided with:
A diaphragm (13) with an edge (14) with an optical effect
and an objective lens (16) that images the edge (14) as a boundary between light and darkness of the light beam onto the roadway. In a motor vehicle headlamp, in particular for a dimming light or a fog lamp, which has regions with different optical properties, the objective lens (16) has a central region (19) with a first focal length; a peripheral region (20) surrounding said central portion having a second focal length different from the first focal length;
A headlamp for a motor vehicle, characterized in that the edge (14) is sharply imaged at different distances by the regions (19) and (20). 2. At the transition between the regions (19) and (20), the angle α is between the tangent (27) tangent to the central region (19) and the tangent (26) tangent to the peripheral region (20).
2. The headlamp according to claim 1, wherein the headlamp has a maximum angle of 5° between the angle and the angle. 3. Headlamp according to claim 1, wherein the transition between regions (19) and (20) is rounded. 4. The objective lens (16) includes a reflecting mirror (10
) with a flat or slightly curved surface (17) and an opposing convex surface (18), in which case the convex surface (
4. The headlamp according to claim 1, wherein 18) is aspherically shaped and the regions (19) and (20) are formed by a corresponding configuration of the convex surface (18). . 5. Headlamp according to claim 4, wherein the convex surface (18) is configured in the form of a toric lens in the central region (19) and/or in the peripheral region (20). 6. Headlamp according to claim 1, characterized in that the surface of the central region (19) and/or the surface of the peripheral region (20) is provided with tangerine skin.