EP1077347B1 - Vehicle headlamp - Google Patents

Abstract

The headlamp has a free area reflector for generating an a symmetrical dipped beam, whereby the reflector is divided into three optically effective areas (2-4) in the vertical direction with a light source associated with the central region (5) of the middle area (3). A sharp light/dark boundary is produced for the light emanating from the light strip via the middle region of the reflector using a cover strip

Description

The invention relates to a vehicle headlamp with an open space reflector for producing an asymmetric low beam, wherein the reflector is divided in the vertical direction into three photometrically effective areas, an upper area, a middle area and a lower area, and the central area has a central area, which Light source is assigned, the upper and the central region of the reflector are separated by an upper transition, the middle and the lower region separated by extending to both sides of the light source lower transitions, the two lower transitions extending from the central region to the outside , are inclined at different angles to a horizontal downwards.

The generation of a desired light distribution by exploiting the highest possible proportion of light can usually only be achieved by segmenting the reflector surface. A reflector, which has an initially mentioned segmentation in an upper, a middle and a lower region, has become known from DE 38 08 086 A1. The segmentation in three areas is used to the light distribution in the horizontal and vertical area perpendicular to the central axis of the headlamp as completely as possible to the desired light distribution, in this case, a dipped beam to adjust. In the calculation of the reflector surface is completely dispensed with mathematical rule surfaces, such as paraboloid or hyperboloid, so it is in fact an open space reflector.

Open space reflectors are increasingly being used in vehicle headlights in recent years. This is due in particular to the fact that with the help of free surface reflectors, in contrast to reflectors with a defined geometric structure, almost any arbitrary light distribution can be generated. A drawback that often occurs when using free-field reflectors is that there are often undesirable side-effects in the light distribution pattern, and it is usually not possible to predict these side-effects, such as when using reflectors based on mathematical rule surfaces , In particular, such unwanted side effects occur in free-field reflectors in connection with a reflector segmentation. In the transition areas between the different reflector areas reflected light is reflected, for example, upwards, which may lead to undesirable glare for oncoming traffic.

A high light output and thus a good illumination of the area ahead of a vehicle is achieved when using high-pressure gas discharge lamps. A high-pressure gas discharge lamp which is familiar to the person skilled in the art and is frequently used is the so-called D2R lamp, which has two cover strips below the horizontal plane of the headlight for producing a low beam. However, in addition to the advantage of a high luminous efficacy, these lamps have the disadvantage that it often comes to headlights, in which these lamps are used to disturbing effects, such as the glare of oncoming traffic.

It is an object of the invention to provide a vehicle headlamp for dipped beam, which generates a sharp bright-dark border while intensively illuminating the lying below the light-dark boundary area.

In particular, it is an object of the invention to provide a vehicle headlamp with an open space reflector for generating low beam, with the aid of a sharp light-dark line is generated with an optimum yield of light emerging from a light source, the above problems, in particular dazzling of oncoming traffic by light reflected over the horizon can be avoided.

This object is achieved by a reflector of the type mentioned above in that according to the invention the light source is assigned two substantially horizontally extending cover strips, the cover strips are arranged on both sides of the light source in their immediate vicinity, in a region below a horizontal plane passing through the light source, by means of the cover strips a sharp cut-off of the light emerging from the light source, emitted over the central region of the reflector light is generated, further the lower transitions are arranged so that they coincide with the shadows generated by the cover strips, substantially upwards emerging light is radiated over the upper portion of the reflector in a lying substantially below the light-dark boundary area, and the lower edges of the cover strips leave a light exit area, and the light emerging from this area on the under In the region of the reflector is radiated in a lying substantially below the light-dark boundary area.

In the following text, the term horizontal plane will be used more often in connection with the reflector or the light source. In order to avoid misunderstandings, it should be noted here that these "horizontal planes" essentially run horizontally, but that these planes do not always have to be arranged horizontally, for example as a result of the headlight swiveling, etc. It This is therefore an idealized term whose use on the one hand significantly increases the readability of the text and on the other hand does not detract from the comprehensibility and comprehensibility of the text.

The vehicle headlight has a reflector in free-field technology, which cooperates with a light source so that a maximum light output is given. For this purpose, the reflector is divided in the vertical direction into an upper, a middle and a lower region. The reflector is combined with a per se known light source which has two cover strips for producing a low beam distribution pattern, such as a D2R high pressure gas discharge lamp, which provides high luminous efficacy. The reflector is designed so that light which is radiated from this light source substantially upwards or downwards, via the upper or the lower region of the reflector in the outer space of the headlamp, d. h is generally reflected on a roadway, where it serves the apron and the width illumination. The areas of the reflector are separated by transitions, the lower transitions being arranged to lie in shadow areas created by the two cover strips. By this arrangement of the technically worthless areas of the reflector in the shadow area of the cover strips on the one hand, a maximum light output is achieved, on the other hand, glare, which are preferably generated by light incident on transitions, avoided. The central region of the reflector substantially reflects light into a region of the cut-off line, whereby a sharp image of the cut-off line itself is achieved by means of the two cover strips.

Due to the central area, the central area of the reflector is divided into two, so that the central area of the reflector has a left (right) and a right (left) partial area, the lower transition between the left (right) partial area and the lower area below a lower angle to the horizontal than the lower transition between the right (left) portion and the lower portion of the reflector. The size of the angle results according to the arrangement of the cover strips.

In a vehicle headlamp intended for standard installation, the lower angle has a value of 5 ° - 10 ° and the larger angle has a value of 17.5 ° - 25 °.

In an advantageous embodiment of a vehicle headlight, the reflector has stepped upper and lower transitions. Are, along one (any) Vertical section of the reflector, extending from top to bottom, the step-like transitions are formed jumping backwards, wherein the upper transition is formed as a substantially horizontally extending transition surface. The formation of the upper transition as a substantially horizontally extending transition surface proves to be beneficial because there is deflected light down and therefore no glare, for example, for oncoming traffic occurs.

In order to achieve the most homogeneous possible light distribution at the light-dark boundary, the middle region has surface grooves in an inner subsection of the left (right) and the right (left) subregion.

It should be noted at this point that the terms "left" and "right" are to be understood as interchangeable, as in countries or states with left-hand traffic, the light asymmetry is mirror image of those with right-hand traffic, the headlamp then having the corresponding asymmetry.

In this case, the surface grooves of the left (right) portion of groove planes, which are substantially normal to a horizontal plane through the optical axis and extend at different angles to the vertical plane through the optical axis. In this way, a homogenization of the light in a substantially horizontal area of the cut-off line, ie. H. essentially in the area of an oncoming traffic side of a roadway.

In order to achieve optimum homogenization of the light along the cut-off line in the region in which the cut-off line shows a rise against a horizontal (of approximately 15 °), the surface grooves of the right (left) sub-region have groove planes which are at different angles to the vertical plane and are initially normal to the horizontal plane, with increasing horizontal distance from the center, the groove planes at different angles through the horizontal plane.

Furthermore, the upper and the lower region of the reflector have surface grooves substantially over their entire surface, these running in the sense of a homogeneous intensity and color mixing of the light reflected from these regions into the outer space. For a uniform apron and width illumination of a roadway is achieved by the vehicle headlamp invention.

Advantageously, the vehicle headlight is designed as a headlight with a clear lens. Such is much cheaper than a corrective diffuser, which may also be omitted in view of the particular reflector design.

A particularly good illumination of the roadway can be achieved if the light source is formed by the arc of a high-pressure xenon lamp, which runs substantially horizontally and parallel to the cover strips.

Fig. 1

eine Vorderansicht eines Freiflächenreflektors eines erfindungsgemäßen Fahrzeugscheinwerfers,

Fig. 2

eine räumliche Darstellung des Reflektors nach Fig. 1,

Fig. 3

einen Vertikalschnitt durch den Reflektor entlang der Linie III-IIII nach Fig. 1,

Fig. 4

eine Vorderansicht eines Freiflächenreflektors eines erfindungsgemäßen Fahrzeugscheinwerfers mit Streurillen in den verschiedenen Reflektorbereichen,

Fig. 5

eine Seitenansicht einer im Zusammenhang mit dem Fahrzeugscheinwerfer verwendeten Lichtquelle mit Abdeckstreifen,

Fig. 6

schematisch eine Vorderansicht einer Lichtquelle mit Abdeckstreifen nach Fig. 5,

Fig. 7

schematisch eine von einem mittleren Bereich des Reflektors erzeugte Lichtverteilung,

Fig. 8

schematisch eine von einem oberen bzw. unteren Bereich des Reflektors erzeugte Lichtverteilung, und

Fig. 9

schematisch eine Überlagerung der Lichtverteilungen nach Fig. 7 und Fig. 8.

In the following the invention including an advantageous embodiment is explained in more detail with reference to the drawing. In this show

Fig. 1

a front view of an open space reflector of a vehicle headlamp according to the invention,

Fig. 2

a spatial representation of the reflector of FIG. 1,

Fig. 3

a vertical section through the reflector along the line III-IIII of Fig. 1,

Fig. 4

a front view of an open space reflector of a vehicle headlamp according to the invention with scattering grooves in the different reflector areas,

Fig. 5

a side view of a light source used in conjunction with the vehicle headlight with cover strip,

Fig. 6

FIG. 2 schematically shows a front view of a light source with cover strips according to FIG. 5, FIG.

Fig. 7

schematically a light distribution generated by a central region of the reflector,

Fig. 8

schematically a light distribution generated by an upper or lower portion of the reflector, and

Fig. 9

schematically a superposition of the light distributions according to FIG. 7 and FIG. 8.

FIG. 1 shows a front view of an open-space reflector 1 of a vehicle headlight according to the invention. In this case, the reflector 1 is subdivided in the vertical direction into three areas relevant for photometry, an upper area 2, a middle area 3, and a lower area 4. The central region 3 is due to a central region 5 in a left (right) portion 3a and a right (left) portion 3b divided. In practice, the central region 5 is formed as a substantially circular opening, which is provided for receiving a lamp 10. The lamp 10 is explained in more detail with reference to FIGS. 5 and 6. The reflector 1 shown here is used in a vehicle headlight for a vehicle intended for right-hand traffic. In order to achieve a light distribution adapted for left-hand traffic, the reflector only has to be mirrored. The following considerations apply mutatis mutandis to reflectors for left-hand traffic, only the words left and right are in each case to swap each other.

The upper region 2 and the middle region 3a are separated from each other by an upper transition 6, the middle region 3 and the lower region 4 by means of lower transitions 7a, 7b. The upper transition 6 runs substantially horizontally, whereas the lower transitions 7a, 7b are inclined downwards at different angles a1, a2 against a horizontal HE. The angle a1 is in a range of 5 ° - 10 °, in a practical embodiment of the invention a1 = 7.5 °, the larger angle a2 is in a range of 17.5 ° - 25 °, in a practical embodiment is a2 = 21.5 °.

2, the reflector 1 described above from FIG. 1 is again depicted in a three-dimensional representation. Furthermore, FIG. 3 shows a vertical section through the reflector 1 along the line III-III from FIG. 1. From FIG. 3, the stepped course of the upper transition 6 and of a lower transition 7b can be clearly seen. The transitions are designed to jump backwards, "backwards" essentially meaning a direction opposite to a light direction Y. From Fig. 3 it can be seen that the upper transition 6 is formed as a substantially horizontally extending transition surface 6. The reason for this embodiment is that the light emerging from the light source 12, which reaches the junction 6, is completely deflected downwards so that no glare can occur.

FIGS. 5 and 6 show a lamp 10 with associated cover strips 13, 14. The lamp 10 used in the vehicle headlight according to the invention is, for example, a type D2R xenon high-pressure gas discharge lamp which is well known to the person skilled in the art. In the side view of FIG. 5 can be seen a holder 11, by means of which the light source 12 in the opening 5 of the reflector 1 can be fastened. The lamp 10 has a light source 12, which is formed as an arc of the xenon high-pressure lamp. The light source 12 is surrounded by a transparent, substantially cylindrical, outer casing 8. On the casing 8, two cover strips 13, 14 are mounted, wherein the cover strips 13, 14 substantially parallel to a longitudinal axis X of the lamp 10.

In the front view of the lamp 10 shown in FIG. 6, the special arrangement of the cover strips 13, 14 can be seen. The two cover strips 13, 14 are arranged on both sides of the longitudinal axis X of the lamp 10, below a plane passing through the longitudinal axis X horizontal plane HE. The left cover strip 13 in this illustration is arranged almost directly below the plane HE and extends over a circular arc at an angle b1, where b1 = 25 ° ± 5 ° with a D2R lamp. The second cover strip 14 is arranged so that an upper edge is located approximately at an angle b3 below the plane HE and the cover strip stretches over an arc at an angle b2. For a D2R luminaire, the values for the angles b2 and b3 are: b2 = 15 °, b3 = 25 ° ± 5 °. In the case of the cover strips 13, 14, this is generally a black coating of the sheath 8, which prevents light from the light source from reaching the outside through the area covered by them.

The light generated in the light source 12 can emerge from the lamp 10 in substantially any direction. Only by those area of the sheath 8, which are provided with cover strips 13, 14, no light from the lamp 10 can get into the outer space. Direct radiated, d. H. Forward radiated light is usually undesirable in vehicle headlamps because it generally exerts a strong dazzling effect. In order to prevent this, in a practical embodiment of the headlamp, a shadowing known to those skilled in the art is arranged in front of the lamp 10, which, however, is not the subject of the invention and therefore not shown in the drawings.

An essential feature of the reflector 1 is that the lower transitions 7a, 7b are located exactly in the area in which the shadows of the cover strips 13, 14 occur. This arrangement of the lower transitions is chosen for the reason that the light reflected from transition regions often leads to strong glare effects. This is mainly due to the fact that a calculation of a ray path of light reflected in the transition regions, in particular in abrupt transitions, often very complicated and difficult and further these transitional regions often deviate from a calculated shape due to production-related inaccuracies. If now the transitions 7a, 7b in the shadow areas of the cover strips 13, 14, so no light from the transitions 7a, 7b are reflected in the outer space of the vehicle headlight, which glare, for example, the oncoming traffic is avoided. Another advantage of this arrangement of the transitions 7a, 7b is that thereby almost all of the light emerging from the light source 12 can be supplied to such reflector areas, which lie to an illumination of the front of the vehicle Contribute to maximum utilization of the produced light. In a practical embodiment of the invention, the lower transitions 7a, 7b are arranged so that they lie completely in the shadow area generated by the cover strips 13, 14, the shadow area in the vertical direction upwards and downwards slightly above that of the transitions 7a, 7b expanded area. This ensures that the vehicle headlight or the light distribution generated by the vehicle headlight behaves tolerant to production and assembly technical deviations of the position of the lamp, the reflector, etc. of the predetermined target values.

The cover strips 13, 14 form two outlet openings for light generated in the light space 12. The light exiting via the upper outlet opening is reflected on the one hand via the central portions 3a, 3b, on the other hand on the upper portion 2 of the reflector 1 in the Au-βenraum. A sharp cut-off line is imaged as an image of the upper edges of the cover strips 13, 14 over the central portions 3a, 3b on the road or a test screen. In this case, the left subarea 3a generates the essentially horizontally extending part of the light distribution along the cut-off line in the region of the oncoming traffic side of the roadway. The right portion 3b of the reflector 1, however, generates that portion of the light distribution, which is located substantially along the inclined at an angle of about 15 ° to a horizontal region of the cut-off line. The interaction of the cover strips with the special design of the central reflector region 3a, 3b produces an extraordinarily sharp cut-off line, with a high illuminance below the cut-off line and vanishing illumination above the cut-off line.

That portion of the light generated in the light source 12, which impinges on the upper portion 2 of the reflector 1, is reflected substantially uniformly in an area lying in front of the vehicle, below the cut-off line. A certain amount of light also reaches the region of the transition 6. Because it is designed as a substantially horizontally extending transition surface, the light incident there is reflected downwards and reaches unillustrated boundary regions of the reflector, which are designed such that There incident light is dissipated, so this light has no more dazzling consequences.

In contrast to many reflectors, in which the lower portion of a reflector for low beam remains unused, is in the headlight of the invention from the light source 12 downwardly exiting, reflected on the lower portion 4 of the reflector 1 in the outer space also in the light under Light-dark border lying Area radiated. The light radiated into the outer space via the lower region 4 forms a light distribution which substantially coincides with the light distribution generated by the upper region 2.

A light distribution generated by the central region 3 of the reflector 1 is shown in FIG. The solid lines correspond to so-called Isolux lines, these are lines with constant illuminance. The illuminance is highest for the innermost Isolux line, the illuminance decreases towards the outside. The course of the cut-off line shows the typical shape with a parallel course to the horizon H in the area of an oncoming traffic side GV a road FB and a bend and the following course at about 15 ° to a horizon H on a separate traffic EV. It is also easy to see that in particular the area of the roadway FB lying directly below the horizon H, to which the highest concentration of a vehicle driver is generally directed, is illuminated most intensely.

FIG. 8 shows a typical light distribution as generated by the upper region 2 and the lower region 4 of the reflector 1, respectively. Here, only one Isolux line is drawn, since the illuminance in the entire region indicated is essentially constant. A striking feature of this light distribution is the substantially wider extent of the light distribution in the horizontal direction compared with the light distribution according to FIG. 7. Furthermore, another area is also illuminated in the direction of the vehicle, below the cut-off line. By the upper portion 2 and the lower portion 4 thus good apron and width illumination is achieved. In the area of the carriageway FB, the light distribution shows a clear reduction below the cut-off line, thus avoiding dazzling of oncoming traffic.

Furthermore, in FIG. 9, an overlay of the entire light image generated by the upper, middle and lower reflector regions 2, 3, 4 is shown. This entire light distribution has a sharp cut-off line, the course of which complies with legal requirements. Furthermore, the good apron and width illumination can be seen. The areas of maximum illuminance are located directly below the horizon H on the carriageway FB.

The vehicle headlight is designed as a headlight with a clear lens. Optics or scattering properties of the lens are not necessary, since the desired light image is generated solely by means of the reflector 1 using a special lamp 10 provided for this purpose. However, an even better homogenization of the light distribution in terms of illuminance and color mixing can be provided that certain areas of the reflector 1 with grooves (2 ', 3a', 3b ', 4'), so-called diffuser or scattering grooves, are provided, as known for example from EP 846 912 A2 of the applicant became. In Fig. 4, the free surface reflector 1 of the headlight according to the invention is again shown in a front view, wherein an advantageous course of the grooves (2 ', 3a', 3b ', 4') in the upper, middle and lower region of the reflector 1 is indicated.

In a preferred embodiment of the invention, approximately the middle portions 3a, 3b on both sides of the central region 5 in an inner portion with grooves (3a ', 3b') provided, which are not shown in the drawing. In an outer partial section, however, the areas 3a, 3b are formed without grooves. This outer portion of the central portions 3a, 3b is responsible for generating a high illuminance at the cut-off line on the carriageway FB, a dispersion of the light is not necessary here. The left portion 3a has in its inner portion grooves (3a ') with groove planes, which are substantially normal to a horizontal plane HE through an optical axis X and extend at different angles to a vertical plane VE through the optical axis X. As an optical axis X, the longitudinal axis X of the lamp 10 is considered here. The groove plane is to be understood as meaning a normal plane to a tangent to a groove bottom assuming a symmetrical groove cross-section, see also EP 846 912 A2. With the help of these Streurillen a homogenization of the light is achieved in the substantially horizontal region of the cut-off line.

The right central portion 3b of the reflector 1 also has grooves (3b ') in an inner portion, the horizontal extent of the portion provided with grooves (3b') being greater in the right portion 3b than in the left portion 3a. Starting from the opening 5, the grooves (3b ') initially show a similar course to the grooves (3a') of the left-hand region 3a. However, as the distance from the central region 5 increases, the groove planes do not only extend at different angles to the vertical plane VE, but the groove planes also increasingly begin to tilt to the right at a decreasing angle to the horizontal plane HE. The initial angle of about 90 ° between the groove planes and the horizontal plane HE through the optical axis X is reduced to about 75 ° for the outermost groove in the right middle portion 3b. This decrease in the angle is associated with the 15 ° increase in the light-dark boundary in the area of the own traffic side EV, with the aid of these grooves (3b ') thus a homogenization of the light in this area of the cut-off line is made possible ,

Finally, in an advantageous embodiment of the invention, the upper region 2 and the lower region 4 of the reflector 1 also have surface grooves (2 ', 4') on their entire surface. These show a variety of courses, which have been computationally adjusted so that the best possible homogenization of the reflected light from these reflector areas 2, 4 is achieved.

Claims (11)

1. A vehicle headlamp equipped with a relief face reflector (1) for generating an asymmetrical dipped beam, the reflector (1) being divided vertically into three active illumination zones, an upper zone (2), a middle zone (3) and a lower zone (4), the middle zone (3) having a central zone (5), to which a light source (12) is assigned, the upper zone (2) and the middle zone (4) of the reflector (1) being separated from each other by a transition region (6), whilst the middle zone (3) and the lower zone (4) are separated from each other by lower transition regions (7a, 7b) extending on both sides of said light source (12), and said two lower transition regions (7a, 7b) are inclined downwardly at different angles (a1, a2) to a horizontal line (HE) extending outwardly from said central zone (5),
   characterized in that
   two substantially horizontal cover strips (13, 14) are assigned to said light source,
   a sharp light-dark boundary of the light emitted by the light source (12) and radiated via the middle zone (3) of said reflector (1) is produced by means of said cover strips (13, 14),
   and said lower transition regions (7a, 7b) are disposed such that they coincide with the shadows produced by the cover strips (13,14),
   the light emitted predominantly upwardly is radiated via the upper zone (2) of said reflector (1) in a zone situated substantially below said light-dark boundary, and
   the lower edges of said cover strips (13, 14) leave a light-emitting zone free and the light emitted from this zone is radiated through the lower zone (4) of said reflector (1) in a zone located substantially below said light-dark boundary.
2. A headlamp as defined in Claim 1, characterized in that the middle zone (3) of said reflector (1) has a left (right) and a right (left) sub-zone (3a, 3b), the lower transition region (7a) extending between the left (right) sub-zone (3a) and the lower zone (4) at a smaller angle (a1) to the horizontal (HE) than that at which the lower transition region (7b) extends between the right (left) sub-zone (3b) and the lower zone (4) of said reflector (1) respectively.
3. A headlamp as defined in Claim 1 or Claim 2, characterized in that the smaller angle (a1) has a value of from 5° to 10° and the larger angle (a2) has a value of from 17.5° to 25°.
4. A headlamp as defined in any one of Claims 1 to 3, characterized by stepped upper (6) and lower transition regions (7a, 7b).
5. A headlamp as defined in Claim 4, characterized in that said stepped transition regions (6, 7a, 7b) are formed along a(n) (arbitrary) vertical cross section of said reflector (1), running from top to bottom, and deflected to the rear, the lower transition region (6) being designed as an substantially horizontal transition surface.
6. A headlamp as defined in any one of Claims 1 to 5, characterized in that said middle zone (3) has surface grooves (3a', 3b') in an inner sub-zone of the left (right) and right (left) sub-zones (3a, 3b) respectively.
7. A headlamp as defined in Claim 6, characterized in that said surface grooves (3a') of the left (right) sub-zone (3a) have groove planes, which are substantially normal to a horizontal plane (HE) through an optical axis (X) and extend through said optical axis (X) at different angles to a vertical plane (VE).
8. A headlamp as defined in Claim 6 or Claim 7, characterized in that the surface grooves (3b') of the right (left) sub-zone (3b) have groove planes which extend at different angles to the vertical plane (VE) and are initially normal to the horizontal plane (HE), which groove planes extend at different angles through the horizontal plane (HE) as the horizontal distance from the central zone (5) increases.
9. A headlamp as defined in any one of Claims 1 to 8, characterized in that the upper (2) and lower zone (4) of said reflector (1) have surface grooves (2', 4') over substantially the entire surface of said reflector, which surface grooves extend so as to create a homogenous intensity and color mix of the light reflected from these areas into the environment.
10. A headlamp as defined in any one of Claims 1 to 9, characterized in that it is designed as a headlamp having a front panel of clear material.
11. A headlamp as defined in any one of Claims 1 to 10, characterized in that the light source (12) is formed by the arc of a high pressure Xenon lamp, which extends substantially horizontally and parallel to the cover strips (13, 14).

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