EP1020681B1 - Spotlight with variable illumination output angle and with an aspherical front lens - Google Patents

Description

The invention relates to a headlight with variable beam angle, in which the change in the emission angle is caused differently than by shadowing of the beam path by aperture or mask, arranged with a headlight interior light source and a first lens, which is the front lens of the headlamp. This class of headlamps does not include profile projectors in which a slight change in the angle of emission occurs as a side effect in the sharpness adjustment of the image.

The variable headlamps known from the prior art can be divided into three classes, namely Fresnel spotlights, headlamps with a very deep reflector and headlamps with a second lens, a light source and a reflector movable relative to the front lens.

Conventional Fresnel lens spotlights have a single Fresnel lens. As a light source bulbs, halogen lamps or discharge lamps are used in these Fresnel spotlights. The light source and a reflector are mounted at a fixed distance from each other on a carriage. The carriage is movable relative to the Fresnel lens. The focusing takes place by means of the movement of the carriage. With such Fresnel spotlights, however, there is a considerable effective loss of light for focusing settings of small emission angle. Since there is no second lens which concentrates the light toward the Fresnel lens, a large part of the light emitted by the light source is simply absorbed by the inner wall of the housing at said focus settings, resulting in loss of light and unnecessary housing heating.

Headlamps with very deep reflector are in general designed so that lamp and reflector can be moved relative to each other, but the lamp always remains within the reflector on the optical axis. By changing the position of the lamp within the reflector, the beam angle of such a headlight is changed. However, the achievable focusing distance is low, so that the emission angle can only be varied within relatively narrow limits. Although such headlamps provide a high luminous efficacy, but a unfavorable light distribution in almost all lamp positions. The reason for this generally poor light distribution is that the reflector shape fixed in each case for each individual such headlight can be optimally matched to only one single lamp position with respect to the resulting light distribution. Focusing movements of the lamp or of the reflector result in uneven light distributions. In order to improve the light distribution is therefore often used in such a headlight interchangeable front lens. This may have a matting, a honeycomb or other design features that serve additional focusing or scattering, however, have been used in headlamps with variable beam angle, however, never aspherical front lenses. It results in these headlights, the need to use different modified front lenses for different beam angles. In some headlamps with very deep reflector even both the lamp and the reflector are rigidly mounted in a housing, ie the change in the light emission angle takes place in this case exclusively by the replacement of differently shaped front lenses. This requires a relatively high labor and time to change the front lens, when such a headlamp is applied in a situation in which the radiation angle must be changed often.

Compared to the just described headlights much improved headlights with variable beam angle are the headlights of the third group according to the above classification. Related headlamps are known from US-A-4 823 243 and EP-A-0 846 913 of the generic type. They have a light source, a reflector associated with the light source, a first convergent lens (front lens) arranged in the beam path in the emission direction of the light source / reflector combination, and a second convergent lens arranged in the beam path between the light source and the first convergent lens. The reflector, the light source and the second condenser lens are mounted as an optical unit movable relative to the first condenser lens along the optical axis of the headlamp. Within the optical unit, according to US-A-4 823 243, the distance between the light source and the second condenser lens is changeable. Commercially also very similar headlamps, in which, however, the mutual distances between the reflector, the light source and the second convergent lens can not be changed. In the latter headlamps, the optical unit can only be moved as a rigid whole. In contrast, in the headlamp known from EP-A-0 846 913, within the optical unit displaceable relative to the first condenser lens, both the distance between the light source and the second condenser lens and the distance between the light source and the reflector can be changed. However, all of the headlights described in this paragraph have in common that the front lens is a spherical lens.

The variable angle headlamps referred to in the previous paragraph, one of which is shown schematically in FIG. 5, provide a wide range of variation of the angle of radiation (see FIGS. 6a, 6b) and have a high efficiency of illuminance achieved with respect to the operation of the Headlamps needed energy. Furthermore, they offer an extraordinarily even light distribution. In addition, with these headlamps, a stray light defined according to the traditional concept (light intensity ≤ 50% of the maximum light intensity) no longer exists due to the steep flanks of the light intensity at the edge of the illuminated area. As can be seen from Fig. 6a, 6b, points Although the illuminance characteristic of an illuminated field on the edge of small intensity increases, whose size depends on the position of the optical unit, but the light intensity over the entire illuminated area is substantially constant. The intensity increases at the edge do not occur in the spot position. They only appear from the spot position as the headlamp moves, and then increase in size continuously until a critical beam angle adjustment is achieved between spot position and flood position, where the magnitude of the intensity increases at the edge is maximum. Upon further movement of the headlamp in the direction of the flood position, the magnitude of the intensity increases at the edge decreases again continuously.

If one provides an area of the second lens with a graining such that a microlens structure is formed on the grained surface, the intensity increases occurring in the illuminance characteristic at the edge are attenuated, but they do not completely disappear. In addition, the reduction of the intensity increases at the edge is paid for by increased scattering effects and light loss.

The invention has for its object to provide a generic headlight, which provides a more uniform light distribution, especially in the Abstrahlwinkeleinstellungen outside the spot position compared to the known from the prior art such headlamps.

According to the invention this object is achieved by a headlamp according to claim 1.

The use of an aspherical lens as the first lens, that is, as the front lens of the generic headlight, ensures a uniform light distribution outside the spot position in comparison with the known headlights of the prior art.

The term "aspherical lenses" refers to lenses in which at least one sub-surface is not spherical, with plane surfaces are always calculated here to the spherical surfaces. Examples of aspherical Lenses are lenses with an ellipsoid and a spherical surface and lenses with a spherical surface and a hyperbolic surface. Fresnel lenses with aspherically designed partial surfaces are also aspherical lenses as defined above.

Advantageous and preferred embodiments of the headlight according to the invention are subject matter of claims 2 to 27.

In the embodiment of the headlamp according to the invention according to claim 13, the prior art edge intensity increases the light distribution are completely smoothed, and it results with high variability of the radiation angle, a particularly uniform illumination of the illuminated area regardless of the selected Abstrahlwinkeleinstellung.

The graining according to claim 14 need not be carried out so deep in the headlight according to the invention, as the commonly known from the prior art graining the second lens. In this way results in a lower loss of light and, especially in the spot position, a higher light intensity with the same input power.

In the particularly preferred embodiment according to claim 16, compared to a second lens designed as a spherical lens, in the spot position the luminous efficacy is increased for the same power fed in.

A particularly uniform light distribution is obtained in the embodiments of the headlamp according to the invention according to claims 7, 10, 21 and 24.

In the embodiment of the headlamp according to the invention according to claim 26 it is ensured that the headlamp also has all the advantages of the known from US-A-4,823,243 headlamp.

In the embodiment of the headlamp according to the invention as claimed in claim 27 when dependent on claim 26 it is ensured that the headlamp also all the advantages of the headlamp known from EP-A-0 846 913, in particular the very large variability of the radiation angle and the light intensity, having.

Fig. 1a-1e

schematisch einen Querschnitt einer Ausführungsform eines erfindungsgemäßen Scheinwerfers bei Bewegung einer aus Lichtquelle, Reflektor und zweiter Linse bestehenden optischen Einheit aus einer dichtmöglichst an einer ersten Linse befindlichen Position in eine weitmöglichst von der ersten Linse entfernte Position,

Fig. 2a-2e

schematisch einen Querschnitt einer weiteren Ausführungsform des erfindungsgemäßen Scheinwerfers bei Bewegung der aus Lichtquelle, Reflektor und zweiter Linse bestehenden optischen Einheit aus der dichtmöglichst an der ersten Linse befindlichen Position in die weitmöglichst von der ersten Linse entfernte Position,

Fig. 3a-3f

schematisch einen Querschnitt einer dritten Ausführungsform des erfindungsgemäßen Scheinwerfers bei Bewegung der aus Lichtquelle, Reflektor und zweiter Linse bestehenden optischen Einheit aus der dichtmöglichst an der ersten Linse befindlichen Position in die weitmöglichst von der ersten Linse entfernte Position,

Fig. 4a-4c

schematisch einen Querschnitt einer vierten Ausführungsform des erfindungsgemäßen Scheinwerfers bei Bewegung der aus Lichtquelle, Reflektor und zweiter Linse bestehenden optischen Einheit aus der dichtmöglichst an der ersten Linse befindlichen Position in die weitmöglichst von der ersten Linse entfernte Position,

Fig. 5

schematisch einen Querschnitt eines aus dem Stand der Technik bekannten Scheinwerfers mit veränderlichem Abstrahlwinkel und sphärischer Frontlinse,

Fig. 6a

Lichtverteilungskennlinien des Scheinwerfers von Fig. 5 für verschiedene Abstrahlwinkeleinstellungen,

Fig. 6b

schematisch einen von dem Scheinwerfer von Fig. 5 beleuchteten Bereich in kritischer Abstrahlwinkeleinstellung zwischen Spotstellung und Flutstellung des Scheinwerfers,

Fig. 7a

Lichtverteilungskennlinien des erfindungsgemäßen Scheinwerfers aus Fig. 3a bis 3f für verschiedene Abstrahlwinkeleinstellungen,

Fig. 7b

schematisch einen von dem erfindungsgemäßen Scheinwerfer aus Fig. 3a bis 3f beleuchteten Bereich bei kritischer Abstrahlwinkeleinstellung zwischen Spotstellung und Flutstellung des Scheinwerfers und

Fig. 8

schematisch ein Ausführungsbeipiel des erfindungsgemäßen Scheinwerfers mit eingezeichnetem Koordinatensystem.

Embodiments of the headlight according to the invention are explained below with reference to figures. Show it:

Fig. 1a-1e

1 is a schematic cross-section of an embodiment of a headlamp according to the invention when an optical unit consisting of light source, reflector and second lens moves from a position as close as possible to a first lens to a position as far away as possible from the first lens;

Fig. 2a-2e

1 schematically shows a cross-section of a further embodiment of the headlamp according to the invention when the optical unit comprising the light source, reflector and second lens moves from the position as close as possible to the first lens to the position as far as possible from the first lens;

Fig. 3a-3f

1 schematically shows a cross-section of a third embodiment of the headlamp according to the invention when the optical unit comprising the light source, reflector and second lens moves from the position closest possible to the first lens into the position as far as possible from the first lens,

Fig. 4a-4c

1 is a schematic cross-sectional view of a fourth embodiment of the headlamp according to the invention when the optical unit consisting of light source, reflector and second lens moves from the position closest to the first lens to the position as far as possible from the first lens;

Fig. 5

schematically a cross section of one of the Prior art known headlamps with variable beam angle and spherical front lens,

Fig. 6a

Light distribution characteristics of the headlamp of FIG. 5 for different radiation angle settings,

Fig. 6b

FIG. 2 shows schematically an area illuminated by the headlamp of FIG. 5 in a critical angle setting between spot position and flood position of the headlamp, FIG.

Fig. 7a

Light distribution characteristics of the headlamp according to the invention from FIGS. 3a to 3f for different radiation angle settings,

Fig. 7b

schematically an illuminated by the inventive headlight of Fig. 3a to 3f range at critical Abstrahlwinkeleinstellung between spot position and flood position of the headlamp and

Fig. 8

schematically a Ausführungsbeipiel the headlamp according to the invention with drawn coordinate system.

mit k= -1,5 und r = 52 mm
(k - Kegelschnittkonstante; r - Scheitelkrümmungsradius) Das zugrundeliegende Koordinatensystem ist aus Fig. 8 ersichtlich.In Fig. 1a, an embodiment of the headlamp according to the invention is shown in cross section. The headlight has a cup-like, opaque housing 1, in which at the light exit side as the front lens of the headlamp, a first converging lens 2 is inserted. The facing in the direction of emission of the headlight surface of the first converging lens 2 is rotationally symmetrical and has the meridional section in the form of a hyperbola section, wherein the apex of the hyperbola lies on the optical axis of the pig launcher. The hyperbola satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{1+\sqrt{1-\left(k+1\right){\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}$$

with k = -1.5 and r = 52 mm
(k - conic constant; r - vertex curvature radius) The underlying coordinate system is shown in FIG.

The interior of the headlight facing surface of the first converging lens 2 is a plane surface. However, it can also be executed concavely curved. This applies in principle for all embodiments of the headlamp according to the invention described below.

Within the housing 1, a light source 4, which is formed by a filament lamp with a small filament, and a light source 4 associated with the reflector 5 are arranged on a carriage 3. The light source 4 and the reflector 5 are mounted so that the resulting light beam path is directed in the direction of the first converging lens 2. In addition, a second converging lens 6 is arranged on the carriage 3 in the beam path between the light source 4 and the first convergent lens 2. In the illustrated embodiment of the headlight according to the invention, the second converging lens 6 is a meniscus lens whose surface facing the first condenser lens 2 is grained.

mit k = -1,1 und r = 24 mm.The second converging lens 6 is rotationally symmetrical with respect to its optical axis. The grainy surface of the second converging lens 6 facing away from the light source 4 has the shape of a hyperbola section in the meridional section, the vertex of the hyperbola lying on the optical axis of the headlight. The hyperbola satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{1+\sqrt{1-\left(k+1\right){\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}$$

with k = -1.1 and r = 24 mm.

The light source 4, the reflector 5 and the second converging lens 6 are mounted so that both the distance between the light source 4 and the second condenser lens 6 and the Distance between the light source 4 and the reflector 5 can be changed.

It is also possible, even with the first converging lens 2 to provide a lens surface with a grain, so that a microlens structure is formed. By this measure, a particularly good uniformity of the light distribution is achieved.

Fig. 1a shows the light source 4, the reflector 5 and the second converging lens 6 in a position maximum radiation angle of the headlamp according to the invention. The distance between the first condenser lens 2 and the second condenser lens 6 and the distance between the second condenser lens 6 and the light source 4 are minimal according to the spotlight dimensions, and the distance between the light source 4 and the reflector 5 is the maximum distance corresponding to the mounting conditions.

In order to reduce the emission angle, the carriage 3 is moved in the direction away from the first converging lens 2. The mechanism of the carriage and cooperating with him guide parts is designed so that the second converging lens 6 initially remains in its original position and move only the light source 4 and the reflector 5 while maintaining their original mutual distance in the direction of the first convergent lens 2 away , This type of movement continues until the distance between the light source 4 and the second converging lens 6 has reached a predetermined value. Fig. 1b shows the optical system of the headlamp according to the invention in just this position.

As the carriage 3 moves further in the direction away from the first converging lens 2, as shown in FIG. 1c, neither the distance between the light source 4 and the reflector 5 nor the distance between the light source 4 and the second converging lens 6 changes. The further the light source 4 and the reflector 5 and the second condenser lens 6 move away from the first converging lens 2, the smaller the angle of radiation and the greater the illuminance on the illuminated field.

Finally, the reflector 5 reaches a corresponding the headlamp dimensions outermost distance to the first converging lens 2 and stops in its movement (see Fig. 1d). This is the position at which the headlamp known from US-A-4 823 243 achieves its minimum beam angle and maximum illuminance.

On the way from the initial position shown in Fig. 1a to the position shown in Fig. 1d, the headlamp undergoes a critical beam angle adjustment, in which the headlamp known from US-A-4,823,243 shows brighter illuminated edges in its light distribution characteristic (see Fig. 6a, 6b). However, the headlamp according to the invention with the aspherical front lens 2, however, shows a very uniform light distribution characteristic in all beam angle settings, in particular also in the beam angle setting critical according to the prior art. Such will be explained in more detail below with reference to FIGS. 7a and 7b with reference to another embodiment of the headlamp according to the invention.

From the mechanical mobility of its individual parts, the headlamp according to the invention shown in FIGS. 1a to le corresponds to the headlamp shown in EP-A-0 846 913. D. h., It is possible, starting from the headlight position shown in Fig. 1d, the light source and the second converging lens 6 while maintaining their mutual distance achieved with the reflector 5 still further away from the first converging lens 2 and thus closer to the reflector 5 introduce (see Fig. 1e).

mit k = -0,6 und r = 52 mm.In FIGS. 2a to 2e, a further embodiment of the headlamp according to the invention is shown. In this exemplary embodiment, too, the surface of the first converging lens 2 directed in the emission direction of the headlight is rotationally symmetrical with respect to its optical axis, and the surface of the first converging lens 2 directed into the headlight interior is a plane surface. The difference from the embodiment of the headlight according to the invention shown in FIGS. 1a to 1e with respect to the first converging lens 2 is that in the emission direction of the headlamp facing surface of the first converging lens 2 has the shape of an ellipse section, wherein the minor axis of the ellipse lies on the optical axis of the headlight. The ellipse satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{1+\sqrt{1-\left(k+1\right){\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}$$

with k = -0.6 and r = 52 mm.

mit k = -0,6 und r = 24 mm.Also in the embodiment of the headlamp according to the invention shown in Figures 2a to 2e, the second converging lens 6 is a meniscus lens. The remote from the light source 4 surface of the second converging lens 6 is rotationally symmetrical with respect to its optical axis and has the meridional section in the form of an ellipse section, wherein the minor axis of the ellipse lies on the optical axis of the headlamp. The ellipse satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{1+\sqrt{1-\left(k+1\right){\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}$$

with k = -0.6 and r = 24 mm.

With regard to the mechanical mobility of the individual parts, the embodiment of the headlamp according to the invention shown in FIGS. 2a to 2e substantially corresponds to the exemplary embodiment of the headlamp according to the invention shown in FIGS. 1a to 1e. The only difference is that, when the reflector 5 has reached its outermost distance to the first converging lens 2 according to the spotlight dimensions, the second converging lens 6 can not be further moved away from the first converging lens 2 in the embodiment according to FIGS. 2a to 2e. In this case, only the light source 4 while maintaining the mutual maximum distance between the second convergent lens 6 and reflector 5 is further brought to the reflector 5, as soon as the reflector 5 and the second converging lens 6 in this embodiment, the greatest possible distance from the first Conveying lens 2 have reached (see Fig. 2e). The advantages of such a mechanical design are described in detail in EP-A-0 846 913. The same applies to the movement of the light source 4, the reflector 5 and the second converging lens 6 in the direction of the first convergent lens 2, which movement is opposite to that described above. Practically only a simple reversal of the movement sequence takes place. For a detailed description, see EP-A-0 846 913.

In addition to mechanical slide systems, which enable the above-described movements, there are in other embodiments of the headlamp according to the invention carriage systems that cause slightly modified movements. Thus, for example, In one embodiment, the second converging lens 6 in the rear portion of the movement of the carriage 3 of the first converging lens 2 are not abrupt, but it is at constant relative speed between the light source 4 and the first converging lens 2, the relative velocity between the second converging lens 6 and the first convergent lens 2 continuously slows down until the second condenser lens 6 finally stops, while the reflector 5 and the light source 4 still move away from the first condenser lens 2 while maintaining their mutual distance (FIGS. 3a to 3e). Finally, the reflector 5 reaches the outermost position shown in Fig. 3e, and only the light source 4 moves away from the first converging lens 2 until the light source 4 finally reaches its outermost position (Fig. 3f). The reversal of this sequence of movements takes place accordingly.

• k = -0,5
• r = 52 mm

The first converging lens 2 of the embodiment of the headlamp according to the invention shown in Figs. 3a to 3f corresponds to the first converging lens 2 of the embodiment shown in Figs. 2a to 2e with the difference that the ellipse constants k and r in the embodiment of Fig. 3a until 3f have the following values:

• k = -0.5
• r = 52 mm

mit k = -1,3 und r = 24 mm.The second converging lens 6 is formed in the embodiment of Fig. 3a to 3f as Meniskuslinse whose remote from the light source 4 surface in meridional section has the shape of a hyperbola section, wherein the vertex of the hyperbola lies on the optical axis of the pig. The hyperbola satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{1+\sqrt{1-\left(k+1\right){\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}$$

with k = -1.3 and r = 24 mm.

FIG. 7a shows illuminance characteristics for the embodiment of the headlamp according to the invention shown in FIGS. 3a to 3f. In comparison with the prior art illuminance characteristics shown in Fig. 6a, the improved uniformity of illumination by means of the headlamp according to the invention becomes clear. The intensity increases at the edge occurring outside the spot position according to the prior art have also disappeared in the hitherto critical emission angle setting between spot position and flood position. A direct comparison for the critical Abstrahlwinkeleinstellung deliver Fig. 6b and 7b.

mit k = -2 und r = 52 mmIn addition to the embodiments of the headlamp according to the invention shown in FIGS. 1a to 3f, there are many other possible variations for embodiments of the headlamp according to the invention. A first converging lens 2 with hyperbolic in the meridional section facing away from the light source 4 surface z. B. also be combined with a second converging lens 6, the surface facing away from the light source 4 in the meridional section has the shape of an ellipse section. Such an embodiment of the headlight according to the invention is shown in FIGS. 4a to 4c. The facing in the direction of emission of the headlight surface of the first converging lens 2 is rotationally symmetric in this embodiment and has the meridional section in the form of a hyperbola section, the apex the hyperbola lies on the optical axis of the headlamp. The hyperbola satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{1+\sqrt{1-\left(k+1\right){\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}$$

with k = -2 and r = 52 mm

The interior of the headlight facing surface of the first converging lens 2 is a plane surface.

mit k = -0,4 und r = 24 mmThe second converging lens 6 is rotationally symmetrical with respect to its optical axis. The facing away from the light source 4, grained surface of the second converging lens 6 has the meridional section in the form of an ellipse section, wherein the vertex of the ellipse lies on the optical axis of the headlamp. The ellipse satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{1+\sqrt{1-\left(k+1\right){\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">y</figure-callout>}}^2/{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}$$

with k = -0.4 and r = 24 mm

The movement mechanism in the fourth exemplary embodiment of the headlamp according to the invention shown in FIGS. 4a to 4c functions as follows: FIG. 4a shows the light source 4, the reflector 5 and the second convergent lens 6 in a position of maximum emission angle of the headlamp. In order to reduce the emission angle, the carriage 3 is moved in the direction away from the first converging lens 2. Here, in this embodiment of the headlamp according to the invention, the mechanism of the carriage and cooperating with him guide parts designed so that the distances of the second converging lens 6, the light source 4 and the reflector 5 with each other initially not change. As soon as the Carriage 3, however, has reached a certain distance from the first converging lens 2, holds the second converging lens 6 in their movement, while the light source 4 and the reflector 5 while maintaining their mutual distance together further from the first convergent lens 2 and now also of Move the second converging lens 6 away until they reach their constructive conditional maximum distance from the first converging lens 2 (see Fig. 4c).

During the movement of the carriage 3 from the spot position (FIG. 4c) into the flood position (FIG. 4a), the movement process just described proceeds in exactly the reverse order. First, the light source 4 and the reflector 5 move while maintaining their mutual distance to the two converging lenses 6 and 2. Once a certain distance between the light source 4 / reflector 5 on the one hand and the second converging lens 6 is reached on the other hand, the second converging lens 6 participates in the movement, and the light source 4, the reflector 5 and the second convergent lens 6 move now while maintaining their mutual Distances to the first convergent lens 2 to.

Mechanically, one can as described above with reference to FIGS. 4a to 4c movement of the mounted on the carriage 3 optical elements z. B. achieve by mounting the second converging lens 6 within the carriage 3 on a movable guide rail 7, which projects beyond the base body of the carriage 3 on the side facing away from the first converging lens 2 side and with respect to the unit light source 4 / reflector 5 with a spring and provided with a suitable stop.

Generally applies to the headlamp according to the invention, that the second converging lens 6 does not necessarily have to be formed as a meniscus lens or as an aspherical lens.

In other embodiments of the headlight according to the invention, the inwardly directed surface of the first converging lens 2 is aspherical. Further, the carriage system need not necessarily be formed as described in US-A-4,823,243 or EP-A-0 846 913. There is therefore also Embodiments of the headlamp according to the invention, in which the distance between the reflector 5, the light source 4 and the second convergent lens 6 can not be changed. In these embodiments, it is only possible to move the three aforementioned elements together with the aid of the carriage 3 as a rigid optical unit relative to the first converging lens 2. The possible design variants of the first lens 2 as an aspherical lens are just as little affected by this mechanical construction as the design variants of the second lens 6.

In addition, it is not absolutely necessary that a rotationally symmetrical lens is used as the aspheric front lens 2. Embodiments with non-rotationally symmetric aspherical lenses are also possible. However, as described above, if aspherical lenses having hyperbolic or ellipsoidal surfaces are used, they need not necessarily be arranged so that the hyperbola apexes or small ellipse ellipses are on the optical axis of the piglet. Embodiments are also conceivable in which the corresponding lenses are arranged offset relative to the optical axis of the pig launcher. This applies both to the first converging lens 2 and to the second converging lens 6.

In FIGS. 1a to 3f, the reflector 5 is always shown as a relatively flat reflector and the light source 4 as an upright filament lamp. However, it is also possible to use a deep reflector and / or a recessed mounted lamp.

Instead of the filament lamp mentioned in the above embodiment, the light source 4 may be e.g. also be formed by a halogen lamp or by a discharge lamp without helix with light spot between two electrodes.

Although the use of an aspherical front lens has been described above in connection with a very special variable-angle headlight, the aspherical front lens is even more uniform, especially in the spotlight positions between spot position and flood position Allows light distribution compared to the known from the prior art such headlamps, aspherical front lenses can also be used in all sorts of other lights with variable beam angle to influence the light distribution of the headlamp. This is especially true for headlamps with replaceable front lens. The aspherical front lens can in this case be rotationally symmetric or non-rotationally symmetrical and centered on the optical axis of the headlight or offset from the optical axis of the pig headlight.

Apart from the values given above, the conic constants r and k can assume many more values. The value range of the r, which is actually important for practical applications, ranges from 15 mm to 150 mm. If k is less than 0 but greater than -1, the equation given above yields an ellipsoidal surface. At k = -1 there is a paraboloidal surface and at k <-1 a hyperboloidal surface. k can take arbitrarily small values, and r is not limited to the above range of values.

Finally, it should be expressly pointed out that the invention is not limited to headlights of a certain power class. For example, headlamps according to the invention can be implemented both as miniature headlamps with a power of a few 10 W and as high-power headlamps with a power of a few 10 kW.

Claims (27)

1. Spotlight with a variable emission angle, in which the variation in the emission angle is caused otherwise than by shading the beam path by means of a diaphragm or mask, having a light source (4) arranged in the spotlight interior, and a first lens (2) which is the front lens of the spotlight and is embossed at least on one face, characterized in that the first lens (2) is an aspheric lens.
2. Spotlight according to claim 1, characterized in that the first lens (2) is designed in a rotationally symmetrical fashion with reference to its optical axis.
3. Spotlight according to one of the preceding claims, characterized in that the surface of the first lens (2) which is directed into the spotlight interior is aspheric.
4. Spotlight according to one of the preceding claims, characterized in that in meridian section the surface of the first lens (2) facing in the direction of emission of the spotlight has the shape of a conic section segment other than a circular segment.
5. Spotlight according to claim 4, characterized in that in meridian section the surface of the first lens (2) facing in the direction of emission of the spotlight has the shape of a hyperbolic segment.
6. Spotlight according to claim 5, characterized in that the apex of hyperbola lies on the optical axis of the spotlight.
7. Spotlight according to claim 6, characterized in that the hyperbola satisfies the following equation: $$\mathrm{Z}\mathrm{=}\frac{\mathrm{1}}{\mathrm{r}}\mathrm{\cdot }\frac{{\mathrm{y}}^{\mathrm{2}}}{\mathrm{1}\mathrm{+}\sqrt{\mathrm{1}\mathrm{-}\left(\mathrm{k}\mathrm{+}\mathrm{1}\right){\mathrm{y}}^{\mathrm{2}}\mathrm{/}{\mathrm{r}}^{\mathrm{2}}}}$$

   

   
   k being a value from the range of -3.0 to -1.1, and r being a value from the range of 40 mm to 100 mm.
8. Spotlight according to claim 4, characterized in that in meridian section the surface of the first lens (2) facing in the direction of emission of the spotlight has the shape of an elliptical segment.
9. Spotlight according to claim 8, characterized in that the minor axis of the ellipse lies on the optical axis of the spotlight.
10. Spotlight according to claim 9, characterized in that the ellipse satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{y^2}{1+\sqrt{1-\left(k+1\right)y^2/r^2}}$$

    

    
    k being a value from the range of -0.9 to -0.5, r being a value from the range of 40 mm to 100 mm.
11. Spotlight according to claim 1, characterized in that the surface of the first lens (2) facing into the spotlight interior is spherical.
12. Spotlight according to claim 1, characterized in that the surface of the first lens (2) facing into the spotlight interior is plane, or convex in the direction away from the light source (4).
13. Spotlight according to one of the preceding claims, characterized by

    - a reflector (5) assigned to the light source (4),
    and

    - a second lens (6) arranged in the beam path between the light source (4) and the first lens (2), the reflector (5), the light source (4) and the second lens (6) being mounted as an optical unit which can move relative to the first lens (2) along the optical axis of the spotlight.
14. Spotlight according to claim 13, characterized in that the second lens (6) is embossed at least on one face.
15. Spotlight according to claim 13 or 14, characterized in that the second lens (6) is designed in a rotationally symmetrical fashion with reference to its optical axis.
16. Spotlight according to one of claims 13 to 15, characterized in that the second lens (6) is an aspheric lens.
17. Spotlight according to claim 16, characterized in that the surface of the second lens (6) facing the light source (4) is aspheric.
18. Spotlight according to claim 16 or 17, characterized in that in meridian section the surface of the second lens (6) averted from the light source (4) has the shape of a conic section segment other than a circular segment.
19. Spotlight according to claim 18, characterized in that in meridian section the surface of the second lens (6) averted from the light source (4) has the shape of a hyperbolic segment.
20. Spotlight according to claim 19, characterized in that the apex of the hyperbola lies on the optical axis of the spotlight.
21. Spotlight according to claim 20, characterized in that the hyperbola satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{y^2}{1+\sqrt{1-\left(k+1\right)y^2/r^2}}$$

    

    
    k being a value from the range of -3.0 to -1.1, and r being a value from the range of 20 mm to 70 mm.
22. Spotlight according to claim 18, characterized in that in meridian section the surface of the second lens (6) averted from the light source (4) has the shape of an elliptical segment.
23. Spotlight according to claim 22, characterized in that the minor axis of the ellipse lies on the optical axis of the spotlight.
24. Spotlight according to claim 23, characterized in that the ellipse satisfies the following equation: $$Z=\frac{1}{r}\cdot \frac{y^2}{1+\sqrt{1-\left(k+1\right)y^2/r^2}}$$

    

    
    k being a value from the range of -0.9 to -0.5, and r being a value in the range of 20 mm to 70 mm.
25. Spotlight according to one of claims 13 to 24, characterized in that the second lens (6) is a meniscus lens.
26. Spotlight according to one of claims 13 to 25, characterized in that the distance between the light source (4) and the second lens (6) inside the optical unit can be varied.
27. Spotlight according to one of claims 13 to 26, characterized in that the distance between the light source (4) and the reflector (5) inside the optical unit can be varied.

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