EP0417672B1 - Headlight, especially for vehicles - Google Patents

Abstract

In a headlight, especially for motor vehicles, having a light source arranged at the focal point of a reflector, a reflector which is configured such that it illuminates a wide area and which is an approximate parabolic section below the optical axis in a vertical section through the optical axis, and a lens which is essentially optically non-corrective and covers the light exit of the reflector, it is the case that in order to provide a headlight which in conjunction with low overall volume permits a high light yield for a large width of the illuminated area, is simple and cost effective, and manages without a corrective lens, the light source is a transverse filament extending perpendicularly to the optical axis and situated horizontally, the reflector is, in a horizontal section through the optical axis, a first approximate elliptical section with a short spacing of the focal points, and above the optical axis the reflector is, in a vertical section through the optical axis, a second approximate elliptical section with a large spacing of the focal points. <IMAGE>

Description

The invention relates to a headlamp, in particular for motor vehicles, with a light source arranged in the focal point of a reflector, with a reflector which is designed such that it produces a large width of the illuminated area in a horizontal axis, and which is in a vertical section through the optical axis is an approximate parabolic section below the optical axis, and with an essentially optically non-correcting lens that covers the light exit of the reflector.

Headlights of this type can be used as dimmed headlights, in particular in motor vehicles, for illuminating the roadway when the motor vehicle is in operation. It is also possible to use headlights of this type, in particular on motor vehicles, as work headlights for illuminating the work area when the motor vehicle is at a standstill or when driving slowly away from public roads. In both cases, the immediate vicinity in front of the motor vehicle should be illuminated as evenly and glare-free as possible.

From DE-PS 22 05 610 such a headlamp is known in which the reflector is designed such that the desired light distribution, namely in a horizontal axis, a large width of the illuminated area, almost without shading the light source and essentially without a correcting lens. is produced. For this purpose, the reflector has a hyperbolic section in a horizontal section through the optical axis and a parabola section in a vertical section through the optical axis. The light source is a longitudinal helix extending in the direction of the optical axis.

However, this known headlight has disadvantages. Thus, a longitudinal helix extending in the direction of the optical axis is used as the light source. Such known incandescent lamps have a large length, so that the known headlamp has a large depth. Because the reflector there has a hyperbola section in a horizontal section through the optical axis, the overall width of the headlight is also large. In addition, the light source is enclosed by the hyperbola section only in a very small solid angle, which leads to a comparatively poor yield of the luminous flux supplied by the light source and reduces the light output which can be generated by the known headlights.

Finally, the overall height of the known headlamp is also large, since the focal length of the parabolic sections used in the vertical section through the optical axis cannot be arbitrarily reduced because of the given dimensions of the incandescent lamp and its inclusion. In addition, the parabola sections also enclose the light source only in a very small solid angle, which likewise leads to the low, usable light efficiency described above.

The previously known headlamp thus has a large construction volume and a comparatively low luminous efficacy.

The object of the invention is to provide a headlight which, with a small construction volume, enables a large luminous efficacy with a large width of the illuminated area, is simple and inexpensive and does not require a correcting lens.

This object is achieved in that the light source is a horizontal spiral extending perpendicular to the optical axis and that the Reflector in a horizontal section through the optical axis is a first approximate ellipse section with a small distance between the focal points and that the reflector in a vertical section through the optical axis above the optical axis is a second approximate ellipse section with a large distance between the focal points.

Due to the design of the light source as a transverse spiral extending perpendicular to the optical axis and lying horizontally, the overall depth of the headlamp according to the invention is less than that of the prior art, since such incandescent lamps are shorter. Characterized in that the reflector is a first approximate ellipse section in a horizontal section through the optical axis, the light source is enclosed much more completely than in the prior art, so that a larger solid angle is detected, which leads to a better light yield of the headlight according to the invention.

By choosing an ellipse with a small distance between the focal points, the desired large width of the illuminated area in the horizontal axis is achieved without a correcting lens. In contrast to what was previously known, the light rays reflected by the elliptical surface cross each other. In the case of the known headlight, on the other hand, the light rays are reflected without crossing the light rays on the hyperbolic surface. Also by choosing an ellipse with a small distance between the focal points, the required overall width of the headlight according to the invention is reduced compared to the known.

Because the reflector in a vertical section through the optical axis above the optical axis is a second approximate elliptical section with a large distance between the focal points, the enclosure of the light source and thus the detected solid angle is also greater than in this section in the prior art, so that for this reason also the luminous efficacy of the headlight according to the invention is greater than in the prior art. In addition, the required height of the headlamp according to the invention can be reduced compared to the known by the second approximate elliptical section.

The headlamp according to the invention thus has the advantages over the known headlamp that its construction volume is smaller and its luminous efficiency is greater. In addition, it is simple and inexpensive to manufacture, since z. B. no optically effective, correcting lens and no lens, such as. B. in a projector headlight, is required. Due to the very extensive enclosure of the light source by the reflector z. B. an extensive directional influence of the light generated by the light source possible. Only a comparatively small proportion of the light from the light source is transmitted through the lens without reflection from the reflector.

Advantageous refinements and developments of the headlight according to the invention result from the subclaims.

In order to enable the closest possible illumination of the near area in front of the headlight according to the invention, in particular when used on motor vehicles, it is advantageous if the focal length of the reflector is shorter above the optical axis than below the optical axis. With these measures, an almost logarithmic increase in luminance up to a maximum can be achieved. A suitable choice of the focal lengths can also be used to avoid illuminating areas above the maximum mentioned, so that the area outside the working area remains dark.

You can train the reflector of the headlight according to the invention as a faceted reflector, in which everyone Facet of reflected light is reflected in a different direction, with a large overlap of the reflected spiral images. Such a facet reflector can be constructed relatively easily. Due to the comparatively large overlap of the reflected helix images, uniform illumination is brought about by the headlight according to the invention.

Such uniform illumination can also be advantageously achieved in that the reflector is designed without steps and contours. Such a stepless design of the reflector is such. B. possible when designing the reflector surface as a free area outside the horizontal and vertical cutting planes through the optical axis. Such a stepless reflector offers the further advantage of uniform luminous field boundaries without any significant fraying.

It is particularly advantageous if the headlight is a worklight with two reflectors in a common housing and with a common lens, the light sources of which can be switched independently of one another. Due to the common housing and the common lens, the construction of such a work light is comparatively simple. The two reflectors, the light sources of which can be switched independently of one another, make it possible to illuminate different areas depending on the work to be carried out. That is, one of the two reflectors can, as previously described, be designed so that it essentially the close range, z. B. in front of a motor vehicle, illuminated to z. B. at a standstill of the motor vehicle to work in this close range with as uniform illumination as possible. However, drives z. B. the motor vehicle in the case of field work, it is advantageous if, in addition to this close range, a far range can be illuminated by the appropriately designed second reflector.

The two reflectors can be combined to form a common double reflector, the second reflector having an optical axis approximately parallel to the optical axis of the first reflector. This measure enables simple and inexpensive training of the worklight. Due to the approximated parallelism of the optical axes, a common maximum of the luminance in the illuminated area can be achieved.

The second reflector can be designed in such a way that it scatters the emerging light beam only slightly in a horizontal axis and in a vertical axis, the scattering being greater in the horizontal direction than in the vertical direction. This design of the second reflector corresponds to that of a typical high-beam headlight reflector. Because the first reflector can be switched on, good illumination of the close range is still possible in addition to the illumination of the far range.

In such a worklight, it is advantageous if the second light source is a second transverse spiral extending perpendicular to the optical axis and lying horizontally, if the second reflector in a horizontal section through the optical axis is an approximate elliptical section with a large distance between the focal points and if the second reflector is an approximate parabolic section in a vertical section through the optical axis. By designing the second light source as a transverse helix, the overall depth of the second reflector can be reduced together with the light source, as previously described. The required width of the second reflector can be reduced by the third approximated ellipse section. By choosing a large distance between the focal points of the third approximate elliptical section, the desired small width of the illuminated surface in the horizontal axis is ensured. By the second approximate Parabola section ensures the narrow width of the illuminated area in a vertical axis. In the described configuration of the second reflector together with the previously described configuration of the first reflector, it is possible to create a worklight which also enables a comparatively large luminous efficiency with a small construction volume. The resulting reflectors often have a greater height than width, so that an arrangement of the reflectors next to one another results in an almost square, common housing for the worklight.

Finally, it is advantageous if the first reflector and the second reflector are arranged pivotably in the housing of the worklight independently of one another. With this measure, the light fields generated by the two reflectors can be set independently of one another and depending on the work to be carried out in the illuminated area. This solution is made possible by the fact that the lens of the worklight is not optically corrective and that the lens does not influence the beam path sent by the reflectors through the lens.

Exemplary embodiments of the headlamp according to the invention are shown in the drawings and are explained in more detail below with reference to the drawings.

• Figur 1 eine Ansicht eines Reflektors eines erfindungsgemäßen Scheinwerfers längs der optischen Achse in den Reflektor hinein,
• Figur 2 einen horizontalen Schnitt durch die optische Achse des Reflektors gemäß Figur 1,
• Figur 3 einen vertikalen Schnitt durch die optische Achse des Reflektors gemäß Figur 1,
• Figur 4 einen zweiten Reflektor für Arbeitsscheinwerfer in einer Ansicht längs der optischen Achse in den Reflektor hinein,
• Figur 5 einen horizontalen Schnitt durch die optische Achse des Reflektors gemäß Figur 4,
• Figur 6 einen vertikalen Schnitt durch die optische Achse des Reflektors gemäß Figur 4,
• Figur 7 ein Diagramm mit Linien gleicher Lichtstärke des Reflektors gemäß Figur 1,
• Figur 8 ein Diagramm mit Linien gleicher Lichtstärke des Reflektors gemäß Figur 4,
• Figur 9 ein Diagramm mit Linien gleicher Lichtstärke, erzeugt durch den gleichzeitigen Betrieb der Reflektoren gemäß Figur 1 und 4,
• Figur 10 einen Reflektor gemäß Figur 1 und einen Reflektor gemäß Figur 4 zusammengefaßt zu einem gemeinsamen Doppelreflektor in einem Arbeitsscheinwerfer,
• Figur 11 einen Arbeitsscheinwerfer mit Reflektoren gemäß den Figuren 1 und 4, die getrennt voneinander ausgebildet und getrennt voneinander schwenkbar im Gehäuse gelagert sind,
• Figur 12 einen horizontalen Mittelschnitt durch den Arbeitsscheinwerfer gemäß Figur 11 und
• Figur 13 einen vertikalen Mittelschnitt durch den Arbeitsscheinwerfer gemäß Figur 11.

Show it

• 1 shows a view of a reflector of a headlight according to the invention along the optical axis into the reflector,
• FIG. 2 shows a horizontal section through the optical axis of the reflector according to FIG. 1,
• 3 shows a vertical section through the optical axis of the reflector according to FIG. 1,
• FIG. 4 shows a second reflector for worklights in a view along the optical axis into the reflector,
• 5 shows a horizontal section through the optical axis of the reflector according to FIG. 4,
• 6 shows a vertical section through the optical axis of the reflector according to FIG. 4,
• 7 shows a diagram with lines of the same light intensity of the reflector according to FIG. 1,
• FIG. 8 shows a diagram with lines of the same light intensity of the reflector according to FIG. 4,
• FIG. 9 shows a diagram with lines of the same light intensity, produced by the simultaneous operation of the reflectors according to FIGS. 1 and 4,
• 10 shows a reflector according to FIG. 1 and a reflector according to FIG. 4 combined to form a common double reflector in a work light, FIG.
• FIG. 11 shows a worklight with reflectors according to FIGS. 1 and 4, which are formed separately from one another and are pivotably mounted separately in the housing,
• 12 shows a horizontal central section through the worklight according to FIGS. 11 and
• 13 shows a vertical central section through the worklight according to FIG. 11.

In FIG. 1, a first reflector (1) has a first push-through opening (2) for a light source, the first incandescent filament of which is designed as a transverse filament and is identified in FIG. 1 by the reference symbol (3). The first incandescent filament (3) is arranged approximately in the optical axis of the first reflector (1), which is shown in FIG. 1 by the intersection of a horizontal plane (H) through the optical axis and a vertical plane (V) through the optical axis is formed. The first filament (3) extends in the horizontal plane (H) perpendicular to the optical axis.

FIG. 2 shows a section through the reflector according to FIG. 1 through a horizontal plane (H) through the optical axis. In addition to the first incandescent filament (3), two first approximate ellipse sections (4) with a small distance between the focal points can be seen.

A vertical section through the optical axis of the reflector according to FIG. 1 is shown in FIG. 3. In addition to the first incandescent filament (3), a first approximate parabola section below the horizontal plane (H) or the optical axis and a second approximate ellipse section (6) above the horizontal plane (H) or the optical axis can be seen.

What is striking about the first reflector according to FIGS. 1 to 3 is that the overall width of the reflector is less than its overall height and that the arrangement of the light source lies far outside the center of gravity of the reflector according to FIG. 1.

FIG. 4 shows a second reflector (7) of a worklight, which has a second push-through opening (8) for a second light source, the second filament (9) of which is designed as a transverse filament, extends in a horizontal plane (H) and perpendicular to it optical axis is arranged. Furthermore, a vertical plane (V) is represented by the optical axis in FIG.

FIG. 5 shows a horizontal section through the optical axis through the second reflector according to FIG. 4. One can see the position of the second filament (9) relative to the vertical plane (V) and a third approximate elliptical section (10), which characterizes the shape of the second reflector (7) in this section. The focal points of the third approximated ellipse section (10) are at a comparatively large distance.

FIG. 6 shows a vertical section through the optical axis through the second reflector (7) according to FIG. 4. The position of the second filament (9) relative to the horizontal plane (H) can also be seen here through the optical axis. In this section, the second reflector (7) according to FIG. 4 has a second approximated parabola section (11) and a third approximated parabola section (12). The approximate parabolic sections (11, 12) are preferably of identical design in order to ensure symmetry of the light reflected by the reflector (7) with respect to the horizontal plane (H) through the optical axis. Depending on the application of the second reflector (7), however, it is also possible to use different approximate parabolic sections (11, 12).

The diagram with lines of the same luminous intensity according to FIG. 7 shows the luminous intensity generated by the first reflector (1) on a 25 m screen. Here too, a horizontal plane (H) and a vertical plane (V) are entered through the optical axis in order to be able to represent the position of a field (13) of the highest light intensity relative to the optical axis. One can see the broad illumination along the horizontal plane (H), the logarithmic increase in light intensity up to field (13) of highest light intensity, starting from the bottom in FIG. 7 to field (13) and the comparatively rapid decrease in light intensity above field (13 ) in Figure 7.

FIG. 8 shows a diagram with fields of the same light intensity, generated by the second reflector (7) according to FIG. 4 on a fluorescent screen 25 m away. Here, too, a horizontal plane (H) of the optical axis and a vertical plane (V) of the optical axis are shown to show the position of a field (14) of maximum light intensity on the 25 m screen through the second reflector (7) relative to the optical axis to represent. It can be seen in FIG. 8 that the extension of the field (14) of maximum light intensity, produced by the second reflector (7), is comparatively small, both in the direction of the horizontal and in the direction of the vertical, so that the typical light intensity diagram of a high-beam headlight results.

FIG. 9 shows a diagram with fields of the same light intensity, generated when headlights are operated simultaneously with a first reflector (1) and a second reflector (7). Here too, a horizontal plane (H) and a vertical plane (V) are entered through the optical axis in order to determine the position of a field (15) of the highest luminance on a 25 m screen for the simultaneous operation of the reflectors (1) and (7) to represent. The light intensities of the spiral images reflected by the first reflector (1) and the second reflector (7) add up on the 25 m screen according to FIG. 9. The light intensity in the diagram according to FIG. 1 in the field (13) was approximately 9 lux and in the diagram according to Figure 8 in field (14) about 16 lux, the light intensity in the diagram of Figure 9 in field (15) is about 25 lux.

It can be seen in FIG. 9 that the contour of the field (15) of maximum light intensity is essentially determined by the second reflector (7), which is designed as a high-beam reflector. In addition, however, the uniform illumination of the apron area between the field (15) of the highest light intensity and z. B. the horizontal plane (H) recognizable in that the Field boundary lines of the same light intensity have an approximately equal distance.

In Figure 10, a work light has a headlight housing (17) which is closed by a lens (16). Inside the headlight housing (17) there is a common double reflector, which is formed from a first reflector (1) and a second reflector (7). Furthermore, the section through the worklight according to FIG. 10 shows the first push-through opening (2) of a first light source and the second push-through opening (8) of a second light source. The reflector parts (1, 7) are combined to form a common double reflector, in particular made of plastic, in such a way that the optical axes of the first reflector (1) and the second reflector (7) are arranged approximately parallel to one another. With this parallel arrangement of the optical axes, the diagram of the fields of the same luminance shown in FIG. 9 results. A worklight with a common double reflector according to FIG. 10 has the particular advantage that it can be produced simply and inexpensively, since only a few parts are required for its production.

FIGS. 11 to 13 show a worklight in which a first reflector (1) and a second reflector (7) are pivotably mounted in a worklight housing (17) independently of one another. This headlight housing (17) is covered by a lens (16) essentially without a light-correcting effect. FIGS. 12 and 13 also show the position of the first filament (3) and the second filament (9). In Figures 12 and 13 it can also be seen that the reflectors (1, 7) are gimbal-mounted in two planes, so that the reflectors (1, 7) can be pivoted independently of one another relative to the headlight housing (17) about two axes. This allows both the first reflector (1) and the second Reflector (7) for the individual illumination of different or overlapping work areas can be used.

Claims (9)

1. A headlamp, particularly for motor vehicles, with a light source disposed at the focus of a reflector (1), with a reflector which is fashioned in such a way that it illuminates a broad area and which in a vertical section through the optical axis of the reflector is approximately a parabolic section below the optical axis, and with a cover lens which is optically substantially non-correcting and which shrouds the light emission from the reflector, characterised in that the light source is a transverse spiral (3) disposed horizontally and extending perpendicularly to the optical axis of the reflector, that in a horizontal section through its optical axis the reflector (1) is a first approximately elliptical section (4) with a short focal distance, and that in a vertical section through its optical axis above the optical axis the reflector (1) is a second approximately elliptical section (6) with a large focal distance.
2. A headlamp according to claim 1, characterised in that the focal length of the reflector (1) is shorter above the optical axis than below the optical axis.
3. A headlamp according to claim 1, characterised in that the reflector (1) is a facetted reflector and that the light reflected from each facet is reflected in a different direction, with a large overlap of the reflected spiral-formers.
4. A headlamp according to claim 1, characterised in that the reflector (1) is fashioned without steps and free from contours.
5. A headlamp according to claim 1, characterised in that the headlamp is a working headlamp with two reflectors (1, 7) in a common housing (17) with a common cover lens (16), the light sources (3, 9) of which can be switched independently of each other.
6. A working headlamp according to claim 5, characterised in that the two reflectors (1, 7) are combined to form a common double reflector and that the second reflector (7) has an optical axis which is approximately parallel to the optical axis of the first reflector (1).
7. A working headlamp according to claim 5, characterised in that the second reflector (7) is fashioned in such a way that the emergent light beam only spreads slightly along a horizontal axis and along a vertical axis, wherein the spread in the horizontal direction is greater than that in the vertical direction.
8. A working headlamp according to claim 7, characterised in that the second light source is a second transverse spiral (9) disposed horizontally and extending perpendicularly to the optical axis, that in a horizontal section through its optical axis the second reflector (7) is an approximately elliptical section (10) with a large focal distance, and that in a vertical section through its optical axis the second reflector (7) is an approximately parabolic section (12).
9. A working headlamp according to claim 5, characterised in that the first reflector (1) and the second reflector (7) are disposed in a housing (17) so that they can swivel independently of each other.

Images