EP2511595B1 - Headlamp with low half-peak divergence - Google Patents

Description

The present invention relates to a headlamp, in particular a downlight, according to the preamble of the independent claims 1 and 7.

Such a headlamp comprises a reflector with a light inlet opening, a light exit opening and an optical axis. Furthermore, the headlamp comprises a light source arranged at the light inlet opening of the reflector and a tubular aperture. The aperture is disposed within the reflector and concentric with the optical axis and has a first end and a second end. The first end of the tubular aperture faces the light entrance opening of the reflector. The first end of the tubular aperture is thus closer to the light entrance aperture of the reflector than the second end of the tubular aperture.

In lighting technology, headlamps with a wide variety of light distributions are required. In particular, headlamps are used for various lighting purposes, which radiate a highly concentrated light with a nearly parallel beam path or merely lightly opening beam path. If an ideal symmetrical, ie circular, light distribution is desired, such headlights can be described by the so-called half-beam angle. This angle indicates at which angle apart from the optical axis of the headlamp half of the maximum light intensity is reached. The smaller this angle, the closer the headlamp focuses the light.

In order to be able to achieve very small half-beam angles, very deep reflectors are needed, ie reflectors whose dimensions along the optical axis are very large. These deep reflectors are required so that as little direct light as possible can escape from the lamp or light source outside the desired narrow light bundle. For an ideal headlight, the reflector would therefore have to be infinitely long. Usually, therefore, it is attempted to seal off the directly exiting light from the light source through either inner or outer shutters. As a result, a tightly focused headlight can be generated even with relatively short reflectors. Outer diaphragms have the disadvantage that in turn the length of the headlamp is increased by them. For aesthetic reasons, external blinds are therefore often undesirable. As described above, the invention is therefore based on a headlamp with inner tubular aperture. The obliquely emitted by the light source light, which would otherwise be emitted through the light exit opening of the reflector, is absorbed by the inner panel. Due to the finite axial extent of the tubular aperture not all unwanted light can be absorbed. It goes without saying that the bundling of the headlight is better, the longer the reflector and aperture are made.

While the bundling of the headlight of such known from the prior art headlight is relatively good even with relatively short reflectors or short overall length of the headlamp, the luminous efficacy and thus the efficiency of such headlights is not optimal, as a significant part of the light emitted from the light source Light is absorbed through the tubular aperture.

From the prior art, it is also known to set up on the light source a light guide, which plays the function of bundling. Such a system is for example off DE 10340039 B4 known. The light source shown there, an LED, is at least partially enclosed by a light guide body. The light guide is solid and made of transparent plastic. In a central region of the optical waveguide around the optical axis of the system, the light exit surface of the optical waveguide is convex, so that the obliquely emitted by the LED light is aligned almost parallel. Outside this central region, the light exit surface of the light guide body is conical. The outer shape of the optical waveguide, on the other hand, corresponds to the shape of a parabolic reflector and is embodied such that a total reflection of the light emitted by the light source takes place on this lateral surface. The light is therefore deflected at this lateral surface obliquely in the direction of the optical axis and also diffracted at the exit from the conical light exit surface to a parallel beam path.

Spotlights with solid light guide, which is based on a similar principle, are also known from DE 102004004772 B4 . US 6547423 B2 and WO 2006/040291 A2 ,

While the bundling effect of this known from the prior art massive light guide can be relatively good depending on the configuration, such light guide are relatively difficult and expensive to produce. The heavy weight due to the massive Therefore, the design of the light-conducting body generally limits the use to small and very small radiators, whereas the use of solid light-conducting bodies in larger headlamps usually ceases due to the large weight and the high material costs. In addition, such light guide are relatively inflexible, as far as the light source used. Such massive light guide are usually sprayed directly on LEDs.

The US 2010/0254128 A1 discloses a radiator equipped with LEDs of different colors. The spotlight has an outer reflector, in whose focal point an inner reflector is arranged. The light emitted by the LEDs light is passed through a tubular light guide to the inner reflector, reflected there, and finally emitted from the outer reflector through the light exit opening of the radiator.

It is an object of the present invention to provide a headlamp of the type mentioned with low half-angle angle and improved efficiency. The headlight according to the invention should also be easy and inexpensive to manufacture.

The object is achieved by the features of independent claim 1. Accordingly, then an inventive solution to the problem, when a arranged in the diaphragm converging lens is provided, whose optical axis coincides with the optical axis of the reflector.

By the converging lens, a large part of the light emitted by the light source, which would be absorbed in headlamps of the type mentioned on the inside of the tubular aperture, be bundled so that it leaves the tubular aperture as a focused spotlight. As a result, far less light is absorbed by the diaphragm compared to the known from the prior art headlamps of the type mentioned. Thus, the light emitted by the light source can be better utilized, which significantly increases the efficiency of the headlamp according to the invention over that of the known from the prior art headlights. In addition, the bundling lens also improves the focusing of the headlight. The headlight according to the invention can be made extremely inexpensive and easy.

The object is further achieved by the features of independent claim 7. Accordingly, even if a solution according to the invention is the task, if a arranged in the aperture bundling additional reflector is provided, the optical axis coincides with the optical axis of the reflector. The above-mentioned advantages of a headlight according to the invention with a converging lens are also achieved when using an additional reflector. Compared to a condenser lens offers the alternative inventive solution with additional reflector the advantage of an extremely lightweight design. Also, the headlamp invention with additional reflector is very inexpensive to manufacture.

Further embodiments of the present invention are the subject of the dependent claims.

The following embodiments relate to the inventive solution with converging lens.

In a particularly preferred embodiment of the present invention, the converging lens is arranged at the first end of the diaphragm. The first end of the aperture is along the optical axis of the headlamp or reflector at some distance from the light source, but the first end of the aperture is closer to the light source than the second end. When the condenser lens is disposed at the first end of the aperture, much of the light passing through the aperture can be diffracted such that it leaves the aperture as collimated spotlight. The arrangement of the converging lens at the first end of the shutter thus prevents a significant portion of the light from being absorbed by the shutter. By this arrangement, therefore, a very good efficiency is achieved.

It has proven to be particularly advantageous if the converging lens is made plano-convex, with the flat side of the condenser lens facing the light source. As a result, the effective light output is further improved.

It is particularly advantageous if the plane side of the converging lens terminates with the first end of the diaphragm. This ensures on the one hand a simple installation and on the other hand a high efficiency.

In a further particularly preferred embodiment of the present invention, the refractive power of the condenser lens is dimensioned such that the beam path of the light passing through the aperture of the light source corresponds in its extension transverse to the optical axis of the inner contour of the aperture. As a result, a very high light output and thus a high efficiency is achieved.

In a further particularly preferred embodiment of the present invention, the converging lens is arranged at a distance from the light source, which corresponds to the focal length of the converging lens. As a result, at least a large part of the light emitted by the light source can be converted by the converging lens into a nearly parallel beam path.

The following embodiments relate to the inventive solution with additional reflector.

In a particularly preferred embodiment of the present invention, the auxiliary reflector is arranged at the first end of the diaphragm. The first end of the aperture is along the optical axis of the headlamp or reflector at some distance from the light source, but the first end of the aperture is closer to the light source than the second end. If the auxiliary reflector is arranged at the first end of the diaphragm, a large part of the light entering the diaphragm can be reflected by the additional reflector in such a way that it leaves the diaphragm as focused headlight light. The arrangement of the additional reflector at the first end of the shutter thus prevents a considerable portion of the light from being absorbed by the shutter. By this arrangement, therefore, a very good efficiency is achieved.

In a further preferred embodiment of the present invention, the additional reflector is designed as a parabolic reflector. This achieves a very good bundling effect.

In a further particularly preferred embodiment of the present invention, the additional reflector comprises a focal point, wherein the light source is located in the focal point of the additional reflector. Since the light source has a finite extent, it is to be understood that the light center of gravity of the light source should be in focus. Thus, much of the light emitted by the light source can be effectively used. The efficiency is particularly high in this case. The following embodiments relate both to the solution according to the invention with additional reflector and to the solution according to the invention with condenser lens.

According to a further preferred embodiment of the present invention it is provided that the tubular diaphragm is cylindrical. This shape of the aperture is particularly suitable for a strong focusing headlamp with extremely low half-beam angle and high efficiency.

In a further particularly preferred embodiment of the present invention, the diaphragm is provided on its outer, the reflector-facing side with a light-absorbing coating. As a result, unwanted scattered light of the outer beam path between the reflector and diaphragm is optimally absorbed on the outer side of the diaphragm. As a result, extremely low half-angle can be achieved.

In a further particularly preferred embodiment of the present invention, the diaphragm is also provided internally with a light-absorbing coating. As a result, unwanted scattered light of the inner beam path, which can not be optimally bundled by the converging lens, in particular due to the extension of the light source transversely to the optical axis, reliably absorbed. This also improves the bundling of the headlight light.

According to a further preferred embodiment of the present invention, the light source is an LED light source. With an LED as a light source, the optical properties of the headlight according to the invention or its arrangement can be used optimally.

In the following, embodiments of the present invention will be explained in more detail with reference to drawings.

Figur 1:

Eine Schrägansicht eines Längsschnitts eines erfindungsgemäßen Scheinwerfers mit Sammellinse,

Figur 2:

Den Längsschnitt aus Figur 1 in der Draufsicht mit Verdeutlichung des Strahlengangs, und

Figur 3:

Einen Längsschnitt eines erfindungsgemäßen Scheinwerfers mit Zusatzreflektor.

Show it:

FIG. 1 :

An oblique view of a longitudinal section of a headlamp according to the invention with a converging lens,

FIG. 2 :

The longitudinal section FIG. 1 in the plan view with clarification of the beam path, and

FIG. 3 :

A longitudinal section of a headlamp according to the invention with additional reflector.

For the following statements applies that the same parts are designated by the same reference numerals.

FIG. 1 shows an oblique view of a headlamp 1 according to the invention, wherein the headlamp 1 is shown cut lengthwise. As the light source of the headlamp 1 is an LED 6, which is located in the light entrance opening 3 of the parabolic reflector 2. The optical axis of the parabolic reflector 2 is designated by the reference numeral 5. At the light source 6 and the light entrance opening 3 opposite end of the reflector 2 is the light exit opening 4 of the reflector 2. The LED 6 is located in the focal point of the parabolic reflector. 2

Within the reflector and concentric with this arranged a tubular cylindrical aperture 7 is provided. The diaphragm 7 is held by suitable struts 11 concentric with the reflector 2 and its optical axis 5. The struts 11 extend between the reflector and the diaphragm and, as in the case shown, can be designed, for example, as radially extending struts. However, it is also possible to perform the struts parallel to the optical axis 5, in which case they are connected, so to speak, as an extension of the cylindrical aperture 7 with the lower end of the reflector at the light inlet opening 3.

In the presentation of the FIG. 1 is at the lower first end 8 of the tubular aperture 7, a plano-convex converging lens 10 is arranged, the plane side with the first end 8 of the tubular aperture 7 terminates. The distance of the converging lens 10 from the LED 6 and the refractive power of the converging lens 10 are dimensioned such that the LED 6 is located at the focal point of the converging lens 10. The plano-convex converging lens 10 is bordered with its edge in the cylindrical tubular aperture 7. The second end 9 of the tubular aperture 7 terminates for aesthetic reasons with the light exit opening 4 of the reflector 2 from. To improve the bundling effect, however, it can also be provided that the tubular diaphragm 7 protrudes beyond the light exit opening 4 of the reflector 2. This version may be desired for aesthetic reasons. Since the tubular diaphragm 7 is arranged concentrically to the reflector 2, the optical axis of the converging lens 10 coincides with the optical axis of the reflector.

In FIG. 2 the effect of the optical system of the headlamp 1 according to the invention is illustrated. The light emitted by the LED 6 is divided into an inner beam path 12. 1, 12. 2 and an outer beam path 13. The beam path 12. 1 widening by the LED 6 is converted by the convergent lens 10 into a nearly parallel beam path 12. On the way between the converging lens 10 and the the second end 9 and the light exit opening 4, a large part of the undesired obliquely emitted to the optical axis 5 light is absorbed on the inner wall of the tubular aperture 7. The inner wall of the tubular diaphragm 7 is provided for this purpose with a light-absorbing coating. The outer beam path 13 is in FIG. 2 symbolized by the rays 13.1, 13.2 and 13.3. On the inner wall of the parabolic reflector 2, the light component of the light emitted by the LED 6, which does not enter the converging lens 10 or the tubular diaphragm 7, but at the lower first end 8 of the tubular diaphragm passes, reflected and almost parallel to the optical axis. 5 radiated. As is clear from the light beam 13.1, the light emitted by the LED 6 can not escape directly through the light exit opening 4 of the parabolic reflector 2. All light of the outer beam path 13 is therefore reflected on the inner wall of the reflector 2. In order to avoid the escape of undesired scattered light, the tubular diaphragm 7 is also provided on the outside with an absorbent coating. The light-absorbing coating consists of a deep black matt finish both inside and out.

FIG. 3 shows a longitudinal section of a headlight according to the invention with additional reflector 14. The headlight 1 is substantially the same structure as the headlight from the Figures 1 and 2 , wherein instead of the converging lens, an additional reflector 14 is used. This is, as well as the condenser lens in the Figures 1 and 2 illustrated embodiment, arranged at the first end 8 of the tubular aperture 7, so that the light inlet opening 15 of the additional reflector 14 terminates with the first end 8 of the tubular aperture 7. The additional reflector 14 is designed as a parabolic reflector, and widens along the optical axis 5, so that the light exit opening 16 of the additional reflector 14 corresponds in diameter to the diameter of the tubular aperture 7. The additional reflector 14 designed as a parabolic reflector is designed in such a way that the light source 6 is at its focal point.

In the inventive headlight 1 off FIG. 3 results in the same outer beam path 13 as in the embodiment of the Figures 1 and 2 , The inner beam path 12.1 is in accordance with the inventive headlight Fig. 3 in a bundled beam path 12.2, but here by reflection of the emitted light from the light source 6 on the wall of the reflector 14 illustrates the effect of the additional reflector 14 on the basis of the light beam 12.3, starting from the LED 6 obliquely impinges on the inner wall of the additional reflector 14 and is reflected there to a nearly paraxial beam. Ideally, the focal point of the main reflector 2 and the focal point of the additional reflector 14 coincide, namely in the location of the light source or its light center.

It is expressly pointed out that the headlights according to the invention are also suitable for light sources other than the LED 6 shown.

Claims (14)

1. A floodlight (1), in particular a downlight, with a reflector (2) with a light inlet opening (3), a light outlet opening (4) and an optical axis (5), a light source (6) arranged on the light inlet opening (3), and with a tubular shield (7), wherein the shield (7) is arranged inside the reflector (2) and concentrically with the optical axis (5) and has a first end (8) and a second end (9), wherein the first end (8) faces the light inlet opening (3) of the reflector (2), characterized in that a converging lens (10), which is arranged in the shield (7) and the optical axis of which coincides with the optical axis (5) of the reflector (2), is further provided.
2. A floodlight (1) according to Claim 1, characterized in that the converging lens (10) is arranged at the first end (8) of the shield (7).
3. A floodlight (1) according to one of Claims 1 or 2, characterized in that the converging lens (10) is made plano-convex, wherein the plane side of the converging lens (10) faces the light source (6).
4. A floodlight (1) according to Claim 3, characterized in that the plane side of the converging lens (10) terminates with the first end (8) of the shield (7).
5. A floodlight (1) according to any one of Claims 1 to 4, characterized in that the refractive power of the converging lens (10) is designed to be such that the beam path (12.2) of the light of the light source (6) passing through the shield (7) corresponds in the extension thereof transverse to the optical axis (5) to the internal contour of the shield (7).
6. A floodlight (1) according to any one of Claims 1 to 5, characterized in that the converging lens (10) is arranged at a distance from the light source (6) which corresponds to the focal length of the converging lens (10).
7. A floodlight (1), in particular a downlight, with a reflector (2) with a light inlet opening (3), a light outlet opening (4) and an optical axis (5), a light source (6) arranged on the light inlet opening (3), and with a tubular shield (7), wherein the shield (7) is arranged inside the reflector (2) and concentrically with the optical axis (5) and has a first end (8) and a second end (9), wherein the first end (8) faces the light inlet opening (3) of the reflector (2), characterized in that a bundling additional reflector (14), which is arranged in the shield (7) and the optical axis of which coincides with the optical axis (5) of the reflector (2), is further provided.
8. A floodlight (1) according to Claim 7, characterized in that the additional reflector (14) is arranged at the first end (8) of the shield (7).
9. A floodlight according to one of Claims 7 or 8, characterized in that the additional reflector (14) is designed in the form of a parabolic reflector.
10. A floodlight according to any one of Claims 7 to 9, characterized in that the additional reflector (14) has a focal point, wherein the light source (6) is situated at the focal point of the additional reflector (14).
11. A floodlight (1) according to any one of Claims 1 to 10, characterized in that the tubular shield (7) is made cylindrical.
12. A floodlight (1) according to any one of Claims 1 to 11, characterized in that the shield (7) is provided on the outer side thereof facing the reflector (2) with a light-absorbing coating.
13. A floodlight (1) according to any one of Claims 1 to 12, characterized in that the shield (7) is provided on the inside with a light-absorbing coating.
14. A floodlight (1) according to any one of Claims 1 to 13, characterized in that the light source (6) is an LED light source.

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