DE102016120743A1 - lighting unit - Google Patents

Abstract

The invention relates to a lighting unit (1) having at least one primary light source (2) emitting primary light (4), a converter (3) receiving the primary light (4) received by the primary light source in a secondary light (5) different in wavelength from the primary light. converts and at least one main reflector (6), which together with an output filter (62) delimits a cavity (11) which has a focal point (7) in which the distance from the main reflector (6) arranged converter (3) is located, and which directs the secondary light (5) emanating from the converter (3) to the output filter (62), which is more transparent to secondary light (5) than to primary light (5), the output filter (62) stronger than secondary light (5) is reflected and the output filter (62) is positioned such that the primary light (4) reflected thereon by a single reflection at the main reflector (6) to the converter (3) is traceable.

Description

The present invention relates to a lighting unit with at least one primary light source, a converter, and at least one main reflector. The main reflector has a focal point and the converter is located at the focal point.

Lighting units, as well as various lighting control systems, have become indispensable in almost all areas of life. In recent years there has been a clear trend towards the most efficient systems possible. On the one hand, this trend follows the idea of achieving the highest possible energy densities and the highest possible luminosity, on the other hand ensuring the highest possible energy efficiency. Also in terms of manufacturing effort and the most efficient installation of the systems provided, there is a constant need for improvement in the context of cost optimization.

For example, the shows DE 10 2014 202 863 A1 a lighting device in which the light of a primary light source in the form of a semiconductor light source is used, for example, to form part of a vehicle lighting. It should be considered disadvantageous that the light of the primary light source is first passed through a light guide over a first portion of a reflector to a converting element. The emitting end of the light guide is arranged at the focal point of the first portion of this reflector. A converting element is arranged in a second focal point of the reflector. The light converted in this converting element is directed to a corresponding further reflector, as is well known in particular in connection with vehicle headlamps. Even after the conversion, the secondary light formed thereby still has portions of the primary light. In order to feed these primary light components to the converting element again, a further subarea of the reflector is defined. This in turn, for renewed reflection, to align with respect to its focal point corresponding to the converting element. The structure thus shows a multiple deflection of the light, until ultimately approximately parallel directed, converted light can be emitted.

As just described, a correspondingly accurate positioning of the individual components, for example the positioning in corresponding focal points, is necessary. Only in this way can the perfect interaction of the individual optical components be guaranteed. Basically, therefore, it is a relatively complicated structure. Compliance with appropriate manufacturing tolerances is associated with high production costs. With increasing number of components also corresponding thermal influences and their effects play an increasing role. This comes into play in particular with consideration of the most varied materials and their different coefficients of expansion.

Depending on the type of primary light source used, it may be undesirable for primary light to exit the illumination device. Reason can be, for example, the harmful effect of the primary light on the human retina. This is called, for example, the US 2011/0148280 A1 Laser radiation as primary light. In order to prevent leakage of laser radiation from the illumination device, a cover blocking the laser radiation is provided

In the same way shows the US 2011/0157865 an absorber, which prevents the exit of primary light from the lighting unit.

The present invention is therefore based on the object to provide a lighting unit with the highest possible energy efficiency, minimal component complexity and the simplest possible structure.

This object is achieved according to the present invention in that an output filter is provided which is at least partially reflective for primary light and permeable to secondary light, wherein the output filter is positioned so that the primary light reflected thereon can be focused on the main reflector in focus. This results in a forced, repeated interaction of the primary light with the converter due to the, with respect to the primary light, reflective property of the output filter. In this way it can be ensured that a large part of the primary light emitted by the primary light source, which is reflected at the output filter, is converted into secondary light. In this way, the efficiency or the efficiency can be increased. In this case, the output filter can advantageously also be designed such that it completely reflects the primary light.

To return the primary light components in the converter, according to the invention, the existing main reflector is used with its associated focus. This, in turn, the particularly simple structure of the lighting unit according to the invention can be seen.

In one embodiment, it is provided that the main reflector has a parabolic basic shape or a parabolic subregion and a spherical subregion. Depending on Shaping can thus be ensured a predetermined propagation direction of the mixture of converted secondary light and unconverted Primärlichtanteilen. The combination of parabolic and spherical sub-range allows targeted beam guidance if given if other optical elements are used.

In a further embodiment, at least one light-guiding element is provided. The use of a light-conducting element makes it possible to direct those portions of the secondary light, which are not emitted by the converter in the direction of the main reflector, also to the output filter. Depending on the light-guiding element used, the effect used in this case may include refraction or reflection, for example, although this should not be considered restrictive.

Further, in one embodiment, the light-guiding element is designed as an optical lens or reflector. Depending on the position of the corresponding light guide, a desired beam guidance is made possible by its selection.

The at least one light-guiding element can be arranged, for example, directly on the converter. Direct arrangement of the light-guiding element on the converter makes construction considerably easier, since no further mounting elements, such as lens holders or the like, are necessary for accurate positioning. In this way, the structure is considerably simplified.

The reflector may be designed to be reflective both for primary light emitted by the primary light source and for converted secondary light formed by the converter. In this way, on the one hand secondary light is deflected by the reflector, for example to the main reflector. On the other hand, not yet converted primary light, at least partially redirected by the converter and optionally converted in this renewal passage in secondary light.

In a further embodiment, it is provided that the primary light source of the illumination unit includes at least one homogenization element. Since many light sources emit light with an inhomogeneous intensity distribution, the homogenization element can be used to form the most homogeneous possible intensity distribution.

The homogenizing element may be formed by an optical fiber having a polygonal cross-section, for example by an optical fiber having a rectangular cross-section. This is particularly advantageous if the primary light source emits primary light with a rectangular steel mold and ultimately secondary light with a rectangular beam shape is to be emitted by the lighting unit. A further beam forming is not necessary or only to a small extent necessary.

The lighting unit may also include a cooling device. It is provided that at least the converter, at least partially, with the cooling device is thermally in contact. Furthermore, the cooling device can be permeable to both primary light and converted light. In particular, at the converter, by which primary light is largely converted into converted light, a part of the introduced light energy is converted into heat. In order to prevent a temperature-induced change in the properties of the converter, the cooling device is provided. If this is permeable to both primary and secondary light, the propagation of light will not be adversely affected by it.

The cooling device may be made, at least in part, of sapphire glass. Sapphire crystal is particularly suitable for this purpose because of its high thermal conductivity and its high light transmission in the optical wavelength range. In a further embodiment, the primary light source supplies the primary light to the converter in the region of the cavity via an optical free-jet region. This has the advantage that the propagation of the light in the cavity of the main reflector is not hindered.

The lighting unit may in particular be part of the lighting of a mobile device. In this case, for example, a use in the field of motor vehicles, for example, for cars, trucks or single-track vehicles just as conceivable, as for means of transport in the air or water. Of course, the application for non-motorized vehicles or other mobile devices, such as portable headlights or the like in question. This list is by no means restrictive.

Likewise, the lighting unit may advantageously be part of the lighting of an immobile device. The use, for example in the context of room lighting in the living and working area, using the advantages already mentioned, is also conceivable.

• 1 eine Beleuchtungseinheit,
• 2 eine weitere Ausgestaltung der Beleuchtungseinheit,
• 3 ein abgewandeltes Ausführungsbeispiel,
• 4 ein weiteres abgewandeltes Ausführungsbeispiel.

Embodiments of the invention will be described below with reference to FIGS 1 to 4 which illustrate exemplary, schematic and non-limiting advantageous embodiments of the invention. Showing:

• 1 a lighting unit,
• 2 a further embodiment of the lighting unit,
• 3 a modified embodiment,
• 4 another modified embodiment.

1 shows, in a schematic way, a lighting unit 1 , The lighting unit 1 includes at least one primary light source 2 for the emission of primary light 4 , Of course, any light source as a primary light source 1 Find application. At least one laser light emitting primary light source is advantageous 2 for use. This can be formed for example by a laser diode. The operation of this, based on a pn junction, bulbs is well known, so why will not be discussed in more detail below. Their monochromatic, high-energy light, in a known manner, particularly well suited for transport over other routes. For at least partial conversion of the from the primary light source 2 emitted, for example, blue primary light 4 , in converted secondary light 5 , is a converter 3 intended. The converted secondary light 5 is then subsequently at least a main reflector 6 directed. The main reflector 6 is designed as a concave concave mirror, for example as a paraboloid, which forms a cavity 11 and a focal point 7 Further, it is provided that the converter 3 in the spotlight 7 of the main reflector 6 is arranged. In this way, that can be done by the converter 3 emitted, converted secondary light 5 without the need for further diversion, from the main reflector 6 to an output filter 62 be led or led.

In 1 and all others 2 to 4 are the light beam patterns of primary light 4 converted secondary light 5 and from the lighting unit 12 leaked output light 12 and their reflections are shown in the form of arrows or double arrows.

As already mentioned, the converter converts 3 the primary light incident on him 4 in converted secondary light 5 with, compared to the primary light 4 , larger wavelength around. For example, before mentioned blue primary light 4 , for example, can convert to yellow or orange converted secondary light 5 respectively. The mentioned colors of primary light 4 and converted secondary light 5 are of course to be regarded as exemplary and not restrictive.

A just mentioned converter 3 , which allows a corresponding conversion of light, is also well known. Such converters usually use the photoluminescent effect of corresponding chemical elements or rare earths. As in the 1 to 4 shown only schematically, passes through the primary light 4 on the way from the primary light source 2 to the converter an optical free jet area 41 , This is to be understood that between primary light source 2 and converter 3 along the optical axis of the primary light source 2 emitted primary light beam no optical elements are arranged, which cause a deflection or change of the optical axis of the primary light beam, in particular that there are arranged no correspondingly shaped reflectors. An optionally closer to the primary light source 2 as the converter 2 arranged, in 1 not shown homogenizing element for beam shaping of the primary light beam 42 , as part of the primary light source 2 regarded as even after such a homogenizing element only primary light 4 is emitted.

At the in 1 illustrated embodiment is the primary light source 2 outside of the main reflector 6 formed cavity 11 arranged. This offers the advantage that the light paths of itself in the cavity 11 spreading light are not obstructed.

In addition, it is also possible that the primary light source 2 directly on the converter 3 is arranged. Also includes the immediate arrangement of the converter 3 at the primary light source 2 , a joint to their connection is not enough. By way of example only and not by way of limitation, an adhesive bond or comparable is mentioned here.

It should be noted that due to reflection and scattering at the converter 3 , from the converter 3 not just converted secondary light 5 but also unconverted primary light 4 , In this respect, the conversion of the primary light takes place 4 only partially. That of the converter 3 emitted light is therefore a multispectral mixture of converted secondary light 5 and unconverted portions of the primary light 4 , Without further action, this would be done with said proportions of primary light 4 and secondary light 5 the lighting unit 1 as output light 12 leave.

According to the invention, and as in the 1 to 4 shown only schematically, is an output filter 62 provided, which for primary light 4 at least partially reflective and for secondary light 5 is permeable. In particular, the transmission coefficient of the output filter is at normal incidence of light 62 for secondary light 5 greater than the transmission coefficient of the output filter 62 for primary light 4 and the reflection coefficient of the output filter 62 for primary light is greater than the reflection coefficient of the output filter 62 for secondary light. Further, the output filter 62 positioned so that the primary light reflected thereon 4 over the main reflector 6 in the spotlight 7 is focusable.

Here is the output filter 62 formed by a dichroic mirror or a dichroic divider. Due to a corresponding coating, dichroic mirrors allow the transmission of light of a certain wavelength range and the reflection of light of a different wavelength range. The dichroic mirror is thus used as a wavelength-selective component. However, it is provided that light in that wavelength range which is reflected is not reflected 100%. This results in at least part of this light, the output filter 62 can happen. By way of example, it should be mentioned that, for example, 70% of the primary light 4 at the output filter 62 is reflected. With appropriate selection of the for the output filter 62 used dichroic mirror is thus the despite conversion still existing proportion of primary light 4 at least partially hindered the lighting unit 1 to leave. Depending on the desired wavelength range or color range, through which the output light 12 should be formed, the proportion of primary light 4 , which can pass the output filter, selected. The previously stated proportion of the reflected primary light 4 is therefore by no means restrictive.

Because of, for the primary light 4 at least partially reflective properties of the output filter 62 and its corresponding positioning, according to the invention, the reflected primary light 4 again the converter 3 fed. This is in the 1 to 4 indicated by the double arrows in the light beam path.

It can thus be ensured that the majority of that of the primary light source 2 emitted primary light 4 , which from the output filter 62 is reflected, converted accordingly. In this way, a corresponding increase in efficiency or efficiency can be achieved.

It should be noted in particular that no additional reflector is necessary by the structure according to the invention to that of the output filter 62 reflected primary light 4 repeated to the converter 3 supply. In this way is also only a single focus 7 to be considered in the structure. The disadvantage of the prior art, referred to at the outset, is thus eliminated by the present invention. As a result, the simple structure and the low component complexity in the present invention is repeatedly illustrated.

As in 2 schematically shown, this has the main reflector 6 a parabolic basic shape or a parabolic subregion 8th and a spherical section 9 on. On the part of the construction is only to ensure that the converter 3 in the spotlight 7 of the main reflector 6 is positioned. This main reflector 6 forms, for example, a reflector of a headlamp or a lighting fixture for a variety of areas.

It can be seen from the structure described that it is the illumination unit according to the invention 1 is a greatly reduced, simple as possible construction with minimal component complexity.

As already out 1 is traceable, not all, from the converter 3 delivered parts of the converted light 5 and possible contained primary light components 4 through the main reflector 6 diverted or diverted. As already mentioned, it comes thus for parts of the unconverted primary light 4 and the secondary light 5 to no interaction with the main reflector 6 , These proportions of converted light 5 are therefore not directed in the desired propagation direction and leave the lighting unit 1 therefore in the form of scattered light, so as light with undirected propagation direction.

2 , as well as the following 3 and 4 , showed that at least one light guide 61 is provided. This light guide 61 allows it, those just mentioned shares of secondary light 5 or the primary light 4 which is not on the main reflector 6 meet, also to steer accordingly. This can, with appropriate positioning of the second light guide 61 ensure that only light in the desired propagation direction, the lighting device 1 leaves. The effect used here can, depending on the light guide used 61 For example, refraction or reflection may be included, and this is not meant to be limiting.

With respect to the light guide 61 is in 2 a variant shown in which the light guide 61 as an optical lens 611 is executed. On the other hand shows 3 a variant in which the light-guiding element 61 as a reflector 612 is executed.

For example, as in 2 schematically illustrated, an optical lens 611 as a light-guiding element 61 used, those light components of the primary light 4 and the secondary light 5 , which refers to the exemplified optical lens 611 meet, directed by refraction on the surface in the corresponding desired propagation direction. This corresponds to the propagation direction in which the secondary light 5 also from the main reflector 6 is steered. As further, only exemplarily in 2 can be seen, the main reflector 6 a spherical section 9 exhibit. This can, for example, the steering of those portions of the secondary light 5 which only affect the light guide 61 especially in the lens 611 to meet.

As already mentioned, shows 3 in this context, a variant in which the light guide 61 as a reflector 612 is executed. The at least one, light guide 61 or the reflector 612 is directly at the converter 3 arranged. It should be noted that the immediate arrangement on the converter 3 not to that variant in which a reflector 612 as a light-guiding element 61 is provided is limited. Of course, also a corresponding optical lens 611 , contrary to the illustration in 2 , directly on the converter 3 be arranged. It should also be noted at this point that the immediate arrangement does not exclude a joint for the corresponding connection.

As in the 3 and 4 is indicated only schematically, is the reflector 612 both for, from the primary light source 2 emitted primary light 4 as well as, through the converter 3 formed, converted secondary light 5 reflective.

In this way, on the one hand, the secondary light 5 from the reflector 612 deflected, for example to the main reflector 6 , On the other hand, is not yet converted primary light 4 , at least partially again by the converter 3 steered and optionally in this re-passage in converted light 5 transformed.

Many light sources emit light with an inhomogeneous intensity distribution. In order to form the most homogeneous possible intensity distribution in the emission characteristic, an in 3 only schematically illustrated embodiment can be used. It is provided that the primary light source 2 the lighting unit 1 at least one homogenizing element 22 includes. In 3 is therefore the primary source of light 2 as a combination of a light source 21 and the homogenizing element 22 shown. As already mentioned, therefore, an optionally arranged homogenizing element is provided 22 for beam shaping, as part of the primary light source 2 to watch.

As a homogenizing element 22 For example, an optical fiber with a polygonal fiber cross section can be used. Homogenization takes place, for example, by multiple reflection within said optical fiber or within the homogenizing element 22 ,

The Polygonal Fiber Cross Section of the Homogenizing Element 22 can with regard to the shape of the primary light source 2 be chosen advantageous. For example, becomes the primary light source 2 formed by a, already mentioned, laser diode, which primary light 4 emitted with rectangular beam shape, and the homogenizing element 22 be formed by an optical fiber having a rectangular cross-section. In this way, losses are avoided, which would occur during the transformation of the beam shape, for example by means of suitable optical elements.

Contrary to the schematic representation in 3 , the conversion element can 22 directly on the converter 3 be arranged, eliminating the primary light 4 the converter is supplied in the just mentioned, for example rectangular beam shape. The same effect occurs when the converter 3 , seen in the direction of radiation, at least in the vicinity of the homogenization element 22 is arranged. In this case, the area in which the beam shape is still the geometry of the cross section of the homogenization element is to be regarded as the near zone 22 having. Otherwise, it is also possible to use a corresponding intermediate optics (not shown) or an optical fiber with a correspondingly advantageously selected fiber cross section around those originally from the primary light source 2 emitted beam shape on the converter 3 map.

By maintaining the beam shape, as already mentioned, losses can be avoided or at least minimized.

That of the converter 3 emitted secondary light 5 and unconverted primary light 4 is due to the reflection and scattering processes on the converter 3 no longer in the aforementioned beam shape, such as rectangular, submitted. However, if this should be advantageous in the application of the illumination unit, the corresponding beam shape can also be formed after the converter by means of a corresponding optical system.

Of course, the rectangular cross-section is merely exemplified as an advantageous embodiment and other geometries are not excluded.

4 shows schematically a structure in which the lighting unit 1 a cooling device 10 includes. In particular, at the converter 3 through which primary light 4 for the most part in secondary light 5 is transformed, a part of the introduced light energy is converted into heat. To a temperature change of the properties of the converter 3 To prevent, a cooling device is thus advantageously provided.

This is at least part of the converter 3 thermally in contact. The cooling device is advantageous both for primary light 4 as well as for secondary light 5 permeable. In particular, at least partially, sapphire crystal comes as Material for the cooling device 10 for use. This is for both primary light 4 as well as converted light 5 permeable. This has an understandable advantage that the propagation of the light, by the cooling device 10 not hindered. Due to the high light transmission of sapphire glass in the wavelength range of 300 nm to 5 microns and the high thermal conductivity is sapphire crystal as a cooling device 10 for the converter 3 particularly suitable.

Next is in 4 , also indicated only schematically, that also several primary light sources 2 can be used. It is only necessary to ensure that the primary light sources 2 the emitted primary light 4 without the use of further optical elements to the converter 3 submit.

A described lighting unit 1 can be advantageously part of the lighting of a mobile device. These include various vehicles, air, land and / or water as well as other devices such as flashlights, portable headlights and the like. Of course, this list is in no way limiting. Only the mobile character in the course of possible applications should be underlined.

Likewise, the lighting unit 1 Be part of the lighting of an immobile device. In this case, for example, the lighting inside and outside of buildings in question. Likewise, the use for the illumination of public spaces in connection with the use of street lighting, parks and the like is conceivable.

The lighting unit just described 1 Thus, it makes it possible to provide lighting for the most varied applications with the highest possible energy efficiency, minimum component expenditure and the simplest possible structure.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014202863 A1 [0003]
• US 2011/0148280 A1 [0005]
• US 2011/0157865 [0006]

Claims (13)

Lighting unit (1) comprising: - at least one primary light source (2) which emits primary light (4), - a converter (3) which converts the primary light (4) received by the primary light source into secondary light (5) different in wavelength from the primary light and - at least one main reflector (6) which, together with an output filter (62), defines a cavity (11) having a focal point (7) in the cavity (11) in which the converter spaced from the main reflector (6) (3), and which directs the secondary light (5) emanating from the converter (3) to the output filter (62) which is more transparent to the secondary light (5) than to the primary light (5), characterized in that - the output filter (62) Primary light (4) stronger than secondary light (5) reflected and that - the output filter (62) is positioned so that the primary light reflected thereon (4) by a single reflection at the main reflector (6) to the converter (3) bar is. Lighting unit (1) after Claim 1 , characterized in that the concave main reflector (6) has a parabolic basic shape or a parabolic subregion (8) and a spherical subregion (9). Lighting unit (1) after Claim 1 or 2 , characterized in that in the cavity between the converter (3) and output filter (62) at least one light-guiding element (61) is provided. Lighting unit (1) after Claim 3 , characterized in that the light-guiding element (61) is designed as an optical lens (611) or reflector (612). Lighting unit (1) after Claim 3 or 4 , characterized in that the at least one light-guiding element (61) is arranged directly on the converter (3). Lighting unit (1) after Claim 4 or 5 , characterized in that the reflector (612) is designed both for, from the primary light source (2) emitted primary light (4) and for secondary light (5) reflective. Lighting unit (1) according to one of Claims 1 to 6 , characterized in that the primary light source (2) of the lighting unit (1) includes at least one homogenizing element (22). Lighting unit (1) after Claim 7 , characterized in that the homogenizing element (22) is formed by an optical fiber with a polygonal cross-section. Lighting unit (1) after Claim 8 , characterized in that the homogenizing element (22) is formed by an optical fiber with a rectangular cross-section. Lighting unit (1) according to one of Claims 1 to 9 , characterized in that the lighting unit (1) includes a cooling device (10), which at least partially thermally contacted, at least the converter (3) and for both primary light (4) and secondary light (5) is permeable. Lighting unit (1) after Claim 10 , characterized in that the cooling device (10) is at least partially made of sapphire crystal. Lighting unit (1) according to one of Claims 1 to 11 , characterized in that the primary light source, the primary light (4) to the converter (3) in the region of the cavity (11) via an optical free jet area (41) supplies. Lighting unit (1) according to one of Claims 1 to 12 , characterized in that the lighting unit (1) is part of the lighting of a mobile or immobile device.

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