EP3169935A1

EP3169935A1 - Headlight with an led light source

Info

Publication number: EP3169935A1
Application number: EP15749992.2A
Authority: EP
Inventors: Erwin Melzner
Original assignee: Arnold and Richter Cine Technik GmbH and Co KG
Current assignee: Arnold and Richter Cine Technik GmbH and Co KG
Priority date: 2014-07-18
Filing date: 2015-07-20
Publication date: 2017-05-24
Also published as: DE202014103329U1; MX2017000744A; CA2955273A1; US20170167712A1; CN106716004A; KR20170039194A; WO2016009089A1

Abstract

The invention relates to a headlight with an LED light source which includes at least one light-emitting diode arranged on a circuit board and which is arranged in a housing that encloses the LED light source, said housing having at least one light outlet surface through which the light emitted by the LED light source exits. According to the invention, the housing encloses the LED light source in a liquid- or gas-tight manner and has at least one coolant inlet and coolant outlet for a liquid or gaseous coolant.

Description

ARNOLD & RICHTER CINE TECHNOLOGY

GmbH & Co. Betriebs KG

PO Box 40 01 49

80701 Munich

AR248WO

Headlamp with a LED light source

description

The invention relates to a headlamp with an LED light source according to the preamble of claim 1. The operation of LEDs as well as of electronic components such as processors, memory chips and the like is associated with a significant power loss, which is released in the form of heat. To reduce the size of LED light sources or electronic devices, however, the packing density of the LEDs or electronic components is steadily increased, so that a large amount of heat is emitted in a confined space, which leads to a deterioration in the function and life of the LEDs or electronic Components leads. However, these work more efficiently and have a longer life on the cooler they are operated. However, since the amount of heat given off by the LEDs and electronic components can not always be overcome by air cooling, liquid cooling systems are used for increased heat dissipation.

The most common form is the so-called single-phase indirect liquid cooling, in which the coolant does not touch the heat sources. Such systems are in the form of so-called. Recirculating air cooling systems, where the coolant to approximately the temperature of the ambient air can be cooled down, also available for personal computers as complete sets or in individual parts. They essentially consist of the following components:

a coolant reservoir or tank for the coolant,

a coolant pump for transporting the coolant,

- A radiator with fan through which the heat absorbed is dissipated to the ambient air and

- A cooler (for example, CPU cooler), which is flowed through by the coolant and must be mounted with the least possible thermal resistance to the heat-emitting component. The latter is also referred to as a cooling plate.

An alternative with higher heat output, which is mainly used in industry, is the so-called (single-phase) immersion cooling. In this case, the heat-emitting components are directly flowed around by a non-conductive coolant and give off their heat to the coolant. This eliminates two layers of material, namely the housing material of the cooling plate itself and the heat transfer agent, for example in the form of a thermal grease, which must be introduced between the cooling plate and the heat source to compensate for minor surface irregularities. This greatly reduces the thermal resistance between the heat source and the coolant, cools all surfaces, and operates more efficiently than indirect liquid cooling.

An even more efficient method is the so-called impact and spray cooling, in which the heat-emitting components are sprayed directly with the coolant.

Both indirect and direct cooling systems also have two-phase versions. In this case, one exploits the even higher heat output, which results from the phase transition of the coolant, for example during the evaporation of water. Such cooling systems are known, for example, under the designations boiling water cooling or evaporative cooling. If there is a requirement that the radiator or coolant must be cooled below the ambient air temperature, then a dual-circuit cooling system must be used. This also applies if the temperature of the cooling plate or the coolant must be precisely controlled. It is then usual to use a recooling system or a water exchange system. A recooling system has, in addition to the primary coolant circuit, a secondary refrigerant circuit. The refrigerant is cooled by the refrigerant as it passes through an evaporator. The refrigerant absorbs the heat energy, evaporates and is re-liquefied by means of a compressor and a condenser. During condensation, the heat is released via a radiator with fan to the ambient air.

In a water exchange system, the coolant from the primary circuit is passed through a heat exchanger where it is cooled by the colder operating water. The process water is supplied here from outside Shen.

In studio lighting and especially in professional movie lighting, there is a demand for very powerful LED headlamps similar to the "daylight headlamps" in use today.These headlamps have so-called halogen metal halide lamps with powers of 575W or more and luminous fluxes of 49,000 lm or more. The light spots of these bulbs, ie the light-generating plasmas are only a few millimeters in size, so that extremely high luminances are achieved.

When used as a "spotlight", cones with half-angles of 10 ° or less are often required, but optical laws require reflectors or lenses, which are larger the larger the light source and the smaller the half-beam angle To build compact and manageable LED spotlights requires more compact LED light sources than those available today, but these require special cooling above a certain power density, so in the field of professional lighting with LED light sources, there are a few indirect ones Water cooling is used to cool compact LED arrays with approximately 25 W to 100 W of power within LED headlamps.To this end, according to the schematic representation in FIGS. 17 to 20, an LED light source 1 soldered on a printed circuit board 2 on a Cooling plate 3 'mounted, which through inlets and outlets 31, 32 of cooling water through If the LED light source 1 is mounted in front of a stepped lens and movably mounted along the optical axis of an LED headlamp, this results in a simple focus on a wide range of less than 10 ° to over 60 ° focusable LED headlamps. Fig. 20 shows a schematic functional representation of such a cooling system according to the prior art. The LED light source 1 is thermally coupled to a cooling plate 3 'which is connected to a coolant line 8. The coolant line 8 is thermally coupled to produce a large heat-emitting surface with a heat sink 71, wherein a fan 70 generates a cooling air flow, which generates a cooling air flow directed toward the heat sink 71 for re-cooling the coolant flowing in the coolant line 8. The circulating air cooling device 7 furthermore has a coolant reservoir 72 for the coolant and a coolant pump 73 for generating a circulating coolant flow.

The power supply of the LED light source 1 via a power cable 14, which is connected to an electronic control, a power supply or ballast 12, which is connected via a power cord 13 to a power supply device.

A major disadvantage of the indirect water cooling described above is that the power density of the LED light source is limited by the thermal conductivity of the materials used of the printed circuit board receiving the LED light source and the cooling plate. Such a cooling system is no longer suitable for cooling compact LED light sources whose power density is above approximately 50 W / cm ² .

The present invention is therefore based on the object to provide a headlamp with an LED light source of the type mentioned, which allows a compact design, a high power density and high durability.

This object is achieved by the features of claim 1.

The solution according to the invention realizes a headlamp with a compact LED light source, which allows a high power density of, for example, more than about 50 W / cm ² without limiting the life or the optical properties of an LED headlamp, as arranged on a circuit board light emitting diodes in a liquid-tight or gas-tight enclosing housing, which has at least one light exit surface through which exits the light emitted from the LED light source, and on the walls has housing openings serving as a coolant inlet and coolant outlet for a liquid or gaseous coolant are formed.

Preferably, the coolant inlet and the coolant outlet for achieving an optimum flow through the housing and thus cooling the LED light source are diametrically opposite one another on the side walls of the housing between the printed circuit board and the light exit. surface arranged. Alternatively, however, a non-diametrical arrangement of the coolant inlet and the coolant outlet at the side, rear or front walls of the housing, possibly in conjunction with flow guide webs possible. Alternatively, the housing can surround both the LED light source and a cooling element connected to the printed circuit board, in particular consisting of cooling fins, so that a coolant flows around both the LED light source and the cooling element and the heat absorbed via a cooling system to the environment or emits to a heat receiving device.

As LEDs, ready-made light-emitting diodes ("packages") in ceramic or plastic housings can be used which are mounted on a printed circuit board Alternatively, LED chips or "dies" without housings can be used, which are "chip-on-board" LED chips and finished LEDs may be covered with an optically inactive material, such as silicon, or with an optically active material, such as a phosphor or applied to a substrate, such as "remote phosphor" technology, to support the cooling effect, it is advantageous to continue to use the LED light source to mount on a very good thermal conductivity PCB, in particular on a so-called "metal core printed circuit board" (MCPCB), which consists of a core of aluminum or Ku pfer, a very good thermally conductive dielectric and a copper overlay with soldering surfaces. Alternatively, a ceramic board with integrated metallic pads can be used. The cooling of the circuit board is advantageously carried out with a metallic cooling plate, which is flowed through by a cooling liquid and which is thermally coupled to the LED light source remote from the back of the circuit board.

In addition, to increase the cooling effect on the LED light source to the required level, it is necessary to bring the coolant directly into contact with the LED light source. The LED light source is therefore surrounded by a liquid-tight or gas-tight housing having one or more inlets and outlets for the coolant, which flows around the LED light source directly. Suitable coolants are preferably non-conductive and non-corrosive liquids with high heat capacity in question, such as fluorosurfactants or ultrapure water with anti-corrosive additives. In order to use the light of the LED light source optically, the housing is provided with a window made of glass, transparent optical plastic or the like, which is also tightly installed. The optical window may consist of a plane-parallel plate or of a structure with curved or stepped surfaces such as a lens, a lens array or a light mixing rod (taper), so that a certain beam shaping and / or color mixing is already performed at this point. Dynamic beamforming may be achieved through an optical window that is liquid-tight but movably disposed in front of the LED light source. The optical window can be coated with a phosphor according to the above-mentioned "remote phosphor" technology, which converts, for example, the light emitted by blue LEDs into white light.

The optical window, the surface and possibly the primary optics of the LED light source as well as the cooling liquid must also be matched with regard to their refractive index and their spectral transmission and spectral reflection to achieve the desired photometric result, such. to achieve a certain beam angle or a specific light output. Furthermore, it may be necessary to use other optical elements, e.g. Reflectors and diaphragms in the housing to install.

The LED light source itself is preferably surrounded by an inert liquid as a coolant with certain thermal and optical properties, while for cooling via the cooling plate usually water with suitable additives to prevent calcification and corrosion is used. In order to achieve an optimal cooling result under certain conditions, such. B. to achieve a maximum size, it may therefore be useful to build a two-stage cooling system, consisting of a primary circuit with water as the cooling medium, a secondary circuit with the suitable for cooling the LED light source cooling medium and a heat exchanger.

The cooling circuits for the cooling of the circuit board and for the cooling of the LED light source can also be combined in a cooling circuit and thus connected in series or in parallel, if in both circuits the same inert coolant is used. The light emitted by the LEDs changes depending on the temperature of the semiconductor layer. It is known that not only does the brightness of the LEDs decrease with increasing temperature, but also that the spectrum shifts so that the color location of a hot LED light source differs from the color location of the same but cold LED light source. To compensate for these effects, a multicolor LED light source with a temperature-controlled electronic control according to WO 2009/034060 can be constructed, with which the color locus is kept stable over the temperature with great accuracy.

If a liquid cooling system and in particular a recooling system or water exchange system is used, then it is also possible to stabilize the temperature of the LED light source by controlling the coolant temperature or the coolant flow so that control of the electronic control of the LEDs can be dispensed with. In a recirculating air cooling system, the fan (fan) can also be controlled so that the heat emission to the ambient air is controlled.

The effort for the hardware and software is greatly reduced in this way, since not every single color channel must be regulated, but only the coolant temperature or the coolant flow and possibly the speed of the fan on the radiator. Since the temperature of the coolant is usually in the range of about 40 - 60 ^, the LEDs are also exposed to a lower heat load and achieve a longer life.

In a particular embodiment, a mixed operation between the two control systems may be useful. If e.g. the cooling system is designed in a compact design for normal operation up to a certain ambient temperature, then it is possible to work up to this temperature with the coolant control and LED stabilization as described above. From this temperature can then use an intensive operation in which the color locus of the LEDs is stabilized by their electronic control.

Since the light emitted by the LED light source is radiated into the far field after passing at least one lens or a reflector and may possibly strike a large receiver surface (scene, actor or the like), it must also have a spatially and temporally homogeneous brightness. and color distribution. Therefore, static light spots, shadows or color spots as well as temporal fluctuations in brightness or color are generally permissible. This can only be achieved if the coolant itself is homogenous, ie has no suspended particles or density fluctuations, and if it is moved and heated in a controlled manner within the housing so that no optically active Density variations occur, which would lead to a whirling or flickering in the light field. It must also be avoided that the coolant already boils on the LEDs, since then - possibly even microscopically small - bubbles are formed, which deteriorate both the heat dissipation, as well as the light outcoupling. Therefore, a laminar flow with a small temperature difference between the coolant inlet and coolant outlet is desirable.

For heat dissipation, the cooling system has at least one recooling device with a coolant reservoir, a coolant pump, a heat sink, cooling fins or cooling fins and a fan.

Alternatively, the entire cooling system or a part of the heat exchanger may be formed as a heat-receiving cooling battery, which is flanged to the light source or to the coolant line, absorbs thermal energy for a limited time and then replaced, i. is replaced by a prepared for receiving heat energy cooling battery.

From a certain power loss, the weight, the size or the noise of the coolant pump and the cooling body or cooling fins or cooling fins blowing fans are so large that no manageable LED headlights can be built more. The limiting factor here is the heat transfer coefficient from the heat sink or the cooling fins or cooling fins to the ambient air. Therefore, a compromise between weight, size and volume is sought, which means in the case of professional studio and film headlights that the cooling system or the recooling device from coolant reservoir, coolant pump, cooling fins or cooling fins and fan no longer installed in the LED headlights, but is operated or installed outside of the LED headlight.

For headlamps used in fixed installations, such as In the television studio, a water exchange system consisting of a central cooling device and a central coolant distribution similar to a sprinkler extinguishing system can be installed. The LED headlamps require standardized coolant connections for entry and exit as well as an electronic and possibly software-technical interface for the control and regulation.

In mobile LED headlamps, such as LED headlights on the film set or events, the power supply for the LED headlights - which is provided today by a so-called. Ballast (ballast) - and the cooling system in accordance with another feature of the invention a common device installed. The combined supply and cooling system can then be detached from the LED headlight and from the front of the vehicle like a ballast possibly noise-sensitive environment. To the LED headlamp then lead the power supply lines, the cooling hoses and the interface for the control and regulation of the cooling system. For certain purposes, it is also useful to integrate the various functional units of the cooling system, such as the coolant reservoir or the coolant pump in various systems or devices. For example, a central cooling system can take over the dissipation of heat to the ambient air, while the LED headlights are equipped with only a coolant pump or an auxiliary pump and a heat exchanger. Also, a two-stage cooling system can be constructed so that the components of the re-cooling system are arranged outside of the LED headlamp, while, for example, the cooling plate and the secondary circuit are installed to save space in the LED headlights themselves.

The supply voltage, the electrical control signals or interfaces and the coolant hoses are advantageously combined in a single hybrid cable to facilitate handling.

If a larger number of LED headlights on a film set is needed and if the connected load and the quality of the existing power supply are not sufficient, generator vehicles are usually used for the supply. In this case, the generators provide the mains voltage with which the LED headlamps are operated directly or via their ballasts. For this application, it is advantageous to arrange a central cooling unit with a central coolant distribution and coolant control in the generator vehicle, to which the LED headlights are connected. Individual combined supply and cooling systems are thus not required in such a configuration and the existing ballasts or power supply units can continue to be operated. The generator vehicle thus provides the mains voltage supply and the coolant supply and / or refrigerant supply for all connected LED headlights. On the basis of exemplary embodiments illustrated in the drawing, the idea underlying the invention will be explained in more detail. Show it:

1 to 3 a side view, isometric view and a plan view of an LED light source with mounted on a cooled circuit board and surrounded by a liquid-tight housing and surrounded by an inert coolant around LED's; 4 to 6 different optical windows in the housing surrounding the LEDs in a section along the line AA of FIG. 3; 7 to 9 a side view, isometric view and plan view of an LED light source with a printed circuit board with LEDs mounted thereon and a housing surrounding a cooling plate, which is flowed through by a coolant flowing in a cooling circuit; 10 shows a longitudinal section through the LED light source along the line BB according to FIG.

9;

1 to 15 a schematic representation of a cooling circuit of an inert coolant flowing through a cooling plate, which is thermally coupled to a printed circuit board with LEDs mounted thereon, and / or flowing around the LEDs as well as being recooled in a recooling device;

Fig. 16 is a schematic representation of a cooling plate, which is thermally coupled to the LEDs receiving circuit board, flowing through the primary cooling circuit and connected via a heat exchanger to the primary cooling circuit, the mounted on the PCB LEDs secondary cooling circuit and

17 to 20 is a schematic representation of a cooling system according to the prior art with a coolant flowed through by a cooling plate, which is thermally coupled to a PCB receiving the LEDs.

1 to 6 in various views and in a longitudinal section shown first embodiment of a direct cooling mounted on a printed circuit board 2 LED light source 1 has a with a printed circuit board 2 thermally tightly coupled cooler 3, which of a coolant is flowed through, which is guided in a first coolant line 81, which is connected via a first coolant inlet 31 and a first coolant outlet 32 to the radiator 3. The heat absorbed by the coolant, as shown in FIGS. 1 to 15, is dissipated to the environment or to heat by means of a cooling system 7a to 7e. given direction, so that during operation of the LED light source 1, a substantially constant temperature on the circuit board 2 can be adjusted with the LEDs mounted thereon. The mounted as a finished light-emitting diodes in the ceramic or plastic housing on the circuit board 2 or alternatively mounted as LED chips without housing by means of "chip-on-board" technology on the circuit board 2 LEDs of the LED light source 1 are of a preferably flat, the Form of the LED light source 1 adapted, generally cuboidal or circular housing 4 surrounded, which is connected via a second coolant inlet 41 and a second coolant outlet 42 to a second coolant line 82 of a cooling system 7a to 7d as shown in FIG. 1 1 to 14, so that the cooling liquid guided in the first coolant line 81 flows directly around the LEDs of the LED light source 1. Via the cooling system 7a to 7d, the heat absorbed by the coolant is released to the environment or to a heat-absorbing device - Taking device in the form of a cooling battery 300 according to the schematic representation in Fig. 15 are flanged directly to the LED light source 1.

For emitting the light emitted by the LEDs of the LED light source 1, the surface of the wall of the housing 4 surrounding the LED light source 1 opposite the LED light source 1 has an optical window 5 which has different optical properties and, as shown in FIG. 4 of a plane-parallel glass or plastic plate 50 or a structure with curved or stepped surfaces such as a lens array 51 according to FIG. 5, a lens array, a diffusion plate 52 according to FIG. 6 or a light mixing rod, in order to carry out beam shaping and / or color mixing already at the optical window 5. In addition, dynamic beam shaping can be achieved by a liquid-tight, but movably arranged in front of the LED light source 1 optical window.

The second exemplary embodiment of an LED light source 1 shown in different views and in a longitudinal section in FIGS. 7 to 10 differs from the first exemplary embodiment described above with reference to FIGS. 1 to 6 and 11 and 12 in that the housing 40 is not only the mounted on a printed circuit board 2 LED light source 1, but also consisting of cooling fins, cooling pins or the like existing cooling element 30 so that guided in a first coolant line 81 and entering the housing 40 via the coolant inlet 41 and the coolant outlet 42nd The housing 40 leaving coolant flows around both the LED light source 1 and the cooling element 30 and delivers the absorbed heat via a cooling system 7 to the environment or to a heat receiving device.

The optical window 5 arranged in the emission direction of the LEDs in front of the LEDs 1 can be designed analogously to the illustrations of FIGS. 4 to 6 as a plane-parallel plate or as a lens, lens array or light mixing rod in order to carry out beam shaping and / or color mixing. In this embodiment too, dynamic beam shaping can be achieved by means of an optical window 5 which is liquid-tight but movably arranged in front of the LED light source 1. It can be coated with phosphor and thus fulfill the function of a "remote phosphor" light source.

The mounted on the circuit board 2 LEDs 1 are connected to a power cable 14 which is connected to an electronic control, a power supply or ballast 12. The control unit, power supply or ballast 12 is connected via a power cable 13 to a voltage source.

1 to 16 are intended to explain various cooling systems 7a to 7e, but the type of cooling and recooling is not limited to the illustrated systems.

The circulating-air cooling system 7a shown in FIG. 11 includes a cooling body 71 thermally coupled to the coolant lines 81, 82, a fan 70 for generating a cooling air flow directed onto the heat sink 71, and a coolant reservoir or tank 72 for the coolant and a coolant pump 73 for generating a circulating coolant flow.

12 shows a schematic representation of a cooling system designed as a re-cooling system 7b with primary coolant circuit and secondary coolant circuit with a mechanical cooling device consisting of a heat exchanger designed as an evaporator 74 with primary-side connection to the coolant lines 81, 82 and secondary side connection to a refrigerant line 77, which connects the evaporator 74 via a compressor 76 with a capacitor 75. The capacitor 75 has in this embodiment analogous to the arrangement shown in FIG. 1 1, a fan 70 and a heat sink 71, which emits the transported via the refrigerant line 77 amount of heat to the environment. The primary-side connection of the evaporator 74 corresponds to the arrangement according to FIG. 11 with a Coolant reservoir or tank 72 and a coolant pump 73 for generating a circulating coolant flow.

In the recooling system 7b shown in FIG. 12, the refrigerant is cooled by the refrigerant as it passes through the evaporator 74. The refrigerant absorbs the heat energy, vaporizes and is re-liquefied by means of the compressor 76 and the condenser 75, wherein during the condensation the heat is released by means of the fan 70 and heat sink 71 to the ambient air. In the embodiment according to FIG. 13, the cooling system consists of a water exchange system 7c with a heat exchanger 78 which is connected on the primary side to the coolant lines 81, 82, the coolant reservoir 72 for the coolant and the coolant pump 73 for generating a circulating coolant flow, while the heat exchanger 78 Secondary side of the service water pipes 84, 85 is connected. In this water exchange system 7c, the coolant from the primary circuit is passed through the heat exchanger 78, where it is cooled by the colder operating water supplied from the outside.

FIG. 14 shows a schematic representation of the use of a heat-absorbing device designed as a cooling battery 300 in an indirect cooling battery system 7d, in which the cooling battery 300 is flanged onto the coolant lines 81, 82. For this purpose, a heat exchanger 79 is connected on the primary side to the coolant circuit consisting of the coolant lines 81, 82, the coolant reservoir 72 for the coolant and the coolant pump 73 for generating the circulating coolant flow and secondary side with a corresponding device for receiving the cooling battery 300 or for flanging the cooling battery 300 is provided.

Fig. 15 shows a schematic representation of the formation of a cooling system as a heat-absorbing direct cooling battery system 7e with a cooling battery 300, which is flanged directly to the LED light source 1 receiving housing 4, 40 or to the coolant line. The cooling battery 300 absorbs the heat energy emitted by the LED light source 1 for a limited time and is then replaced by a second cooling battery 300 prepared for receiving heat energy when a predetermined temperature is reached.

In an alternative arrangement, according to the schematic representation of FIG. 12, the coolant flowing around the LED light source 1 is guided in a coolant line 83, which lasts one second. Därkreislauf forms and is thermally coupled via a heat exchanger 9 with a primary cooling circuit having a coolant line 81, which is connected via the first Kühlmittelein- lass 31 and first Kühlmittelauslass 32 with the cooling plate 3 and a cooling system 7. The secondary cooling circuit has a reservoir 10 for receiving coolant and a coolant pump 1 1 for transporting the coolant through the secondary circuit. The cooling system 7 can be designed analogously to the cooling systems 7a to 7c described above with reference to FIGS. 11 to 13.

LIST OF REFERENCE NUMBERS

1 LED light source

2 circuit board

3 coolers

3 'cooling plate

4 housing

5 optical window

7; 7a - 7e cooling system

8 coolant line

9 heat exchangers

10 reservoir

1 1 coolant pump

12 power supply or ballast

13 power cable

14 power supply cables

30 cooling element (cooling fins, cooling pins)

31. 41 coolant inlet

32. 42 Coolant outlet

40 housing

50 plane-parallel glass or plastic plate

51 lens

52 diffusion plate

70 fans

71 heat sink, cooling fins or cooling fins

72 coolant reservoir

73 coolant pump

74 evaporator

75 capacitor

76 compressor

77 Refrigerant line

78, 79 heat exchangers

81 - 83 Coolant lines

84, 85 service water pipes

300 cooling battery

Claims

claims

1 . Headlamp with an LED light source, which contains at least one light-emitting diode arranged on a printed circuit board and is arranged in a housing enclosing the LED light source, which has at least one light exit surface through which the light emitted by the LED light source emerges, characterized in that the housing (4, 40) surrounds the LED light source (1) in a liquid-tight or gastight manner and has at least one coolant inlet (41) and a coolant outlet (42) for a liquid or gaseous coolant.

2. Headlight according to claim 1, characterized in that the housing (4, 4 '), the LED light source (1) and one with the circuit board (2) connected, in particular consisting of cooling fins cooling element (30) encloses.

3. Headlight according to at least one of the preceding claims, characterized in that the light exit surface (5) as an optical element or optical window (5) is formed.

4. Headlight according to at least one of the preceding claims, characterized in that the optical element or optical window (5) liquid or gas-tight with the housing (4, 4 ') is connected.

5. Headlight according to at least one of the preceding claims, characterized in that the optical element or optical window (5) consists of a transparent, optical plastic or glass.

6. Headlight according to at least one of the preceding claims, characterized in that the optical element or optical window (5) consists of a plane-parallel glass or plastic plate (50).

7. Headlight according to at least one of the preceding claims 1 to 5, characterized in that the optical element or optical window (5) for beam shaping and / or color mixing is optically active.

8. Headlight according to at least one of the preceding claims 1 to 7, characterized in that the optical element or optical window (5) has curved or stepped optical surfaces for directing light.

9. Headlight according to claim 8, characterized in that the optical element or optical window (5) consists of a lens (51), a lens array, a scattering plate (52) or a light-mixing rod.

10 Headlight according to claim 8, characterized in that the optical element or optical window (5) is coated with a phosphor.

1 1 headlight according to at least one of the preceding claims, characterized in that the distance and / or the orientation of the optical element, optical window (5) or the housing (4, 4 ') relative to the position of the LED light source (1) dynamic beam shaping of the at least one LED of the LED light source (1) emitted light is variable.

12 headlight according to at least one of the preceding claims, characterized in that the refractive index and the spectral transmission and reflection of the optical element or optical window (5), the surface of the LED light source (1), a primary optics of the LED light source (1) and the coolant for achieving a predetermined photometric result, in particular a predetermined radiation angle or a predetermined light output, are tuned.

13 headlight according to at least one of the preceding claims, characterized in that within the housing (4, 4 ') or on a wall surface of the housing (4, 4') further optical elements such as reflectors or lenses are arranged.

14. Headlight according to at least one of the preceding claims, characterized in that the printed circuit board (2) is formed as a cooling plate or connected to a cooler (3).

15. Headlight according to claim 13, characterized in that the coolant flows through the circuit board formed as a cooling plate (2) and / or the radiator (3) and / or the housing (4, 40).

16. Headlight according to at least one of the preceding claims, characterized by a coolant containing the cooling system (7; 7a to 7e), which cools the coolant to a predetermined operating temperature.

17. Headlight according to claim 15, characterized in that the cooling system (7, 7a to 7e) is disposed within the headlight.

18. Headlight according to at least one of the preceding claims 1 to 15, characterized in that the cooling system (7; 7a to 7e) is arranged au ßerhalb the headlamp.

19. Headlight according to at least one of the preceding claims, characterized in that the LED light source (1) and / or the cooler (3) are flowed through by a coolant which is distributed from a distributed over several systems or devices cooling system (7; 7e) is movable and can be cooled down to working temperature.

20. Headlight according to at least one of the preceding claims, characterized in that the LED light source (1) in a secondary cooling circuit and the cooling plate (3) are arranged in a primary cooling circuit and that the primary and secondary cooling circuit thermally via a heat exchanger (9) are coupled.

21. Headlight according to at least one of the preceding claims, characterized in that the cooling system (7) has a coolant reservoir (72), a coolant pump (73), a heat sink, cooling fins or cooling fins (71) and a fan (70).

22. Headlight according to at least one of the preceding claims 1 to 20, characterized in that the cooling system consists of a heat receiving, replaceable cooling battery (300).

23. Headlight according to at least one of the preceding claims, characterized in that the cooling system (7, 7a to 7e) is connected to a central cooling device with a coolant distribution via a predetermined, standardized coolant connection.

24. Headlight according to claim 22, characterized in that the standardized coolant connection has an interface for an electrical connection and / or a control bus for controlling and regulating the LED light source (1).

25. Headlight according to claim 22 or 23, characterized in that the standardized coolant connection can be connected to a hybrid cable having the interfaces for an electrical connection, electrical control signals, a supply voltage and the cooling liquid.

26. Headlight according to at least one of the preceding claims, characterized in that a central coolant system (7; 7a to 7e) dissipates the heat emitted by the coolant and that the headlight has a pump for the coolant up.

27. Headlight according to at least one of the preceding claims, characterized in that the cooling system (7; 7a to 7e) consists of a central cooling device with central coolant distribution and coolant control of a generator vehicle for power supply more connected to the generator vehicle cooling devices.

28. Headlight according to at least one of the preceding claims, characterized in that the at least one LED of the LED light source (1) consists of a light emitting diode in the ceramic or plastic housing, which is mounted on the printed circuit board (2).

29. Headlight according to claim 30, characterized in that arranged in a ceramic or plastic housing LED of the LED light source (1) is covered with an optically active or inactive material.

30. Headlight according to at least one of the preceding claims, characterized in that the at least one LED consists of an LED chip, which is mounted in "chip-on-board" technology on the printed circuit board (2).

31. Headlight according to at least one of the preceding claims, characterized in that the color locus of the LEDs of the LED light source (1) in dependence on the temperature of the LEDs is electronically controlled and stabilized.

32. Headlight according to at least one of the preceding claims, characterized in that the color locus of the LEDs of the LED light source (1) by controlling the coolant temperature, the coolant flow or the speed of the fan (70) on the heat exchanger (9; 78, 79) is stabilizable.

33. Headlight according to claim 30 and 31, characterized in that the color locus of the LEDs of the LED light source (1) in a mixed operation both as a function of the temperature of the LEDs and in dependence on the coolant temperature, the coolant flow or the rotational speed the fan (70) on the heat exchanger (9; 78, 79) can be regulated and stabilized.

34. Headlight according to claim 32, characterized in that the color locus of the LEDs of the LED light source (1) in a normal operation up to a predetermined ambient temperature by controlling the coolant temperature, the coolant flow or the speed of the fan (70) on the heat exchanger (9; 78, 79) and when exceeding the predetermined ambient temperature in an intensive operation by electronic control of the LED light source (1) is stabilized.