DE102011082396A1 - Lighting device has semiconductor light source, reflector optically downstream semiconductor light source, and screen optically downstream reflector, where semiconductor light source is fastened to screen - Google Patents

Abstract

The lighting device (11) has a semiconductor light source, a reflector (12) optically downstream the semiconductor light source, and a screen (15) optically downstream the reflector. The semiconductor light source is fastened to the screen. The screen is formed as a heat spreading body and has an optical edge. A rear side (16) of the screen is arranged on a part of a light emitting opening of the reflector.

Description

The invention relates to a lighting device, comprising at least one semiconductor light source, a reflector, which is optically connected downstream of at least one semiconductor light source, and a diaphragm, which is optically connected downstream of the reflector. This lighting device is particularly suitable for vehicles, in particular motor vehicles, in particular in connection with headlamps.

In the design of headlamp projection systems, tolerances in the alignment or adjustment of the reflector (s), light source (s) and a shutter (also referred to as a "shutter", as for example for the formation of a cut-off line) is commonly used in a light distribution) to each other and can greatly affect a light distribution and performance of the headlamp projection system. In particular, the exact arrangement of the aperture in relation to the light source (s) can significantly affect a quality of a light distribution. The light sources are always integrated as a single component or, in the case of LEDs, on a heat spreading element (also referred to as "heat slug") in the headlight projection system. An exact positioning of the light sources or of the heat spreading element can only take place via specially referenced surfaces on which the individual elements are aligned.

In headlamp projection systems, it is also a challenge to dissipate waste heat from their light source (s) efficiently, without having to be down-regulated or destroyed.

So far, the headlamp projection systems have been designed for high tolerances at the expense of performance losses.

The removal of the waste heat generated by the light sources is realized so far via a connection of the light sources to a rear side of the reflectors. This comes at the expense of the reflective surface, which in turn impairs performance. The heat dissipation is also reduced by contact surfaces and a geometrically caused unfavorable connection of the heat sink.

It is the object of the present invention to overcome the disadvantages of the prior art at least partially and in particular to provide a possibility for a simplified assembly, more efficient heat dissipation and more precise adjustment of a lighting device of the type mentioned, in particular a headlight projection device. As a result, a more accurate light emission pattern can also be provided.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a lighting device comprising at least one semiconductor light source, a reflector, which is optically connected downstream of at least one semiconductor light source, and a diaphragm, which is optically connected downstream of the reflector, wherein at least one semiconductor light source is attached to the diaphragm.

By attaching at least one semiconductor light source to the diaphragm, a critical adjustment between these elements during assembly of the lighting device can be saved. This simplifies the assembly, reduces tolerances and improves the performance of the lighting device. The photometric performance is further improved by the fact that the attachment of the light source no longer needs to be realized by the back of the reflectors, the reflector thus requires the rear side no implementation of thermal elements and an electrical connection. As a result, this area is available as an additional reflection surface. In particular, this reflective surface has the additional advantage that it tends to generate paraxial rays which produce less aberrations in the image by a downstream lens.

Preferably, the at least one semiconductor light source comprises at least one light-emitting diode. If several LEDs are present, they can be lit in the same color or in different colors. A color can be monochrome (eg, red, green, blue, etc.) or multichrome (including achromatic, eg, white). The light emitted by the at least one light-emitting diode can also be an infrared light (IR LED) or an ultraviolet light (UV LED). Several light emitting diodes can produce a mixed light; z. B. a white mixed light. The at least one light-emitting diode may contain at least one wavelength-converting phosphor (conversion LED). The phosphor may alternatively or additionally be arranged remotely from the light-emitting diode ("remote phosphor"), z. B. on the reflector. The at least one light-emitting diode can be in the form of at least one individually housed light-emitting diode or in the form of at least one LED chip. Several LED chips can be mounted on a common substrate ("submount"). The at least one light emitting diode may be equipped with at least one own and / or common optics for beam guidance, z. At least one Fresnel lens, collimator, and so on. Instead of or in addition to inorganic light emitting diodes, z. Based on InGaN or AlInGaP, organic LEDs (OLEDs, eg polymer OLEDs) are generally also used. Alternatively, the at least one semiconductor light source z. B. have at least one diode laser.

The fact that the reflector is optically connected downstream of the at least one semiconductor light source may mean, in particular, that at least part of the light emitted by the at least one semiconductor light source, which is fastened to the diaphragm, is incident on the reflector.

The fact that the diaphragm is optically connected downstream of the reflector may in particular mean that part of the light reflected by the reflector is blocked by the diaphragm and another part of the light reflected by the reflector exits the reflector past the diaphragm. In particular, the diaphragm can form a sharp cut-off line.

Consequently, in particular at least one semiconductor light source, which is set up and arranged such that light emitted by it at least partially (in particular completely) strikes the reflector (ie, at least one reflection surface of the reflector) and partially from the reflector, is attached to the diaphragm of the lighting device the aperture hits and partially runs past the aperture (in particular on the aperture past a light exit opening, in particular light exit level, emerges). Thus, at least one semiconductor light source, which is set up and arranged such that light emitted by it does not hit the reflector (i.e., at least one reflection surface of the reflector), and which, consequently, the reflector is not optically connected, can also be attached to the diaphragm of the lighting device.

The reflector and the aperture may be followed by at least one further optical element, for. As a lens or a lens system, which in particular can make a beam shaping of the light exiting from the reflector on the aperture or light is formed and arranged.

The reflector is in particular a shell-shaped reflector with an inside reflection surface. The reflector may be configured in one piece or in several parts. The reflector may be specular or diffuse reflective. The reflector can be equipped with at least one wavelength-converting phosphor, z. B. occupied, be.

It is an embodiment that the diaphragm is designed as a heat spreader. This makes it possible to dispense with a separate assembly of a dedicated heat spreader. In addition, this type of heat dissipation is particularly effective. Consequently, the combined component exerts both the lighting function of the shutter or the shutter and the thermal function of a heat spreader.

It is a further embodiment that the diaphragm has an optical edge and widened from this edge. In particular, the optical edge is an edge that influences a shape of a light beam generated by the reflector. In particular, the optical edge can form the cut-off line. A comparatively narrow optical edge enables a precise cut-off or beam cut-off, even with a slightly angled or canted aperture. Due to the broadening of this edge of improved thermal conductivity and thus better heat spreading is achieved. From the optical edge of the aperture, for example, in cross-section triangular or one-sided or two-sided curved widen.

It is yet another embodiment that the diaphragm has a reflector-aligned side (hereinafter referred to as "rear side") and a side facing away from the reflector (hereinafter referred to as "front side") and at least one semiconductor light source is mounted on the rear side , As a result, a direct and large-area irradiation of the reflector is made possible by means of this at least one semiconductor light source. In addition, a particularly simple installation is possible. The at least one light source can wholly or partially irradiate the reflector, d. H. Align all or part of their light onto the reflector.

It is yet a further embodiment that the rear side of the diaphragm is arranged on a part of a light exit opening of the reflector. As a result, the panel can be attached easily and with high mounting accuracy at one edge of the reflector. In addition, a precisely defined light beam can thus be output essentially without light losses.

It is also an embodiment that the at least one mounted on the back of the aperture semiconductor light source is disposed in a region of a focal point or an optical axis of the reflector. This allows a particularly precise light emission from the reflector and also a high degree of parallelism of the exiting light beam. In this case, the at least one semiconductor light source need not be located exactly in the focal point, but may be arranged in particular in its vicinity. This is particularly advantageous in the presence of a plurality of semiconductor light sources. It is a development that, in the presence of a plurality of semiconductor light sources, their focus lies in the focus.

It is also an embodiment that at least one semiconductor light source is mounted on the front of the panel. As a result, it is also possible to produce a light emission pattern which is not influenced by the diaphragm. Thus, particularly with respect to a vehicle headlamp, the aperture may produce a cut-off for a low beam (emitted by the semiconductor light sources disposed at the rear of the bezel), while the at least one semiconductor light source mounted on the front of the bezel may produce a daytime running light without bright -Dark border or similar generated.

The reflector may also have an open side (eg bottom side) that does not constitute a light exit opening, and the panel may at least partially cover this open side. Thus, the panel can be made particularly voluminous and effective heat dissipating. The diaphragm may be designed to be specular or diffusely reflecting at least in regions on its surface covering this open side of the reflector. The diaphragm may have at least one semiconductor light source on its surface covering this open side of the reflector. This at least one semiconductor light source can be set up to emit its light at least partially onto the reflector.

In general, if a plurality of semiconductor light sources are present at the diaphragm, they can be subdivided into one or more groups, which can each be activated jointly. One group may each comprise one or more semiconductor light sources. A semiconductor light source may be associated with one or more groups. It is thus possible to generate different light emission patterns by activating different groups. For example, a light-emitting pattern may be changed by activating different groups of semiconductor light sources or by activating or deactivating one or more groups. For example, a group of a plurality of light emitting diodes arranged at the rear side of the diaphragm may produce a low beam and a high beam may be generated by connecting a further group of light emitting diodes arranged at the rear side of the diaphragm. Also, the arranged on the back of the aperture LEDs may be switched off to switch to a daytime running lights and activated in their place at the front of the aperture LEDs are activated.

The semiconductor light sources, in particular a group or on one side of the diaphragm, can be arranged in any spatial arrangement. For example, the semiconductor light sources may be arranged in a linear array or a curved array. The semiconductor light sources can be arranged in particular in a field, in particular in a rectangular matrix arrangement, for. In a 5x1, 4x1 or 3x2 matrix array. The arrangement may also be one-sided or two-sided L-shaped or T-shaped, annular, zigzag, etc.

The at least one semiconductor light source may be inclined to its support, for. B. to the aperture, be aligned, for example, tilted vertically or horizontally.

It is also an embodiment that the aperture, preferably, is designed as a heat sink and / or is highly thermally conductive connected to a heat sink. As a result, waste heat from mounted on the diaphragm semiconductor light sources can be derived particularly effective. For this purpose, the diaphragm can have, for example on optically non-relevant surfaces (which in particular do not block light) at least one cooling structure, eg. As cooling fins, cooling fins, cooling pins, etc. and / or be designed so that there a high heat radiation is achieved, for. B. by painting or anodizing. In particular, an integral design of the panel as a heat sink has the advantage of effective heat spreading and heat dissipation, since there are no thermal expansion inhibiting contact surfaces or transition areas. Also, an assembly is facilitated especially for this case. However, the diaphragm or the diaphragm / heat spreader combination component can also be connected with good thermal conductivity with a separately manufactured heat sink, z. For example, by a direct contact (for example via a thermally well conductive interface material, eg a TIM "Thermal Interface Material" such as a thermal grease) or by at least one heat pipe (or "heat pipe") Alternatively, the aperture itself a function as a heat pipe or be a heat pipe.

It is still an embodiment that the reflector is a shell reflector, in particular a full-shell reflector (with a reflection surface extended in a complete half-space) or a half-shell reflector (with a reflection surface extended in a half-space once more halved).

The shape of the reflector is basically not limited and may be, for example, spherical or spheroidal, ellipsoidal, paraboloidal and / or free-calculative. The reflector may in particular be divided into different areas (facets), z. B. vertically and / or horizontally in different areas, which may be divided in percentage depending on the form.

It may be particularly advantageous to form an inner region of the reflector near the optical axis in a spherical or elliptical manner, while an outer region farther from the optical axis has another basic shape, e.g. B. non-spherical or non-elliptical, since the outer regions are due to large angles of the rays to the optical axis for subsequent imaging with a spherical reflection range photometrically worse exploit. The outer regions may, for example, be elliptical (in particular in the case of a spherically formed inner region) or as a free form (in particular in the case of an elliptically formed inner region).

It is yet an embodiment that the reflector is formed in a parallel and at the same height to an optical edge of the diaphragm lying inner intersection spherical or elliptical and otherwise non-spherical or non-elliptical. This inner intersection region can also be an area lying parallel to a plane spanned by the optical edge of the diaphragm and a plane parallel to the optical axis.

It is yet another refinement that at least one semiconductor light source is designed as a semiconductor chip (in particular bare die or nude chip), in particular an LED chip, attached to the diaphragm via a substrate. Such an arrangement is particularly compact and can transfer heat particularly effective. The substrate may in particular be a submount. The substrate may in particular be equipped with a plurality of semiconductor chips, in particular LED chips. The substrate may consist of a ceramic material of high thermal conductivity, for. B. AlN.

It is a further embodiment that the diaphragm consists of a ceramic material of high thermal conductivity, for. For example, aluminum nitride, silicon nitride, silicon carbide, etc., and the LED chips are mounted directly on the panel or embedded, so without intervening substrate (eg Submount).

It is a particularly preferred embodiment that the lighting device is a vehicle lighting device, in particular a headlight projection system. The vehicle may be a land vehicle, a waterborne vehicle (eg, a ship, etc.), and / or an airborne vehicle (eg, an airplane, a helicopter, an airship, etc.). The land-based vehicle may in particular be a motor vehicle, for. As a motorcycle, a car or a truck.

It is a preferred development that the vehicle lighting device is a headlight or a part of a headlight.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments which will be described in detail in conjunction with the drawings. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 shows a sectional side view of a first lighting device;

2 shows the first lighting device in a view obliquely from the front;

3 shows a sectional side view of a second lighting device;

4 shows the second lighting device in a view obliquely from the front;

5 shows a sectional side view of a third lighting device; and

6 shows the third lighting device in a view obliquely from the front.

1 shows a sectional view in side view, in particular as a vehicle headlight or as a part thereof deployable lighting device 11 according to a first embodiment. 2 shows the lighting device 11 in a view from diagonally forward.

The lighting device 11 has a reflector 12 in the form of a full-shell reflector, which has on its inside a spherically shaped, specularly or diffusely reflecting, reflection surface 13 having. The reflector 12 or its reflection surface 13 is thus present as a full, hemispherical shell, whose free edge 14 defines a light exit opening E. In the present illustration, the reflector 12 vertically aligned, ie, that its light exit opening E is upright.

A, in this illustration lower, part of the light exit opening E is through a diaphragm 15 covered. This lower part covers about one half of the light exit opening E. The aperture 15 is plate-shaped and is vertical. Your flat back 16 is in the direction of the reflector 12 aligned (the reflector 12 facing), and its front 17 is the reflector 12 away. Its upper, at the light exit opening E of the reflector 12 lying edge is called an "optical edge" 18 designated.

At the back 16 the aperture 15 are several semiconductor light sources in the form of white LEDs 19 arranged here in a horizontally aligned row of four or five light-emitting diodes 19 (5 × 1 matrix arrangement). The light-emitting diodes 19 are here as on a common ceramic substrate (o.Abb.) arranged LED chips designed, which thus on the ceramic substrate on the panel 15 are attached. The light-emitting diodes 19 are located approximately at the level of an optical axis A of the reflector 12 and also approximately at the light exit opening E. Thus, the LEDs are also in a range of a focal point of the reflector 12 , The light-emitting diodes 19 or their main emission or optical axes are aligned horizontally and thus parallel to a surface normal n the back 16 the aperture 15 ,

In an operation of the LEDs 19 They shine their light on the reflector 12 , and completely. The reflector 12 is the light emitting diodes 19 consequently optically downstream. That of the reflector 12 reflected light partially hits the aperture 15 and is blocked by her. Another part of the reflector 12 reflected light passes through the upper half of the light exit opening E, at the aperture 15 over, out. The aperture 15 is therefore the reflector 12 (at least partially) optically downstream. The optical edge 18 creates a sharp cut-off at the border by means of the reflector 12 reflected light beam. The optical edge 18 can therefore also as the optically active, ie, the light beam influencing edge of the aperture 15 be considered.

The optical edge 18 is not configured here in a straight line, but has an oblique step in its center 18a on, leaving the optical edge 18 is higher on one half than on the other half. As a result, an asymmetrical Lichtabstrahlmuster can be obtained in a simple manner.

Not pictured but may be present at least one of the aperture 15 downstream optical element, z. As a lens, for further beam shaping of the through the aperture 15 partially hidden or blocked light beam.

The aperture 15 is also designed as a heat spreader to the light-emitting diodes 19 dissipate generated heat. This is indicated by the aperture 15 one from its optical edge 18 outgoing slope 20 the front 17 on, so that the aperture 15 Widened wedge-shaped in cross section. The widening further improves the heat dissipation. The aperture 15 can also consist of a good thermal conductivity material (with more than 15 W / (m · K)), z. B. aluminum.

The aperture 15 can be connected to a dedicated heat sink (o.Fig.) For particularly effective heat dissipation, for example, with its bottom, in particular a good heat conducting material, such as a TIM ("Thermal Interface Material"). The aperture 15 can also be configured as a heat sink itself, for. B. by providing a heat sink structure on its outside, z. B. of cooling fins or cooling pins. The aperture 15 can therefore also serve as a heat sink.

Further, on a front side 17 the aperture 15 another light emitting diode 21 appropriate. This LED 21 thus does not shine in the reflector 12 , and her beam will not pass through the aperture 15 influenced or shaped. This LED 21 may have a different light function than the light emitting diodes 19 fulfill, z. B. a daytime running light function. The light-emitting diode 21 For example, instead of the LEDs 19 be activated.

3 shows a sectional view in side view of a second lighting device 31 , 4 shows the second lighting device 31 in a view from diagonally forward. At the lighting device 31 is the reflector 32 now as a half shell reflector (as half of a solid shell reflector) with an open bottom 33 educated.

The aperture also serving as a heat spreading element 35 is now shaped to fit in one area 35a , which the light exit opening E of the reflector 32 covered and the light-emitting diodes 19 and 21 carries, plate-shaped is formed with a constant thickness. At the adjoining, below the bottom 33 located area 35b is the aperture 35 thickened in a backward direction so much that they are the bottom 33 of the reflector 32 at least partially covering. Should the area 35b the bottom 33 not completely cover, she can z. B. by a dedicated cover, z. As a reflective plate to be covered.

On a top of this area 35b (Which may be diffuse or specularly reflective) is at least one light emitting diode 39 , The lighting device 31 can both the light emitting diodes 19 as well as the at least one light emitting diode 39 have, alternatively, the LEDs 19 or the at least one light emitting diode 39 , The light-emitting diode 21 can also be optional here. Due to the large volume and the short range 35a allows the aperture 35 an effective heat spreading. The large volume also makes it particularly easy to provide a significant portion of its surface with a heat sink structure, for. B. with cooling fins, cooling pins, etc., or with a heat convection improving coating, for. B. a paint job.

The aperture 35 Consequently, it can also serve as a heat sink, wherein the size and shape of the heat sink can be adapted to the heat dissipation to be accomplished. That's how the aperture works 35 For example, be performed solid and / or made so large that it projects beyond the reflector or surrounds him. The aperture can generally, for. B. behind the reflector, have a connection area to an independent heat sink or integrally there have a dedicated heat sink area. Alternatively or additionally, the diaphragm generally likes at least one heat sink structure, for. B. cooling fins, have.

At the lighting device 31 can the reflector 32 be configured so that the at least one light emitting diode 39 at least near its focal point. The reflector 32 is here to emit a substantially parallel beam through the at least one light emitting diode 39 Paraboloid trained.

5 shows a sectional side view of a third lighting device 41 , 6 shows the third lighting device 41 in a view from diagonally forward.

The lighting device 41 has an aperture 45 on which in their the light exit opening E of the reflector 42 covering area 45a similar to the aperture 15 the lighting device 11 is formed, namely from the optical edge 18 widening out. In the adjoining area 45b is the aperture 45 similar to the aperture 35 the lighting device 31 designed. The area 45b also covers an open bottom here 43 of the reflector 42 off, and all over. However, it is at the top of this area 45b no LED.

The aperture 45 can also serve as a heat sink, the size and shape of the heat sink to bewerkstelligenden heat dissipation are adjusted. Thus, the heat sink part can be made massive and / or made so large that it projects beyond the reflector or surrounds it.

The reflector 42 now has no uniform form, but is in different areas or facets 42a -E different shape divided. These facets 42a -E extend essentially in horizontal sections of the reflector 42 , One parallel and at the same height to the optical edge 18 the aperture 45 lying inner facet 42a is elliptical. Above the inner facet 42a subsequent outer facets 42b -D are non-elliptical, here: formed free form.

Although the invention has been further illustrated and described in detail by the illustrated embodiments, the invention is not so limited and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

So can the inner facet 42a also be spherical, while the outer facets 43b -D can be configured elliptical or free-form.

Also, the optical edge may not only be directed vertically upwards, but may point in any direction, z. B. forward.

The panel may be generally suitable for laying electrical lines, z. B. by providing at least one cable channel and / or at least one cable / contact guide, etc. and / or for example also in that are integrated in the panel suitable electrical lines.

Claims (13)

Lighting device ( 11 ; 31 ; 41 ), comprising - at least one semiconductor light source ( 19 . 21 ; 39 ), - a reflector ( 12 ; 32 ; 42 ), which at least one semiconductor light source ( 19 ; 39 ) is optically downstream, and - a diaphragm ( 15 ; 35 ; 45 ), which the reflector ( 12 ; 32 ; 42 ) is optically connected downstream, wherein - at least one semiconductor light source ( 19 . 21 ; 39 ) at the aperture ( 15 ; 35 ; 45 ) is attached. Lighting device ( 11 ; 31 ; 41 ) according to claim 1, wherein the diaphragm ( 15 ; 35 ; 45 ) is formed as a heat spreader. Lighting device ( 11 ; 41 ) according to claim 2, wherein the diaphragm ( 15 ; 45 ) an optical edge ( 18 ) and from this edge ( 18 ) widened out. Lighting device ( 11 ; 31 ; 41 ) according to one of the preceding claims, wherein the diaphragm ( 15 ; 35 ; 45 ) one on the reflector ( 12 ; 32 ; 42 ) facing back ( 16 ) and one of the reflector ( 12 ; 32 ; 42 ) facing away from the front ( 17 ) and at least one semiconductor light source ( 19 ) on the back ( 16 ) is attached. Lighting device ( 11 ; 31 ; 41 ) according to claim 4, wherein the rear side ( 16 ) the aperture ( 15 ; 35 ; 45 ) at a part of a light exit opening (E) of the reflector ( 12 ; 32 ; 42 ) is arranged. Lighting device ( 11 ; 31 ; 41 ) according to one of the preceding claims, wherein the at least one on the back ( 16 ) the aperture ( 15 ; 35 ; 45 ) mounted semiconductor light source ( 19 ) in a region of a focal point or an optical axis (A) of the reflector ( 12 ; 32 ; 42 ) is arranged. Lighting device ( 11 ; 31 ; 41 ) according to one of claims 4 to 6, wherein at least one semiconductor light source ( 21 ) on the front side ( 17 ) the aperture ( 15 ; 35 ; 45 ) is attached. Lighting device ( 11 ; 31 ; 41 ) according to one of the preceding claims, wherein the diaphragm ( 15 ; 35 ; 45 ) is designed as a heat sink or is thermally conductively connected to a heat sink. Lighting device ( 11 ; 31 ; 41 ) according to one of the preceding claims, wherein the reflector ( 12 ; 32 ; 42 ) a shell reflector, in particular a half-shell reflector ( 32 ; 42 ) or a full shell reflector ( 12 ) is. Lighting device ( 41 ) according to one of the preceding claims, wherein the reflector ( 42 ) in a parallel and at the same height to an optical edge of the diaphragm lying inner cut area ( 42a ) is spherical or elliptical and otherwise has a different basic shape. Lighting device ( 11 ; 31 ; 41 ) according to one of the preceding claims, wherein at least one semiconductor light source ( 19 ; 39 ) as a via a substrate at the diaphragm ( 15 ; 35 ; 45 ) attached semiconductor chip is formed. Lighting device ( 11 ; 31 ; 41 ) according to one of claims 1 to 10, wherein at least one semiconductor light source ( 19 ; 39 ) is attached directly to a made of electrically insulating, in particular ceramic, material diaphragm. Lighting device ( 11 ; 31 ; 41 ) according to one of the preceding claims, wherein the lighting device ( 11 ; 31 ; 41 ) is a vehicle lighting device, in particular headlight projection system, is.

Images