Lighting device with reflector, lens and aperture

Abstract

Lighting device (11) comprising: - a reflector (13) that can be illuminated by means of at least one light source (12), in particular a light-emitting diode; - a lens (14) downstream of the reflector (13); and - an aperture (15, 15a-j) interposed between the reflector (13) and the lens (14), wherein the aperture (15, 15a-j) is designed and arranged to: - block a portion of the light (L2) reflected from the reflector (13) onto the aperture (15, 15a-j); and - direct another portion (L2t) of the light (L2) reflected from the reflector (13) onto the aperture (15, 15a-j) onto the lens (14), wherein the aperture (15, 15j) has a light guide (24) on its upper side and on its front side (19j) that can be illuminated by the reflector (13). and wherein light shining onto the aperture from the rear is blocked and light shining onto the light guide (24) from the top (L2t) is passed to the front (19j) and coupled out there.

Description

The invention relates to a lighting device, comprising a reflector that can be illuminated by means of at least one light source, in particular a light-emitting diode, a lens connected downstream of the reflector, and a diaphragm connected between the reflector and the lens. The invention can be used particularly advantageously for vehicle lighting devices, in particular headlights.In headlights for cars and trucks, a screen is brought into a beam path between a reflector and a lens of the headlight in order to generate a low beam. The aperture blocks a portion of the light rays passing from the reflector to the lens, so that a sharp light-dark boundary results in the light emission pattern generated behind the lens in the far field. However, it may be desirable, for example in order to increase the visibility of the headlight, to diffusely illuminate the basically dark region. For this purpose, it is known to modify a light entry or light exit surface of the lens by light deflection structures in such a way that it also casts light at least slightly into the basically dark region. Light deflection structures may include, for example, wells or rings. However, this reduces the brightness of the area primarily to be illuminated. In addition, shaping and adapting the lens is comparatively complicated.Various approaches are known from the prior art for designing the light distribution of vehicle headlights. DE 10 2008 015 510 A1 and DE 10 2009 010 558 A1 show, for example, screens with transparent sections or openings in order to conduct light in a targeted manner into the region above the light-dark limit. DE 10 2010 035 767 A1 discloses a shutter with structured edges in order to make the transition of the light-dark boundary softer. The use of photoluminescent materials on screens or lamp caps is known from DE 10 2006 057 748 A1 and DE 10 2006 054 937 A1. DE 693 01 645 T2 describes a panel with a laterally attached light guide for improving the lateral visibility of the luminaire. DE 202 11 305 U1 discloses an illumination device in which a light guide unit, which can be designed as a diaphragm, is integrated in a reflector unit.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 lighting device which can provide scattered light in a spatial region shaded by a screen in a particularly simple and / or light-technically flexible manner.This object is achieved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.The object is achieved by a lighting device, comprising a reflector illuminatable by means of at least one light source, a lens connected downstream of the reflector and a diaphragm interposed between the reflector and the lens, wherein the diaphragm is designed and arranged to block a part of light reflected by the reflector onto the diaphragm and to direct another part of the light reflected by the reflector onto the diaphragm onto the lens.Due to the part of the light directed from the aperture onto the lens, the light can in particular also be illuminated into spatial regions which would otherwise be blocked or shaded by the aperture. Consequently, provision of an, in particular comparatively weak, additional light to the light radiated directly from the reflector onto the lens is easily achieved. A design modification of the front or rear side of the lens with light deflection structures can be dispensed with.In one development, the light reflected by the reflector onto the aperture is generated by a diffusely reflecting region of the inner reflector surface. This light generated in this way has, in particular, a brightness which is significantly lower than the directed (useful) light reflected directly onto the lens by the reflector.The light source can emit in particular UV light, visible light and / or IR light. The light source can be, in particular, a semiconductor light source. Preferably, the at least one semiconductor light source comprises at least one light emitting diode. If a plurality of light emitting diodes are present, these can illuminate in the same color or in different colors. A color may be monochrome (e.g., red, green, blue, etc.) or multi-chrome (e.g., 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). A plurality of light emitting diodes may generate mixed light; e.g., white mixed light. The at least one light emitting diode can contain at least one wavelength-converting phosphor (conversion LED). The phosphor can alternatively or additionally be arranged remote from the light-emitting diode ("remote phosphor"). The at least one light emitting diode can be present in the form of at least one individually packaged light emitting diode or in the form of at least one LED chip. Multiple LED chips may be mounted on a common substrate ("submount"). The at least one light emitting diode can be equipped with at least one dedicated and / or common optical unit for beam guidance, e.g. at least one Fresnel lens, collimator, and so forth. Instead of or in addition to inorganic light-emitting diodes, e.g. based on InGaN or AlInGaP, organic LEDs (OLEDs, e.g. polymer OLEDs or small molecule OLEDs) can generally also be used.Alternatively, the at least one semiconductor light source can have, for example, at least one diode laser.In another embodiment, the at least one light source for illuminating the reflector is dimmable. Thus, light emission patterns or light functions that are more weak in light can also be provided in a targeted manner, for example a daytime running light.In one configuration, the aperture is a partially transmissive aperture, that is to say a part of the light radiated by the reflector onto the rear side of the aperture is transmitted and another part is blocked (e.g. absorbed and / or reflected in a useless manner). The transmitted light can then generate the additional, in particular low, light component, in particular scattered light component, on the light emission pattern.The main body of the aperture can be formed, for example, translucent or milky (in particular for generating a scattered light without significant brightness peaks) and / or have a light-scattering surface structure on its light outlet side (the front side).In one configuration thereof, the panel has a partially transmissive coating. Such a configuration can be provided particularly easily. The partially transmissive coating can be applied, for example, to a transparent or translucent main body.In a particularly simple embodiment, the aperture has at least one light passage opening and is otherwise opaque. The light impinging from the reflector on the aperture (in particular its rear side) can therefore pass through the aperture in the region of the at least one light passage opening and emerge again (in particular on the front side) and then be radiated, for example, onto the lens.In one embodiment, for shaping the desired additional portion of the light emission pattern, in particular the scattered light portion, the aperture has a beam-shaping base body, e.g. in the form of a lens, in particular a free-form lens.However, the shape of the aperture is basically arbitrary. For example, the panel can also be designed to be plate-shaped, wherein the front side and the rear side of the panel correspond to the two main sides of the plate. Such a diaphragm can be arranged in particular on or in a light outlet plane of the reflector or outside the reflector.The panel can also be shaped, for example, such that its rear side is oriented at an angle to the front side, e.g. is perpendicular thereto. For example, the rear side can lie in the reflector, e.g. horizontally, and form at least a part of the inner side of the reflector, for example. The rear side can form, for example, a base or base region lying in a main plane of the reflector.In another embodiment, the aperture is designed and arranged such that light falling from the reflector onto its rear side can be at least partially blocked and its front side is designed to be reflective at least in regions. The aperture may be opaque or, for example, also partially transmissive. This embodiment has the advantage that the diaphragm can be produced particularly easily.An associated front-side, at least one reflection surface may be designed to be specular or diffusely reflecting. It is also preferred that the front-side, at least one reflection surface is Gaussian-reflective or is designed as a Gaussian mirror, the reflectance of which is location-dependent, in particular decreases or decreases in Gaussian form from a center.The shape of the at least one front-side reflection surface is fundamentally arbitrary and may be e.g. concave mirror-shaped (ellipsoid, paraboloid, free-form, etc.) in order to be able to shape a spatial limitation of the additional light emitted therefrom in a targeted manner. However, the shape of the at least one front-side reflection surface is not limited thereto and may also be otherwise free-shaped, for example.In another embodiment, the screen has a light guide that can be illuminated by the reflector on the top and on its front side, and the light guide is configured to couple out light on the front side. Light radiated on the rear side of the aperture is thus blocked, and light radiated on the upper side of the light guide is forwarded to the front side (not illuminated by the reflector) and coupled out there. The decoupling takes place, for example, at impurities, reflecting or roughened regions and / or by means of decoupling structures located in the material and / or introduced on the surface. Alternatively or additionally, a dedicated or additional light source can be used to feed the light guide.In addition, it is an embodiment that the front side of the aperture is covered with at least one phosphor, in particular with at least one phosphor layer. As a result, a diffusely scattering mixed light can be generated as scattered light, etc. in a particularly simple manner. The mixed light is composed in particular of the primary light originally generated by the at least one additional light source and the wavelength-converted secondary light generated by the at least one phosphor from the primary light. Depending on the density, thickness, etc. of the phosphor, the conversion degree from primary light to secondary light can be adjusted and, if necessary, only secondary light can be radiated onto the lens.In yet another embodiment, the reflector has a half-shell reflector or is configured as such. This results in a particularly cost-effective and compact configuration, in particular since often only one half of the emission pattern of a full-shell reflector is required and the light emission pattern advantageously has a longest width at the light-dark boundary. However, the reflector is not limited thereto and can in particular comprise any suitable type of hollow reflector, for example also a full-shell reflector.In another embodiment, the aperture has a cut-off edge (i.e. an edge for generating the light-dark boundary) on a main plane of the reflector. This results in a sharp light-dark boundary at the widest point of the light emission pattern.The lighting device can generally comprise one or more optical elements connected downstream of the shell reflector, e.g. one or more lenses, further reflectors, light-transmissive covers, etc.In addition, it is an embodiment that the lighting device is a vehicle lighting device, in particular headlights. In particular, the light-dark limit and the scattered light generation can be used advantageously here, in particular at least for generating a low beam.The type of vehicle is not limited and may include, for example, water-based vehicles (ships, etc.), air-based vehicles (aircraft, helicopter, etc.), as well as land-based vehicles (e.g., passenger car, truck, motorcycle, etc.).The above-described properties, features and advantages of this invention and the manner in which these are achieved become clearer and more clearly comprehensible in conjunction with the following schematic description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. For the sake of clarity, identical or identically acting elements can be provided with identical reference numerals. FIG. 1 is a sectional side view of a vehicle lighting device; FIG. 2 shows the vehicle lighting device as a sectional illustration in plan view; FIG. 3 is a front view showing a light emission pattern generated behind the vehicle lighting device; and FIGS. 4-13 show various exemplary embodiments of a panel, for example of the vehicle lighting device according to FIGS. 1, 2 to 3.FIG. 1 shows a sectional illustration in side view of a vehicle lighting device 11 which is suitable in particular for use as a headlight of a motor vehicle. FIG. 2 shows the vehicle lighting device 11 in a plan view.The vehicle lighting device 11 includes at least a light generation unit 12, an approximately ellipsoidal reflector 13, a lens 14, and a shade 15. These elements can be accommodated in a dust- and / or moisture-proof housing (see FIG. ).The reflector 13 is here designed purely by way of example as a half-shell reflector with an approximately ellipsoidal reflection surface. The reflector 13 has a base body made of plastic with a specular reflecting surface on its inner side. A front edge 25 of the reflector 13 is curved laterally forwardly and terminates at apexes T as shown in FIG. 2. A lower edge of the reflector 13 lies on a plane which also represents a horizontal main plane H of the reflector 13. In the main plane H, the optical axis O of the lens 14 lies, and the main plane H notionally divides the space represented into an upper half space OH and a lower half space UH. While the lens 14 is located half in the upper half space OH and half in the lower half space UH, the reflector 13 is located in the upper half space OH and the aperture 15 is located in the lower half space UH.The reflector 13 has an inner focal point F1 curved over by the reflector 13 and an outer focal point which lies between the inner focal point F1 and the lens 14. The second focal point may correspond in particular to a focal point of the lens 14.In the region of the inner focal point F1, there is a light exit surface (see FIG. ) of the light generation unit 12. The light generation unit 12 here has conversion light-emitting diodes 21 emitting white light or blue-yellow mixed light. A diffuser can be connected downstream of the conversion light-emitting diodes 21, for example. When light-emitting diodes 21 or activated light-generating unit 12 are activated, light L emerging at the light exit surfaces of light-emitting diodes 21 is radiated into reflector 13. The reflector 13 is thus optically connected downstream of the light-generating unit 12.The lens 14 optically downstream of the reflector 13 has an aspherical shape and is designed rotationally symmetrically about its optical axis O. The optical axis O is shown here lying horizontally. The lens 14 consequently has a plano-convex basic shape, wherein a convex front surface 16 has an aspherical shape and a planar rear surface 17 lies perpendicular to the optical axis O, which here corresponds to the x-axis. The lens 14 is made of PMMA. A diameter of the lens 14 perpendicular to the optical axis O (which corresponds to a circle diameter of the planar rear surface 17) is here approximately 50 mm with a thickness along the optical axis O of approximately 20 mm. A length of the vehicle lighting device 11 is in particular between 80 mm and 90 mm.The panel 15 is designed here as a vertical plate with a rear side 18 oriented toward the rear and a front side 19 oriented toward the front side. The diaphragm 15 is partially connected into a beam path between the reflector 13 and the lens 14. An upper edge, the cut-off edge 10, of the aperture 15 touches the optical axis O. At the intersection between the optical axis O and the cut-off edge 10, the second (outer) focal point or focal spot of the reflector 13 can be located. The diaphragm 15 generates a light-dark boundary G in the image projected by the lens 14 or light emission pattern M 1 (see FIG. 3 ) by means of the cut-off edge 10, which is generated by means of the light L 1 irradiated directly from the reflector 13 onto the lens 14. The light-dark limit G may be prescribed, for example, for operation of a vehicle in road traffic. More specifically, the light emission pattern M1 projected behind the lens 14 (i.e., in the direction of the x-axis) has a light-dark boundary G at its upper edge in the far field, while the light emission pattern at the output of the reflector 13 has a lower light-dark boundary.The aperture 15, which is thus optically connected between the reflector 13 and the lens 14, is furthermore designed and arranged to block a part of a light L 2 reflected by the reflector 13 onto the aperture 15 and to direct another part L 2 tof the light L 2 reflected by the reflector 13 onto the aperture 15 onto the lens 14, as will be explained in more detail below.In another variant, the diaphragm 15 (then drawn in dashed lines) lies horizontally on the main plane H of the reflector 13 and thus at least partially represents its bottom. However, the diaphragm 15 may also be inclined, etc.FIG. 3 shows a front view of a light emission pattern M generated along the optical axis O behind the lens 14 by the vehicle lighting device 11 in the far field. A lower region M 1 of the light emission pattern M situated below the main plane H. A lower region M 1 of the light emission pattern M has a sharp light-dark boundary G at its upper edge R 1 and is generated by the light L 1 which passes directly from the reflector 13 into the lens 14. An upper region M 2 of the light emission pattern M situated above the main plane H adjoins the light-dark boundary G at its lower edge R 2 and is generated by light L 2 twhich passes from the reflector 13 first onto the aperture 15 and from there partly into the lens 14. A relative brightness of the regions M 1 and M 2 may be adjusted, for example, by a light transmissivity of the aperture 15, the shape of the upper region M 2, for example, by the shape of the aperture 15.FIG. 4 shows a sectional illustration in side view of a possible configuration of the panel 15 in the form of a partially transmissive panel 15 a. A rear side 18 aof the aperture 15 acan be irradiated (directly) with light L 2 by the reflector 13. The aperture 15 ais partially transmissive in that it absorbs a part of the light L 2 incident on its rear side 18 a, transmits another part L 2 tthrough its light transmissive main body 20, 20 aand subsequently emits it on its front side 19 atoward the lens 14. This light L2t emitted at the front side 19a and passing through the lens 14 can fall in the far field in particular into a spatial region outside the light emission pattern M1, e.g. generate the upper region M2 of the light emission pattern M. The light L2t emitted at the front side 19a of the aperture 15a may also pass in part past the lens 14 and then be used or absorbed in particular for effect illumination.A partial permeability of the diaphragm 15 acan be achieved, for example, by a corresponding covering (layer, layer stack, etc.) of the base body 20, 20 a, in particular of the rear side 18 a.The light-transmissive main body 20 may generally be a transparent or a translucent (diffusely scattering) main body. Quite generally, the base body 20 can serve as an optical element, e.g. for beam shaping and / or beam guidance or beam deflection. For this purpose, the base body 20, 20 ahere has, for example, a triangular shape in cross section.The base body 20 may generally be designed in particular as a profile body in the sense that it is continued perpendicularly to the plane of the image (perpendicularly to the longitudinal axis in the main plane H).FIG. 5 shows a top view of a further possible embodiment of the screen 15 in the form of a partially transmissive screen 15 b, with a corresponding rear side 18 band front side 19 b. The aperture 15 bis not designed as a linear profile body here, but rather has a front side 19 bcurved in the transverse direction, for example for multi-shaped light directing of the light L 2 tand configuration of the light emission pattern M 2.FIG. 6 shows a sectional illustration in side view of yet another possible configuration of the panel 15 in the form of a partially transmissive panel 15 clike the panel 15 a. However, for the changed beam guidance in the base body 20, 20 c, the rear side 18 cof the aperture 20 cis concave, while the front side 19 cis planar. However, alternatively, the front side 19 cmay also have a non-planar, e.g. convex or concave, basic shape.FIG. 7 shows a sectional illustration in side view of yet another possible configuration of the panel 15 in the form of a partially transmissive panel 15 dlike the panel 15 a. However, for the changed beam guidance in the base body 20, 20 d, the rear side 18 dis formed here to be curved at the rear, e.g. concave, while the front side 19 dis formed to be planar. However, alternatively here too, the front side 19 dmay have a non-planar, e.g. convex or concave, basic shape.FIG. 8 shows a sectional illustration in side view of yet another possible configuration of the diaphragm 15 in the form of a diaphragm 15 ewith a light-absorbing rear side 18 eand a diffusely or specularly reflecting front side 19 e. The aperture 15 eis arranged such that a portion of the light L 2 incident thereon from the reflector 13 impinges on the rear side 18 eand another portion L 2 tof the light L 2 incident thereon from the reflector 13 impinges on the front side 19 e. The light L2t incident on the front side 19e is reflected, in particular diffusely, into the lens 14, e.g. to form the light emission pattern M2. The screen 15 ehere has in particular a planar front side 19 e.FIG. 9 shows a sectional illustration in side view of yet another possible configuration of the diaphragm 15 in the form of a diaphragm 15 fwhich differs from the diaphragm 15 eby its concave reflecting front side 19 f. As a result, a stronger light beam can be achieved.FIG. 10 shows a sectional illustration in side view of yet another possible configuration of the diaphragm 15 in the form of a diaphragm 15 gwhich differs from the diaphragm 15 eby its convex reflective front side 19 g. This allows a greater beam expansion to be achieved.FIG. 11 shows a sectional illustration in side view of a variant of the diaphragm 15 f, namely a diaphragm 15 h, the front side 19 gof which is coated with a phosphor layer 22. The phosphor layer 22 includes one or more wavelength-converting phosphors capable of converting at least partially the light L 2 irradiated from the reflector 13 into light of longer wavelength. This allows the light emission pattern M 2 to be also color-differentiated or adapted from or to the light emission pattern M 1. The light L 2 tradiated by the phosphor layer 22 is typically radiated non-directionally or diffusely.FIG. 12 shows a front view of yet another possible embodiment of the cover 15 in the form of a cover 15 iwhich has a plurality of light transmission openings 23 running from the rear side 18 hto the front side 19 hin an otherwise opaque base body 20 h. The diaphragm 15 iis in particular only imageable on the rear side, and the light emission pattern M 2 can be generated by means of light L 2 ttransmitted through the light transmission openings 23.FIG. 13 shows a sectional illustration in side view of a further aperture 15, namely an aperture 15j with a light guide 24 arranged on the top side and on the front side 19j. The rear side 18j is designed to be opaque. In this aperture 15 j, light L 2 tthat is incident on the top side of the reflector 13 can be guided by means of the light guide 24 to the front side 19 j, where it is coupled out at least partially in the direction of the lens 14.Additionally or alternatively, the light guide 24 may be illuminated by an additional, in particular dedicated, light source, e.g. by at least one light emitting diode 26 or other semiconductor light source (drawn in dashed lines).Although the invention has been illustrated and described in more detail by the exemplary embodiment shown, the invention is not restricted thereto and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.Thus, the convex surface of the lens may also be an ellipsoidal or paraboloidal surface. In general, the lens is not limited to convex lenses, but can also comprise concave or convex-concave lenses, for example. A lens can generally be understood to mean an optical imaging element or imaging system, which can also comprise a lens in the narrower sense.Generally, the position and rotational position of the elements of the vehicle lighting device relative to each other may vary. Thus, the light generating unit or its light exit surface can be angled against the main plane of the reflector or be displaced out of the inner focal point. The aperture may also be rotated and / or displaced with respect to the lens.In addition, the reflector may be angled with respect to the lens. In particular, the main plane H of the reflector may be oblique to the optical axis of the lens. An associated angle of inclination α is preferably not more than about 20°. Color mixtures can thereby be compensated for at least partially, and monochrome color fringes are reduced.The aperture may furthermore be removable from the beam path and re-insertable, e.g. tiltable or pivotable, in order to be able to illuminate a larger area, e.g. when using the electric wheel off-road.The aperture may have shapes other than those shown. In particular, features of the diaphragms can be used alternatively or additionally. For example, all the diaphragms shown may be provided with phosphor and / or have a non-planar shape in plan view.

Claims

Lighting device (11), comprising - a reflector (13) which can be illuminated by means of at least one light source (12), in particular a light-emitting diode, - a lens (14) which is connected downstream of the reflector (13), and - a diaphragm (15, 15a-j) which is connected between the reflector (13) and the lens (14), wherein the diaphragm (15, 15a-j) is designed and arranged to - block a part of a light (L2) which is reflected by the reflector (13) onto the diaphragm (15, 15a-j), and - direct another part (L2t) of the light (L2) which is reflected by the reflector (13) onto the diaphragm (15, 15a-j) onto the lens (14), wherein the diaphragm (15, 15j) has, on the top side and on its front side (19j), a light guide (24) which can be illuminated by the reflector (13), and wherein light radiated on the rear side of the aperture is blocked and light (L2t) radiated on the upper side of the light guide (24) is forwarded to the front side (19j) and coupled out there.Lighting device (31) according to claim 1, wherein the rear side (18j) of the panel (15j) is designed to be opaque.Lighting device (31) according to claim 1, wherein the light guide (24) can be illuminated by means of an additional light source (26).Lighting device (11; 31) according to one of the preceding claims, wherein the aperture (15, 15h) is coated with at least one phosphor.Lighting device (11; 31) according to one of the preceding claims, wherein the reflector (13) is designed as a half-shell reflector and the aperture (15, 15a-j) has a cut-off edge (10) on a main plane (H) of the reflector (13).Lighting device (11) according to one of the preceding claims, wherein the lighting device (11) is a vehicle lighting device, in particular headlight.The lighting device (11) according to claim 6, wherein the vehicle lighting device is a lighting device (11) for an electric wheel.

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