Emitter

Abstract

The present invention relates to an emitter having at least one light source and a lens for shaping a beam for illuminating a target area. According to the invention, the lens has a through opening for allowing passage of an unreflected and undeflected direct light beam, on the input side of which the light source is positioned, wherein an inner circumferential surface enclosing said through opening at least partially forms a light entrance surface of the lens, at which some of the light rays emitted by the light source enter the lens, and are deflected by the lens by way of total internal reflection and are emitted as an indirect light beam from a light exit surface, wherein said inner circumferential surface is contoured in such a way that Fresnel reflections occurring at said inner circumferential surface are emitted through said through opening and illuminate the target area as part of the direct light beam and / or of the indirect light beam.

Description

[0001] spotlight

[0002] The present invention relates to a spotlight with at least one light source and a lens for shaping a beam of light for illuminating a target area.

[0003] In illuminators that use non-imaging optics, such as a lens or reflector, to form a beam of light to illuminate a target area, the aim is twofold: firstly, to minimize light losses to achieve high illuminant efficiency; and secondly, to achieve the desired high optical quality of the beam. This can include, for example, achieving uniform light distribution across the target area, forming a defined beam cutoff or sharply defined beam, and avoiding glare and scattering effects caused by uncontrolled deviations in the light beam.

[0004] Even with high-quality reflective surfaces, reflectors used to shape the beam of light can only achieve limited efficiency. In practice, reflective elements, typically made of high-purity aluminum, can achieve a maximum reflectance of around 85%. Even if the reflector itself is only monoreflective, the optical efficiency of the light source is correspondingly reduced. Higher reflectances could be achieved using highly reflective coatings, such as silver-containing coatings, but these are expensive and also fragile.

[0005] Lenses used to shape the beam of light can achieve comparatively better efficiencies, which can vary depending on the application and, for example, whether the lens is intended to emit a wide or narrow beam, or how much the light rays are deflected by refraction at the lens surfaces. Typically, in wide-beam applications with beam angles greater than 2 x 45°, i.e., with low deflection, optical efficiencies—defined by the ratio of the luminous flux of the light source to the luminous flux exiting the optics—can be achieved in the range of 92–93%.

[0006] One cause of the losses that also occur in lenses is so-called Fresnel reflections, which prevent a portion of the light from refracting at a lens surface or interface and allowing it to pass through the interface, instead reflecting it off. For example, when Fresnel reflections occur at the light entrance surface of a lens, a light ray does not enter the lens completely, but rather a portion of the light ray is reflected off the entrance surface, so that the reflected portion does not take the intended path through the lens body.

[0007] Such Fresnel reflections not only reduce the light-emitting efficiency of the spotlight due to reflections back into the luminaire housing, but also negatively affect the optical quality of the beam. This is because the Fresnel reflections, while small, can be quite bright and visible from certain positions. Furthermore, they can soften the beam's separation or delineation, creating a degree of blurring as scattered light. Therefore, attempts have been made to avoid or minimize such Fresnel reflections. This can be achieved either through the use of anti-reflective coatings or by recapturing the Fresnel reflections and redirecting them through the lens.

[0008] For example, the patent EP 31 23076 B1 proposes a converging lens which, in a manner known per se, has a cup-shaped light-entry surface on the side facing the light source, roughly speaking, shaped like a blind hole. Light from the light source shining directly onto the bottom of the blind hole is deflected once at the aforementioned bottom surface and then again at the light-exit surface of the lens, while light striking the circumferential surface of the blind hole largely enters the lens body there, with a corresponding deflection, and is directed at the outer circumferential surface of the lens by total internal reflection to the light-exit surface, where it may then be emitted, possibly with a further deflection. The Fresnel reflections occurring at the aforementioned circumferential surface of the blind hole are projected onto the bottom surface of the blind hole by a convex contouring of the circumferential surface when viewed in longitudinal section.The aforementioned convex contouring is intended to throw these Fresnel reflections onto the bottom surface of the blind hole, in order to allow the Fresnel reflections to enter the lens there and be directed further as part of the beam of light.

[0009] However, the hourglass-like constriction of the inner circumferential surface of the blind-shaped light entry area of ​​the lens creates an undercut, which complicates injection molding and results in a negative draft angle. This inherently hinders the simple axial extraction of a molded part to form the blind hole. The aforementioned EP 31 23076 B1 therefore proposes manufacturing the lens in multiple parts and subsequently joining them together, or alternatively, manufacturing the lens from an elastic silicone material that is sufficiently flexible to allow enough expansion of the blind-shaped light entry area to extract the core. Both variants, however, have their respective disadvantages.Apart from these manufacturing disadvantages, in this previously known TIR lens according to EP 31 23076 B1, the Fresnel reflections are deflected at least twice at the lens interfaces by being recaptured and passed through the lens material, which can lead to further losses and also to further Fresnel reflections.

[0010] As mentioned above, attempts have already been made to apply elaborate anti-reflective coatings to lenses in order to reduce Fresnel reflections overall. However, such anti-reflective coatings are economically expensive, as they involve costly post-processing after the actual injection molding, typically target only one wavelength and angle of incidence, and are also susceptible to damage during subsequent use of the lens if it is not reliably protected from external influences.

[0011] The present invention is therefore based on the objective of creating an improved emitter of the type mentioned above, which avoids disadvantages of the prior art and advantageously develops the latter further. In particular, an increased optical efficiency of the emitter and a high optical quality of the beam with clear separation edges and defined beam boundary should be achieved, without requiring elaborate post-processing or complex manufacturing and assembly methods or special lens materials.

[0012] According to the invention, the aforementioned problem is solved by a radiator according to claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

[0013] It is therefore proposed to allow Fresnel reflections at the lens interfaces, but to direct them by cleverly contouring the lens so that they remain within the intended beam of radiation with which the emitter illuminates the target area.According to the invention, the lens has a passage opening for allowing an unreflected and undeflected direct light beam to pass through, on the entrance side of which the light source is positioned, wherein an inner circumferential surface enclosing said passage opening forms at least a partial light entrance surface of the lens, at which a portion of the light rays emitted by the light source enters the lens, is deflected by the lens by total internal reflection and emitted from a light exit surface as an indirect light beam, wherein said inner circumferential surface is contoured such that Fresnel reflections occurring at said inner circumferential surface are emitted through said passage opening and illuminate the target area as part of the direct light beam and / or the indirect light beam.

[0014] The Fresnel reflections occurring at the light entry surface of the lens can be emitted directly through the aforementioned aperture of the lens, without further deflection by refraction or reflection, and without the Fresnel reflections touching the lens surface again, thus avoiding corresponding light losses.

[0015] Since the light rays of the Fresnel reflections are kept within the direct light beam and / or within the indirect light beam, losses in photometric quality such as structural formation, scattered light artifacts or point-like light reflections, which would be visible from certain points or could even lead to glare, can also be avoided.

[0016] Depending on the lens design, the direct and indirect light beams can overlap or complement each other in the far field and on the target area, respectively. In particular, the direct and indirect light beams can overlap at least approximately congruently on the target area, with minor non-overlaps at the edges being negligible. For example, the coverage can be at least 75%, or even more than 85% or more than 95% of the target area illuminated by the two beams, i.e., the direct and indirect light beams. Alternatively, it would also be conceivable to direct the direct and indirect light beams onto different parts of the target area, especially in such a way that the illuminated areas do not overlap but are adjacent to each other.For example, this can be achieved by ensuring that the target area illuminated by the direct light beam and the target area illuminated by the indirect light beam are adjacent to each other along a straight or curved line. In the case of such non-overlap or complementary direct and indirect light beams within the target area, the inner circumferential wall of the lens aperture can be contoured so that the resulting Fresnel reflections strike the area illuminated by the direct light beam and / or the area illuminated by the indirect light beam.

[0017] The target area can be, for example, a flat surface, such as the surface of a tabletop to be illuminated. In this case, the spotlight can act as a downlight and / or emit a cone of light or a corresponding beam directed primarily downwards towards the tabletop. The main downward beam direction of the spotlight can be perpendicular to the plane of the tabletop or the flat target area, or it can be at an acute angle to it, so that the flat target area is illuminated at a slightly oblique angle.

[0018] The target area can also be an evaluation surface, as is frequently used for planning and designing room-, area-, or partial-area-related lighting in a space. This could be, for example, an upright evaluation surface defined for reading activities on cabinet and shelf surfaces, or a horizontal evaluation surface defined for a work area for meetings at a table or a group of chairs or armchairs, or for a work area for screen or office work at a desk. This is sometimes done in accordance with DIN 4543-1, DIN 5035-8, or DIN EN 12464-1. Instead of upright or horizontal evaluation surfaces, inclined or curved surfaces, such as cylindrical or semi-cylindrical ones, can also be considered.The spotlight can also function as a different type of indoor spotlight, for example, a wallwasher that can illuminate a wall surface with a sweeping beam, in which case the wall surface would be the flat target area. Similarly, the spotlight can also illuminate, for example, the floor surfaces of a hallway, a room, or an outdoor area, with the floor being the target area. The spotlight can also implement hybrid configurations, for example, using part of its beam to sweep a wall or shelving unit and another part to illuminate the floor, in particular such that the boundary between the areas illuminated by direct and indirect light lies at the transition between the wall and the floor. Further applications for the spotlight are conceivable.

[0019] Depending on the illumination task and the arrangement or orientation of the target area relative to the light source, the direct light beam and / or the indirect light beam formed by the lens can be symmetrical, particularly rotationally symmetrical. For example, if a rectangular target area such as a tabletop is to be illuminated, the lens can form a pyramid-shaped beam, particularly in the form of a right pyramid, whereas for a round or rounded target area, the lens can form, for example, a conical beam or a beam with an elliptical cross-section.

[0020] When illuminating a flat target area at an oblique angle, or even slightly convex or concave target areas, the lens can also be designed to form an asymmetric beam or to generate an asymmetric light distribution within the beam in order to achieve at least an approximately uniform light distribution in the target area. In principle, however, such an asymmetric beam configuration can also be projected perpendicularly onto a flat target area or a differently contoured target area, depending on the desired illumination scenario. In both cases, i.e.,For symmetrically or asymmetrically shaped beams of light, the aforementioned Fresnel reflections are advantageously kept within the direct light beam and / or the indirect light beam by directing the Fresnel reflections from the aforementioned inner circumferential surface of the lens, which surrounds the aperture, directly through the aperture into the target area.

[0021] The aforementioned inner circumferential surface could, in principle, be designed to emit light convergently, in order to radiate the Fresnel reflections convergently through the aperture. The rays entering the lens body at this inner circumferential surface are deflected only shallowly at the interface. However, this can be compensated for by giving the outer circumferential surface of the lens a sufficiently steep contour to ultimately direct the indirect light beam in the desired direction.

[0022] Alternatively, the aforementioned inner circumferential surface surrounding the aperture can also be designed to emit light divergently, so that the Fresnel reflections are emitted divergently through the aperture. With such a divergent design, a compact lens contour, requiring only a small height, can be achieved, since light rays entering the lens body are deflected more strongly at the interface of the inner circumferential surface, allowing the outer circumferential surface of the lens to be made flatter, resulting in an overall compact and flat lens contour. In other words, a low lens height can be achieved through the divergent design.

[0023] The aforementioned inner circumferential surface, viewed in longitudinal section of the lens, can have a convex or concave curvature, which may extend, for example, over essentially the entire height of the inner circumferential surface or over the portion of the inner circumferential surface that acts as the light-entry surface. Alternatively, the aforementioned inner circumferential surface, again viewed in section, may have a straight contour, for example, a conical shape, although hybrid forms of concave and / or convex curved sections and / or straight sections are also possible.

[0024] The lens can have a totally reflective outer circumferential surface, at which the light rays entering at the inner circumferential surface are reflected by total internal reflection, either directly or, if necessary, via further deflection at another lens contour, onto the light-exiting surface of the lens. In this case, the lens forms a TIR lens, which is advantageously designed to be singly reflective and can be configured so that the light rays are reflected only at the aforementioned outer circumferential surface.

[0025] If necessary, the aforementioned outer circumferential surface can also be coated with a reflective material, which ensures reflection at the outer circumferential surface of the lens without excessively restricting the contouring of the outer circumferential surface.

[0026] Instead of such a reflective coating on the outer circumferential surface of the lens, an alternative embodiment of the invention can also employ a reflector element, in particular a shell-shaped reflector element, which is spaced apart from the outer circumferential surface of the lens and captures light rays exiting the outer circumferential surface of the lens and directs them into the target area by reflection. With such a hybrid design of the optical system of the emitter, which then comprises the aforementioned lens on the one hand and a reflector shell spaced apart from it on the other, the emitter can be built compactly overall, particularly with regard to its height in the longitudinal direction of the aperture.

[0027] However, in order to keep the light losses low, it can be advantageous if the optics consist solely of the aforementioned lens or if a separate, spaced-away reflector is dispensed with, in particular the lens can be designed to be totally reflective in the manner mentioned.

[0028] In a further development of the invention, the lens aperture can continuously widen from the light source to the light-exit side of the lens, such that the cross-sectional area of ​​the aperture increases with increasing distance from the light source in cross-sectional planes perpendicular to the longitudinal axis of the aperture. In particular, the aperture can have a minimum cross-sectional area at its inlet and a maximum cross-sectional area at its outlet on the light-exit side of the lens, with the cross-sectional area increasing continuously from the light source to the light-exit side of the lens.

[0029] The contour of the circumferential wall surrounding or limiting the aperture, which also forms at least a partial light-entry surface, can fundamentally vary depending on the desired illumination of the target area and its orientation relative to the light source. However, an advantageous variant is always one where the aperture, viewed in a longitudinal section (which may include the aperture's longitudinal axis), widens in a harmonious curve, particularly in a trumpet-like shape, exhibiting a convex curvature in longitudinal section.

[0030] Alternatively, if the aperture widens continuously from the light source to the light exit side, it can also have an approximately straight contour when viewed in longitudinal section. With a rotationally symmetric lens, the aperture can be conical or frustoconical. However, with an asymmetric or non-rotationally symmetric lens, such a straight contour of the inner circumferential surface in longitudinal section can also result in, for example, a tulip-shaped or shell-segmented contour of the aperture.

[0031] In a further development of the invention, the inner circumferential wall, viewed in longitudinal section, can also exhibit hybrid forms consisting of straight and curved contour sections. For example, the inner circumferential wall, viewed in longitudinal section, can have a curved section, which may be oriented towards the light source, and a straight contour section, which may be oriented towards the light emission side. The aforementioned curved section can be concave or convex.

[0032] The straight contour section on the exit side can be spread out at a greater opening angle than the tangents to the curved contour section on the entrance side. For example, the contouring can be designed such that light rays entering the aperture from the light source illuminate only the curved contour section, and the section of the aperture with a straight contour on the exit side serves merely as a light-emitting surface, particularly for light rays that are reflected from the totally internally reflecting outer circumferential surface onto the aforementioned straight contour section.

[0033] The lens body can completely enclose the aforementioned opening circumferentially, forming a closed ring / body around it. Alternatively, it would also be possible to design the lens body only as a partial ring or a slotted ring, in which case the aforementioned opening is not completely enclosed by the inner circumferential surface, but, for example, only over a circumferential angle of more than 180°, more than 270°, or more than 315°.

[0034] The invention is explained in more detail below with reference to preferred embodiments and accompanying drawings. The drawings show:

[0035] Fig. 1: a perspective view of a spotlight for illuminating a worktable according to an advantageous embodiment of the invention,

[0036] Fig. 2: a sectional view through the lens of the emitter from Fig. 1 according to an advantageous embodiment of the invention, wherein the representation shows a beam path of the direct light beam, the indirect light beam, and the Fresnel reflections; Fig. 3: a graphical representation of the luminous intensity distribution of the beam produced by such lenses in the target area and in the far field, respectively, in a Cartesian and a polar representation, wherein partial view a) shows a symmetrical distribution and partial view b) shows a distribution asymmetrical in at least one plane.

[0037] Fig. 4: a sectional view of the lens from Fig. 2, in which an additional Fresnel reflection at the light exit surface of the lens and its beam path are shown schematically,

[0038] Fig. 5: a half-section of a lens according to a further advantageous embodiment of the invention, the light-emitting surface of which, viewed in longitudinal section, is inclined or, viewed overall, has a conical contour, so that the totally reflected beam of light - unlike in Figures 2 and 4 - is more strongly expanded and has an angle of expansion similar to the direct light beam, wherein the Fresnel reflections occurring on the aforementioned inner circumferential surface and the Fresnel reflections occurring on the light-emitting surface are each shown with a beam path.

[0039] Fig. 6: a half-section through a lens similar to Fig. 5, wherein the inner circumferential contour and the outer circumferential contour as well as the light exit surface of the lens are positioned differently than in Fig. 5, so that, unlike in Fig. 5, the direct light beam is wider than the indirect light beam.

[0040] Fig. 7: a half-section of a lens according to a further embodiment of the invention, the inner circumferential, outer circumferential and light-exit surfaces of which are contoured such that the Fresnel reflections behave convergently and the rays entering the lens are divergent after the first boundary transition; Fig. 8: a perspective view of a lens according to a further embodiment of the invention, the inner circumferential surface of which comprises several segments, each composed of differently curved sections or of a curved section and a straight section.

[0041] Fig. 9: a perspective view of a lens according to a further advantageous embodiment of the invention, which, in contrast to the lens according to Fig. 8, is not contoured in a segmented manner.

[0042] Fig. 10: a longitudinal half-section through a hybrid optic of the emitter according to a further embodiment of the invention, which, in addition to a lens, has a separate reflector spaced apart from the lens,

[0043] Fig. 11: Longitudinal section views of three lenses for different radiation angles,

[0044] Fig. 12: a longitudinal section through a lens according to a further embodiment of the invention, which emits an asymmetrically shaped beam of light, wherein the luminous intensity distribution of the asymmetric beam of light in the target area is shown next to the lens,

[0045] Fig. 13: a perspective view of the lens from Figure 12, and

[0046] Fig. 14: a perspective view of several ceiling spotlights for illuminating a workroom with several worktables according to an advantageous embodiment of the invention, wherein each ceiling spotlight illuminates a partial area of ​​the workroom and an evaluation area serving as a target area is shown, which is partially illuminated by the ceiling spotlights.

[0047] As shown in Fig. 1, the spotlight 1 can, for example, serve as workplace lighting and illuminate the tabletop 16 of a worktable 14 on which, for example, a monitor 15 of a computer workstation is placed. The tabletop 16, or rather its surface, forms an example of a flat target area 4 that is illuminated by the spotlight 1.

[0048] As shown in Fig. 1, the emitter 1 can illuminate the target area 4 with its main emission direction 13 approximately perpendicularly, but a sweeping illumination of the target area 4 can also be provided, in which the main emission direction 13 can be inclined at an acute angle to the target area 4.

[0049] For example, the spotlight 1 can be positioned off-center above the tabletop 16, see Fig. 1, although, as mentioned, this is only one application example of the spotlight 1.

[0050] As illustrated in Figure 14, the spotlight 1 can also be designed or mounted as a ceiling spotlight and likewise illuminate a horizontal target area 4 approximately vertically from above, with several spotlights 1 being able to illuminate a workspace together. The target areas 4 of the several spotlights can lie in a common evaluation area 40 and overlap there, whereby the aforementioned evaluation area 40 can be a horizontal evaluation plane approximately at the height of the worktables 14, cf. Figure 14.

[0051] As further figures 2-13 illustrate, the spotlight 1 comprises a light source 3, the light of which is captured by a lens 2 and shaped into a beam 11 that illuminates the aforementioned target area 4, cf. Fig. 1 and 14.

[0052] Light source 2 can be a hemisphere radiator and / or a point source, with light source 3 being, for example, an LED. However, light source 3 does not necessarily have to be a point source; it can also have a limited area, for example, in the form of an LED cluster.

[0053] The lens 2 is designed and arranged relative to the light source 3 in such a way that only a part of the light emitted by the light source 3 is actually captured, and an uncaptured part is emitted past the lens 2 as a direct light beam D.

[0054] The portion of the light from the light source 3 captured by the lens 2 is shaped by the lens 2 into an indirect light beam T, see Fig. 2, Figs. 4 to 7, Fig. 10, and Fig. 12, which also illuminates the target area 4 at least partially. The lens 2 can be designed and arranged relative to the light source 3 such that the aforementioned direct and indirect light beams D, T overlap at least approximately completely or are congruent with each other in the target area 4, for example, on the tabletop 16. To illuminate the tabletop 16 or a rectangular target area 4, the direct and indirect light beams D, T can be pyramid-shaped or contoured like a pyramid with a rectangular base, although conical beams can also be formed depending on the target area, see Fig.14, or beams of light can also be formed in cross-section as elliptical, hexagonal, or generally polygonal shapes. Asymmetrical beams of light can also be formed, see Figs. 12 and 13.

[0055] As illustrated in Figures 2, 4-7, 10, and 12, Fresnel reflections F occur at lens 2. These reflections are unintentional and are generated by a portion of the light that is intended to be captured by or strikes lens 2. Lens 2 is contoured in such a way that at least some of these Fresnel reflections F, particularly those generated at the light-entry surface 8, are contained within the direct light beam D and / or within the indirect light beam T, thus contributing to the illumination of the target area 4.

[0056] Fresnel reflections occurring at the light-emitting surface 10 can be reflected back, whereby such Fresnel reflections V can be directed at least approximately back towards the light source 3 by skillfully contouring the light-emitting, outer, and inner circumferential surfaces, cf. Figures 4 and 6. As Figures 2 and 4-11 show, the lens 2 can, in particular, have a passage opening 5, which can be designed like a through-hole and, for example, can pass approximately centrally through the lens 2. Regardless of this, the passage opening 5 can be arranged with its longitudinal axis 17 at least approximately parallel or at least approximately coaxial to the main emission direction of the light source 3. For example, the aforementioned longitudinal axis 17 of the passage opening 5 can form an axis of symmetry of the lens 2, which is of course not the case if the lens is designed asymmetrically, as shown in Figure 12.

[0057] The light source 3 can advantageously be arranged in the region of the inlet 6 of the passage opening 5 and oriented such that at least a large part of the light emitted by the light source 3 falls into said passage opening 5 and onto the inner circumferential surface 8 of the lens 2 surrounding the passage opening 5, cf. Fig. 2 and Figs. 4-10. In particular, said light source 3 can be positioned in the inlet 6 or in the inlet-side opening cross-section of the passage opening 5, so that, if the light source 3 is designed as a hemispherical radiator, on the one hand the light emitted by the light source 3 falls completely into the passage opening 5 or the inner circumferential surface 8 surrounding it, and on the other hand the inner circumferential surface 8 is used efficiently for deflection, so that a short overall height of the lens 2 can be achieved.

[0058] The part of the light emitted by the light source 3 that passes through the aperture 5 without striking the inner circumferential surface 8 of the lens 2 and without touching any other lens surface forms the direct light beam D, the radiation angle of which is determined by the contouring of the aperture 5 and the position of the light source 3.

[0059] The portion of the light emitted by the light source 3 that falls on the inner circumferential surface 8 of the lens 2 largely enters the body of the lens 2, where the light rays undergo a corresponding deflection at the interface, i.e., at the inner circumferential surface 8 (see Figures 2 and 4-10), so that the entering and deflected light rays fall on the outer circumferential surface 9 of the lens 2. The outer circumferential surface 8 can be contoured, or its contour can be adapted to the inner circumferential surface 8 and the light rays deflected by it, such that the light rays are deflected at the aforementioned outer circumferential surface 9 by total internal reflection and directed onto the light-exiting surface 10 of the lens (see Figures 2, 4-10, and 12).

[0060] The aforementioned light-emitting surface 10 can be formed, in particular, by the side of the lens 2 that faces the light source 3. Considering the orientation of the lens 2 according to Figures 2 and 4-11, the upper surface of the lens 2 forms the aforementioned light-emitting surface 10, while the side facing the light source forms the lower surface.

[0061] As already explained, the aforementioned outer circumferential surface 9 may optionally be coated with a reflective material to enhance reflection at the outer circumferential surface 10 or to reduce the restriction of the contouring of the outer circumferential surface 10. Optionally, a reflector 18 may also be provided opposite the outer circumferential surface 9, which may be arranged and contoured in such a way as to deflect light rays emerging from the outer circumferential surface 9 and direct them into the target area 4, whereby in this case, see Fig. 10, the lens 2 together with the reflector 18 forms the indirect light beam T.

[0062] The inner circumferential surface 8 surrounding the passage opening 5 thus forms at least partially the light entry surface 10 of the lens 2, at which part of the light rays 12 emitted by the light source 3 enters the lens 2.

[0063] On the other hand, the aforementioned inner circumferential surface 8 is contoured with regard to the inherently undesirable Fresnel reflections F in such a way that Fresnel reflections F occurring on the inner circumferential surface 8 are emitted through the aperture 5 and illuminate the target area 4 as part of the direct light beam D and / or the indirect light beam C. The inner circumferential or light-entry surface 8 thus fulfills the dual function of, firstly, directing the light rays actually entering the lens material in a suitable direction towards the outer circumferential surface 9 of the lens 2, and secondly, emitting the resulting Fresnel reflections F through the aperture 5 and thereby retaining them within the direct light beam D and / or the indirect light beam C in order to illuminate the target area 4.

[0064] The aforementioned inner circumferential surface 8 of the lens 2 can be contoured in such a way that the aforementioned Fresnel reflections F are emitted directly into the target area 4 through the aforementioned aperture 5 without deflection or reflection and without further contact with the lens 2, cf. e.g. Fig. 2 and 4 to 10.

[0065] As illustrated by Figures 2, 4, 5, and 6, the aforementioned inner circumferential surface 8 can be configured to emit the Fresnel reflections F divergently. A comparison with Figure 7, whose lens 2 emits the Fresnel reflections F convergently, shows that a lens configuration for divergent emission of the Fresnel reflections helps to achieve a compact lens size, in particular a short height H.

[0066] Regardless of this, it may be advantageous if the aforementioned passage opening 5 widens continuously in the cross-sectional area from the light source 2 to the light exit side of the lens 2.

[0067] As shown in Figures 2, 4, 5 and 6, it can be advantageous if the passage opening 5 widens continuously and harmoniously in a curved shape from the light source 2 to the light exit side of the lens 2, in particular widening in a trumpet shape and having a convex curvature when viewed in longitudinal section.

[0068] Alternatively, the passage opening 5 can also widen continuously from the light source 3 to the light exit side of the lens 2 and, viewed in longitudinal section, have at least an approximately straight contour.

[0069] According to a hybrid form, the aperture 5 can also widen continuously from the light source 3 to the light exit side of the lens 2 and thereby have at least two sections with different contours, in particular a curved section viewed in longitudinal section and a straight contour section viewed in longitudinal section, cf. Fig. 8.

[0070] Regardless of this, the lens 2 can have a segmented contour, e.g., be composed of several segments that are identical or different from each other in the circumferential direction, see also Figure 8.

[0071] Overall, the lens 2 can form an annular lens body that extends around the central aperture 5 in a closed ring or in the manner of a slotted ring, see Fig. 2 and 4 to 9. The lens 2 can also have an annularly closed lens body if the lens has differently contoured sections and / or is designed to form an asymmetrical beam of light, see Fig. 13.

[0072] Regardless of this, the lens body can have a maximum height H which, measured in the direction of the longitudinal axis of the passage opening 5, is less than 75% or less than 50% or less than 33% of a maximum transverse extent of the lens body, measured perpendicular to the height H, cf. Figure 11.

[0073] Regardless of this, the lens 2 can have a convex or, in longitudinal section, straight outer circumferential surface 9, which can continuously widen in the direction from the light source 3 to the light exit surface 10, cf. Fig. 2 as well as 4 to 9 and 11, wherein a / the maximum transverse extent of the lens 2 can be located at the light exit side of the lens and is, for example, more than 150% or more than 200% of a minimum transverse extent of the lens, which can be located at the lens side opposite the light exit side.

[0074] In particular, the outer circumferential surface 9 can be harmoniously and / or shell-shaped curved and / or consist of harmoniously and / or shell-shaped curved segments, similar to how the inner circumferential surface 8 is shown in Figure 8.

Claims

Claims 1. A luminaire comprising at least one light source (3) and a lens (2) for forming a beam (11) for illuminating a target area (4), wherein the lens (2) has a passage opening (5) for allowing an unreflected, undeflected direct light beam (D) to pass through, in the entrance region (6) of which the light source (3) is positioned, wherein an inner circumferential surface (8) surrounding said passage opening (5) forms at least a partial light entry surface (10) of the lens (2), at which a portion of the light rays (12) emitted by the light source (3) enters the lens (2), is deflected by the lens (2) and emitted from a light exit surface (10) of the lens (2) as an indirect light beam (T), wherein said inner circumferential surface (8) is contoured in such a way thatthat Fresnel reflections (F) occurring on the inner circumferential surface (8) are emitted through the passage opening (5) and illuminate the target area (4) as part of the direct light beam (D) and / or the indirect light beam (C).

2. Radiator according to the preceding claim, wherein the lens (2) is not designed to be imaging and the direct light beam (D) and the indirect light beam (T) overlap at least partially in the target area (4), in particular being at least approximately congruent in the target area (3).

3. Radiator according to one of the preceding claims, wherein the inner circumferential surface (8) of the lens (2) is contoured such that the Fresnel reflections (F) occurring on the inner circumferential surface (8) are emitted directly into the target area (4) through the passage opening (5) without deflection or reflection.

4. Radiator according to one of the preceding claims, wherein said inner circumferential surface (8) is configured to emit the Fresnel reflections (F) divergently.

5. Radiator according to one of the preceding claims, wherein the lens (2) has a totally reflective outer circumferential surface (9) on which light rays entering at the inner circumferential surface (8) are reflected directly onto the light exit surface (10) of the lens (2) by total internal reflection.

6. Emitter according to one of the preceding claims, wherein the said passage opening (5) continuously widens in the cross-sectional area from the light source (2) to the light exit side of the lens (2).

7. Radiator according to the preceding claim, wherein the passage opening (5) widens continuously and harmonically in a curved manner from the light source (2) to the light exit side of the lens (2), in particular widening in a trumpet shape and having a convex curvature when viewed in longitudinal section.

8. Radiator according to claim 6, wherein the passage opening (5) widens continuously from the light source (3) to the light exit side of the lens (2) and has an at least approximately straight contour when viewed in longitudinal section.

9. Emitter according to one of claims 1 to 5, wherein the passage opening (5) extends continuously from the light source (3) to the light exit side of the lens (2). lieh extended and has at least two sections with different contouring, in particular a curved section viewed in longitudinal section and a straight contour section viewed in longitudinal section.

10. Emitter according to one of the preceding claims, wherein the direct light beam (D) and / or the indirect light beam (T) is asymmetrically shaped in the target area (4).

11. Emitter according to one of claims 1 to 9, wherein the direct light beam (D) and / or the indirect light beam (T) is symmetrically shaped, in particular rotationally symmetrically shaped, in the target area (4).

12. Radiator according to one of the preceding claims, wherein the target area (4) forms a flat surface which is arranged inclined at right angles or at acute angles to a main emission direction (13) of the lens (2).

13. Radiator according to one of the preceding claims, wherein the lens (2) forms an annular lens body which extends around the central passage opening (5) in a closed ring or in the manner of a slotted ring, wherein the lens body has a maximum height (H), measured in the direction of the longitudinal axis of the passage opening (5), which is less than 75% or less than 50% or less than 33% of a maximum transverse extent of the lens body, measured perpendicular to the height (H).

14. Emitter according to one of the preceding claims, wherein the lens (2) has an outer circumferential surface (9) which continuously widens in the direction from the light source (3) to the light emission surface (10), and / or a maximum transverse extent of the lens (2) is present at the light emission side of the lens and is more than 150% or more than 200% of a minimum transverse extent of the lens which is present at the lens side opposite the light emission side.

15. Radiator according to the preceding claim, wherein the outer circumferential surface (9) is harmonically and / or bowl-shaped curved and / or consists of harmonically and / or bowl-shaped curved segments.

16. Emitter according to one of the preceding claims, wherein the light source (3) is a hemisphere emitter arranged at the entrance (6) of the passage opening (5) such that the light emitted by the light source (3) falls completely into the passage opening (5) and onto the inner circumferential surface (8) of the lens (2) surrounding the passage opening (5).

17. Emitter according to one of the preceding claims, wherein the light source (3) is a point light source, in particular in the form of an LED, or a planar extended light source, in particular in the form of an LED cluster.

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