Light generating system comprising truncated ball lens

Abstract

: The invention provides a light generating system (1000) comprising a light source array (1010) and a first lens (100), wherein the light source array (1010) comprises a plurality of light sources (10), wherein the first lens (100) is a solid truncated sphere lens (400), the truncated sphere lens (400) comprising a planar surface (110) and a rounded surface (120), wherein the planar surface (110) is arranged in a light receiving relationship with the plurality of light sources (10), wherein the rounded surface (120) is shaped according to a surface of a virtual sphere (425) having a radius (R0) and takes up at least 66% of a spherical surface (420) of the virtual sphere (425), wherein an axis (A) perpendicular to the planar surface (110) intersects the first lens (100) for a distance (d1), wherein d1 is selected from the range of 1.33*R0 – 1.90*R0.

Description

[0001] LIGHT GENERATING SYSTEM COMPRISING TRUNCATED BALL LENS

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light generating system. The invention further relates to a lighting device comprising the light generating system. The invention further relates to an arrangement comprising the lighting device.

[0004] BACKGROUND OF THE INVENTION

[0005] Light generating systems are known in the art. For instance, US2012287621 Al describes a LED array spot illuminator for providing light along an optical axis comprising a substrate and at least one array of multiple LED chips without individual packaging supported by the substrate, wherein the LED chips emit light within the same or different wavelength ranges and are distributed laterally with respect to the axis over a lightemitting area. The LED chips have light emitting surfaces for emitting light in directions transverse to the area. An optical device collects and directs light emitted by the LED chips of the at least one array along the axis. An aperture passes the light emitted by the LED chips of the at least one array along the axis, wherein light collected by the optical device and passed by the aperture forms a beam of light illuminating a spot. Electric current is supplied to the multiple LED chips, causing them to emit light. Light emitted by the multiple LED chips that passed through the optical device and the aperture form a beam of light illuminating a spot. A distance between the multiple LED chips and one or more elements of the optical device is controlled to select a size of the spot.

[0006] WO2022253821 Al discloses a lighting device comprising a truncated sphere lens as a light distributing body.

[0007] US2012268945A1 discloses a LED illumination device comprising a truncated sphere lens.

[0008] EP2208988A1 discloses a LED lighting device comprising a truncated sphere lens.

[0009] DE202023101765U1 discloses a LED lighting device comprising a substantially spherical lens as a light distributing body. SUMMARY OF THE INVENTION

[0010] The invention is set out in the appended set of claims. Multi-zone shelf lighting may provide a promising development for making retail lighting more attractive and effective. A lighting system, centrally mounted in an aisle can illuminate different areas or zones on the shelves of the retail shop. Such a system may illuminate various products on the shelves, with the objective, for instance, to draw attention to the exposed products, or to help customers decide, or to create a dynamic, energizing atmosphere. Such a lighting system may require a multitude of light beams that can be individually addressed.

[0011] The prior art may describe mechanical systems to steer light beams. However, such systems may have relatively poor reliability. Therefore, in practice, many luminaires may be required, as many as there are addressable zones, which may lead to a high system complexity and prohibitively high installation costs.

[0012] The prior art may further describe a lighting system that can generate various light beams illuminating various zones by installing a multitude of small spotlights, i.e., LED light sources with optics, each pointing in a different direction. This, however, may lead to a bulky system due to the optics required to generate a narrow beam.

[0013] The prior art may further describe a lighting system comprising an addressable array of LEDs with a single free-shape lens configured such that each pixel creates a diffuse spot on a target surface. However, the optics may have relatively poor efficiency, leading to a low lighting efficiency and low lighting intensity.

[0014] The prior art may further describe lighting systems using free-shape and / or aspheric lenses, the manufacturing of which may involve high-precision machining and molding and, as a consequence, relatively high manufacturing complexity and costs.

[0015] Hence, it is an aspect of the invention to provide an alternative light generating system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0016] According to a first aspect, the invention provides a light generating system comprising a light source array and a first lens. The light source array may comprise a plurality of light sources. Further, the first lens may comprise a solid truncated sphere lens. The first lens, especially the solid truncated sphere lens, may comprise a planar surface and a rounded surface, especially wherein the planar surface is arranged in a light receiving relationship with the plurality of light sources. In embodiments, the rounded surface may be shaped according to a (portion of a) surface of a virtual sphere, wherein the virtual sphere has a radius RO. The rounded surface may especially take up (or “match”) at least 66% of a spherical surface of the virtual sphere. Especially, a (virtual) axis (A) perpendicular to the planar surface intersects the first lens for a (longest) distance (dl), wherein dl is selected from the range of 1.33*R0 - 1.90*R0.

[0017] In specific embodiments, the invention may provide a light generating system comprising a light source array and a first lens, wherein the light source array comprises a plurality of light sources, wherein the first lens is a truncated sphere lens comprising a planar surface and a rounded surface, wherein the planar surface is arranged in a light receiving relationship with the plurality of light sources, wherein the rounded surface is shaped according to a [portion of a rounded / spherical] surface of a virtual sphere having a radius (RO) and takes up at least 66% of a spherical surface of the virtual sphere, wherein an axis (A) perpendicular to the planar surface intersects the first lens for a distance (dl), wherein dl is selected from the range of 1.33*R0 - 1.90*R0.

[0018] Thereby, the light generating system of the invention may facilitate generating various light beams illuminating various zones while maintaining high lighting efficiency. In particular, the directions of the beams can be selected in an electronic (non-mechanical) way by controlling the operation of the light source array. The system of the invention may be particularly suitable for applications in shelf (high-)lighting.

[0019] Other application areas for the light generating system are shopping windows where details of mannequins and accessories and other displayed products are to be highlighted. Also, in museums and art galleries, the light generating system of the invention may enable a more versatile and tailored illumination of the artwork while simultaneously reducing cluttering at the ceiling. Other potential application areas are office lighting, entertainment lighting for dynamic patterning, and road & street lighting, where targeted lighting enables to illuminate only the zones needed (e.g., where people are present, or where the road is) hence leading to energy saving.

[0020] Hence, the invention may provide a light generating system. Such system may herein also be referred to as a lighting system. The light generating system may especially be configured to generate system light, wherein the system light comprises at least part of light source light (see below).

[0021] The light generating system may comprise a light source array. The light source array may especially comprise a two-dimensional light source array, i.e., the light source array may comprise a plurality of light sources arranged according to a 2D grid, especially an nl*n2 2D grid, wherein nl*n2=n (see also below), and wherein nl > 2, and wherein n2 > 2, and especially wherein nl=n2. In further embodiments, the light source array may comprise a one-dimensional light source array, especially a l*n array. The light source array may, in embodiments, comprise n solid state light sources, especially wherein n > 4, such as > 6, especially > 12, such as > 24, especially > 36. In further embodiments, n < 1296, such as < 1024, especially < 900. In further embodiments, n < 225, such as < 144, especially < 100, such as < 64. In further embodiments, n < 49, such as < 36, especially < 25. For instance, n may be selected from the range of 12 - 144, especially from the range of 24 - 100, such as from the range of 36 - 64. In further embodiments, n may be selected from the range of 9 - 49, such as from the range of 16-36. In embodiments, the light source array may comprise a laser bank comprising n solid state (laser) light sources. Hence, in embodiments, the light sources may comprise solid state (laser) light sources.

[0022] The light sources, especially the solid state (laser) light sources, may be configured to provide light source light. In embodiments, the light sources may be configured to generate blue light source light, optionally wherein (at least part of) the blue light source light is provided to a luminescent material configured to convert the blue light source light into light of a different wavelength, such as green light source light. In further embodiments, the solid state (laser) light sources may be configured to provide (cool) white light source light. For instance, in embodiments, the solid state (laser) light sources may comprise one or more of: a first subset of light sources configured to provide red light source light, a second subset of light sources configured to provide blue light source light, and a third subset of light sources configured to provide green light source light.

[0023] In particular, in embodiments, the light generating system may comprise a plurality of light source arrays, especially aligned light source arrays. The term “aligned” in “aligned light source array” may herein especially refer to light sources of the light source arrays being configured to provide light source light along the same optical axis. Especially, the term “optical axis” may be defined as an imaginary line that defines the path along which light propagates through a system starting from the light generating element, here especially the light source. Especially, the optical axis may coincide with the direction of the light with the highest radiant flux. Hence, especially the light sources of the plurality of light source arrays may have essentially parallel optical axes.

[0024] Especially, in embodiments, each light source array may comprise a (respective) plurality of light sources, wherein the light sources of different light source arrays are configured to provide light source light with different spectral distributions. In particular, in embodiments wherein the light generating system comprises a plurality of light source arrays, the light generating system may further comprise a plurality of first lenses, wherein each first lens is arranged in a light receiving relationship with a respective light source array.

[0025] Specifically, multiple light source arrays may be used to provide for a color tunable pixelated spot, e.g., providing 3 pixelated sources - 1 for each primary color - and arranging them such that the “images” are overlaid in the far field. Arranging the arrays in close proximity may improve the overlay. In embodiments further comprising condenser lenses (see below), it may be preferred to truncate the condenser lenses to provide shared interfaces between the condenser lenses, at least at the sides where they are adjacent to one another. In that case the pixels in the corners (of the light source arrays) will not be used as the light from those pixels of at least one of the primaries will not get the proper optical path. This implies that the image of the source gets rounded edges, which may be desired for certain lighting applications.

[0026] In further embodiments, each light source array may comprise n light sources, wherein for each light source array n is individually selected from the range of > 4, such as > 6, especially > 12, such as > 24, especially > 36. In further embodiments, for each light source array n is individually selected from the range of < 225, such as < 144, especially < 100, such as < 64.

[0027] In further embodiments, each light source array may comprise n light sources, wherein n is selected from the range of > 4, such as > 6, especially > 12, such as > 24, especially > 36. In further embodiments, n is selected from the range of < 225, such as < 144, especially < 100, such as < 64. For instance, n may be selected from the range of 12 - 144, especially from the range of 24 - 100, such as from the range of 36 - 64. Each light source array having a same number of light sources may be particularly convenient as sets comprising light sources from different arrays may together illuminate the same location (or “pixel” in a target plane, i.e., different colors may have the same resolution.

[0028] In embodiments wherein the light generating system comprises a plurality of (aligned) light source arrays, the light source arrays may especially be configured to provide light source light having different spectral distributions. For instance, in embodiments, a first light source array may comprise blue light sources configured to provide blue light source light, a second light source array may comprise green light sources configured to provide green light source light, especially wherein each green light source comprises a blue LED and a luminescent material layer configured to convert blue light to green light, and a third light source array may comprise red light sources configured to provide red light source light, especially wherein each red light source comprises a blue LED and a luminescent material layer configured to convert blue light to red light.

[0029] In embodiments, the light generating system may further comprise a first lens, especially wherein the first lens is a solid truncated sphere lens. The first lens, especially the solid truncated sphere lens, may comprise a planar surface and a rounded surface. In particular, the first lens may have a total surface area (Atot), wherein the planar surface has a planar surface area (Ap), wherein the rounded surface has a rounded surface area (Ar), and wherein (Ap+Ar) / Atot > 0.8, such as > 0.9, especially > 0.95, such as > 0.99, including 1. Hence, in embodiments, the planar surface and the rounded surface may (together) essentially define the (total) surface of the first lens.

[0030] The term “truncated sphere lens” may herein refer to a lens having a shape approximating the shape of a truncated sphere. Specifically, the truncated sphere lens may have a shape approximating a spherical cap, especially wherein the height H of the spherical cap exceeds the radius of the sphere (from which the cap was removed).

[0031] In further embodiments, the first lens may comprise a third surface, wherein the third surface borders the planar surface and / or the rounded surface, especially the planar surface and the rounded surface. The third surface may especially be a further planar surface, such as arranged at an angle to the planar surface. However, such a further planar surface may generally be detrimental to the performance of the light generating system, e.g., due to an increase of total internal reflection. Hence, in general, the first lens may be devoid of a third surface. In particular, in embodiments, a total surface of the first lens may consist of the planar surface and the rounded surface.

[0032] The planar surface may, in embodiments, comprise an (essentially) smooth surface. In particular, in further embodiments, the planar surface may have an arithmetic average profile roughness Ra < 30 nm, such as < 20 nm, especially < 15 nm.

[0033] Similarly, the rounded surface may, in embodiments, comprise an (essentially) smooth surface. In particular, in further embodiments, the rounded surface may have an arithmetic average profile roughness Ra < 30 nm, such as < 20 nm, especially < 15 nm. The rounded surface may especially be devoid of lenslets.

[0034] The term “arithmetic average profile roughness Ra” herein refers to the average height deviation on a surface relative to the mean height of the surface. In particular, Ra herein refers to the profile roughness parameter Ra as defined in the ISO 4287: 1997 standard. In specific embodiments, the planar surface may comprise a lens surface.

[0035] In embodiments, the planar surface may be arranged facing and (essentially) parallel to the light source array. In particular, an (average) optical axis of the plurality of light sources may be (essentially) perpendicular to the planar surface, especially wherein the (average) optical axis intersects the planar surface at the center of the planar surface, such as at a distance d4 from the center, wherein d4 / R0 < 0.10 (see also below), such as < 0.05, especially < 0.01, including (essentially) 0. Especially, the planar surface may be arranged in a light receiving relationship with the plurality of light sources. In embodiments, the first lens may be arranged (relative to the first light source array) such that the first lens captures at least 80% of light source light escaping the plurality of light sources, such as at least 90%, especially at least 95%, including (essentially) 100%.

[0036] In particular, in embodiments, the planar surface and the plurality of light sources may be arranged separated by a second distance (d2), i.e., the plurality of light sources may be arranged at a second distance (d2) from the planar surface, wherein d2 is selected from the range of 0.005 - 1 mm, especially from the range of 0.01 - 0.5 mm, such as from the range of 0.02 - 0.25 mm.

[0037] The first lens may especially be configured such that light source light captured by the planar surface will exit the first lens through the rounded surface.

[0038] The rounded surface may especially be shaped according to (a portion of) a surface of a virtual sphere having a radius R0. The phrase “surface of a virtual sphere” may especially refer to a rounded surface of the virtual sphere or, in other words, to a spherical surface of the virtual sphere. In particular, the rounded surface may take up (or “match”) at least 60% of a spherical surface of the virtual sphere (having radius R0), such as at least 66%, especially at least 75%, such as at least 80%.

[0039] Hence, the first lens may have a shape partially approximating a ball lens (or “sphere lens”), wherein the shape is truncated, thereby defining the planar surface, i.e., the first lens may comprise a truncated sphere lens. In particular, the rounded surface may approximate (the surface of) a ball lens or a sphere, i.e., the rounded surface may define a 3D shape, wherein the 3D shape approximates part of a ball lens or a sphere.

[0040] The term “approximate” and its conjugations herein, such as in “to approximate a shape”, refers to being nearly identical to, especially identical to, the following term, for example nearly identical to a ball lens or a sphere. For example, a rounded surface may define part of a sphere, but for a defect. Similarly, for example, the rounded surface defined by the first lens may not be perfectly round but slightly ellipsoidal. In particular, an object approximating a first shape may herein refer to: a first shape realization encompassing the object, wherein the first shape realization is defined as the smallest encompassing shape of the (2D or 3D, respectively) object wherein the first shape realization has the shape of the first shape, wherein a ratio of the area (volume) of the first shape realization to the area (volume) of the object is < 1.2, especially < 1.1, such as <1.05, especially <1.02. For instance, the first lens may approximate a truncated ball lens, wherein the first shape realization may be defined as the smallest encompassing truncated ball shape of the first lens, wherein a ratio of the volume of the first shape realization to the volume of the first lens is < 1.2, especially, especially < 1.1, such as <1.05, especially <1.02, including 1. Further, if the dimensions of the first shape are defined, the term approximate may refer to the object and the first shape being superimposable (in 2D or 3D, respectively) such that an intersection between the object and the first shape covers at least m% of the object and at least m% of the shape, wherein m is at least 90%, such as at least 95%, especially at least 98%, such as at least 99%, including 100%.

[0041] A further advantage of a truncated ball lens is that sphere shaped lenses may be relatively easy and cost-effective to produce relative to aspheric lenses.

[0042] In further embodiments, a (virtual) axis (A) perpendicular to the planar surface may intersect the first lens for a (longest) distance (dl), especially wherein dl is selected from the range of 1.33*R0 - 1.90*R0, such as from the range of 1.4*R0 - 1.85*R0, especially from the range of 1.5*R0 - 1.8*R0, such as from the range of 1.6*R0 - 1.75*R0. Hence, in embodiments, dl < 1.9*R0, such as < 1.85*R0, especially < 1.80*R0, such as < 1.75*R0. In further embodiments, dl > 1.33*R0, such as > 1.4*R0, such as > 1.5*R0, such as > 1.6*R0. The axis (A) may especially be centered on the planar surface. In embodiments, the axis (A) may coincide with the (average) optical axis (see above). In particular, in embodiments, the axis (A) may pass through the center of the sphere.

[0043] It appears to be particularly beneficial when dl is selected in view of the refractive index p of the (material of the) first lens, in view of overall system efficiency, focal distance (see below) and in avoiding spherical aberrations, i.e., in avoiding that rays that travel through the outer part of the lens are focused at a different distance than those that travel through the center part of the lens. In particular, it appears beneficial for dl to be equal to R0(l+l / p). For values of dl below R0(l+l / p), the focal distance increases, the full-width half-maximum beam angle decreases, and the overall lighting efficiency decreases. For values of dl above R0(l+l / p), the image uniformity and the overall lighting efficiency decreases. In other words, the lens strength and the beam divergence can be chosen by the truncation distance, where, generally, values of dl close to R0(l+l / p) may be considered beneficial in view of, amongst others, overall lighting efficiency.

[0044] In embodiments, the (material of the) lens has a refractive index p, especially wherein p is selected from the range of 1.3 - 2.6, such as from the range of 1.4 - 2.5, especially from the range of 1.45-2.1.

[0045] In further embodiments, dl is selected from the range of 0.8*R0*(l+l / p) - 1.2*R0*(l+l / p), such as from the range of 0.9*R0*(l+l / p) - l.l*R0*(l+l / p), especially from the range of 0.95*R0*(l+l / p) -1.05*R0*(l+l / p), such as from the range of 0.99*R0*(l+l / p) -1.01*R0*(l+l / p). In other words, in embodiments, dl may be within 20% of R0*(l+l / p), such as within 10%, especially within 5%, such as within 1%.

[0046] In further embodiments, dl / (R0*(l+l / p)) > 0.8, such as > 0.9, especially > 0.95, such as > 0.99, including 1. In further embodiments, dl / (R0*(l+l / p)) < 1.2, such as < 1.1, especially < 1.05, such as < 1.01, including 1.

[0047] As described above, the rounded surface may be shaped according to a (portion of a) surface, e.g., of a spherical surface, of a virtual sphere, wherein the virtual sphere has a radius R0.

[0048] In embodiments, the first lens, especially the planar surface, may be defined by a (single) truncation at a (single) truncation plane intersecting the sphere, wherein the truncation plane is arranged at a distance (d5) from a center of the sphere, wherein d5 / R0 is selected from the range of 0.33 - 0.90, such as from the range of 0.4 - 0.85, especially from the range of 0.5 - 0.8, such as from the range of 0.6 - 0.75. In particular, in embodiments, d5+R0=dl.

[0049] The size of the first lens, and especially the area of the planar surface, may be selected to capture (essentially) all light source light. Further, the size of the first lens, and especially the area of the planar surface, may be selected to avoid total internal reflection (TIR) of the light source light in the first lens. In particular, the planar surface may have a sufficiently large surface area to capture (essentially) all the light source light. Hence, in embodiments, the planar surface may have a radius (Rin), and the light source array may (in a cross-sectional plane parallel to the planar surface) have a (largest) diagonal length (d6) (between opposite comers), wherein Rin / d6 > 0.5, such as > 0.55 especially > 0.75, such as > 1. In further embodiments, Rin / d6 < 2.5, such as < 2, especially < 1.5.

[0050] It will be clear to the person skilled in the art that the radius (Rin) of the planar surface will depend both on the sphere radius (R0) and on the distance (dl). For instance, for embodiments wherein dl=R0*(l+l / p) (see above), the following applies:

[0051] In an exemplary embodiment, taking a 2*2mm light source array arranged at a distance of about 1 mm from the first lens: d6 is about 2.8 mm, Rin may be selected to be 2.9 (or larger), and RO may be 4.1 mm for p=1.4. or, for example, 3.5 mm for p=1.8. To obtain an essentially optical performance using a smaller or larger light source array, the indicated values may be scaled linearly with the size of the light source array.

[0052] As will be clear from the description as a whole, other absolute and relative sizes may also be selected, for instance in view of performance and / or sizing considerations.

[0053] In embodiments, the sphere radius RO may be selected from the range of 1 - 16 mm, such as from the range of 2-8 mm, such as from the range of 3 - 6 mm.

[0054] In further embodiments, the first lens may have an effective focal length (f), wherein f is selected from the range of < 30 mm, such as from the range of < 24 mm, especially from the range of < 18 mm. In further embodiments, f may be selected from the range of < 12 mm, such as from the range of < 10 mm, especially from the range of < 9 mm. Especially, f may be selected from the range of > 2 mm, such as from the range of > 5 mm, especially from the range of > 7 mm, such as from the range of > 9 mm. For instance, in embodiments, f may be selected from the range of 2 - 18 mm, especially from the range of 5 - 10 mm, such as from the range of 7 - 9 mm.

[0055] For first lenses for which dl= R0*(l+l / p), the paraxial value of the effective focal length may be calculated from R0 and p as f = R0 / (p - 1), i.e. for a ray very close to the optical axis, the focal length can be calculated. For practical rays, the effective focal length can be experimentally determined (see below).

[0056] In embodiments, the light generating system may comprise a condenser lens. In particular, the condenser lens may be arranged in a light-receiving relationship with the first lens, especially with the rounded surface of the first lens. The condenser lens may be configured to (a) capture (essentially all of) the light source light escaping the rounded surface, and (b) focus the light source light in the distance. For instance, in embodiments, the condenser lens may be configured to focus the light source light at a distance selected from the range of 1-8 m, such as from the range of 2-6 m.

[0057] In embodiments, the condenser lens may be a spheric condenser lens. In further embodiments, the condenser lens may be an aspheric condenser lens. Aspheric condenser lenses may be particularly suitable as they may be relatively compact and may provide relatively little distortion. Further, in comparison to hyperbolic lenses, condenser lenses may have a smaller diameter and may suffer less Fresnel reflection losses. In embodiments, a first side of the condenser lens may be configured in the light receiving relationship with the first lens. Especially, the condenser lens may taper from the first side to a second side (opposite of the first side).

[0058] As describes above, the condenser lens may be configured to capture (essentially all of) the light source light escaping the rounded surface. Therefore, the condenser lens may at the first side especially have a larger radius than the radius of the sphere. For instance, in embodiments, the first side may have a radius Rl, especially half of an equivalent circular diameter (of the condenser lens), selected from the range of RO - 6*R0, such as from the range of 1.5*R0 - 4*R0, especially from the range of 2*R0 - 3*R0.

[0059] The equivalent circular diameter (or ECD) (or “circular equivalent diameter”) of an (irregularly shaped) two-dimensional shape is the diameter of a circle of equivalent area. For instance, the equivalent circular diameter of a square with side a is 2*a*SQRT(l / 7t). For a circle, the diameter is the same as the equivalent circular diameter. Would a circle in an xy-plane with a diameter D be distorted to any other shape (in the xy-plane), without changing the area size, then the equivalent circular diameter of that shape would be D.

[0060] In embodiments, the light sources may be arranged to provide light source light to the planar surface of the first lens, wherein the first lens is configured to provide (via the rounded surface) a first beam (of light source light) to the condenser lens. In such embodiments, the condenser lens may be configured to receive at least 80% of (a total intensity of) the first beam, such as at least 90%, especially at least 95%, including 100%.

[0061] The condenser lens may especially have a back focal length (LBF), wherein LBF > R0*(l + p). With a smaller (too small) LBF the image may be blurry. With a larger LBF the distance between the lenses can be adjusted to provide a sharp image. The back focal length (LBF) may especially be the distance between the (flat) surface of the condenser lens and the focal point on that side of the condenser lens. In particular, the back focal length of the condenser lens may herein refer to the back focal length of the surface of the first side of the condenser lens, i.e., of the surface of the condenser lens that faces the first lens.

[0062] In embodiments wherein the light generating system comprises a plurality of light source arrays and first lenses (see above), the light generating systems may further comprise a plurality of condenser lenses, wherein each condenser lens is arranged in a light receiving relationship with a respective first lens.

[0063] In particular, in embodiments, the light generating system may comprise a plurality of lighting subunits, wherein each lighting subunit comprises a light source array and a first lens, wherein for each lighting subunit applies that: the light source array comprises a plurality of light sources, wherein the first lens comprises a solid truncated sphere lens, the truncated sphere lens comprising a planar surface and a rounded surface, wherein the planar surface is arranged in a light receiving relationship with the plurality of light sources, wherein the rounded surface is shaped according to a (portion of a) surface of a virtual sphere having a radius RO and takes up at least 66% of a spherical surface of the virtual sphere, wherein an axis (A) perpendicular to the planar surface intersects the first lens for a distance dl, wherein dl is selected from the range of 1.33*R0 - 1.90*R0. In further embodiments, each lighting subunit may further comprise a condenser lens, wherein for each lighting subunit applies that: the condenser lens is arranged in a light-receiving relationship with the first lens, especially with the rounded surface of the first lens. In yet further embodiments, the condenser lenses of two or more different lighting subunits may be physically connected or be monolithic, especially physically connected, or especially monolithic. In particular, in such embodiments, the condenser lenses may effectively be truncated at their mutual interface(s).

[0064] In embodiments, the light generating system may comprise a control system. The control system may be configured to control the light generating system, especially the light source array, such as independently control (proper subsets of) light sources of the plurality of light sources. For instance, in embodiments, the control system may be configured to control an on / off state of the light sources. In further embodiments, the control system may be configured to control an intensity of the light sources.

[0065] The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and / or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface.

[0066] In further embodiments, the light source array may comprise a pixelated (LED) light source array, especially wherein the control system is configured to independently control two or more proper subsets of light sources of the light source array. For instance, different (proper) subsets may correspond to light sources configured to illuminate different shelves or different products. Hence, by independently controlling the different subsets, the control system may selectively illuminate one or more locations and / or spatially vary a lighting intensity, such as to focus attention on specific locations (e.g., at specific products).

[0067] In further embodiments, the control system may (additionally) temporally vary a lighting intensity or spectral distribution, which may facilitate (further) focusing attention on specific locations. For instance, light patterns can be projected like growing and shrinking bright circles or arrows.

[0068] The invention may herein primarily be discussed in the context of selectively illuminating different locations, particularly in the context of a pixelated light source array. However, the light generating system of the invention is not limited to such embodiments, and could also be applied to provide specific lighting patterns, optionally varying temporally. For instance, the light generating system may also facilitate providing a batwing light distribution by switching all pixels ON but suitably boosting the outer pixels compared to the inner ones.

[0069] In a further aspect, the invention may provide a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system according to any one of the preceding claims. The lighting device may especially be selected from the group of a lamp and a luminaire.

[0070] In embodiments, the lighting device may comprise a sensor, especially wherein the lighting device is configured to control the light generating device in dependence of the sensor. For instance, in embodiments, the sensor may be configured to detect the presence of a subject, such as a person or an object, and to provide a related sensor signal to the control system (of the light generating system), wherein the control system is configured to control the light sources based on the related sensor signal.

[0071] The control in dependence of the related sensor signal may be useful for selectively (or predominantly) illuminating locations, such as product locations, based on the subject. For instance, if the subject is a person, the control system may be configured to (have the light generating system) selectively illuminate locations that are expected to be of interest to the person, such as (further) based on a customer profile, past purchases, or a predefined (shopping) list. In the latter case, the subject may have provided a shopping list and the control system may be configured to provide illumination to guide the subject to the desired products and, optionally, an alternative product in case, for instance, a desired product is unavailable or an alternative product may be expected to be of interest, e.g., due to it being new or discounted. For instance, in embodiments, the lighting system may be coupled to an Artificial Intelligence system that helps customers in a supermarket to pick their preferred products by highlighting the products. Similarly, the control system may employ the selective illumination to guide a warehouse employee to to-be-collected items based on a predefined list, thereby increasing collection efficiency and comfort. As a further example, if the subject is an object, the control system may be configured to (have the light generating system) selectively illuminate locations that are expected to be of interest based on the object, such as based on products frequently purchased together, compatible products (e.g., in view of sizing or connection requirements), or products of the same brand. For instance, this may facilitate finding replacement pieces for an object brought in for repair, which may increase process efficiency and may reduce issues resulting from selecting incompatible replacement parts.

[0072] Hence, in embodiments, the control system may be configured to select one or more items based on the related sensor signal and a second input, especially wherein the second input is selected from the group comprising a list of items (e.g., a shopping list), a product matching input (e.g., products frequently purchased together), a subject-specific input (e.g., products often purchased by specific customer or expected to be of specific interest for customer), and historic information (e.g., products of interest in specific time of day or time of year).

[0073] The term “subject” may herein also refer to a plurality of different subjects, such as a plurality of different products. For instance, the control system may have a (rough) overview of products present in a shopping cart based on the sensor related signal (and optionally past sensor related signals related to the same cart), and may selectively illuminate further products based on the plurality of different products.

[0074] In specific embodiments, the subject may comprise an identification tag, such as an RFID tag. The identification tag may, for instance, be product-specific but may also, for instance, relate to a shopping cart. In embodiments, the identification tag may comprise or refer to information on a person associated with the tag, such as a customer or warehouse employee. The use of tags may be particularly suitable for subject identification and, where appropriate, access to subject associated information.

[0075] In embodiments, the lighting device may be configured to be arranged in an indoor space selected from the group comprising a shop and a warehouse, especially wherein the control system is configured to select one or more items (or “products”) based on the related sensor signal, and to control the light sources to highlight the items (or “products”).

[0076] In a further aspect, the invention may provide an arrangement comprising the lighting device of the invention and an indoor space, wherein the indoor space comprises a plurality of locations, such as shelve locations, wherein the lighting device is configured to individually illuminate the plurality of locations.

[0077] The light generating system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating system (or luminaire) may be part of or may be applied in e.g. optical communication systems or disinfection systems. Specifically, the light generating system may be part of or may be applied in e.g., retail shelf lighting systems, shop window lighting systems, decorative lighting systems, museum and art gallery lighting systems, office lighting systems, road & street lighting systems, and entertainment lighting systems.

[0078] Preferably, the light source is a light source that during operation emits (light source light) at least light at a wavelength selected from the range of 200-490 nm, especially a light source that during operation emits at least light at wavelength selected from the range of 400-490 nm, even more especially in the range of 440-490 nm. This light may partially be used by wavelength converter nanoparticles, e.g., in a luminescent material. Hence, in a specific embodiment, the light source is configured to generate blue light.

[0079] The term “white light”, and similar terms, herein, is known to the person skilled in the art. It may especially relate to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700- 20000 K, for general lighting especially in the range of about 2000-7000 K, such as in the range of 2700 K and 6500 K. In embodiments, e.g. for backlighting purposes, or for other purposes, the correlated color temperature (CCT) may especially be in the range of about 7000 K and 20000 K. Yet further, in embodiments the correlated color temperature (CCT) is especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL.

[0080] In specific embodiments, the correlated color temperature (CCT) may be selected from the range of 6000-12000 K, like selected from the range of 7000-12000 K, like at least 8000 K. Yet further, in embodiments the correlated color temperature (CCT) may be selected from the range of 6000-12000 K, like selected from the range of 7000-12000 K, in combination with a CRI of at least 70.

[0081] In an embodiment, the light source may also provide light source light having a correlated color temperature (CCT) between about 5000 and 20000 K, e.g. direct phosphor converted LEDs (blue light emitting diode with thin layer of phosphor for e.g. obtaining of 10000 K). Hence, in a specific embodiment the light source is configured to provide light source light with a correlated color temperature in the range of 5000-20000 K, even more especially in the range of 6000-20000 K, such as 8000-20000 K. An advantage of the relative high color temperature may be that there may be a relatively high blue component in the light source light.

[0082] The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light.

[0083] The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm. Herein, UV may especially refer to a wavelength selected from the range of 190-380 nm, such as 200-380 nm. The terms “violet light” or “violet emission” especially relates to light having a wavelength in the range of about 380-440 nm. The terms “blue light” or “blue emission” especially relates to light having a wavelength in the range of about 440-495 nm (including some violet and cyan hues). The terms “green light” or “green emission” especially relate to light having a wavelength in the range of about 495-570 nm. The terms “yellow light” or “yellow emission” especially relate to light having a wavelength in the range of about 570- 590 nm. The terms “orange light” or “orange emission” especially relate to light having a wavelength in the range of about 590-620 nm. The terms “red light” or “red emission” especially relate to light having a wavelength in the range of about 620-780 nm. The term “pink light” or “pink emission” refers to light having a blue and a red component. The term “cyan” may refer to one or more wavelengths selected from the range of about 490-520 nm. The term “amber” may refer to one or more wavelengths selected from the range of about 585-605 nm, such as about 590-600 nm. Herein, IR (infrared) may especially refer to radiation having a wavelength selected from the range of 780-3000 nm, such as 780-2000 nm, e.g. a wavelength up to about 1500 nm, like a wavelength of at least 900 nm, though in specific embodiments other wavelengths may also be possible. Hence, the term IR may herein refer to one or more of near infrared (NIR (or IR-A)) and short- wavelength infrared (SWIR (or IR-B)), especially NIR. The phrase “light having one or more wavelengths in a wavelength range” and similar phrases may especially indicate that the indicated light (or radiation) has a spectral power distribution with at least intensity or intensities at these one or more wavelengths in the indicate wavelength range. For instance, a blue emitting solid state light source will have a spectral power distribution with intensities at one or more wavelengths in the 440-495 nm wavelength range.

[0084] The control system may also be configured to receive and execute instructions from a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system.

[0085] Hence, in embodiments the control system may (also) be configured to be controlled by an App on a remote device. In such embodiments the control system of the lighting system may be a slave control system or control in a slave mode. For instance, the lighting system may be identifiable with a code, especially a unique code for the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control system which has access to the lighting system on the basis of knowledge (input by a user interface of with an optical sensor (e.g. QR code reader) of the (unique) code. The lighting system may also comprise means for communicating with other systems or devices, such as on the basis of Bluetooth, Thread, WIFI, LiFi, ZigBee, BLE or WiMAX, or another wireless technology.

[0086] The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation” or “operational mode”. The term “operational mode may also be indicated as “controlling mode”. Likewise, in a method an action or stage, or step may be executed in a “mode” or “operation mode” or “mode of operation” or “operational mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and / or after executing the mode one or more other modes may be executed.

[0087] However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operation mode (i.e. “on”, without further tunability).

[0088] Hence, in embodiments, the control system may control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and / or a predetermined time scheme.

[0089] In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. etc... The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein. Hence, in an aspect the invention also provides a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system.

[0090] BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0092] Fig. 1 schematically depicts an embodiment of a light generating system 1000; Fig. 2 schematically depicts an embodiment of a light generating system 1000 and a comparative example;

[0093] Fig. 3 schematically depicts an embodiment of a lighting device 1200.

[0094] The schematic drawings are not necessarily to scale.

[0095] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0096] Fig. 1 schematically depicts a light generating system 1000 comprising a light source array 1010 and a first lens 100. In the depicted embodiment, the light source array 1010 comprises a plurality of light sources 10. Further, the first lens 100 is a solid truncated sphere lens 400, the truncated sphere lens 400 comprising a planar surface 110 and a rounded surface 120, wherein the planar surface 110 is arranged in a light receiving relationship with the plurality of light sources 10. The rounded surface 120 is shaped according to a (portion of a) surface of a virtual sphere 425 having a radius R0 and takes up at least 66%, such as at least 80%, of a spherical surface 420 of the virtual sphere 425 (having a sphere radius R0). In Fig. 1, the dotted line represents an outline of the virtual sphere 425, which outline is largely taken up (or matched) by the rounded surface 120, i.e., the rounded surface 120 defines a 3D shape, wherein the 3D shape approximates part of the virtual sphere 425. In the depicted embodiment, an axis A is arranged perpendicular to the planar surface 110 and intersects the first lens 100 for a (largest) distance dl, wherein dl is selected from the range of 1.33*R0 - 1.90*R0, such as wherein dl < 1.85*R0.

[0097] In the embodiment of Fig. 1, the planar surface 110 and the rounded surface 120 together define a total surface area (Atot) of the first lens 100, i.e., in the depicted embodiment, the surface of the first lens 100 consists of the planar surface 110 and the rounded surface 120. In particular, in the depicted embodiment, the first lens 100 comprises a truncated sphere lens 400.

[0098] In further embodiments, the first lens 100 has a total surface area Atot, wherein the planar surface 110 has a planar surface area Ap, wherein the rounded surface 120 has a rounded surface area Ar, and wherein (Ap+Ar) / Atot > 0.9, especially > 0.95, such as > 0.99.

[0099] The planar surface 110 of the first lens 100 may, as depicted in Fig. 1, be arranged in a light-receiving relationship to and parallel with the light source array 1010. In particular, light sources 10 of the light source array 1010 may be configured to provide light source light 11 to the planar surface 110. The light source array 1010 may especially be arranged at an (average) second distance d2 from the planar surface 110. In embodiments, d2 may be selected from the range of 0.005 - 1 mm, especially from the range of 0.01 - 0.5 mm, such as from the range of 0.02 - 0.25 mm.

[0100] The effect of the sphere radius R0 corresponding to the rounded surface 120 of the first lens 120 was evaluated using optical ray tracing modelling using the program LightTools as reported in the table below. For each tested value, the radius Rin of the planar surface was set to be 0.75*R0, i.e., dl was selected to be equal to R0*(l+l / p) with p=1.5, and a 2x2mm light source array was used.

[0101] R0 [mm] Focal length f [mm] HWHM angle [°] Efficiency

[0102] 4 7.3 7.9 +

[0103] 3 5.2 10.9

[0104] 2 2.8 19.4

[0105] For values of R0 below 4 mm or, more specifically, below 3.9 mm, the overall lighting efficiency decreased due to total internal reflection. For R0 = 3.9 mm, Rin is 2.9 mm, which, for the light source array of 2x2mm, was found suitable to substantially prevent total internal reflection.

[0106] The (effective) focal length of the first lens was determined by shooting a test ray at 1mm from the optical axis and recording the angle of the outgoing ray, wherein f = 1 / tan(HWHM).

[0107] Fig. 2 schematically depicts a light generating system 1000 of the invention in panel (I) and a comparative example using a half ball lens in panel (II). For both the light generating system 1000 and the comparative example, Fig. 2 schematically depicts predicted light rays (top), a predicted lighting profile on a target surface ((I) bottom left; (II) bottom right) and a 2D representation of the first lens 100 ((I) bottom right) and of the half ball lens ((II) bottom left).

[0108] In particular, in the depicted embodiment and the comparative example, a condenser lens 200 is configured in a light-receiving relationship with the first lens 100 or the half ball lens, respectively. In the depicted embodiment, the condenser lens is arranged at a (third) distance d3 (or “lens-to-lens distance”) from the first lens.

[0109] In embodiments, the (third) distance d3 may be selected from the range of < 9 mm, such as from the range of < 7 mm, especially from the range of < 5 mm, such as from the range of < 4 mm. In further embodiments, the (third) distance d3 may be selected from the range of > 2 mm, such as from the range of > 3 mm, especially from the range of > 4 mm, such as from the range of > 5 mm.

[0110] Specifically, in the depicted embodiment, the light generating system 1000 comprises an condenser lens 200, wherein the condenser lens comprises an aspheric condenser lens, wherein condenser lens 200 is configured in a light receiving relationship with the first lens 100. Further, in the depicted embodiment, the condenser lens 200 tapers from a first side 210 to a second side 220, wherein the first side 210 is configured in the light receiving relationship with the first lens 100.

[0111] In the depicted embodiment, the first side 210 may have a radius R1 of about 2.25 *R0. In further embodiments, the first side 210 may have a radius R1 selected from the range of 1.5*R0 - 4*R0.

[0112] As depicted in Fig. 2, the light sources 10 are arranged to provide light source light 11 to the planar surface 110 of the first lens 100, wherein the first lens 100 is configured to provide a first beam 101 (of light source light 11) to the condenser lens 200, wherein the condenser lens 200 is configured to receive at least 90% of (a total intensity of) the first beam 101. Specifically, the condenser lens 200 may be configured to provide a second beam 201 (of system light 1001) from the second side 220 of the condenser lens 200. The system light 1001 may (thus) comprise at least part of the light source light 11.

[0113] In further embodiments, the condenser lens 200 may have a back focal length LBF, wherein LBF > R0*(l + p).

[0114] Specifically, the magnification of a doublet lens system as depicted in Fig. 2 was evaluated using optical ray tracing modelling using the LightTools program for varying truncation distances as reported in the table below. For all tested configurations for varying truncation distances, R0=4mm. The truncated ball lens was combined with an aspherical condenser lens of focal distance = 20mm and diameter = 18mm, and the lens-to-lens distance was selected to create a sharp focus at 3m distance of the light source array.

[0115] Distance dl [R0] Distance d3 [mm] Focal length f [mm] HWHM angle [°]

[0116] Efficiency

[0117] 1.667 3 7.1 8 +

[0118] 1.5 5 9.5 6 + / -

[0119] 1.33 7 11.4 5

[0120] 1 9 14.3 4 Specifically, the focal length f and the half-width half-maximum angles refer to properties of the first lens 100, whereas the efficiency refers to the overall lighting efficiency of the light generating system 1000.

[0121] These results demonstrate that truncation at 2 / 3 of the radius (dl=1.667R0) makes the first lens 100 2x stronger compared to the half-sphere lens. Moreover, the condenser lens, here especially an aspherical condenser lens, can be much smaller when truncating at 2 / 3 of the radius (see Fig. 2), while capturing (essentially) all light source light 11 exiting the rounded surface 120. In contrast, the efficiency of the half-sphere is degraded compared to the truncated case with dl > R0 as part of the light source light is not captured by the condenser lens; note, as mentioned above, that the distance d3 was selected to create a sharp (insofar possible) focus at 3m.

[0122] In a further example, a 7x7 pixelated LED source was positioned close to a truncated ball lens of diameter 7.6 mm, i.e., with R0=3.8 mm. The truncation distance was set at RO / p where R0 is the radius of the sphere and p the refractive index of the truncated ball lens, i.e., with dl=R0*(l+l / p), and with p=1.5. The resulting lens showed low spherical aberration, and - in combination with an aspherical condenser lens of focal distance = 20mm and diameter = 18mm and set a lens-to-lens distance d3 of 3 mm - gave a compact, very efficient pixelated spotlight. The effective focal length of the dual lenses was observed to be approximately 8mm, with an angular spreading of approximately 8° in horizontal and vertical direction. The term “angular spreading” may herein refer to the total beam width when all pixels are on. The light generating system 1000 was used to provide a checkerboard pattern on the floor, which pattern measured approximately lxlm2, and the illuminance value of each (illuminated) pixel in the pattern equaled 500 lux. The optical system efficiency was observed to be 98%.

[0123] A wider angular spread than 8° can be achieved by using a smaller diameter ball lens, as also described above. Specifically, with a truncation distance of R0 / 3, i.e. with dl=l .33, for a ball lens of 4mm diameter the beam angles are +-13deg, and with 5mm +- 1 Ideg. The smaller value of dl leads to some distortion of the outermost corner pixels, i.e., the imaging quality of the truncated lens system may deteriorate when the truncation distance is not equal to the preferred R / n value stated above.

[0124] In embodiments, a spatial variation in maximum flux per pixel can be applied to compensate for a locally reduced illumination, e.g., in view of a distortion in the outermost corner pixels. Fig. 3 schematically depicts an embodiment of the light generating system 1000, wherein the light generating system 1000 comprises a control system 300. The control system 300 may especially be configured to control the plurality of light sources 10, such as to independently control two or more proper subsets of light sources 10 of the light source array 1010.

[0125] Fig. 3 schematically depicts an embodiment of a lighting device 1200 selected from the group of a lamp, a luminaire 2, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system 1000 of the invention. In particular, in the depicted embodiment, the lighting device 1200 comprises a plurality of light generating systems 1000, wherein the light generating systems are configured to (selectively) illuminate shelves - or items 30 on shelves - in an aisle in an indoor space 1300.

[0126] Hence, the lighting device 1200 may, in embodiments, be configured to be arranged in an indoor space 1300 selected from the group comprising a shop and a warehouse.

[0127] In the depicted embodiment, the light generating systems 1000 are angled relative to a ceiling 1301, i.e., the planar surface is arranged at an angle a to the ceiling 1301, such as an angle > 10°, which may facilitate selectively illuminating the shelves at the side of the aisle.

[0128] Hence, in embodiments, the lighting device 1200 may comprise a light generating system 1000, wherein the lighting device 1200 is configured to be physically coupled to a (suspended) ceiling 1310 such that the planar surface 110 of the light generating system 1000 is arranged at an angle a relative to the ceiling 1310, wherein a > 10°, such as > 20°, especially 30°. In further embodiments, a < 80°, such as < 70°, especially < 60°.

[0129] The lighting device 1200 may, in embodiments, be configured for illuminating multiple locations in different directions, such as on two opposite sides of an aisle. Hence, in further embodiments, the lighting device 1200 may comprise a plurality of light generating systems 1000, wherein planar surfaces 110 of at least two light generating systems 1000 are arranged at a mutual angle > 20°, such as > 40°, especially > 60°. In further embodiments, the planar surfaces 110 of the at least two light generating systems 1000 are arranged at a mutual angle < 160°, such as < 140°, especially < 120°.

[0130] In the depicted embodiment, the lighting device 1200 further comprises a sensor 500, wherein the sensor 500 is configured to detect the presence of a subject 20, such as a shopping cart, and to provide a related sensor signal to the control system 300. In such embodiments, the control system 300 may be configured to control the light sources 10 based on the related sensor signal.

[0131] In further embodiments, the control system may be configured to select one or more items 30 based on the related sensor signal, and to control the light sources 1010 to highlight the items 30.

[0132] In yet further embodiments, the control system may be configured to select one or more items 30 based on the related sensor signal and a second input, wherein the second input is selected from the group comprising a list of items, a product matching input, a subject-specific input, or historic information.

[0133] Fig. 3 further schematically depicts an arrangement comprising the lighting device 1200 of the invention and an indoor space 1300, wherein the indoor space 1300 comprises a plurality of locations 1310, e.g., locations comprising items 30, wherein the lighting device 1200 is configured to individually illuminate the plurality of locations 1310.

[0134] The term “plurality” refers to two or more.

[0135] The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

[0136] The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’.

[0137] The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

[0138] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0139] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0140] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0141] Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0142] The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0143] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In yet a further aspect, the invention (thus) provides a software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein.

[0144] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0145] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating system (1000) comprising a light source array (1010) and a first lens (100), wherein the light source array (1010) comprises a plurality of light sources (10), wherein the first lens (100) is a solid truncated sphere lens (400), the truncated sphere lens (400) comprising a planar surface (110) and a rounded surface (120), wherein the planar surface (110) is arranged in a light receiving relationship with the plurality of light sources (10), wherein the rounded surface (120) is shaped according to a surface of a virtual sphere (425) having a radius (R0) and takes up at least 66% of a spherical surface (420) of the virtual sphere (425), wherein an axis (A) perpendicular to the planar surface (110) intersects the first lens (100) for a distance (dl), wherein dl is selected from the range of 1.33*R0 - 1.90*R0, wherein the light generating system (1000) further comprises a condenser lens (200), wherein the condenser lens (200) is configured in a light receiving relationship with the first lens (100), wherein the condenser lens (200) tapers from a first side (210) to a second side (220), wherein the first side (210) is configured in the light receiving relationship with the first lens (100), and wherein the first side (210) has a radius (Rl) selected from the range of 1.5*R0 - 4*R0.

2. The light generating system (1000) according to claim 1, wherein dl < 1.85*R0.

3. The light generating system (1000) according to any one of the preceding claims, wherein the lens has a refractive index p, wherein dl is selected from the range of 0.9*R0*(l+l / p) -l.l*R0*(l+l / ).

4. The light generating system (1000) according to any one of the preceding claims, wherein the rounded surface (120) takes up at least 80% of the spherical surface (420).

5. The light generating system (1000) according to any one of the preceding claims, wherein the first lens (100) has a total surface area (Atot), wherein the planar surface (110) has a planar surface area (Ap), wherein the rounded surface (120) has a rounded surface area (Ar), and wherein Ap+Ar > 0.99*Atot.

6. The light generating system (1000) according to any one of the preceding claims, wherein R0 is selected from the range of 2-8 mm, and wherein the first lens (100) has an effective focal length (f) selected from the range of < 18 mm.

7. The light generating system (1000) according to any one of the preceding claims, wherein the light sources (10) are arranged to provide light source light (11) to the planar surface (110) of the first lens (100), wherein the first lens (100) is configured to provide a first beam (101) to the condenser lens (200), wherein the condenser lens (200) is configured to receive at least 90% of the first beam (101).

8. The light generating system (1000) according to claim 3, wherein the condenser lens (200) has a back focal length LBF, wherein LBF > R0*(l + p).

9. The light generating system (1000) according to any one of the preceding claims, wherein the condenser lens (200) is arranged at a third distance (d3) from the first lens (100), wherein d3 is selected from the range of 2 - 7 mm.

10. The light generating system (1000) according to any one of the preceding claims, wherein the light source array (1010) comprises at least 25 light sources (10), and wherein the light sources are arranged at a second distance (d2) from the planar surface (110), wherein d2 is selected from the range of 0.01 - 0.5 mm.

11. The light generating system (1000) according to any one of the preceding claims, wherein the light source array (1010) comprises a pixelated light source array, and wherein the light generating system (1000) comprises a control system (300), wherein the control system (300) is configured to independently control two or more proper subsets of light sources (10) of the light source array (1010).

12. A lighting device (1200) selected from the group of a lamp, a luminaire (2), a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system (1000) according to any one of the preceding claims.

13. The lighting device (1200) according to claim 12, the lighting device (1200) comprising a sensor (500) and the light generating system (1000) according to claim 12, wherein the sensor (500) is configured to detect the presence of a subject (20) and to provide a related sensor signal to the control system (300), and wherein the control system (300) is configured to control the light sources (10) based on the related sensor signal.

14. An arrangement comprising the lighting device (1200) according to any one of the preceding claims 12-13 and an indoor space (1300), wherein the indoor space (1300) comprises a plurality of locations (1310), wherein the lighting device (1200) is configured to individually illuminate the plurality of locations (1310).

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