Lighting fixtures with identical curved LED modules and LED modules suitable for said lighting fixtures

Abstract

The lighting fixture has identical curved LED modules in the inner and outer arrays of LED modules. The LED module includes a curved PCB having a major surface and a number of LEDs disposed on the major surface. The LED module has a width W, and its major surface is curved to extend in a plane Q. The LED module extends on a circle having a radius Rc, where 200 mm≦Rc≦450 mm, and extends over an angle α on the circle, where 36°≦α≦72°. The number of LEDs is between 3 and 150. Each LED has a respective donut-shaped lens such that, in operation, the LED emits a rotationally symmetric batwing beam with a maximum intensity Imax of the batwing beam at an angle β relative to the optical axis and a FWHM in the range of 15 to 30°, where 60°≦β≦80°.

Description

[Technical field]

[0001] The invention relates to a luminaire according to the invention, comprising a plurality of identical curved LED modules.The invention further relates to an LED module suitable for being applied in a luminaire according to the invention. [Background technology]

[0002] Functional ceiling luminaires in Asia, also called center pieces, are generally diffuse luminaires with a large diameter, for example up to a diameter of about 850 mm, and a relatively small thickness, i.e. a total thickness of less than about 100 mm. There are several options to create the desired uniform brightness in the diffuser, which is placed at the light exit window of the luminaire. A commonly used solution is to use LED modules with a PCB on which a relatively small number of LEDs are mounted in combination with a lens that broadens the intensity distribution of the LEDs. Such LED modules are commonly called L2 modules or L2 LED modules. Lenses suitable for this purpose are known as batwing lenses or TV lenses, which are / were commonly used in TV backlights. The lenses can be provided as a large integral lens plate or so that each LED has an individual separate lens. Large integral lens plates have the disadvantage of misalignment between the LEDs and their associated lenses, for example due to differences in thermal expansion. Furthermore, the tooling costs for these large lens plates are relatively high and relatively heavy machines are required. Moreover, these known LED modules have the disadvantage of non-uniform illumination of the light exit window of the luminaire. A simple alternative is to mount a relatively large number of LEDs on a large PCB. This makes the luminaire have a uniform illumination of the light exit window, but to create said uniform brightness in a large luminaire, a relatively large PCB area with many, typically many more LEDs than are needed for the light output, is required. This has the disadvantage that the manufacture of the luminaire is laborious and relatively expensive. Summary of the Invention [Problem to be solved by the invention]

[0003] It is an object of the present invention to provide a PCB-LED-optics combination, i.e. an LED module and a luminaire comprising a number of said LED modules, in which the disadvantages of the known devices are mitigated. [Means for solving the problem]

[0004] In response, the luminaire has a housing with a base having a first carrier surface on which a plurality of LED modules are arranged, and a cover arranged on a light exit window of the luminaire opposite to the first carrier surface, The LED module is a curved LED module having a curved PCB with a main surface on which a number N of LEDs are mounted, the LEDs facing the light exit window and being shielded by the cover; the LED modules are arranged to have an inner arrangement of LED modules surrounded by an outer arrangement of LED modules; All LED modules are identical.

[0005] In each luminaire of the prior art devices, there is an inner and outer arrangement of curved LED modules, for which dedicated curved LED modules of each type are provided, and the dedicated curved LED modules of each type are different, i.e. not identical, from each other. The present invention describes the characteristics of curved LED modules and luminaires that can serve a wide range of luminaires according to the present invention with reduced variety, with known advantages such as cost and resource savings for portfolio maintenance.

[0006] Typically, a curved LED module according to the invention has the technical feature that its main surface extends in a plane Q and has a curved shape with a width W transverse to its curve, said LED module is a circular arc segment of a circle 0, usually called a disk, with a radius Rc, covering only the outer boundary area, not the entire surface, 120 mm≦Rc≦450 mm, said LED module extends over an angle α on said circle, 30°≦α≦90°, preferably 36°≦α≦72°, the number N of LEDs is at least Nmin and at most Nmax, Nmin=3 and Nmax=150; - the LEDs are evenly distributed on the PCB in at least one row with a respective pitch between adjacent LEDs;

[0007] Further features of the LED module are that each LED has a respective lens positioned on the optical axis of the associated LED die, the LED die are housed in a cavity in a lens base of the lens having an inner light entrance surface for coupling light from the LED die into the lens, the lens has a concave light exit surface circular about the optical axis opposite the lens base, the concave light exit surface is surrounded by a convex light exit surface such that in operation the LED emits a rotationally symmetric batwing beam with a maximum intensity Imax of the batwing beam at an angle β relative to the optical axis and with a FWHM in the range of 15 to 30°, where 60°≦β≦80°.

[0008] The curved LED module has a curved or kinked profile and is instead referred to as a curved LED module or simply an LED module. Similarly, the curved PCB is instead referred to as a curved PCB. The curvature may follow a polyline, such as a circular arc segment, an ellipse segment, a parabolic segment, or a single or multiple kinked shape. The curvature of the LED module, respectively, the PCB, is generally only in one plane, i.e., a flat object such as the curved LED module and the curved PCB is not given a larger 3D dimension as a result of its curvature. The shape of the lens can be roughly described as a donut shape with a central cavity as a light input surface at the lens base side of the lens and a smooth central concave portion at the light output surface of the lens, in other words, with a convex light output surface with a central concave portion.

[0009] The pattern in which the LEDs with lenses are arranged, as well as their typical light emission beam profile and direction, are favorable for the desired uniform brightness of the light exit window. Therefore, in prior art devices, each luminaire has its own dedicated LED module. The present invention describes one LED module that can serve a wide range of luminaire geometries, reducing the variety, with known advantages such as saving costs and resources for portfolio maintenance. Moreover, the LED module according to the present invention requires less PCB material, which reduces costs. In a basic embodiment of the LED module, only one LED color is used. In other embodiments, multiple LED colors are applied, for example at least two different types of LEDs in the emission spectrum.

[0010] The curved LED module may have the feature that the number of LEDs comprises a plurality of LED subsets, essentially each LED subset having the same number and type of LEDs, each LED subset consisting of at least two different types of LEDs in the emission spectrum. In a basic embodiment of the LED module, only one LED color is used. In other embodiments, a plurality of LED colors, for example LEDs of at least two different types in the emission spectrum, are applied. For example, two different color temperatures White 1 + White 2 are applied, for example White 1 is a warm white with a color temperature of about 2500K and White 2 is a cool white with a color temperature of about 5000K. Other examples of combinations of different types of LEDs are White 1 LED + White 2 LED + Lime LED, Red LED + Green LED + Blue LED, Red LED + Green LED + Blue LED + White 3 LED, or Red LED + Green LED + Blue LED + White LED + Amber LED, White 3 having a color temperature of about 3000K, for example.

[0011] The curved PCB, curved LED module and lighting fixture of the present invention are: - Less diversity in the number of stock-keeping units (SKUs) since only one type of LED module is needed for a wide range of luminaire geometries, instead of two or more types of known LED modules. - the cost is relatively low due to the efficient use of the surface area of ​​the curved PCB by the curved array of LEDs mounted on the curved PCB; - Effective use of PCB material and cost is acceptable by efficiently nesting curved PCBs in PCB panels; - the beam emission profile and beam direction of the LEDs and the balanced arrangement of the LED modules in the luminaire result in a relatively good uniformity of the light exit window even in luminaires with a small thickness, i.e. a thickness of ≦50 mm; - Advantages include that due to a suitably profiled stepped profile of the luminaire base in combination with the specific beam emission profile of each LED, electronic components, e.g. a power supply unit (PSU), can be placed within the optical cavity.

[0012] The curved LED module may be characterized in that the LEDs are arranged on the PCB with an average pitch Pavg between them, the respective pitches between adjacent LEDs being at least Pmin and at most Pmax, Pmin=5mm and Pmax=100mm, the ratio Emax=Pmax / Pavg being at most 1.4 and the ratio Emin=Pmin / Pavg being at least 0.4. In practice, the maximum LED pitch Pmax is at most 100mm, but since a larger pitch risks insufficient overlap of light from one LED with that from an adjacent LED resulting in dark areas and / or non-uniformity, an increase in Pmax is accompanied by an increased risk of said dark areas and / or non-uniformity, and therefore should not exceed 1.4*Pavg, preferably 1.2*Pavg. There is no indication of a minimum (smallest) LED pitch (Pmin), but Pmin is generally determined by the size of the lens of the LED die and in practice is at least 5mm. If multiple, e.g. three, colored LEDs are used, the equal pitch requirement is preferably applied separately for each color. In that case, this means that the total number of LEDs in the LED row in each curved LED module is preferably an integer multiple of three. Broadly, this understanding can be expressed as: if the multiple LEDs have T different types of LEDs, then the number N of LEDs in the LED module is an integer multiple of T. It is preferable to use only white LEDs in the outer corners of the LED module. In compact luminaires, the LEDs in the outer corners are near the edge. This is fine for white LEDs, but for colored LEDs there is a risk of color being observed.

[0013] The present invention is applicable to curved LED modules comprising LEDs of one or more colors (e.g. warm white, cool white, lime, RGB). If the curved LED module has more than one row of LEDs, the pitch requirement is preferably applied for each row and for each color separately.

[0014] The curved LED module may be characterized in that the curved LED module has a length L, 180mm≦L≦280mm. The length of the LED module combined with the radius Rpcb of the curved PCB determines the curvature of the PCB. If the radius Rpcb is too large and the length L is too small, an almost straight line of LEDs of the LED module will result, which will cause too much deviation in small lighting fixtures. On the other hand, if the radius Rpcb is too small and the length L is too long, this will cause too much deviation in large lighting fixtures, which will increase the cost of PCB materials.

[0015] The curved LED module may be further optimized in shape and size to suit a wider range of lighting fixtures, whereas the curved LED module may have more narrowly defined characteristics, i.e. Nmin=12 and Nmax=36, and / or 50°≦α≦70°, and / or 65°≦β≦75° and FWHM in the range of 18° to 24°, and / or 5mm≦W≦65mm, preferably 20mm≦W≦50mm, and / or the curvature of the LED module itself is curved according to a circular arc segment, the curvature having a radius Rpcb, and 200mm≦Rpcb≦450mm.

[0016] The curved LED module may be characterized in that the plurality of LEDs are arranged on the main surface in at least two essentially parallel rows, each row having at least nine LEDs, and each row extending essentially following a curve or curvature of the LED module.

[0017] As described above, the luminaire has a housing with a base having a first carrier surface and a cover arranged on a light exit window of the luminaire opposite to the first carrier surface, and curved LED modules, for example at least four, of the above type are evenly arranged on the first carrier surface, pointing their LEDs towards the light exit window and shielded (from direct view) by the cover. In order to uniformly illuminate the light exit window of a diffuse luminaire of a certain shape and size, some optical constraints or best practices have been found, namely: - The diffuser needs to be uniformly lit, with the intensity preferably being somewhat higher in the center and decreasing somewhat towards the edges. This has the advantage of providing a natural look. - The diffuser needs to be diffusive enough so that you cannot look directly into the diffuser and see the LEDs. - The LEDs must be equally spaced on the circle on which they are placed. The maximum pitch is determined experimentally using a suitable diffuser and suitable luminaire diameter. The minimum pitch is when the lenses are (almost) touching each other. If more light is required than can result from this minimum pitch, additional rings of LEDs must be added. - The position and diameter of the circle of the LED module depends on the diameter of the luminaire. - If more than one color LED is used, each of the LED types should be equally spaced resulting in alternating LED types. - The distance between LEDs of different types / colors needs to be relatively small to ensure proper color mixing. - If more than one circle of LEDs is used, the pitch between the LEDs does not have to be the same in each of said circles. - The sides of the luminaire are preferably made of a specific material, i.e. the areas where the light may accidentally go directly are preferably reflective (white) or preferably consist of a double layer of diffusers (placed at some distance) to achieve that the unmixed light reaching those zones does not result in visible colored spots on the sides. The material properties of the upper part of the sides and of the front surface of the luminaire can be more transparent. - The shape of the luminaire may be tapered from the centre to the edges, making the sides thinner than the centre, to make the luminaire appear thinner.

[0018] The LED module circle diameter is determined by placing the average continuous circular LED pitch between the LED modules. The lens pitch between the end lens of a first LED module and the start lens of an adjacent second LED module should be as equal as possible to the lens pitch between lenses in a single LED module. Slight unroundness of the LED module circle diameter does not have a (large) observable optical effect on uniformity.

[0019] The lighting fixture may be characterized in that the lighting fixture has a circular light exit window with a diameter Dl, and has at least seven LED modules, at least five of the LED modules arranged to form a circular configuration with a diameter Dc around a central array of at least two LED modules, and 1.2≦Dl / Dc≦1.6.

[0020] The luminaire may be characterized in that the circular configuration has a radius Rc, where Rc=0.5*Dc, and 120mm≦Rc≦450mm.

[0021] The luminaire may be characterized in that the central array has a radius Ra and is surrounded by at least one further, essentially concentric, circular configuration of curved LED modules, each subsequent further circular configuration having an increasing diameter Ri, such that 1.8*Ra≦Ri≦2.2*Ra. Thus, in a radial direction from the center outwards, a first circular configuration has a diameter Dc of approximately 2*Ra, a second circular configuration has a diameter of approximately 4*Ra, a third circular configuration has a diameter of approximately 6*Ra, etc.

[0022] The luminaire may be characterized in that the base has a stepped height profile, the highest part of which, taking into account the orientation of the luminaire with the LEDs facing upwards with respect to gravity, creates a cavity on a second carrier side of the base opposite to the first carrier side. Such a cavity has the advantage of providing a place for (unobtrusively) accommodating a PSU. The luminaire is generally applied as a ceiling luminaire with the LEDs facing downwards with respect to gravity, in which case the cavity is preferably located above the lowest part of the stepped profile, so that the base shields the electronic components housed in the cavity, such as a PSU, from being visible through the light exit window. Generally, such highest (or lowest) part of the base is located closest to the light exit window when viewed in a direction along the optical axis. [Brief description of the drawings]

[0023] The invention will now be further explained using schematic drawings in which some features may be exaggerated for clarity, the drawings being in no way intended to limit the scope of the invention, but rather to illustrate the abundant possibilities of the invention. [Figure 1A] 1 shows two different embodiments of a luminaire according to the invention; [Figure 1B]1 shows two different embodiments of a luminaire according to the invention; [Figure 2A] 1 shows the basic parameters of a curved LED module according to the present invention. [Figure 2B] 1 shows the basic parameters of a curved LED module according to the present invention. [Figure 2C] 1 shows the basic parameters of a curved LED module according to the present invention. [Figure 3A] FIG. 2 shows a top perspective view of a lens of a curved LED module according to the present invention. [Figure 3B] FIG. 2 shows a bottom perspective view of a lens of the curved LED module according to the present invention. [Figure 3C] 2 shows a vertical cross-sectional view of a lens of a curved LED module according to the present invention. [Figure 4A] 1 shows a perspective view of an embodiment of a curved LED module according to the present invention. [Figure 4B] 1 shows a top view of an embodiment of an interconnection of curved LED modules according to the present invention. [Diagram 5] 4 shows a cross section of a typical beam emission of an LED die with the lens of FIGS. 3A-3B. [Figure 6A] 2 shows a schematic cross section through a luminaire according to the invention and a beam radiation profile. [Figure 6B] 2 shows a schematic cross section through a luminaire according to the invention and a beam radiation profile. [Figure 7] 1 shows some basic parameters of an arrangement of curved LED modules in a luminaire according to the invention. [Figure 8] 1 shows some basic parameters of an arrangement of curved LED modules in a luminaire according to the invention. [Figure 9A] 1 shows several embodiments of a lighting fixture according to the present invention; [Figure 9B] 1 shows several embodiments of a lighting fixture according to the present invention; [Figure 9C] 1 shows several embodiments of a lighting fixture according to the present invention; [Figure 9D]1 shows several embodiments of a lighting fixture according to the present invention; [Figure 9E] 1 shows several embodiments of a lighting fixture according to the present invention; [Figure 9F] 1 shows several embodiments of a lighting fixture according to the present invention; [Figure 10] Demonstrates efficient use of PCB material to mount LEDs on curved PCBs. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Fig. 1A shows a first embodiment of a luminaire 1 according to the invention. The luminaire has a housing 3 with a base 5 having a first carrier surface 7 and a cover 9 arranged on a light exit window 1 of the luminaire opposite said first carrier surface. In the figure, the cover, instead of being shown as a diffusive semi-transparent cover for the sake of clarity, is shown as a transparent grey cover to allow viewing an arrangement of seven curved LED modules 13 (normally shielded by said cover from direct view by a person / user) evenly arranged on said first carrier surface and pointing their LEDs 15 towards the light exit window. The base has a stepped height profile 17. Five of the seven curved LED modules 13' are arranged in a circular arrangement, thereby surrounding two centrally arranged curved LED modules 13'' arranged on a raised central part 19 of the stepped profile of the base. The central part of the base has a recess 21 between the two centrally disposed curved LED modules in which a PSU / driver 23 for driving and controlling the LEDs and / or the curved LED modules individually is accommodated. Both the curved LED module and the PSU / driver are mounted on the same side of the base, although it is possible that the PSU / driver is instead arranged discreetly on the opposite side of the base to the side on which the LED modules are mounted. FIG. 1B shows a second embodiment of a luminaire 1 according to the invention with nine curved LED modules 13 evenly mounted on the luminaire base 5. Six of the nine curved LED modules 13′ are arranged in a circular array, thereby surrounding three centrally disposed curved LED modules 13″, which are arranged on the raised central part 19 of the stepped profile of the base. The central part of the base has a recess 21 between the three centrally disposed curved LED modules in which a PSU / driver 23 for driving and controlling the LEDs and / or the curved LED modules individually is accommodated.

[0025] 2A-2C show schematic diagrams of basic parameters of a curved LED module 13 according to the invention. In these figures, the curved LED module includes only a single row of seven LEDs mounted on a PCB 14 and is shown as a curved LED module in the form of a circular arc segment, in the form of a segment of an ellipse and in the form of a polyline, for example in the form of a single or multiple kinks. These basic parameters relate to the geometrical boundaries of the LED module and include, for example:

[0026] The LED pitch "p" is preferably equal over the entire curvature of the LED module over the entire circle in the luminaire and is Pavg on average. The geometry of the LED module must support this pitch, i.e. not too much PCB material outside the LEDs in the direction of curvature extension, which relates to "m", the maximum pitch between adjacent LEDs, i.e. Pmax. In practice, the maximum LED pitch Pmax is at most 100 mm, but with a larger pitch there is a risk of insufficient overlap of the light from one LED with the light from the adjacent LED, resulting in dark areas and / or non-uniformity, so that an increase in Pmax is accompanied by an increase in the risk of said dark areas and / or non-uniformity, and therefore must not exceed 1.4*Pavg, preferably 1.2*Pavg. There is no indication of a minimum (smallest) LED pitch (Pmin), but Pmin is generally dictated by the size of the lens of the LED die and in practice is at least 5 mm.

[0027] The curved LED module has a useful length, which is defined as the pitch "L" between two adjacent LED modules;

number

[0028] The radial distance of the LEDs in a single LED module is a measure of the degree of bending of the curved LED module (or in other words, the curvature of the LED module). The radial distance is determined via a parameter "c", which can typically range from 15 mm to 30 mm, but preferably c=20 mm±2 mm. For "c" smaller than 15 mm, this results in a nearly linear row of LEDs, resulting in too large a deviation in small luminaires. For "c" larger than 30 mm, this results in too large a deviation in large luminaires, increasing the cost of PCB materials.

[0029] 3A-3C show top, bottom and vertical cross-sectional views of a lens 25 of an LED as mounted on a PCB of a curved LED module according to the invention. The shape of the lens can be roughly described as a donut shape with a central cavity 27 providing a light entrance surface 29 on the lens base 31 side of the lens and with a smooth central depression 33 on the light exit surface 35 of the lens, or in other words with a convex light exit surface 35 with a central concave portion 33. Each lens central cavity houses at least one associated LED die 37, which can be a single LED die or multiple LED dies, for example RGB LED dies. As shown in FIG. 3B, the base side is provided with at least locally scattering structures 39 to hide the PCB and / or to enhance the mixing and / or uniformity of the light emitted by the LED die, for example if an RGB LED die is housed in the cavity. It should be noted that the scattering structures are not a required feature, but rather optional.

[0030] Figures 4A and 4B show a perspective view of an embodiment of a curved LED module 13 according to the invention and a top view of an embodiment of an interconnection of curved LED modules 13 according to the invention. In the embodiment shown in Figures 4A and 4B, a number of LEDs 15 are arranged on the first main carrier surface 7 of the PCB 14 in at least two essentially parallel rows, each row having at least 9 LEDs, i.e. the inner row 41 has 9 LEDs and the outer row 43 has 12 LEDs, each row essentially following the curvature of the LED module. As shown, the LED modules each have a connector 45 with a respective connecting wire 47 that allows easy electrical throughput connection of adjacent LED modules. The connectors can be arranged on the LED modules for loop-through of electrical connections, for example to create "strings" of LED modules, which are easier to assemble.

[0031] FIG. 5 shows a cross section of a typical beam emission of an LED 15 with an LED die and a lens of FIGS. 3A and 3B. The intensity distribution of the LED is preferably a batwing light distribution that is rotationally symmetric around the respective optical axis OA of the associated respective LED. The beam angle β, i.e. the direction of the highest beam intensity, is preferably between 60 and 80 degrees from the optical axis, in the figure β is about 70 degrees. The full width at half maximum FWHM of the emitted beam is preferably about 20 degrees, between 15 and 30 degrees. The figure illustrates the intensity profile of a suitable lens. A too small FWHM width of the peak will result in a bright ring around the LED. A too wide peak will result in less mixing. The LED pitch as defined for the curved LED module ensures the overlap of light from the multiple LEDs. The configuration of the LED modules results in a pitch, said pitch having a value that is the maximum value of the values ​​of the LED pitch and the radial distance between the LED modules located at different radial distances from the optical axis, such as the difference in the radial distance from the optical axis of the concentric rings. The pitch-to-height ratio in this application is generally about 1.2, which can be considered as a preferred pitch-to-height ratio, where height is the distance along the optical axis between the PCB and the light exit window or diffuser (if present). The pitch-to-height ratio should not be higher than 1.5, because a higher value would result in non-uniformity due to insufficient overlap of the light of the multiple LEDs. The pitch-to-height ratio should not be less than 0.5, because this would result in an undesirable and / or unnecessarily deep / tall / thick luminaire. The diffusion cover provided over the LED module, for example as shown in FIG. 1A, is preferably a Lambertian diffuser, and light should not be transmitted unscattered to prevent the LEDs and lenses from being viewed directly through the diffusion cover. Preferably, the diffusion cover should not absorb too much light, because this would negatively affect the optical efficiency.

[0032] 6A and 6B respectively show schematic partial cross-sectional and perspective cross-sectional views through a luminaire 51 according to the invention, illustrating typical desired specifications for the angle β of the orientation of the batwing beam radiation profile. The luminaire has a power supply unit (PSU) 23 in a central recess 21 of the luminaire base 5. The PSU is surrounded by a relatively centrally located central array 53 of inner LED modules 13'' and a further circular array 55 of circularly arranged further LED modules 13' arranged around the central array. The inner LED modules are spaced apart from each other at approximately a distance R about the optical axis OA. a and a further circular array is arranged at a radius R c and the luminaire has a radius R l The luminaire has an outer edge 57 to which a cover 9 is attached, said cover extending over the LED modules and the PSU and forming a light exit window 11 of the luminaire. The outer edge is connected to the base 5 and in the figures is formed integrally with the base, but this could instead be a separate part. The base has a stepped height profile 17 in which a central, lowest part 21 (with the LEDs 15 facing upwards against gravity) is surrounded by the highest, raised part 19 of the array of inner LED modules, thus creating a recess 21 in the first carrier face 7 of the base to accommodate the PSU. In another example, the central part is the highest part to accommodate the PSU discreetly in a recess in a second carrier face 59 opposite the first carrier face. The height position of the LED module and LEDs relative to the PSU and edge of the luminaire in combination with a particular beam profile and direction of the beam emitted by the LEDs (as described with respect to FIG. 5) is such that the beam passes just along the PSU and has a beam direction / angle with the optical axis of β1, and the beam passes just along the edge and has a beam direction / angle with the optical axis of β2. Preferably / typically, β1=β2=β, since one type of LED module is applied to the luminaire of the present invention. Alternatively or in addition, the recess and / or the LED module may include other electronic components such as a power supply, an antenna, an LED controller, a connector, etc.

[0033] Figures 7 and 8 show some basic parameters for the arrangement of curved LED modules 13 in a luminaire according to the invention. In Figure 7 a circular luminaire 51 with diameter Dl is shown, where a concentric arrangement of light-emitting LED modules around an optical axis OA in the luminaire covers an area Am with diameter Dc, where Am is 0.5*π*Dc. 2 The ratio Dl:Dc is preferably in the range of 1.2 to 1.6 to ensure a uniform appearance of the light exit window / cover (not shown) of the luminaire. The required number of LED modules to be used and whether more than a single circular array of LED modules is required for a luminaire depends on the size (or diameter Dl) of the luminaire. In the embodiment of the luminaire shown in Fig. 7, two concentric circular arrays 53, 55 are provided, the LED modules in the outer circular array 55 each having three substantially parallel extending rows 41, 42, 43 of LEDs 15 mounted on the PCB 14 according to the curvature of the curved PCB. Generally, if the circular array of circularly arranged LED modules in the luminaire becomes larger, for example larger than 170 mm, a further array, for example a circular array, of inner LED modules inside the larger circular array should be provided to prevent too low brightness in the center of the luminaire. In the luminaire shown in Fig. 7, the inner modules each have two substantially parallel extending rows of LEDs mounted on the PCB. The roundness of the inner LED modules, which are more centrally arranged, is less important due to the local mixing effect of many LEDs. The number of LED modules is determined by the surface Al of the luminaire, Al=π*Rl 2 The surface area of ​​the LED module can be defined by calculating according to the formula: where each LED should cover a surface area of ​​substantially equal size. As shown in FIG. 7, the luminaire has two concentrically arranged substantially circular arrays of LED modules. The inner circular array of LED modules is covered by the surface area of ​​the cover A1=π*Ra1. 2While it is necessary to illuminate, the circular array outside the LED module needs to illuminate the surface area A2 of the cover, where A2 = π * (Rl 2 - Ra1 2 )). Furthermore, in contrast, it is preferable that the inner array does not cover a larger surface area than the outer array, that is, A1:A2 < M:L, where - A1: the surface area of the inner array of the LED module, - A2: the surface area of the outer circular array of the LED module, - L: the number of LED modules in the outer array, - M: the number of LED modules in the inner array.

[0034] Figure 8 shows an example of a circular array of LED modules for a lighting fixture that requires at least three concentric circular arrays of LED modules centered on the optical axis OA. In the lighting fixture 51 shown in Figure 8, the same type of, that is, only one type of LED module 13 is used in all the circular arrays 53, 54, 55. The innermost circular array 53 of the LED module has a respective radius R, where R is Ra, and each subsequent further circular array 54, 55 of the LED module has a radius increased by Ri, where

Number

Number

Number

[0035] Figures 9A to 9F show some embodiments with different arrangements of LED modules that can be applied in a luminaire according to the invention. The shown embodiments are only examples, other LED module arrangements with different numbers of LED modules are possible for luminaires with the same diameter / size. Figure 9A shows an arrangement of LED modules for a circular luminaire with a diameter of 500 mm, with a circular outer array 55 of LED modules and a concentric inner array 53 of LED modules. Figure 9B shows an arrangement of LED modules for a circular luminaire with a diameter of 650 mm, with a circular outer array 55 and a concentric inner array 53. Figure 9C shows an arrangement of LED modules for a circular luminaire with a diameter of 750 mm, with a circular outer array 55 and a concentric inner array 53. Figure 9D shows an arrangement of LED modules for a circular luminaire with a diameter of 850 mm, with a circular outer array 55 and a concentric inner circular array 53. Figure 9E shows an arrangement of LED modules for a circular luminaire with a diameter of 900 mm, with a circular outer array 55 and a concentric inner circular array 53. Figure 9F shows an arrangement of LED modules for a 600mm*500mm rectangular luminaire (square in this case) where the inner array 53 is non-rotationally symmetric with respect to the outer array 55. In all the examples shown in Figures 9A-9F, the same, single type of LED module is used. Thus, the present invention is illustrated to describe one LED module that can serve a wide range of luminaire geometries, reducing diversity, with known advantages such as cost and resource savings for portfolio maintenance.

[0036] example: The one chosen is for a 3-channel 24V based architecture. The smallest LED module consists of three types of LEDs with 7 LEDs of each type, i.e., in this case, 2200K like warm white LEDs, 6500K like cool white LEDs, and lime LEDs. Thus, the smallest module has a total of 21 LEDs. Furthermore, each larger LED module has an integer multiple of 21 LEDs, i.e., 42, 63, 84... LEDs. It should be noted that the different color LEDs make the LED module tunable white, but tunable white is not directly related to the present invention, which also relates to fixed correlated color temperature (CCT). In further embodiments, it may be considered to have LEDs in more than one color / CCT. In this case, uniformity becomes more important than in the case of fixed CCT, since the eye is more sensitive to color changes than to intensity changes. Based on this smallest unit cell, several scenarios for LED selection were calculated and evaluated with respect to technical feasibility, cost, and best match requirements between light output and geometry. This resulted in a luminous flux of about 650 lm for each LED module with 7 LEDs in each color. This results in the minimum number of LED modules listed in Table 1 being required to generate the required light output for each geometry / size, considering an optical efficiency of about 80%. [Table 1] Table 1. Examples of lighting fixtures

[0037] The optimal arrangement of LEDs with lenses is when they are arranged concentrically with no gaps in the circle, especially since a regular pattern of missing LEDs in the circle tends to be noticeable. Therefore, the arrangement of LED modules in the luminaire was simulated for some of the luminaires listed in Table 1. Some of the embodiments that gave good results are listed in Table 2. [Table 2] Table 2. Optical simulation results / data

[0038] During further experiments with samples of LED modules in this configuration, it was found that it is the closed outer ring that is most important in terms of the uniformity of illumination of the light exit window, both in terms of brightness and color. The inner ring is less important in this respect. In the center of the luminaire, the light mixing is relatively good. As a result, the inner "ring" of the LED module can be made with the same curved LED modules that are used for the further, more outer rings. Especially the round luminaire has a very good uniformity, while for the rectangular luminaire an acceptable uniformity is obtained, although not as good as the round version.

[0039] 10 shows an efficient use of PCB material 14 for mounting LEDs 15 in a curved LED module 13. Due to the nested column arrangement of curved PCBs in a larger PCB panel and the alternating orientation of the curved PCBs in the rows, efficient use of PCB material is achieved with less material loss.

Claims

1. A lighting device having a housing with a base having a first carrier surface on which a plurality of LED modules are arranged, and a cover arranged on a light exit window of the lighting device opposite to the first carrier surface, Each LED module is a curved LED module having a curved PCB with a main surface on which a number N of LEDs are mounted, the LEDs facing a light exit window and covered by the cover; the LED modules are arranged having an inner array of LED modules surrounded by a concentric outer array of LED modules; All LED modules are identical 1. A luminaire, wherein the light exit window is circular with a diameter Dl and has at least seven evenly arranged curved LED modules on the first carrier surface, at least five of the LED modules being arranged as an outer array forming a circular configuration with a diameter Dc around a central inner array of at least two LED modules, and 1.2≦Dl / Dc≦1.

6.

2. the LED module has a curved shape with its main surface extending in a plane Q and with a width W transverse to its curvature, the LED module covering an arc segment of a circle with a radius Rc, 120 mm≦Rc≦450 mm; the LED modules extend over an angle α on the circle, where 30°≦α≦90°; The number N of LEDs is at least Nmin and at most Nmax, where Nmin=3 and Nmax=150; 10. The lighting fixture of claim 1, wherein the LEDs are evenly spaced on the PCB in at least one row with a respective pitch between adjacent LEDs.

3. 3. A lighting fixture as claimed in claim 1 or 2, wherein each LED has a respective lens located on the optical axis of an associated LED die, the LED die being housed in a cavity in a lens base of the lens having an inner light entrance surface for coupling light from the LED die into the lens, the lens having a concave light exit surface circular about the optical axis on an opposite side to the lens base, the concave light exit surface being surrounded by a convex light exit surface such that in operation the LEDs emit a rotationally symmetric batwing beam with a maximum intensity Imax of the batwing beam at an angle β relative to the optical axis and with a FWHM in the range of 15 to 30°, where 60°≦β≦80°.

4. 4. A luminaire as claimed in claim 1, 2 or 3, wherein the LED modules are arranged in an array having a circular inner array concentric with a circular outer array about an optical axis.

5. 4. A luminaire as claimed in claim 1, 2 or 3, wherein the LED modules are arranged in an array having at least three concentric circular arrays about an optical axis.

6. 6. A luminaire as claimed in claim 4 or 5, wherein the central array has a radius Ra, and each subsequent further circular arrangement has an increasing diameter Ri, where 1.8*Ra≦Ri≦2.2*Ra.

7. 7. A luminaire as claimed in any preceding claim, wherein the circular formation has a radius Rc, where 120mm < Rc < 450mm.

8. 8. A luminaire as claimed in any one of the preceding claims, wherein the base has a stepped height profile, the highest portion of which creates a cavity in a second carrier surface of the base opposite the first carrier surface.

9. 9. A lighting fixture as claimed in any one of claims 1 to 8, wherein the LEDs are arranged on the PCB with an average pitch Pavg between them, the respective pitches between adjacent LEDs being at a minimum Pmin and at a maximum Pmax, Pmin = 5 mm, Pmax = 100 mm, the ratio Emax = Pmax / Pavg being at most 1.4 and the ratio Emin = Pmin / Pavg being at least 0.

4.

10. 10. A luminaire according to any one of the preceding claims, wherein the number of LEDs comprises T different types of LEDs, where N is a multiple of T.

11. 11. A luminaire according to any one of the preceding claims, wherein the curved LED module has a length L, where 180mm < L < 280mm.

12. 12. A luminaire as claimed in any one of the preceding claims, wherein 5mm < W < 65mm.

13. 13. A luminaire as claimed in any one of claims 1 to 12, wherein the curved portion of the LED module itself is curved according to a circular arc segment, the curved portion having a curvature with a radius Rpcb, where 200mm≦Rpcb≦450mm.

14. 14. An LED module suitable for use in a luminaire according to any one of claims 1 to 13, comprising: the LED module has a curved shape with its main surface extending in a plane Q and with a width W transverse to its curvature, the LED module covering an arc segment of a circle with a radius Rc, 120 mm≦Rc≦450 mm; the LED modules extend over an angle α on the circle, where 30°≦α≦90°; The number N of LEDs is at least Nmin and at most Nmax, where Nmin=3 and Nmax=150; the LEDs are evenly spaced on the PCB in at least one row with a respective pitch between adjacent LEDs; When the multiple LEDs include T different types of LEDs, N is a multiple of T, and 2≦T≦6.

15. 15. The LED module of claim 14, wherein each LED has a respective lens positioned on the optical axis of an associated LED die, the LED die being housed in a cavity in a lens base of the lens having an inner light entrance surface for coupling light from the LED die into the lens, the lens having a concave light exit surface circular about the optical axis on an opposite side of the lens base, the concave light exit surface being surrounded by a convex light exit surface such that in operation the LEDs emit a rotationally symmetric batwing beam with a maximum intensity Imax of the batwing beam at an angle β relative to the optical axis and with a FWHM in the range of 15 to 30°, where 60°≦β≦80°.

Images