Lighting fixtures

Abstract

Lighting fixtures (10), comprising: a light source (12) comprising an array (20) of light-emitting diodes (LEDs); a reflector (14) comprising an input end (34) adjacent to the array (20) of LEDs and an output end (36) opposite the input end (34) such that the light source (12) emits light through the reflector (14) from the input end (34) through the output end (36), the reflector (14) further comprising a first, a second, a third and a fourth side wall (40a - 40f) extending from the input end (34) to the output end (36), the first and the second side wall each comprising an interior surface (42), the third and the fourth side wall each comprising an interior surface (42) having a reflectivity that is more diverging than the interior surfaces (42) of the first and second side walls; and a lens (16) adjacent to the exit end (36) of the reflector (14), wherein the inner surface (42) of the first side wall is reflective, wherein the inner surface (42) of the second side wall is reflective, wherein the inner surface (42) of the third side wall comprises a scattering structure, wherein the inner surface (42) of the fourth side wall comprises a scattering structure, and wherein the scattering structure comprises a scattering grain oriented along a longitudinal axis (50) of the reflector (14).

Description

BACKGROUND

[0001] The present invention relates to lighting fixtures and, more particularly, to lighting fixtures using light-emitting diodes or LEDs.

[0002] Various lighting systems are known from the prior art. US 2008 / 0 170 392 A1 describes various lighting modules characterized by the thermal coupling of light-emitting elements with one or more heat extraction elements. Wippermann et al. Optics Express 15 (2007), no. 10, pp. 6218-6231 relates to various lens arrangements used to homogenize laser beams. US 2010 / 0 033 948 A1 describes a lighting module that enables manipulation of the spectral distribution and color temperature of the emerging light by changing the relative position of a reflector to a side wall with differently coated sections. US 2013 / 0 155 671 A1 relates to an arrangement for point illumination with a convex-shaped and an additional cylindrical reflector in combination with an optical projection system.US 2016 / 0 208 999 A1 describes a device for bundling light beams with a light integrator that collects and integrates or homogenizes the light from a plurality of light sources. US 2017 / 0 299 958 A1 relates to a lighting device and a projection display device using the same. US 2010 / 0 097 802 A1 relates to a method for controlling the light output of an array of LEDs when used in a luminaire generating a light beam. SUMMARY

[0003] The invention relates to a lighting fixture according to claim 1. Advantageous embodiments are defined in the subclaims. Disclosed herein is a lighting fixture comprising a light source having an array of light-emitting diodes (LEDs) and a reflector having an input end adjacent to the array of LEDs and an output end opposite the input end, such that the light source emits light through the reflector from the input end through the output end. The reflector further comprises first, second, third, and fourth sidewalls extending from the input end to the output end. The first and second sidewalls each include an inner surface, and the third and fourth sidewalls each include an inner surface with a reflectivity that is more dispersive than the inner surfaces of the first and second sidewalls. A lens is located adjacent the output end of the reflector.

[0004] Also disclosed is a lighting fixture comprising a light source with an array of light-emitting diodes (LEDs) and a reflector with an input end adjacent to the array of LEDs and an output end opposite the input end, such that the light source emits light through the reflector from the input end to the output end. A tandem lens array is located adjacent to the output end of the reflector. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is an exploded view of a portion of the lighting fixture of Fig. 14. Fig. Figure 2 is an alternative exploded view of the lighting fixture of Fig. 1. Fig. 3 is an alternative exploded view of the lighting fixture of Fig. 1. Fig. 4 is an exploded cross-sectional view of the lighting fixture of Fig. 3 along line BB in Fig. 3 Fig. 5 is a perspective view of an LED array of the lighting fixture of Fig. 1. Fig. 6 shows an LED color arrangement of the LED array of Fig. 5. Fig. Figure 7 is an exploded view of the lighting fixture of Fig. 1, which controls the color mixing and collimation of the LED array of Fig. 5 represents. Fig. 8 shows the surface finish of a reflector of the lighting fixture of Fig. 1. Fig. 9 illustrates a reflector according to another embodiment of the invention. The Fig. 10A - 10C show possible arrangements of the surface finish of the reflector of the lighting fixture of Fig. 1. Fig. 11 illustrates a reflector according to another embodiment of the invention. Fig. 12 shows a possible arrangement of surface finishes of the reflector of Fig. 11. Fig. 13A and Fig. 13B illustrate possible arrangements of surface finishes of a reflector according to another embodiment of the invention. Fig. 14 is a perspective view of a lighting fixture according to an embodiment of the invention. Fig. Figure 15 is a partially exploded view of the lighting fixture of Fig. 14. Fig. 16 is a perspective view of a tandem lens array according to one embodiment. Fig. 17 is a cross-sectional view of the lens of Fig. 16 along line 17 - 17 from Fig. 16. Fig. 18 is an enlarged section of Fig. 17. Fig. 19 is a perspective view of a tandem lens array according to another embodiment. Fig. 20 is a perspective view of a tandem lens array according to another embodiment. Fig. 21 is a perspective view of a tandem lens array according to another embodiment. Fig. 22 is a perspective view of a reflector according to another embodiment. Fig. 23 is a perspective view of a reflector according to another embodiment. DETAILED DESCRIPTION

[0005] Before embodiments of the invention are explained in detail, it should be understood that the invention is not limited in its application to the details of construction and arrangement of components shown in the following description or in the following drawings. The invention may have other embodiments and may be practiced or carried out in various ways.

[0006] Fig. 14 represents a lighting fixture or a luminaire 10 with a housing 11. With reference to the Fig. 1 - 4, the lighting fixture 10 comprises within the housing 11 a light source 12, a light guide or reflector 14 and lenses 16. The lighting fixture 10 is particularly suitable for use in live performances, including theater productions, concerts, television or film studio productions and the like.

[0007] With reference to the Fig. 5 and Fig. 6, the light source 12 includes an array 20 of light-emitting diodes (LEDs). In the illustrated embodiment, the array 20 of LEDs has the shape of a hexagon, generally conforming to or corresponding to the cross-sectional shape of the reflector 14. The illustrated array 20 includes 52 individual Luxeon C LEDs closely spaced together and producing approximately 10,000 lumens. The array 20 includes 26 red, 24 neon green, 30 green, and 28 indigo blue color LEDs. A ring of 30 green and 24 neon green LEDs is arranged around the outer perimeter of the array 20. A ring of 26 red LEDs in a hexagonal shape is located immediately inward of the row of 30 green and 24 neon green LEDs. Within the row of red LEDs 26 there are two groups of indigo blue LEDs 28 with two green LEDs 30 between the groups of indigo blue LEDs 28 within the row of red LEDs 26. The array 20 shown comprises 12 indigo blue LEDs, 8 green LEDs, 16 neon green LEDs and 16 red LEDs in the Fig. 6. In some embodiments, array 20 includes 10 to 20 red LEDs, 10 to 20 neon green LEDs, 5 to 12 green LEDs, and 8 to 16 indigo blue LEDs.

[0008] The light guide or reflector 14 includes a first end or input end 34 adjacent to the array 20 of LEDs and a second end or output end 36 opposite the first end 34. The illustrated reflector 14 includes six side walls 40a-40f extending from the first end 34 to the second end 36. The six side walls 40a-40f are arranged to define the reflector 14 with a hexagonal cross-section. The side walls 40a-40f each include an inwardly facing inner surface 42 and an outwardly facing outer surface 44. The reflector 14 is tapered such that a distance 46 (see Fig. 5) between the inner surfaces 42 of the opposite sidewalls 40a-40f increases in a direction from the first end 34 of the reflector 14 to the second end 36. The distance 46 is the smallest at the first end 34 and the largest at the second end 36. In one embodiment, the distance 46 at the second end 36 is in a range of about 3 to 5 times the distance 46 at the first end 34. It has been found that improved collimation of the array 20 is obtained when the distance 46 at the second end 36 is in a range of about 3 to 5 times the distance 46 at the first end 34.

[0009] At the first end 34, the distance 46 is approximately the same as a corresponding width of the array 20 of LEDs to form the gap 48 ( Fig. 5) between the array 20 and the side walls 40a - 40f. The reflector 14 tapers, thereby collimating the light from the LED array 20 that bounces off the side walls 40a - 40f, as shown in Fig. 7. In the Fig. 1 - 7, the taper of the side walls 40a-40f is straight or linear between the first end 34 and the second end 36. With reference to Fig. 3, a longitudinal axis 50 of the reflector 14 is defined as an axis extending centrally through the first end 34 and the second end 36 of the reflector 14. The side walls 40a - 40f are at an angle 52 ( Fig. 4) tapered relative to axis 50. In one embodiment, angle 52 ranges from approximately 10 degrees to approximately 20 degrees. It has been found that improved collimation of array 20 is obtained when angle 52 ranges from approximately 10 degrees to approximately 20 degrees.

[0010] With further reference to Fig. 3, a length 54 of the reflector is defined as the distance from the first end 34 to the second end 36, measured along the axis 50. In one embodiment, the length 54 is approximately 7.5 times the distance 46 at the first end 34, and the distance 46 at the second end 36 is approximately 4 to 5 times the distance 46 at the first end 34, with the angle 53 of the sidewalls 40a-40f being in a range of approximately 8 to approximately 14 degrees. It has been found that the reflector 14 with these relative dimensions provides good collimation of the array 20.

[0011] The Fig. 8-10C illustrate the surface properties of the inner surfaces 42 of the side walls 40a-40f of the reflector 14. According to the invention, some of the side walls 40a-40f have an inner surface 42 that is reflective, while some of the side walls 40a-40f have an inner surface 42 that includes a scattering structure. The scattering structure supports color mixing. Fig. Figure 8 illustrates an example of such a scattering structure on an aluminum surface with a grain referred to as mill finish. The scattering grain extends along or is aligned with the longitudinal axis 50 of the reflector 14. Orienting the grain parallel to the longitudinal axis 50 causes a variation in the azimuthal angle of the light reflected from the surface. This improves color mixing while minimizing lumen loss caused by scattering. In further embodiments, other types of scattering structures may be utilized on the inner surfaces 42 of the sidewalls 40a-40f, including other types of mill finishes or stamped finishes. In one embodiment, the scattering structures have a diffuse reflectance value in a range of approximately 80% to approximately 90%. The mirrored inner surfaces 42 of some of the sidewalls 40a-40f may be made of silver-coated aluminum.In other embodiments, other suitable materials, including glass, plastic, and / or other types of aluminum, may be used.

[0012] In one embodiment, one half of the sidewalls 40a-40f includes an inner surface 42 with a scattering structure, and one half of the sidewalls 40a-40f includes an inner surface 42 that is specular. This arrangement has been found to provide good color mixing of the array 20 with reduced lumen loss. Fig. 10A- 10C illustrate possible configurations of the inner surfaces 42. In the embodiment of Fig. 10A and Fig. 10B, the inner surfaces 42S comprise reflective inner surfaces 42, and the inner surfaces 42D comprise inner surfaces 42 with a scattering structure. The inner surfaces 42D with a scattering structure, which may be the same or a different scattering structure, have a reflectivity that is more scattering than the reflective inner surfaces 42S. In the embodiment of Fig. 10A, the reflecting inner surfaces 42S alternate with the dispersing inner surfaces 42D. In the embodiment of the Fig. 10B, one side of the reflector 14 comprises specular inner surfaces 42S, while the other side comprises scattering inner surfaces 42D. The reflector 14 in the embodiment of Fig. 10C includes interior surfaces with three different surfaces: reflective interior surfaces 42S, dispersive interior surfaces 42D, and interior surfaces 42SD with different interior surface properties. For example, dispersive interior surfaces 42D have a reflectivity that is most dispersive, Reflective inner surfaces 42S have a reflectivity that scatters the least, and the inner surfaces 42SD have a reflectivity with a scattering power that lies between 42D and 42S.

[0013] The Fig. 11 and Fig. 22 show a reflector 114 according to another embodiment that can be used with the lighting fixture 10 instead of the reflector 14. The reflector 114 has side walls 140 that are curved and parabolic in the illustrated embodiment. Fig. 9 and Fig. 23 illustrate a reflector 314 according to yet another embodiment. The reflector 314 is generally trumpet-shaped with sidewalls 340, which in the illustrated embodiment are curved and parabolic. Furthermore, the cross-sectional shape of the reflectors 114, 314 may be circular, elliptical, or polygonal. The reflectors 114, 314 may further include portions of the inner surface(s) of the sidewall(s) 140, 340, with some surfaces being specular and some surfaces including a diffusing structure. Fig. 12 shows a possible inner surface configuration for the reflectors 114, 314 of the Fig. 9 and Fig. 11. As in Fig. 12, approximately one half of the side walls 140, 340 comprise the reflective inner surface 42S, while the other half of the side walls 140, 340 comprise the dispersive inner surface 42D.

[0014] Although the reflectors 14, 114 and 314 of the Fig. 10A-10C comprise six side walls 40a - 40f, in other embodiments the reflector may have more than six side walls or fewer than six side walls. Fig. For example, Figures 13A-13B show a reflector 214 that includes four side walls 240a-240d. In the embodiment of Fig. 13A, the side walls 240b and 240d have inner surfaces 42D that include a scattering structure, and the side walls 240a and 240c have inner surfaces 42S that include a specular surface. In the embodiment of Fig. 13B, adjacent sidewalls 240a and 240d on one side of reflector 214 include inner surfaces 42S comprising a specular surface, and adjacent sidewalls 240b and 240c on the opposite side include inner surfaces 42D comprising the scattering structure.

[0015] With reference to Fig. 1, in some embodiments, the sidewalls 40a-40f may be made of folded metal or from individual metal pieces that are tabbed, welded, or adhesively secured to the inside of a corrugated housing to form the reflector 14. In other embodiments, the reflector 14 may further be made of glass or plastic, with portions of the reflector having a molded pattern or a surface finish created by sandblasting or etching.

[0016] With reference to Fig. 2, the lighting fixture further comprises an effect module 60. The illustrated effect module 60 comprises a first gobo wheel 62, a second gobo wheel 64 and an iris diaphragm 66. The gobo wheel 64 comprises diaphragms 68, each having a diameter or internal dimension 70. In one embodiment, the design for the dimensions of the reflector 14 begins with the aperture dimension 70. In one embodiment, the distance 46 at the second end 36 of the reflector 14 is in the range of approximately 1.3 to approximately 1.4 times the aperture dimension 70. Then, as discussed in the example above, the length 54 of the reflector 14 is approximately 7.5 times the distance 46 at the first end 34, and the distance 46 at the second end 36 is approximately 4 to 5 times the distance 46 at the first end 34, with the angle 53 of the sidewalls 40a-40f in a range of approximately 8 to approximately 14 degrees. These dimensions provide for good color mixing of the assembly 20.

[0017] With reference to the Fig. 3-4, the lenses 16 include a field lens 72 and a zoom projection lens 74. In one embodiment, the zoom projection lenses 74 provide an achromatic design with a 3:1 zoom. The zoom projection lenses 74 project the gobo or iris onto a wall or screen. The field lens 72 adjusts the angle of the light received from the reflector 14 and the light source 12 to correspond to the apertures 68 and the zoom optics 74. The illustrated lighting fixture 10 further includes diffusion media 76 that can pivot into and out of the light path to diffuse light from the lighting fixture 10.

[0018] The Fig. 16 and Fig. 17 illustrate a lens 172, which is a tandem lens array that can be used in a lighting fixture according to another embodiment. The tandem lens array 172 is hexagonal and can be positioned adjacent to or within the second end 36 of the hexagonal reflector 14 instead of the lens 72 of Fig. 4. In such an embodiment, the lighting fixture may not include the zoom projection lens 74. Rather, the lighting fixture may include a Fresnel lens that is movable along the longitudinal axis 50 to change the angle of emission of the light beam from the lighting fixture. In other embodiments, the tandem lens assembly 172 may have other suitable shapes to conform to the shape of the second end of the reflector. Generally, all of the light emitted by the reflector 14 passes through the tandem lens assembly 172. The tandem lens assembly 172 is particularly suitable for use in a wash beam type lighting fixture.

[0019] The tandem lens array 172, in one embodiment, is a single substrate that includes a first side 174 facing the array 20 of LEDs and a second side 176 opposite the first side 172. The first side 174 includes an array of approximately hemispherical lenses 178 arranged in a repeating pattern. The second side 176 includes the same array of approximately hemispherical lenses 178. The lenses 178 are approximately hemispherical because the lenses 178 have an f-number, which in the illustrated embodiment is approximately 1.159. An f-number of 1.0 would correspond to lenses that have a precise or exact hemispherical shape. In other embodiments, the pattern of the lenses may be random rather than repeating.The tandem lens array 172, after mixing and collimating the light in the reflector 14, splits it into multiple overlapping beams or Köhler illuminations, which further mix the light for better uniformity.

[0020] With reference to Fig. 18, the lenses 178 on the first side 174 in the illustrated embodiment have corresponding lenses 178 (or a matching pair) on the second side 176 with a common axis 179 extending centrally through the corresponding lenses 178. A pair of lenses 178a and 178b from the sides 174, 176 is shown in Fig. 18 with the common axis 179. In one embodiment, the lenses 178 have a radius of curvature 180 ( Fig. 18) of approximately 1.6 mm, and the lens 172 has a thickness 182 which, measured from the first side 174 to the second side 176, is approximately 5 mm. In such an embodiment, the numerical aperture of the lens pair 178a, 178b is approximately 0.43 with an f-number of approximately 1.159. The tandem lens array 172 can be used in a lighting fixture with approximately 44 multi-color LEDs with a maximum array diameter of 46 ( Fig. 5) of approximately 19.5 mm may be used. The light fixture may further comprise a hexagonal reflector 14 having a maximum diameter at the input end 34 of approximately 21 mm. It has been found that in the exemplary lens 172 and the light fixture described in this section, a reflector 14 having a taper angle 52 ( Fig. 4) between approximately 5 degrees and 20 degrees is preferred for adequate color mixing of the multi-colored LEDs. It has been found that a reflector length specified in the following table (i.e., the distance from input side 34 to output side 36 ( Fig. 4)) is preferred for each of the specified angles 52 in order to achieve the maximum possible optical efficiency of about 80 percent or more. The reflector length for all of the listed angles 52 can be significantly shorter if somewhat lower efficiencies (e.g., from about 60 percent to about 75 percent) are acceptable. For example, if an optical efficiency of 60 percent is desired or acceptable, the length at 5 degrees is about 150 mm, at 10 degrees the length is about 75 mm, at 15 degrees the length is about 65 mm, and at 20 degrees the length is about 50 mm. The reflector length and the reflector angle 52 then result in the maximum diameter of the output 36 shown in the table. The tandem lens arrangement 172 has been found to reduce the reflector length required for adequate color mixing of the multi-color LEDs. Winkel 52 (Grad) Länge des Reflektors (mm) Max. Durchmesser Ausgangsende 36 (mm) 5 200 56 10 150 74 15 110 80 20 95 90

[0021] Fig. Figure 19 illustrates a tandem lens array 272 according to another embodiment, which may be used instead of the tandem lens array 172 described above. The tandem lens array 272 includes individual lenses 278 that have an outer perimeter in the shape of a circle instead of a hexagon. The lenses 278 form a repeating hexagonal pattern. Fig. 20 illustrates another embodiment of a tandem lens array 372. The tandem lens array 372 includes lenses 378 arranged in a circular pattern about a center 373 of the tandem lens array 372. Fig. 21 illustrates a tandem lens array 472 according to another embodiment. The tandem lens array includes lenses 478 having a randomly shaped arrangement.

Claims

[1] Lighting fixture (10), comprising: a light source (12) comprising an array (20) of light-emitting diodes (LEDs); a reflector (14) comprising an input end (34) adjacent to the array (20) of LEDs and an output end (36) opposite the input end (34) such that the light source (12) emits light through the reflector (14) from the input end (34) through the output end (36), the reflector (14) further comprising first, second, third, and fourth sidewalls (40a-40f) extending from the input end (34) to the output end (36), the first and second sidewalls each comprising an inner surface (42), the third and fourth sidewalls each comprising an inner surface (42) having a reflectivity that is more dispersive than the inner surfaces (42) of the first and second sidewalls; and a lens (16) adjacent the output end (36) of the reflector (14), wherein the inner surface (42) of the first sidewall is specular, wherein the inner surface (42) of the second sidewall is specular, wherein the inner surface (42) of the third sidewall comprises a scattering structure, wherein the inner surface (42) of the fourth sidewall comprises a scattering structure, and wherein the scattering structure comprises a scattering grain aligned along a longitudinal axis (50) of the reflector (14). [2] The lighting fixture (10) of claim 1, wherein the reflector (14) further comprises a fifth and a sixth side wall such that the reflector (14) has a hexagonal cross-section. [3] The lighting fixture (10) of claim 2, wherein the fifth and sixth side walls each have an inner surface (42), wherein the third, fourth and fifth side walls each have an inner surface (42) with a reflectivity that is more dispersive than the inner surfaces (42) of the first, second and sixth side walls. [4] The lighting fixture (10) of claim 1, wherein the inner surface (42) of the first sidewall and the inner surface (42) of the second sidewall have a first reflectivity that is the same, and wherein the inner surface (42) of the third sidewall and the inner surface (42) of the fourth sidewall have a second reflectivity that is the same. [5] Lighting fixture (10) according to claim 1, wherein the reflector (14) is tapered such that the input end (34) is smaller than the output end (36). [6] The lighting fixture (10) of claim 5, wherein the reflector (14) includes a longitudinal axis (50) extending centrally through the input end (34) and the output end (36), the first, second, third and fourth sidewalls being angled in a range of about 10 degrees to about 20 degrees relative to the longitudinal axis (50). [7] Lighting fixture (10) according to claim 1, wherein the array (20) comprises 40 to 90 LEDs. [8] The lighting fixture (10) of claim 1, wherein the array (20) comprises red, neon green, green and indigo blue LEDs. [9] Lighting fixture (10) according to claim 8, wherein the array (20) consists only of red, neon green, green and indigo blue LEDs. [10] The lighting fixture (10) of claim 8, wherein the array (20) comprises 10 to 20 red LEDs, 10 to 20 neon green LEDs, 5 to 12 green LEDs, and 8 to 16 indigo blue LEDs. [11] The lighting fixture (10) of claim 10, wherein the array (20) comprises 12 indigo blue LEDs, 8 green LEDs, 16 neon green LEDs, and 16 red LEDs. [12] The lighting fixture (10) of claim 1, wherein the lens (16) comprises a tandem lens array (172). [13] The lighting fixture (10) of claim 12, wherein the tandem lens array (172) includes a first side facing toward the array (20) of LEDs and a second side opposite the first side, the first side including an array of lenses (178) and the second side including an array of lenses (178). [14] Lighting fixture (10) according to claim 1, further comprising an effects module (60) comprising a gobo wheel (62). [15] Lighting fixture (10) according to claim 1, wherein the lens (16) comprises zoom projection lenses (74).

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