TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates, in general, to the creation of artificial light or illumination and, in particular, to an optical zoom assembly for a non- imaging illumination application and luminaire using the same that control the distribution of light energy.

BACKGROUND OF THE INVENTION

[0002] With respect to non-imaging illumination applications, the growing commitment to the environment and sustainability is refiected in the shift from filament and high- intensity discharge lamps to Light Emitting Diodes (LEDs). As opposed to filament and high-intensity discharge lamps, LED solutions include LED chip packages typically containing multiple LED chips per package. These LED chip packages have relatively simple optics on the package itself that necessitate a secondary optics system to provide any needed color mixing, collimation, zoom or other beam shaping. The recent change in lighting source necessitates new zoom lenses that consider the unique properties of LED lighting sources including temperature and spectrum.

SUMMARY OF THE INVENTION

[0003] It would be advantageous to achieve an optical zoom assembly for a nonimaging illumination application and luminaire using the same. It would also be desirable to enable a solid-state solution that controls the distribution of light energy in the context of LED light sources having specific color mixing and collimation demands. To better address one or more of these concerns, in one aspect of the invention, one embodiment of an optical zoom assembly is presented having a light emitting diode chip that provides light to an optical conductor having a plurality of transmission paths that enable the mixing of the light. A collector lens is disposed serially and coaxially with the optical conductor to the mixed light received from the optical conductor. A zoom subassembly, including one or more optical lenses located serially and coaxially with the central optical axis, is movable coaxially with respect to the optical lens to create a beam of light having a divergence profile controlled by a variable spacing between the one or more optical lenses and the collector lens.

[0004] Additionally, to better address one or more of the aforementioned concerns, in one aspect of the invention, one embodiment of a luminaire is presented that may provide a complete lighting fixture for various applications. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:

[0006] Figure 1 is a perspective illustration of one embodiment of a luminaire incorporating an an optical zoom assembly according to the teachings presented herein;

[0007] Figure 2 is a perspective illustration of the luminaire depicted in figure 1 with a partial cut-away to better reveal internal components;

[0008] Figure 3 is a perspective illustration showing in further detail a nested array of optical zoom assemblies originally shown in figures 1 and 2;

[0009] Figure 4 is a front elevated view of one embodiment of an optical zoom assembly; [0010] Figure 5 is a transverse sectional view of the optical zoom assembly illustrated in figure 4;

[0011] Figures 6 and 7 are top plan views from different vantage points of the optical zoom assembly illustrated in figure 4;

[0012] Figures 8-10 are side views of one embodiment of light propagating through a series of lenses of the optical zoom assembly;

[0013] Figures 11-13 are side views of another embodiment of light propagating through a series of lenses of the optical zoom assembly;

[0014] Figure 14 is a graph of angle versus zoom travel for the optical zoom assembly;

[0015] Figure 15 is a graph of intensity versus vertical angle representing an optimized baseline intensity an LED collimation optics modules; and

[0016] Figure 16 is a graph of intensity versus vertical angle representing a baseline intensity for a circular spaced-packing array of LED collimation optics modules.

DETAILED DESCRIPTION OF THE INVENTION

[0017] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.

[0018] Referring initially to figures 1 through 3, therein is depicted one embodiment of a luminaire according to the teachings presented herein that is schematically illustrated and generally designated 10. A housing 12 is adapted to accommodate a framework 14 and optical zoom assemblies, collectively numbered 16, and secured by the framework 14 within the housing 12. The framework 14 includes a base 18, a series of platforms 20, 22, 24, and an end-piece 26 interconnected by a series of axial braces, such as brace 28. The optical zoom assemblies 16 include individual optical zoom assemblies 16-1, 16-2, and 16-3. A heatsink subassembly 30, which is also mounted to the base 18 and enclosed in the housing 12, absorbs and dissipates heat produced by the optical zoom assemblies 16. In one embodiment, the heatsink subassembly 30 includes virtually silent fans that provide forced- air cooling for internal components including the optical zoom assemblies 16.

[0019] The housing 12 is fitted in place by a yoke 32 swivelly connected to a support structure 33. An electronics subassembly 34 located throughout the framework 14 provides motorized movement and electronics to the luminaire 10. The electronics subassembly 34 may include multiple on-board processors providing diagnostic and self-calibration functions as well as internal test routines and software update capabilities. The luminaire 10 may also include any other required electronics such as connection to power. As illustrated, a finishing lens or lenses 36 may be included for adding end effects.

[0020] The optical zoom assemblies 16 are disposed in a single layer close-packing arrangement 38 with the optical zoom assemblies 16-1 through 16-3 being located in a triangular positioning in wherein a side of each optical zoom assembly 16 is contact with an edge or side positioned in contact with another optical zoom assembly 16. It should be appreciated that although a particular clustering or nesting with a certain number and position of optical zoom assemblies 16 is depicted, the number and positioning of optical zoom assemblies 16 may vary within the teachings presented herein. It should be appreciated that the optical zoom assemblies 16 modules may be arranged in arrays other than those illustrated in figures 1 through 3. Any number of optical zoom assemblies may be utilized in an array and the array may take different forms including those providing for close contact between the optical zoom assemblies and those providing for space between the optical zoom assemblies and even those that provide for a combination thereof. Moreover, the optical zoom assemblies 16 may be arranged in an angular manner, with linear displacement, or combinations thereof.

[0021] Figures 4 through 7 depict optical zoom assembly 16-1 in additional detail.

An LED chip package 40 provides sources of light and includes multiple colored LED chips G, R, B, W arranged in an array 42 on a single elongated base member 44, which may include provisions for bonding lead wires (not shown). As illustrated, the LED chips G, R, B, W have been positioned to provide a desired angular emission pattern with respect to optical zoom assembly 16-1 to increase color mixing. It should be appreciated, however, that depending on the application, the LED chips G, R, B, W may be arranged in other types of arrays.

[0022] The LED chips G, R, B, W of the array 42 comprise conventional green, red, blue, and white LED chips that respectively emit green, red, blue, and white light. Such LED chips facilitate efficient injection into the optical zoom assembly 16-1 and strongly enhance color mixing. As depicted, in order to further enhance the quality of the white light generated by the LED chip package, four LED chips including one red LED chip (R), one green chip (G), one blue LED chip (B), and one white LED chip (W) are utilized. It is contemplated, however, that as LED chip design advances, different numbers of LED chips and/or different color LED chips may be used in the array to optimize the quality of the light generated by the LED chip package 40. By way of example, in one embodiment, four LED chips including one red LED chip (R), one green chip (G), one blue LED chip (B), and one amber LED chip (A) are utilized. By way of further example, in another embodiment, four LED chips including one red LED chip (R), two green chips (Gl, G2), and one blue LED chip (B) are utilized. It is further contemplated that both low-power and high-power LED chips may be used in the LED chip package 40.

[0023] In one embodiment of the teachings presented herein, the elongated base member 44, which is coupled to the platform 20, may comprise an electrically insulative housing, made for example, of plastic or ceramic that encases a metal heat sink with a silicon submount disposed thereon. The metal heat sink provides heat sinking to the LED chip package 40 disposed thereon. Further heat dissipation is provided by the heatsink

subassembly 30 which, as alluded, includes a virtually silent fan that furnishes forced-air cooling proximate to the metal heat sink. The elongated base member 44 may further include lead wires, which are electrically isolated from the metal heat sink and the LED chips G, R, B, W by the housing. Bond wires electrically connect the LED chips G, R, B, W to the lead wires.

[0024] The optical zoom assembly 16-1 includes an optical conductor 46, a collector lens 48, and a zoom subassembly 50. The optical conductor 46 extends from the platform 20 and through the platforms 22, 24. A coupling collar 52 and seal secure the collector lens 48 to the optical conductor 46. As shown, foundation members 56, 58 in combination with vertical supports 60, 62 maintain the position of the coupling collar 52 and are secured thereto by fasteners 64, 66. The zoom subassembly 50 is located in a variable spaced relationship, as shown by arrow 78, with the collector lens 48 and movable coaxially with respect thereto. An extension arm 70 coupled to the brace 28 supports the zoom subassembly 50 and the zoom subassembly 50 is coupled thereto by securing collars 72, 74. As shown, the variable space 78 or distance is adjusted by actuation of the extension arm 70 by a linear actuator which may include a threaded drive shaft actuated by a servomotor, for example. Such movement of the extension arm 70 is depicted by an arrow 76, the movement thereof corresponding to a change in the variable spacing or space 78.

[0025] Other types of actuators are within the teachings presented herein as well.

Such actuators include, but are not limited to electric servo motors, pneumatic or hydraulic actuators, or even manually-operated actuators depending on the application. These same types of actuators may be used to control the individual movement of optical lenses within the zoom subassembly 50, as will be discussed in further detail hereinbelow. The control system for the luminaire 10 may be capable of operation independently of a supervisory control console or even be free-running, if so desired, to oscillate between two extents of travel. In one operational embodiment, the luminaire 10 having the optical zoom assembly forms a part of an automated, multiple-parameter lighting array providing remotely controlled and coordinated azimuth and elevation adjustment as well as light controlled light beam presentation.

[0026] The optical conductor 46 has at a first end 80 an input aperture 82 of a cross- sectional area %r , wherein the radius is r\, and at a second end 84 an output aperture 86 of a second cross-sectional area nr ₂ ² , wherein the radius is r ₂ . The optical conductor 46 is superposed on the LED chip package 40 and the LED chips G, R, B, W to receive the light from the sources at the input aperture 82 and deliver the light to the output aperture 86. The first cross-sectional area 7iri ² may be substantially equal to the second cross-sectional area 7ir ₂ ² so that the input aperture 82 and output aperture 86 have substantially equal diameters and r _\ may equal r ₂ . Alternatively, the first cross-sectional area 7iri ² may taper to the second cross-sectional area 7ir ₂ ² wherein r _\ is greater than r ₂ . As another alternative, the second cross-sectional area 7ir ₂ ² may taper to the first cross-sectional area %r , wherein r ₂ is greater than r _\ . A wall portion 88, which may be a cylindrical wall portion or a portion of an irregular wall or tapered wall, connects the input aperture 82 with the output aperture 86 and may include a surface of revolution generally forming a cylinder.

[0027] The wall portion 88 includes a reflective material defining multiple transmission paths enabling mixing of the light within an interior space 102 from the input aperture 82 to the output aperture 86. In one implementation, the wall portion 88 may be a wall means for mixing light connecting the input aperture 82 with the output aperture 86. The length l\ of the optical conductor 46 is determined by design parameters related to the mixing of the light emitted by the light sources. Additionally, the length l _\ of the optical conductor 46 is measured along a longitudinal or central optical axis of the optical conductor 32 which, in one embodiment, is substantially orthogonal to a horizontal axis of the LED chip package 40.

[0028] A sleeve 100 is connected to the LED chip package 40, or simply LED chip,

40 and positioned about the optical conductor 46 such that an annulus is located

therebetween. Moreover, in one embodiment, the longitudinal axis of the optical conductor 46 is aligned with a longitudinal axis of the sleeve 100. A seal, which may be an O-ring seal, for example, is located between the sleeve 100 and optical conductor 46 at an upper end of the annulus. A collar may be located at a lower end of the annulus and disposed around the optical conductor 46 to form a seal thereat. It should be appreciated, however, that alternative sealing techniques may be used instead of or in addition to the seal and the collar.

[0029] A support structure 104 may be coupled to the base 14 in order to seat and support the optical conductor 46 and the sleeve 100. In particular, a shoulder ring may seat the sleeve 100. A sealing gasket may seal the support structure 104 to the LED chip package 40 and fasteners 112, 114 couple the support structure 104 thereto. A thermally conductive path is present between the LED chip 40 and the sleeve 100 to provide for heat dissipation.

[0030] In one embodiment, the collector lens 48 is disposed serially and coaxially with the central optical axis of the optical conductor 46 at the output aperture 86 of the optical conductor 46. With respect to the collector lens 48, a body 120 may include spherical or aspherical surfaces 122, 124. In this embodiment, the collector lens 48 has a geometry furnishing the gathering of light may comprise a reflecting material 126 made of a prismatic, transparent, low-transmission loss dielectric material. It should be appreciated that other geometries are within the embodiments presented herein.

[0031] The zoom subassembly 50 includes one or more optical lenses 130, 132 located within a housing 142 having apertures aligned with the central optical axis of the optical conductor 46, in one implementation. These lenses may be serially and coaxially with this central optical axis. The zoom subassembly 50 is movable coaxially with respect to the optical lens 130, 132. The zoom subassembly 50 forms a beam of light from the mixed, gathered light from the collector lens 48. As will be discussed in further detail below, the beam of light has a divergence profile controlled by a variable spacing between the one or more optical lenses 132, 132 and the collector lens 48. As shown light entering the housing 142, passes through surfaces 134, 136 of the optical lens 130 and surfaces 138, 140 of the optical lens 140 before exiting at plane 146 of the finishing lens 36. It should be appreciated that the surfaces 134 - 140 may have similar or differing curvatures depending on the specific application. Additionally, the spacing between the optic lenses 130, 132 will depend on the application. Moreover, the zoom subassembly 50 may include various mechanical apparatus for repositioning the optic lenses 130, 132 with respect to each other. In this implementation, not only does the spacing between the optic lenses 130, 132 vary, but the spacing between the zoom subassembly 50 and the collector lens 48 varies as well.

[0032] Figures 8-10 depict multiple light beams traversing the optical zoom assembly 16-1. Referring initially to figure 8, which is one operational embodiment of figures 4 and 5, the optical conductor 46, which may be a light-mixing rod or lightpipe, homogenizes the light bundle 150 transmitted therein by the light sources. The intensity centroid of the light bundle 150 moves in a longitudinal fashion from the input aperture 82 to the output aperture 86 in a direction consistent with the central optical axis 154. The reflecting surfaces of the reflecting material disposed along the optical conductor 46 include surface normals that are

perpendicular or inclined relative to the longitudinal or axial direction of the movement of the light therethrough. The reflective material furnishing pathways, such as pathways 152 for light beams to travel and thereby mix with each other. As previously mentioned, the LED chips (G, R, B, W) may have at least a partial direction of orientation toward the interior space 102 of the optical conductor 46 to initiate the reflections and mixing. [0033] More particularly, the optical conductor 46 provides multiple pathways 152 that are traversed by multiple light beams, collectively light bundle 150. The multiple pathways 152 mix the received light beams and cause the intensity centroid of the light bundle 150 to move in a longitudinal fashion from the input aperture 82 to the output aperture 86. The light bundle 150 then exits the optical conductor 46 and enters the collector lens 48 at surface 122 before existing at surface 124. In one embodiment, the collector lens 48 may enable single-reflection, collimated transmission within the collector lens 48. At the collector lens 48, the light bundle 150 is gathered, so at exit at surface 124, the light bundle 150 is transformed to gathered light bundle 158. The mixed, gather light of the gathered light bundle 158 traverses the distance di which is the separation between the collector lens 48 and the optical lens 130. In this figure, the location of the zoom subassembly 50 is denoted by the bracketed position of the housing 142 of the zoom subassembly 50.

[0034] The gathered light bundle 158 is incident upon the planar surface 134 of the optical lens 130, which is depicted as a secondary collector lens. At optical lens 130, the gathered light bundle 158 is further gathered when passing therethrough from the surface 134 to the surface 136. The light bundle, which is represented by intra-zoom- subassembly light bundle 160, then traverses the distance d ₂ , which represents the distance between the optical lenses 130, 132 that are within the zoom subassembly 150. The intra-zoom-subassembly light bundle 160 passes through surfaces 138, 140 of the optical lens 132, which is depicted as a collimation lens. It should be appreciated, however, that optical lens 130 and 132 may have functions different from those depicted in the instant embodiment, depending on application. Collimated transmission of the light bundle then occurs to produce a

substantially homogenous pupil or beam of light 162 therefrom having a divergence profile 148 controlled by the variable spacing di, d ₂ between the one or more optical lenses 130, 132 and the collector lens 48. That is, the variable spacing di, d ₂ controls the zoom.

[0035] It should be appreciated that construction of the of LED collimation optics modules illustrated in figures 1 through 8 may vary. For example, the optical conductor 46 and collector lens 48 may be integrally formed or bonded together to form integral units. In which instance, the two components are still referred to as the optical conductor 46 and the collector lens 48. Factors such as application specific characteristics and cost may determined the preferred construction technique.

[0036] It should be appreciated, however, that the optical conductors are not limited to cylindrical wall portions. The optical conductors may comprise non-cylindrical shapes, as well, that create different wall portions and respective interior spaces. By way of example, an optical conductor may include a faceted wall portion having 6-sides. By way of further example, the optical conductor may comprise a wall portion having 8-sides. That is, the optical conductor may include any number of sides or facets and it may further include circular or cylindrical wall portions. Moreover, as previously discussed, the optical conductor may be tapered.

[0037] Other embodiments of optical conductors 46 for use with the optical zoom assemblies 16 are within the teachings presented herein. As previously discussed, the optical conductor 46 may take a variety of shapes. In addition to having a variety of shapes, the optical conductor 46 may be a tubular or mixing tubular having a sidewall), a rod, a tubular having a body therein, or a combination therefore, for example.

[0038] Similar to the optical conductor 46, the body of a collector lens 48 may have a variety of forms including a body having a sidewall, a body being a solid member with the wall portion and reflective material, the body having a sidewall member and a solid member disposed therein with wall portions and the reflective materials, or combinations thereof, for example. Likewise, as mentioned, the construction and placement of the optical lenses 130, 132 may similarly vary.

[0039] Referring now to figure 9, the optical lenses 130, 132 of the optical zoom assembly 50 have been moved mutually closer. In particular, the secondary collector lens 130 and the zoom lens 132 have been uniformly moved toward the collector lens 48 such that the variable space between the collector lens 48 and the secondary collection lens 130, di, is reduced and the variable space between the secondary collector lens 48 and the zoom lens 132, d ₂ , remains the same. As shown, the light bundle 150 is mixed as it passes through the optical conductor 46 and then gathered at the collector lens 48. The mixed, gather light 158 is incident upon the planar surface 134 of the secondary collector lens 130 and is further gathered when passing therethrough. The light bundle 160 then traverses the distance d ₂ and passes through the zoom lens 142 before exiting as a beam of light 162 having a divergence profile 148.

[0040] As will be noted, the divergence profile 148 is controlled by the variable spacing di, d ₂ between the one or more optical lenses 130, 132 and the collector lens 48. In this embodiment, the divergence profile 148 in figure 9 is greater than the divergence profile 148 in figure 8 as the variable spacing di has been reduced. The divergence profile 148 of the beam of light 162 widens as the variable spacing di, d ₂ between the one or more optical lenses 130, 132 and the collector lens 48 decreases. For example, an actuation of the optical zoom assembly 16-1 from figure 8 to figure 9. On the other hand, the divergence profile 148 of the beam of light 162 narrows as the variable spacing di, d ₂ between the one or more optical lenses 130, 132 and the collector lens 48 increases. For example, an actuation of the optical zoom assembly 16-1 from figure 9 to figure 8.

[0041] In figure 10, the collection or collector lens 48 is positioned as closely as possible to the optical conductor 46 and, similarly, the collector lens 48, the optical lens 130, and the optical zoom lens 132 are positioned as closely as possible to form a nesting arrangement within a tight volume. In this embodiment, when the distance between the lenses 48, 130, 132 are minimized, the refracting effects result in a net effect maximizing the divergence profile 148 of the beam of light 162..

[0042] Figure 10 depicts in instance wherein both variable spacings di, d ₂ are adjusted. This is achieved by an actuation of the zoom subassembly 50 to adjust variable spacing di and an internal actuation within the zoom subassembly 50 to adjust the variable distance d ₂ . It should be understood that the amount of divergence in the divergence profile 148 through the chain of optics depends on the distance of separation between the surfaces of the lenses 48, 130, 132 and the composition of the lenses 48, 130, 132 themselves.

Moreover, the development and behavior of the light beam passing through the series of lenses is governed by Snell's Law, in accordance with which a light ray passing from air to glass or, more generally, from a more dense medium to a less dense medium, is refracted away from the surface normal. In the illustrated embodiment, given the dynamics of the optics, as the lenses 48, 130, 132 are positioned closer together, the divergence profile 148 increases. That is, as the separation between the lenses 48, 130, 132 generally increases, the divergence profile 148 generally decreases.

[0043] Figures 11 and 12 depict multiple light beams 150 traversing another embodiment of an optical zoom assembly 16. In this embodiment, the zoom subassembly 50, which includes a single zoom lens 170 having surfaces 172, 174 in this embodiment, has a variable spacing di with respect to the collector lens 48. As shown by comparing figures 11 and 12, the variable spacing di is selectively controlled and decreased between the collector lens 48 and the zoom lens 170 to increase the divergence profile 148 of the light beam. It should be appreciated that the variable spacing di could be selectively controlled by increasing the distance di in order to decrease a divergence profile 176 of the light beam 178. It should be understood that the zoom subassembly 50 may include any number and arrangement of optical lenses therein, such that variable spacings di ... d _n are created to provide as robust an optics chain and divergence profile 148 as required. Moreover, the form and function of the optical lenses within the zoom subassembly 50 may vary with application also.

[0044] Figure 13 depicts multiple light beams traversing a further embodiment of an optical zoom assembly 16. As shown, compared to figure 12, the optical lens 170 has different internal optical properties. This results in a different collection pattern within the optical lens 170 and also results in a different divergence profile 176 to the light beam 178.

[0045] Experimental results obtained from modeling a prototype optical zoom arrangement will now be presented and discussed. Figure 14 depicts a graph of angle versus zoom travel representing baseline intensity for a single layer close-packing arrangement. Herein the vertical angle of light incidence is expressed in degrees and zoom travel is expressed in millimeters such that angle is a function of zoom travel as shown by line 190. Figure 15 depicts an illuminance chart having a profile 192 and figure 16 shows a cross- section or slice having a profile 194 of the same along the x axis.

[0046] While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other

embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.