APPARATUS, METHOD, AND SYSTEM FOR A MULTI-PART VISORING AND OPTIC SYSTEM FOR ENHANCED BEAM CONTROL
20180010772 · 2018-01-11
Inventors
- Myron Gordin (Oskaloosa, IA)
- JOEL D. DEBOEF (NEW SHARON, IA, US)
- Steven T. Heaton (Oskaloosa, IA)
- CHRIS P. LICKISS (NEWTON, IA, US)
- LUKE C. MCKEE (OSKALOOSA, IA, US)
Cpc classification
F21V13/04
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V14/04
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V7/0066
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V5/007
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V17/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V11/183
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V21/30
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V11/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21W2131/105
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21Y2105/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21Y2115/10
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F21V13/04
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V21/30
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V14/04
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F21V5/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
Precision lighting design is a subcategory of lighting design which benefits from a concerted, synergistic effort to improve beam control; sports lighting is one such example. Beam control is improved when all light directing and redirecting devices are considered together, and insomuch that adverse lighting effects are best avoided when considering how all the lighting fixtures in an array interact with one another. To that end, envisioned is a multi-part visoring (i.e., light redirecting) and optic (i.e., light directing) system designed with consideration towards how a fixture lives in a mounted space—how its photometric and physical presence affects other fixtures in or proximate said space—while demonstrating improved beam control over that which is available to general purpose (e.g., indoor residential) lighting.
Claims
1. A lighting fixture for precision lighting comprising: a. a housing comprising: i. an interior space; ii. an opening; iii. a light transmissive material over the opening to at least substantially seal the interior space; b. internal light control in the interior space of the housing comprising: i. an array of densely packed LED light sources; ii. an optic on each LED light source to produce a preliminary light output beam pattern from individual light source output beam patterns; iii. an internal visor at or near at least some of the LED light sources to selectively redirect a portion of the preliminary light output beam patterns; iv. so that a composite light output is directed out of the opening and light transmissive material of the housing from the plurality of individual redirected LED light sources outputs; c. external light control on the housing outside the interior space comprising: i. an external visor at or near the opening having: 1. at least a first surface that is extendable at least partially into the composite light output from the housing and has selectable: a. reflectivity to control incident light from the composite light output; b. pivotability relative to the housing to selectively adjust cutoff of the composite light output from the housing; 2. at least a second surface outside the composite light output from the housing; and d. an adjustable armature to selectively aim the housing in space so to collectively provide precision lighting.
2. The lighting fixture of claim 1 wherein: a. the housing is substantially box-shaped and the opening comprises substantially one side of the box-shape; b. the densely-packed LED light sources are distributed substantially across a mounting substrate having a substantially planar surface on the order of size of the perimeter of the box-shape with each LED light source a fraction of an inch from adjacent LED light sources.
3. The lighting fixture of claim 2 wherein the optic comprises: a. an emitting face formed from a substantially thin sheet of optical quality material; and b. a holder to removably clamp and closely position the sheet over a subset of the LED light sources.
4. The lighting fixture of claim 3 wherein the optic comprises: a. a silicone-based material; b. the holder restrains the silicone-based material from flexing; and c. the silicone-based material is truncated in a truncation plane which is substantially coplanar with at least one plane defining length or width of the interior space of the housing.
5. The lighting fixture of claim 3 wherein the emitting face of the optic includes at least one portion having a tilt relative the substantially planar surface of the LED mounting substrate to shift a portion of the composite light output in one or more directions.
6. The lighting fixture of claim 1 wherein the internal visor comprises: a. an elongated rail along a subset of the densely packed LED light sources; and b. wherein the rail is selectively configured regarding: i. height; ii. length; iii. thickness; iv. material; and v. position relative the subset of densely packed LED light sources for at least one of horizontal or vertical cutoff of the corresponding preliminary light output beam patterns.
7. The lighting fixture of claim 1 wherein the first surface of the external visor comprises one of: a. one continuous portion or two or more separate portions, each portion selectively configured regarding: i. specularity; ii. material; iii. light absorption; iv. shape; or v. angular adjustability relative to the other portions of the external visor or the housing.
8. The lighting fixture of claim 1 wherein the second surface of the external visor comprises ribbing.
9. The lighting fixture of claim 8 wherein the ribbing is selectively configured regarding: a. rib height; b. rib spacing; c. rib width; d. rib angle; e. material or processing method; f. reflectivity; and g. continuous or separated sections.
10. The lighting fixture of claim 1 in combination with a plurality of additional said fixtures mounted in a fixture array on a support structure comprising one of the following positioned relative to a target area to be illuminated: a. a pole; b. a tower; and c. a superstructure.
11. The combination of claim 10 further comprising a plurality of additional said fixture arrays each on a said support structure placed at different locations relative to the target area to be illuminated.
12. The combination of claim 10 wherein the second surface of the external visor of at least some of said fixtures comprises ribbing.
13. The combination of claim 12 wherein the at least some fixtures with second surface ribbing are lower in position in the fixture arrays than the fixtures without second surface ribbing.
14. A method of illuminating a target area or space with precision lighting fixtures comprising: a. elevating a plurality of aimed arrays of lighting fixtures on support structures at different locations relative to a target area or space, each lighting fixture comprising a plurality of densely packed LED light sources sealed in a housing with a light transmissive material; b. controlling light and glare at each lighting fixture for a given location and elevation and aiming direction of each lighting fixture relative to the target area or space by: i. producing preliminary light output beam patterns from each LED light source by positioning an optic relative the LED light sources; ii. selectively redirecting a portion of the preliminary light output beam patterns by positioning a visor in the housing relative to the LED light sources to produce a composite light output which is directed out of the housing the light transmissive material; and iii. selectively cutting off the composite light output near the LED light sources but outside the sealed housing with a first surface of an external visor that at least partially extends into a portion of composite light output.
15. The method of claim 14 wherein the target area or space comprises a plane and a space above the plane, and wherein the method further comprises aiming a subset of the arrays of lighting fixtures towards the plane and aiming a subset of the arrays of lighting fixtures towards the space above the plane.
16. The method of claim 15 wherein the step of aiming a subset of the arrays of lighting fixtures towards the plane comprises pivoting a plurality of adjustable armatures each affixed to a lighting fixture of said subset.
17. The method of claim 16 wherein the supporting structures comprise poles and a plurality of adjustable armatures are mounted near the top of the poles and the subset of the arrays of lighting fixtures aimed towards the plane are aimed towards the bottom of the poles.
18. The method of claim 17 wherein the step of aiming a subset of the arrays of lighting fixtures towards the space above the plane comprises pivoting a plurality of adjustable armatures each affixed to a lighting fixture of said subset of the arrays of lighting fixtures aimed towards the space above the plane.
19. The method of claim 18 wherein the plurality of adjustable armatures affixed to each of the lighting fixtures in the subset of the arrays of lighting fixtures aimed towards the space above the plane are mounted near the bottom of the poles and the subset of the arrays of lighting fixtures aimed towards the space above the plane are aimed towards the top of the poles.
20. The method of claim 14 wherein at least one portion of the external visor is pivotable relative to the housing.
Description
IV. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] From time-to-time in this description reference will be taken to the drawings which are identified by figure number and are summarized below.
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V. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
A. Overview
[0033] To further an understanding of the present invention, specific exemplary embodiments according to the present invention will be described in detail. Frequent mention will be made in this description to the drawings. Reference numbers will be used to indicate certain parts in the drawings. Unless otherwise stated, the same reference numbers will be used to indicate the same parts throughout the drawings. Likewise, similar parts follow a similar numbering sequence. For example, a luminaire housing 81 for a state-of-the-art fixture might take on a new reference number 91 after a first iteration of fixture modification according to aspects of the present invention, a new reference number 101 after a second iteration of fixture modification according to aspects of the present invention, and so on. In each case said luminaire housing may or may not have been modified; regardless, a similar numbering convention is followed between iterations because the core functionality (i.e., housing the LEDs) is the same or similar between iterations.
[0034] Regarding terminology, as previously stated the terms “luminaire(s)” and “lighting fixture(s)”, and “fixture(s)” are used interchangeably throughout; all of which are understood in the art of lighting design to be used interchangeably in the colloquial. The terms “light directing” and “light redirecting” devices are also used a number of times herein, and are generally understood to be devices internal or external (or both) to lighting fixtures which are adapted to in some way modify, shape, direct, redirect, or otherwise provide control of the beam issued forth (i.e., emitted) from said lighting fixture. Some non-exhaustive, non-limiting examples of light directing devices include: adjustable armatures or devices which move or pivot some portion of the lighting fixture, lenses, color gels, and phosphors. Some non-exhaustive, non-limiting examples of light redirecting devices include: visors, reflective rails or components, light absorbing rails or components, and diffusers. Any number of light directing and/or light redirecting devices could be used alone or in combination according to aspects of the present invention; some particularly synergistic combinations are set forth in the exemplary embodiments.
[0035] Further regarding terminology, the terms “horizontal” and “vertical” are used to describe particular directions of movement, pivoting, aiming, etc. It is important to note that what comprises horizontal as opposed to vertical should be taken in the context of operational orientation of the lighting fixture or device described and illustrated. That being said, the present invention is not limited to the operational orientations described and illustrated herein, nor to moving, pivoting, aiming, etc. solely in orthogonal planes. Aiming of a lighting fixture relative a target according to the present invention could include a wide range of aiming angles in all three dimensions—which is beneficial since some target areas require adequate illumination of not only a plane (e.g., a playing field) but also a space above the plane (e.g., the area of sky above a playing field where a hit ball may enter). Lighting of a space above a plane—whether or not to the same intensity level as that of the plane, whether from a low mounting position angling upward or from a high mounting position angling downward—is generally known as “uplighting”.
[0036] Further regarding terminology, reference herein to a “lens” is generally intended to reference the secondary lens of an LED which already has a die and a primary lens; though, of course, this could differ if the LED does not already have a primary lens, the light source is something other than an LED (e.g., laser diode), or for other reasons. Lastly regarding terminology, “undesirable lighting effects” can mean a number of things in a lighting design. Some specific examples discussed herein include onsite glare, offsite glare, spill light, shadowing, hot spots, and center beam shift. Onsite glare refers to undesirable lighting effects as perceived by someone at the target area (e.g., a player) and offsite glare refers to undesirable lighting effects as perceived by someone outside the target area (e.g., a driver on a nearby road). Typically offsite glare is in reference to someone far removed from the target area (e.g., in a residence on a different property) rather than someone just outside the target area (e.g., in the parking lot adjacent to the athletic field), though this could differ. Spill light refers to any light that falls outside the target area irrespective of whether it produces perceived glare. Shadowing and hot spots—where the light intensity in a region of the target area is too low or too high, respectively—is generally due to physical or photometric interference of components of the lighting system and defined with respect to either lighting specifications or other regions of the target area, though this could differ. Center beam shift generally refers to the undesirable shifting of either the photometric center or maximum candela (or both, if colocated or proximate) due to either excessive pivoting of an entire fixture (e.g., via adjustable armature 4) or too severe an angle of a reflective visor relative the composite beam issued forth from the lighting fixture; as used herein, “center beam shift” refers to perceivable center beam shift (i.e., where shift is enough to perceivably impact beam shape or distribution).
[0037] The exemplary embodiments envision a multi-part visoring and optic system which addresses, among other things, fixture interaction within an array, avoiding undesirable lighting effects, and onsite and/or offsite glare control. By way of introduction, consider again the example of a sports lighting application; generic sports lighting systems and components thereof are illustrated in
[0038] As can be seen in
[0039] When lighting fixtures interfere with one another—either physically as in
[0040] With respect to
[0041] Light at point T is often also viewable from off site, thereby also causing offsite glare. Furthermore, at an offsite location a viewer is often adapted to a much lower light level, and so a less intense light than that seen by a player could be perceived as causing glare to someone far from the playing field. As such, light from a fixture higher in an array could produce glare as perceived from off site when even a small amount of light strikes the top of a lighting fixture lower in the array; this is illustrated at point Q of
[0042] Onsite and offsite glare can occur when a lighting designer fails to take into consideration how all parts of a lighting system exist in a space, but it is important to note that onsite and offsite glare can also occur when everything has been designed and aimed correctly—purely due to a lack of tools for beam control—and so a state-of-the-art LED lighting fixture designed for precision lighting may still benefit from aspects of the present invention. One such state-of-the-art LED lighting fixture 80 (
B. Exemplary Method and Apparatus Embodiment 1
[0043] A more specific exemplary embodiment for improved beam control, utilizing aspects of the generalized example described above, will now be described. The present embodiment addresses issues common in the art of precision lighting design—namely, fixture interaction within an array, avoiding undesirable lighting effects, and providing onsite and/or offsite glare control—in a lighting fixture designed to be luminously dense with sharp beam cutoff; this is achieved through a multi-part visoring and optic system which is presently discussed.
[0044] Ribbing on External Visor
[0045] As previously stated, offsite glare can occur when light from a lighting fixture higher in an array of lighting fixtures strikes the top of a lighting fixture lower in the array of lighting fixtures. As such, state-of-the-art LED lighting fixture 80 is modified so to include ribbing on top side 85 of visor 83; the result is LED lighting fixture 90 of
[0046]
TABLE-US-00001 TABLE 1 Design H.sub.1 H.sub.2 D.sub.1 D.sub.2 α 2000A 0.10 0.15 0.08 0.08 — 2000B 0.10 0.15 0.08 0.08 45° 2000C 0.10 0.17 0.16 0.16 — 2000D 0.10 0.24 0.17 0.17 45° 2000E 0.10 0.23 0.30 0.30 —
[0047] Three series of tests were performed to determine a relative level of perceived offsite glare using luminance as the relevant metric; all tests used a control sample which was flat and similar to surface 85 of
[0048] Table 2 below details testing in footlamberts using a 1-degree luminance meter (model Mayo-Spot 2 available from Gossen Photo and Light Measurement GmbH, Nürnberg, Germany); Table 3 below details testing in footlamberts using a 1-degree luminance meter (model 301664 available from Minolta Camera Company Ltd. (now Konica Minolta Sensing Americas, Inc., Ramsey, N.J., USA)); and Table 4 below details testing in candela/sq. meter using a ⅓-degree luminance meter (model 501457 available from Minolta Camera Company Ltd. (now Konica Minolta Sensing Americas, Inc., Ramsey, N.J., USA)).
TABLE-US-00002 TABLE 2 Control (flat Test Condition 2000A 2000B 2000C 2000D 2000E surface) fixture panned 52 82 62 57 122 214 45° fixture panned 55 74 54 52 109 187 60° fixture tilted 42 62 36 38 106 216 10° fixture tilted 148 163 85 72 320 670 30° fixture tilted 31 45 27 31 59 125 40° Relative 22% 24% 13% 11% 48% 100% percentage for worst case Relative 23% 30% 19% 18% 51% 100% average over all test states
[0049] As can be seen from Table 2, ribbing design 2000D had the lowest recorded footlamberts as compared to the control for both the worst case scenario and overall average.
[0050] The test performed in Table 3 was a repeat of the worst case scenario using a different luminance meter to confirm the results recorded in Table 2 were reasonable; as can be seen from Table 3, test results are similar to that of Table 2 and ribbing design 2000D shows the best result (i.e., least amount of recorded photometric brightness).
TABLE-US-00003 TABLE 3 Control (flat Test Condition 2000A 2000B 2000C 2000D 2000E surface) fixture tilted 120 131 73 63 280 600 30° Relative 20% 22% 12% 11% 47% 100% percentage for worst case
[0051] The test performed in Table 4 was a repeat of the worst case scenario using a different luminance meter to confirm the results recorded in both Tables 2 and 3 were reasonable; as can be seen from Table 4, test results are similar to that of Tables 2 and 3 and design 2000D shows the best result (i.e., least amount of recorded photometric brightness).
TABLE-US-00004 TABLE 4 Control (flat Test Condition 2000A 2000B 2000C 2000D 2000E surface) fixture tilted 278 330 200 185 633 1390 30° Relative 20% 24% 14% 13% 46% 100% percentage for worst case
[0052] So it can be seen that over the conditions tested ribbing design 2000D sets forth a preferred design of ribbing to be applied to the top surface of an external visor so to minimize offsite glare which results from light from a different lighting fixture in an array striking said surface. Extruding the part as a whole from aluminum or aluminum alloy (i) ensures integrity of thermal dissipation paths for the LED sources (as compared to using plastic as in some prior art approaches), and (ii) avoids unnecessary processing or assembly steps (as compared to affixing a sheet of ribbing material to a flat visor). It is estimated that for an LED luminaire such as that in
[0053] Multi-Part Visor
[0054] While a degree of beam control is provided via adjustable armature 4 and a pivotable external visor 95, more can be done to provide sharper cutoff, increase useful light, and reduce undesirable lighting effects such as center beam shift. To that end, LED luminaire 90 is further modified such that the pivotable visor is divided into a fixed portion (i.e., stationary proximate the housing) and a pivotable portion (i.e., independently pivotable from the rest of the external visor and/or housing); see LED luminaire 100 of
[0055] Sharper cutoff is provided, as one example, by permitting a wider range of aiming angles for the distalmost tip of visor 103 than is permitted by conventional one-piece visors when one takes into account minimizing center beam shift (which has been previously described). Conceptually, a visor could start in a more-or-less neutral position (see
[0056] However, the present invention contemplates even greater possible beam control.
[0057]
[0058] By combining a fixed external visor with a pivotable external visor, cutoff can be selective (thereby also providing a degree of offsite glare control) without impacting the center beam. Additional configurations and options all of which could be combined within a single lighting system (even within a single array) to further improve beam control are illustrated in
[0059] As can be seen and understood by those skilled in the art, the external visor sections or portions can be produced from sheet metal (e.g. aluminum or aluminum alloy) and formed into the illustrated shapes. Such materials allow the designer to deform flat sheet metal into the desired curvatures and shapes with tools or forms. In these examples, the visor sections are hollow to decrease weight but allow such external form factors, which can have almost infinite variability.
[0060] Improved Optic Design
[0061] Luminous density of LED fixture 100 can be improved upon by more efficiently using the space within the housing to (i) more tightly pack LEDs, (ii) extract more light from said LEDs and transmit it out of said housing, and (iii) cooperate with the external multi-part visoring system so to make said extracted light more useful, all of which also aids in minimizing onsite and/or offsite glare and providing overall improved beam control. To that end, LED luminaire 100 is further modified to include a multi-part optic system such as that illustrated in
[0062] Within LED luminaire 200 several LED/secondary lens combinations are grouped together to form a linear optical array; each linear optical array is resiliently restrained by a two-part lens array holder 5002/5004 because, as envisioned, lenses 5003 are formed from silicone (which can operate at a much higher temperature than state-of-the-art acrylic lenses but must be restrained due to flexing during thermal expansion) on the order of approximately an inch in total thickness (including the portions which encapsulate the LEDs). Reference numeral 5000 refers generally to this whole combination. Lenses in general typically demonstrate higher transmission efficiency than reflectors but less glare control; as such, each LED in array/board 5001 in the interior of housing 201 includes an associated optic on a one-to-one basis (e.g., one secondary lens 5003 per LED) for enhanced glare control. Each linear optical array is truncated in a plane to increase the number of LEDs possible in the interior of housing 201; said truncation is in the same plane as control provided by the external visor (in this case, the vertical plane) since testing has shown no loss in beam control (as opposed to, for example, truncating in the horizontal plane). A front portion of housing 201 (see reference number 210) is bowed outwardly (or otherwise extended or enlarged) so to accommodate one or more reflective visors/rails 5005/5006 in the interior of the housing to control beam spread (which also reduces haze), all of which is designed to work with the aforementioned multi-part visoring system to provide a synergistic approach to improved beam control. This synergy is also evidenced in the manner in which all parts are colocated during assembly; see fastening devices 211 and 213 relative housing 201 in
[0063] However, the present invention contemplates even greater possible beam control.
[0064] Testing has shown that truncating lenses 5003 in the same plane as that already adequately controlled by external visor 203 results in no loss of beam control in that plane, but permits including more LEDs in housing 201, thereby making LED luminaire 200 more luminously dense. In fact, testing has shown that truncating a lens array 5003 in the vertical plane to remove approximately 0.047″ from the top and bottom of lenses normally having a face diameter of 0.5″ resulted in a 2% loss in light transmission, but permitted two additional LEDs per array—with no adverse impact to beam control. This minor light loss has been found to be well overcome by the additional LEDs for a given luminaire when operated at high currents, as is the case in sports lighting applications. Furthermore, this approach to increasing luminous density can be equally applied to a number of different beam types; see
TABLE-US-00005 TABLE 5 General Approximate Beam Angle Beam (horizontal degrees × Configuration Type vertical degrees) 5002/5003/5004A 5M 38 × 34 5002/5003/5004B 5N 31 × 31 5002/5003/5004C 4W 28 × 29 5002/5003/5004D 3W 22 × 19 5002/5003/5004E 5W 44 × 38 5002/5003/5004F 4N 24 × 22 5002/5003/5004G 4M 26 × 21
[0065] If desired, each LED lens array could include a different configuration of lenses 5003 together with an LED and any number of reflective devices (e.g., 5005/5006) to effectuate beam types to achieve a different purpose—to taper light back to a pole, to partially overlap with the light from another fixture to provide uniformity on the field, to provide uplight for aerial sports, etc. As a bonus, each component of the multi-part optic system can be selectively switched in and out (e.g., via removal and insertion of pins 5009 in apertures 5008 for a linear array of lenses 5003) so to produce custom beam patterns to avoid spill light, adequately light target areas of complex shape, and generally improve beam control.
[0066] So given a footprint (i.e., the internal space of housing 201), and given the restriction of a one-to-one ratio of optic to LED, optimization of LED light sources may be in accordance with the following.
[0067] A plurality of LEDs are arranged to produce an initial composite beam pattern. As can be seen from
[0068] A step (perhaps included in step 6001 (
TABLE-US-00006 TABLE 6 General Approximate Beam Angle Beam (horizontal degrees × Configuration Type vertical degrees) 5002/5003/5004A 5M 38 × 34 5002/5003/5004B 5N 31 × 31 5002/5003/5004C 4W 28 × 29 5002/5003/5004D 3W 22 × 19 5002/5003/5004E 5W 44 × 38 5002/5003/5004F 4N 24 × 22 5002/5003/5004G 4M 26 × 21
[0069] A final step (perhaps included in step 6005 (
[0073] This method could be performed for each lighting fixture in an LED lighting system, or only for each lighting fixture dedicated to a different purpose; to taper light back to a pole, to partially overlap with the light from another fixture to provide uniformity on the field, to provide uplight for aerial sports, etc.
[0074] Efficiency is increased in wide/large area lighting design by maximizing the number of said higher efficacy sources for a given footprint (i.e., internal space in a lighting fixture). Maximizing the number of LEDs for a given footprint permits a lighting designer to operate said LEDs at as low a current as possible to achieve a designed luminous output, which increases longevity of LEDs and optics.
[0075] As previously stated, reflectors have demonstrated poor longevity when used with tightly packed LEDs operating at high current; it is believed this is due to poor metalizing. Metalizing in general is a consistent and satisfactory process of depositing a suitably uniform reflective surface on an inexpensive plastic component. That being said, in a one-to-one optic to LED configuration at sometimes very narrow beam angles, metalizing becomes inconsistent: the part is narrow and deep, and the finish is not of uniform thickness, reflective properties, or fails to coat the entire substrate. Furthermore, it is well known that there is a large difference in thermal expansion of plastic versus aluminum, and so there are challenges in maintaining integrity of the part at higher temperatures. If LEDs were operated at a low current or with a great deal of space between them (perhaps with active air flow), it may not be an issue, but in sports lighting and other wide/large area lighting applications this leads to premature failure of the reflector. Switching to a lens is a boon insomuch that transmission efficiency is increased, but glare control becomes more difficult. Most commercially available secondary lenses are formed from acrylic, regardless of whether they produce “standard” beam types or custom beam types. While most acrylics are rated to 95° C., this is at the edge of what is acceptable for the aforementioned lighting applications where LEDs are driven at high current. Even with an adequate heat sink in place such that thermal transfer on the whole is adequate, the tight packing of narrow and deep optics has demonstrated localized failure; it is believed this is due to absorption of optical radiation. Switching to silicone provides a buffer for operation; silicone can be operated safely to around 150° C. Silicone is also a boon insomuch that it has better flow properties and a lower refractive index than traditional acrylic secondary lenses, but the use of silicone in such an application is widely untested and tolerances are very different than with acrylic lenses. This is another reason why plastic holder 5002/5004 is constructed in its particular way and bolted directly to the housing.
[0076] Efficiency is increased in wide/large area lighting design by improving the longevity of optics associated with the LEDs. Improving the longevity of the optics permits the lighting designer to retain beam control over the entire life of the lighting fixture.
C. Options and Alternatives
[0077] The invention may take many forms and embodiments. The foregoing examples are but a few of those. To give some sense of some options and alternatives, a few examples are given below.
[0078] Generally speaking, it is to be appreciated that while a variety of light directing, light redirecting, and fastening devices have been described and illustrated, these could vary and not depart from at least some aspects of the present invention. For example, reflective rails 5005 and/or 5006 could produce diffuse reflection, specular reflection, spread reflection, or even be coated or processed to be light absorbing instead of reflective. Fastening devices might not be threaded screws; they could be clamps or something considered less removable such as glue or welds.
[0079] Regarding lighting design, as previously stated undesirable lighting effects may include shadowing and hot spots; namely, where the light intensity in a region of the target area is too low or too high, respectively, as compared to lighting specifications or other regions of the target area. Instead of a thin silicone sheet which is relatively flat on the emitting face,
[0080] In practice, an LED luminaire designed according to aspects of the present invention could be built from the foundation of a prior art LED luminaire—as is the case in Embodiment 1—but an LED luminaire according to aspects of the present invention could also be designed from the ground up. Such an approach could follow method 6000 of
[0081] Regarding light directing and light redirecting devices, as has been stated and illustrated a number of options and alternatives are contemplated according to aspects of the present invention; one specific alternative is illustrated in
[0082] Some other possible options and alternatives include: fewer or more light directing and/or light redirecting devices (see additional reflective surfaces 316 of