Patent Publication Number: US-2015062925-A1

Title: Multi-part reflector for outdoor light design

Description:
I. TECHNICAL FIELD 
     The present invention relates generally to light fixture design. More particularly, the present invention relates to a multi-part reflector for a light fixture. 
     II. BACKGROUND 
     Outdoor light fixtures typically include a light source, a lens, and/or a reflector. The reflector, lens, and any shielding typically define the light distribution pattern. 
     Highway and roadway lighting, for example, have historically used incandescent and, more recently, high intensity discharge (HID) lamps that can provide adequate amounts of light. HID lighting has several drawbacks, including frequent lamp maintenance or poor color performance. Many optical systems have badly designed reflectors that equate to poor control of the light. 
     This poorly controlled, light can be wasted in lighting areas around the roadway (and potentially, sidewalk) that do not require light. Poorly controlled light also contributes to trespass light and light pollution, which can interfere with the preservation of the nighttime environment. A major contributing factor to poorly controlled light relates to the optical system&#39;s reflector design. 
     Some light fixtures include a two piece reflector design, including a left reflector and a right reflector. Given the need for reflecting the light, most reflectors are manufactured using coating processes including physical vapor deposition process and chemical vapor deposition process. Because most of coating process relies on line-of-sight and sometimes the parts are orbitally rotated during the coating process, certain areas of the reflector can be “shaded” or blocked during the=coating process. 
     Manufacturing is also largely limited to coating process because an end portion of the reflectors is cup-shaped, i.e. has contours in multiple axes. Since the end portion is cup shaped, it&#39;s difficult to form pre-metalized materials into this shape without destroying the specular properties of the material. 
     III. SUMMARY OF THE EMBODIMENTS 
     Given the aforementioned deficiencies, a need for a reflector design that addresses the issues and takes into account the considerations noted above. 
     In at least one embodiment, the present invention provides a reflector for an optical source. The reflector includes an elongated piece formed or configured for reflecting light from the optical source onto a first reflective lighting zone. The reflector also includes at least two end-pieces connectable to respective ends of the elongated piece, each being configured to reflect the light onto second and third reflective lighting zones, respectively. 
     Embodiments of the present invention provide a three piece optical reflector manufactured using improved manufacturing and coating techniques. The improvement occurs primarily because the deep cavities created in the two-piece design noted above, are eliminated. A three-piece design caters to the coating process and will easily allow for improved and more uniform coating on all of the optical surfaces including the elongated center portion. 
     A three-piece design also allows the flexibility to use multiple manufacturing methods and materials to achieve superior reflectivity of the elongated center section. These superior materials include, but are not limited to, pre-polished aluminum sheet metal commonly used in the industry. The three-piece design will also allow for flexibility in the optical platform. This is due to the interchangeable end-pieces and center pieces of the three-piece design. 
     Further features and advantages, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. 
    
    
     
       IV. BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments may take form in various components and arrangements of components. Exemplary embodiments are illustrated in the accompanying drawings, throughout which like reference numerals may indicate corresponding or similar parts in the various figures. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention. Given the following enabling description of the drawings, the novel aspects of the present invention should become evident to a person of ordinary skill in the art. 
         FIG. 1  is an illustration of a roadway optical platform in which embodiments of the present invention can be practiced. 
         FIG. 2  provides a more detailed illustration of LED array assemblies included in  FIG. 1 . 
         FIG. 3  is a more detailed illustration of the conventional two-part reflector assembly illustrated in  FIG. 2 . 
         FIG. 4  is an illustration of a reflective cavity in the conventional two-part reflector design of  FIG. 3 . 
         FIG. 5 . is an illustration of a multi-part reflector design constructed in accordance with embodiments of the present invention. 
         FIG. 6  is an illustration a vacuum metallization chamber used in the manufacture of reflectors. 
         FIG. 7  is an illustration of a two end-piece pair design configured for use with a common centerpiece to provide different beam patterns in accordance with the embodiments. 
         FIGS. 8A and 8B  illustrate views of a multi-part reflector design in accordance with a second embodiment of the present invention 
         FIG. 9  illustrates views of a multi-part reflector design in accordance with a third embodiment of the present invention. 
     
    
    
     V. DETAILED DESCRIPTION OF THE EMBODIMENTS 
     While exemplary embodiments are described herein with illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those skilled in the art with access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the multi-reflector design described herein would be of significant utility. 
       FIG. 1  is an illustration of a roadway optical platform  100  in which embodiments of the present invention can be practiced. The optical platform  100  is configured, for example, for use in a roadway streetlight system. The optical platform  100  has a lighting segment  102 , including two LED light engine modules  104  and  106 .  FIG. 2  provides a more detailed illustration of the LED array light engine modules  104  and  106 . 
     As illustrated in  FIG. 2 , each of the LED light engine module  104  and  106  includes an LED lighting array  200  comprised of a plurality of LEDs, such as LEDs  202 . The LED lighting array  200  also includes a conventional two-piece reflector assembly  204  for reflecting and distriting light produced by the LEDs  202  across an area, such as the surface of a roadway. 
       FIG. 3  is a more detailed illustration of the conventional two-piece reflector assembly  204  illustrated in  FIG. 2 . The two-piece reflector assembly  204  includes two portions  302  and  304 . Due to the depth of the portions  302  and  304 , a deep pocket  320  is formed in the corners, as depicted in  FIG. 4 . During the manufacture of this type of reflector, uneven reflective coating occurs in the reflective cavity  320 . This uneven coating causes non-uniform reflection of light from the light source, such as the LEDs  202 , ultimately resulting in non-uniform coverage of the light from the reflector. 
     By way of background, streetlights are configured to provide reflective lighting primarily in three different zones along a roadway. A first zone, for example, is referred to by those of skill in the art as Nadir: the area directly below the street light. In the case of roadways, for example, where a vehicle travels along the roadway at night, a second zone includes an area in the direction of the traveling vehicle (e.g., shinning away from a driver). A third zone includes light shining towards the driver, which is a vitally important aspect. These areas generally represent the three roadway reflective lighting zones. 
     The coating of the conventional two-part reflector design  204 , due to the reflective cavity  320 , provides suboptimal LED roadway lighting control. More specifically, the two-part reflector design  204  has severely limited ability to use the two portions  302  and  304  to provide predictive light reflectivity across the three roadway reflective lighting zones noted above. 
     Other conventional lighting systems use one or more small optics to illuminate all of the zones. These conventional lighting systems, however, do not provide significant control over the light going into the reflective zones, thus limiting their utility. Many of these conventional lighting systems use LEDs and can use, for example, one optic per LED. That is, if a conventional roadway lighting system uses  100  LEDs, this lighting system would include  100  clear plastic refractive optic segments. This approach, however, also provides suboptimal roadway lighting control. 
       FIG. 5  is an illustration of a multi-part reflector design  500  constructed in accordance with embodiments of the present invention. The embodiments provide a multi-part reflector design  500  that enables the creation of uniform predictive reflectivity across each of the three roadway reflective lighting zones. A greater number of reflector portions, multi-part reflector  500 , reduce the occurrence reflective cavities in each of the portions. Although the multi-part reflector design  500  depicts three portions, the present invention is not limited to only three portions. 
     In  FIG. 5 , the multi-part reflector  500  includes an elongated center portion  502 , a left end-cap portion  504 , and a right end-cap portion  506 . In the illustrious embodiments, each of the three portions  502 ,  504 , and  506  has a slightly less depth than the portions  302  and  304  of the two-part reflector design  300  of  FIG. 3 . Due to the slightly less depth, aluminum surfaces of the portions  502 ,  504 , and  506  can be manufactured more uniformly during coating process because the three-piece design affords line of sight coating process. 
     By way of example, and not limitation, each of the portions  502 ,  504 , and  506  of the multi-part reflector  500  reflects light in a different direction. Generally, for example, the elongated center portion  502  primarily reflects light into a first of the reflective lighting zones. More specifically, the elongated center portion  502  primarily directs light on Nadir, below the light fixture. The left end-piece  504  and right end-piece reflect light into the second and third of the reflective lighting zones. 
     In the manner described above, the multi-part reflector  500  enables the creation of uniform predictive reflectivity across the surfaces of the three roadway reflective lighting zones, as noted above. The two-piece reflectors in LED light engine module  104  and  106  of the roadway optical platform  100 , for example, could be retrofitted with the multi-part reflector  500 . 
     More particularly, each of the portions  502 ,  504 , and  506  of the multi-part reflector  500  provides better optics to balance the light reflected across the three reflective lighting zones. That is, the multi-part reflector  500  provides better control and balancing of the surface light reflected toward a roadway driver (i.e., counter-beam), the light directed below the poll, and the light reflecting away from the driver (i.e., pro-beam). The ability to control light reflectivity of these different surfaces, produced by the streetlight, ultimately provides increased predictive results. 
     Increased predictability affects the total lumens produced by the light fixture and the distribution pattern of the light, which leads to more reliable efficiency calculations. The cost of LEDs is generally about 50% of the costs of entire lighting system. Increased predictability and efficiency results in lower electricity costs to the customer of the light since products can be reliably designed to produce greater lumens with fewer LEDs. This ultimately results in lower costs. 
     As noted above, the increased predictive results of the multi-part reflector  500  are due to the fact that the aluminum surfaces of the portions  502 ,  504 , and  506  can be manufactured more uniformly during coating process. This process is explained in greater detail below. 
       FIG. 6  is an illustration a thermal deposition chamber  600  used in the manufacture of the multi-part reflector  500  illustrated in  FIG. 5 . In  FIG. 6 , reflectors (not shown) are positioned within fixtures groups  602  and  604  to begin the coating process. The fixtures groups  602  and  604  are shown in the chamber  600  before a chamber door has been closed. During coating process, a round plate  605  spins around a center axis  606  of the chamber  600 . The fixture groups  602  and  604 , holding the reflectors, spin around axes  608  and  610  during the=coating process. 
     Each of the portions  502 ,  504 , and  506  can be manufactured using, for example, an injection molding process, although the present invention is not so limited. The multi-part reflector  500  (e.g., constructed of plastic) is manufactured as the separate portions  502 ,  504 , and  506  to reduce the occurrence of shaded areas, or reflective cavities that create non-uniformity. As a result of the multi-part design, more uniform coating can be achieved. Consequently, the multi-part reflector  500  performs more predictably with respect to the amount of light reflected across the surfaces of the three roadway reflective lighting zones. 
     By way of example, during coating process, each of the portions  502 ,  504 , and  506  (e.g., positioned within a respective one of the fixtures within the groups  602  and  604 ) is rotated orbitally to provide optimal coverage and aluminum coating for all of the surfaces thereon. Because each of the portions  502 ,  504 , and  506  is less deep, there are fewer shaded areas. As a result, during coating process, there is a reduced chance that a reflective cavity, such as the reflective deep cavity  320  of the two-piece reflector  300 , can develop on any of the surfaces, or other areas, of the portions  502 ,  504 , and  506 . Since the reflector  500  is designed as three pieces, each of the pieces can be manufactured using different materials and manufacturing methods other than injection molding. 
     In one exemplary embodiment, with respect to other materials, a sheet-metal material can be used. For example, and not limitation, this sheet metal can be pre-coated with a highly specular reflective coating and can be used to construct the elongated center portion  502 . The end-pieces could also be coated with an enhanced aluminum or could be silver coated with silver having a much higher reflectivity. For example, where normal aluminum coating might be on the order of 80 to 85% reflectivity, a silver coating could provide up to 95 to 98% reflectivity. 
     In the manner described above, the elongated center section  502  and the ends  504  and  506  can be constructed by mixing and matching different technologies beyond the single technology of injection molding and aluminum metallization. 
     Zinc die-cast is another suitable material that can be used with a type of reflective coating. This approach can help overcome the heat limitations associated with standard plastic portions, using some type of die-cast, whether zinc or aluminum. Although, the elongated center portion  502  can be manufactured from plastic or from die-cast, an advantage is afforded using the pre-metallized sheet-metal for the elongated portion  502 . As noted above, the end-pieces  504  and  506  can be made from die-cast or plastic. 
     By way of example, and not limitation, glass could be used to construct the end-pieces  504  and  506 . The glass can be coated using other types of coatings suitable for glass, but not suitable for coating sheet-metal or plastic. This process allows for use of sheet-metal for construction of the elongated center portion  502  and different materials for the end-pieces  504  and  506 . An additional advantage provided by embodiments of the invention is described below. 
     Since the elongated center portion  502  and the end-pieces  504  and  506  are separate portions, the end-pieces  504  and  506  can be viewed as a single set. With the end-pieces  504  and  506  being seen as a single set, the multi-part reflector  500  can be viewed as having essentially two basic parts. A first of the two parts is the elongated centerpiece  502 . The second part is the end-cap set  504 / 506 . In this manner, the elongated centerpiece  502  can be paired with not only the end-cap set  504 / 506 , but the elongated centerpiece  502  can be paired with other end-cap sets to provide different beam patterns. 
     With a single elongated centerpiece and an end-cap set, a design can be created that facilitates use of a common elongated centerpiece with different end-piece sets. Such an arrangement can be particularly applicable in situations where different roadways have different requirements and different pole spacings. For example, one street can have a 4-to-1 pole spacing, and another street can have a 6-to-1 pole spacing. As understood by those of skill in the art, pole spacing refers to the light pole spacing to the mounting height ratio. 
     By pairing different elongated center portions with different end-cap sets, one can optimize optical platforms for a specific spacing between the poles. For example, two different end-cap sets could be designed for two different respective roadways, using one common elongated centerpiece. The shape of the elongated centerpiece relates more to the road width and across the road uniformity, distribution, and control. More specifically, for example, the shape of the elongated centerpiece relates to how many lanes might require lighting. The shape of the end-cap sets has more to do with the spacing between the poles and down the road uniformity, distribution, and control. 
     Thus, a product can be created that can mix and match an elongated centerpiece with different end-cap sets. The elongated centerpiece more or less influences the projected shape of the ends. If a wider, or more narrow, centerpiece was provided, such a configuration would necessitate correspondingly, wider or more narrow end-pieces. On the other hand, if a roadway has a width of three lanes, with a centerpiece optimized for three lanes, one end-piece set could be used and configured for one pole spacing, and another end-cap set could be used and configured for another pole spacing. 
       FIG. 7  is an illustration of a two end-cap design  700  (e.g., end-cap sets) configured for use with a common centerpiece, such as the elongated centerpiece  502 , to provide different beam patterns. For example, a first end-cap pair  702  can be used with the elongated centerpiece  502  to produce a first beam pattern. A second end-cap pair  704  can be used with the elongated centerpiece  502  to provide a second beam pattern. 
       FIGS. 8A and 8B  are illustrations of a multi-part reflector design in accordance with a second embodiment of the present invention. 
     Referring to  FIG. 8A , a reflector  800 A includes an elongated piece  820  and two end caps  810 A and  810 B.  FIG. 8B  illustrates a similar design in which a reflector  800 B has an elongated piece  840  and end-pieces  830 A and  830 B. In both designs, the end-pieces slide in from the sides of the elongated piece  820 . This is shown in more detail in  FIG. 8B , which illustrates how end-pieces  810 B and  830 B are connected to the elongated portions  820  and  840 , respectively. It should be appreciated that the end caps  810 A and  830 A may be connected to the elongated portions  820  and  840 , respectively, in a similar manner. 
     Referring to  FIG. 8B , the ends  810 B and  830 B have ridges  815  on the sides that snap into tabs  805  on the respective sides of the elongated pieces  820  and  840 , respectively, locking the parts together. A dovetail  835  on the bottom of the ends  810 B and  830 B slides into an opening  825  on the elongated pieces  820  and  840 , respectively. 
       FIG. 9  is an illustration of a multi-part reflector design  900  in accordance with a third embodiment of the present invention. Referring to  FIG. 9 , the reflector  900  includes an elongated piece  920  and two ends  910 A and  910 B. In this design, the ends  910 A and  910 B slide into place from above the elongated piece  920 . 
     Alternative embodiments, examples, and modifications which would still be encompassed by the invention may be made by those skilled in the art, particularly in light of the foregoing teachings. Further, it should be understood that the terminology used to describe the invention is intended to be in the nature of words of description rather than of limitation. 
     Those skilled in the art will also appreciate that various adaptations and modifications of the preferred and alternative embodiments described above can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.