Abstract:
An arena light reflecting assembly includes an asymmetric parabolic shaped reflector having an exit aperture. The reflector surrounds a horizontally extending high intensity light source and has a focal axis that lies along an axis of an arc tube of the light source so that the reflector acts as a collimator redirecting light from the light source into essentially parallel rays from the exit aperture. A pan circumscribes the exit aperture and a louver assembly is disposed within the exit aperture behind a front surface of the pan.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This is a utility application of provisional application filed Sep. 20, 2001, Serial No. 60/323,578.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to sports and recreational area lighting, and more particularly, to an improved reflector assembly for television coverage level illumination of the Primary Play Area in an indoor arena, while controlling glare to the spectators seated around the PPA.  
           [0004]    2. Description of Prior Art  
           [0005]    In the past, arena lighting for sports and recreational events covered by television broadcast has been driven by the television requirements for intense and uniform light levels for the television cameras to capture the often quick moving action of the event.  
           [0006]    Since the Primary Play Area (PPA) in most arenas is rectangular or oblong shaped for most events, such as basketball, ice hockey or rodeo, the need for adequate horizontal and vertical illuminance levels has led to the placement of large numbers of high intensity luminaires along catwalks suspended along arena ceilings parallel to and outside of the long sides of the PPA.  
           [0007]    Uniform illumination of the PPA can be achieved by aiming the luminaires at various target locations in the PPA. Since light intensity varies inversely as the square of the distance between the light source and the point being illuminated, it is necessary to aim more luminaires at target locations on the opposite side of the PPA from the catwalk location. This placement has proven to provide adequate horizontal and vertical illumination of the PPA, but also has caused intense illumination of the spectator seating areas in the lower arena, particularly from luminaires aimed at target locations from the opposite catwalk. This spill light is seen as glare to the spectators seated in such areas, causing visual discomfort in viewing the event.  
           [0008]    Additionally, a popular light source of choice among arena lighting designers is the position oriented high intensity discharge (HID) metal halide type lamp, which provides high lumens per watt efficacy and good color rendering. These types of lamps do not reach full light output immediately upon starting, but must warm up over a period of several minutes. Upon reaching operating temperatures, if the lamp is extinguished, it will not relight until it is cooled sufficiently to allow the arc to restrike with the available starting voltage. This time could be 15 minutes or longer.  
           [0009]    However, event planners have requested the ability to darken the arena for special effects, such as spotlights and fireworks, at pre-selected times during events, such as player introductions and half-time shows, while being able to return the arena to full brightness immediately upon completion of the special effects portion of the event.  
           [0010]    Thus, arena luminaire designers have developed systems for HID type luminaires to simulate instant on/off of the luminaire for special effects while the lamp continues to remain on within the luminaire. These shutter systems require that the components of the optical system of the luminaire be contained within the front opening of the luminaire, so that the shutter doors may close and block the light produced by the lamp.  
           [0011]    Further, since the luminaires must be installed and maintained by workers on the small catwalks high above the arena floor, the size of the luminaires, and thus the size of the components within the luminaires, must be kept to a manageable size.  
         BRIEF SUMMARY OF THE INVENTION  
         [0012]    Thus, it is an object of the present invention to provide a narrow beam reflector assembly with sharp cutoff optics.  
           [0013]    It is a further object of the present invention to provide a reflector assembly that controls spill light to reduce glare to spectator seats in the lower arena.  
           [0014]    It is a further object of the present invention to provide a HID reflector assembly with spill light control that can also be used with a shutter system to simulate instant on/off of the luminaire.  
           [0015]    It is even a further object of the present invention to provide a reflector assembly with spill light control that has a reflector and louver assembly which is positioned behind the plane of a front pan.  
           [0016]    It is even a further object of the present invention to provide a reflector assembly with spill light control of compact size.  
           [0017]    More particularly, the present invention provides an arena light reflecting assembly. The arena light reflecting assembly includes an asymmetric parabolic shaped reflector having an exit aperture. The reflector surrounds a horizontally extending high intensity light source and has a focal axis that lies along an axis of an arc tube of the light source so that the reflector acts as a collimator redirecting light from the light source into essentially parallel rays from the exit aperture. A pan circumscribes the exit aperture and a louver assembly is disposed within the exit aperture behind a front surface of the pan.  
           [0018]    The elements outlined herein are given primarily for the purpose of better understanding of the present invention. Many additional inventive concepts will be understood herein and none of these objectives are to be considered as limiting without taking into consideration the entirety of the teachings of the figures and specification together with any appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a perspective view of a reflector assembly of the present invention.  
         [0020]    [0020]FIG. 2 is a side view of a representative arena showing typical aiming angles of arena luminaires utilizing the reflector assembly of the present invention.  
         [0021]    [0021]FIG. 3 is an enlargement of the area designated by  3 - 3  of FIG. 2, showing a side view of the catwalk with arena luminaires utilizing the reflector assembly of the present invention.  
         [0022]    [0022]FIG. 4 is a top view of the reflector assembly of FIG. 1.  
         [0023]    [0023]FIG. 6 is a sectional view taken through line  6 - 6  of FIG. 4.  
         [0024]    [0024]FIG. 7 is a ray trace diagram showing light emitted from an arc tube in a plane normal to the longitudinal axis of the arc tube with respect to the reflector assembly of FIG. 1.  
         [0025]    [0025]FIG. 8 is a ray trace diagram showing the arc of light from the arc tube not directly used by the reflector of the present invention.  
         [0026]    [0026]FIG. 9 is a ray trace diagram showing light emitted directly from the arc tube with respect to the louver assembly of FIG. 1.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    The reflector assembly of the present invention utilizes HID sources, achieving the highest efficiencies possible, concentrating the light energy where required, while eliminating unwanted stray or spill light. The reflector assembly provides energy efficient, televisable light levels, but also keeps light levels on the audience to a minimum—reducing viewer glare and creating a more intimate venue for the observers.  
         [0028]    [0028]FIG. 1 shows an embodiment of the reflector assembly  10  of the present invention. As shown in FIG. 1, the reflector assembly  10  has a parabolic reflector  12 , a louver assembly  14 , and a front pan  16 . Also shown is a HID lamp  18 .  
         [0029]    [0029]FIG. 2 shows an arena  22  having a Primary Playing Area (PPA)  24  and a catwalk  24 , which is suspended from the ceiling of the arena parallel to and outside of the PPA  24 . Luminaires  28 ,  30  are attached to the catwalk  24  and have aiming vectors  32 ,  34 . For example, the luminaire  28  having aiming vector  32  is aimed at a target area located on the opposite side of the PPA  24  from the location of the catwalk  26 . The luminaire  30  having aiming vector  34  is aimed at a target area located on the closer side of the PPA  24  to the location of the catwalk  26 . It should be noted that the luminaire  28  therefore has a higher aiming angle with respect to luminaire  30 .  
         [0030]    Since the object of the reflector assembly  10  of the invention is to provide adequate illumination of the PPA  24  while providing cut off of illumination from the spectator seats  36  adjacent to the PPA  24 , this higher aiming angle requires a more intense cutoff of spill light exiting at the top  40  of the parabolic reflector  12  than it does at the bottom  42  of the reflector  12 .  
         [0031]    The reflector assembly  10  is preferably received within a housing  38 , as shown in FIG. 3, to form a complete arena luminaire  28 .  
         [0032]    In the embodiment shown in FIG. 1, front pan  16  provides a mounting base for the reflector  12  and louver assembly  14 . Front pan  16  has an oblong shaped opening, which receives the reflector  12  and louver assembly  14  such that the entire reflector  12  and louver assembly  14  are held behind the front surface  20  of the pan  16 . The pan may be made of sheet metal or the like, and the reflector  12  and louver assembly  14  may be attached to the pan  16  by rivets, screws, or the like.  
         [0033]    As shown in FIG. 3, a planar lens  44  may be placed over the reflector assembly  10  against the pan front surface  20  in order to create a barrier between the environment outside of the luminaire  28  and the inside of the luminaire  28 . This not only protects the inside components of the luminaire  28  from the outside environment, but also protects the outside environment from non-passive failure of the HID lamp  18 . In the preferred embodiment, a sheet of tempered glass is utilized as the planar lens  44 .  
         [0034]    Thus, the reflector assembly  10  of the present invention provides a planar front surface with no protruding light control devices, such as visors, louvers, or special lamp shields, in order to allow a shutter system  46 , such as that shown in FIG. 3, to properly operate. Shutter system  46  includes a pair of moveable shutters  46   a ,  46   b , positionably attached to housing  38 .  
         [0035]    As shown in FIGS. 4 through 9, the reflector assembly  10  cooperates with HID lamp  18  to redirect and control the light output from the HID lamp  18 .  
         [0036]    As is well known, high wattage HID lamps have an arc tube which is approximately 3 inches long and ½ inch in diameter. When in operation, the arc fills this tube, producing visible light output throughout the tube. Since the tube is cylindrically shaped, more light is emitted from the cylindrical walls of the tube than from the ends.  
         [0037]    Further, it is known that position oriented HID lamps are capable of achieving higher efficacy (lumens per watt) than non position oriented (universal burn) type HID lamps. However, the horizontal burn HID lamp must be positioned such that the axis of its arc tube is parallel to the ground during operation.  
         [0038]    Thus, as shown in FIG. 1, the reflector assembly  10  of the embodiment described herein utilizes a horizontal burn type HID metal halide lamp. The principals of the invention, however, may be applied to reflector assemblies having alternate lamps and orientations. The lamp of the embodiment described may be rated for either 750, 1000, or 1500 watts.  
         [0039]    As shown in FIGS. 4 through 6, the reflector assembly  10  of the embodiment described herein has an asymmetric parabolic shaped reflector  12  which has a focal axis  52  that lies along the axis  54  of the arc tube  56  of the HID lamp  18 . Since the arc tube  56  of the HID lamp  18  is a horizontally oriented cylinder, the parabolic shaped reflector  12  has an oblong shape and produces an oblong shaped light output.  
         [0040]    Further, as shown in FIG. 7, since the focal axis  52  of the parabolic shaped reflector  12  is located coincident with the arc tube  56 , the parabolic shaped reflector  12  will act as a collimator, redirecting light from the HID lamp  18  into essentially parallel rays  48  at the exit aperture  50  of the parabolic shaped reflector  12 .  
         [0041]    The width of the beam pattern of the reflected light from the HID lamp  18  may be controlled by the reflector designer by controlling the shape of the parabolic reflector  12 . However, the depth of the parabolic reflector  12  bowl is limited by the size of the luminaire housing  38 , which in turn is limited by the physical requirement that the luminaire must be manageable by one person for installation and maintenance on a catwalk  26 . Further considerations in reflector design include the need to illuminate the PPA  24  with good uniformity, which precludes ‘spotlight’ type narrow beams which would cast harsh shadows.  
         [0042]    Thus, the parabolic shaped reflector  12  of the embodiment described herein has been chosen to produce a NEMA 4×2 type beam pattern.  
         [0043]    As shown further in FIG. 8, the parabolic shaped reflector  12  of the described embodiment thus envelopes the HID lamp  18  by approximately 258°, leaving a 102° arc of direct light  66  from the lamp, along a vertical section of the reflector assembly  10  approximately in the center of the assembly  10 . Illumination in the 258° arc is redirected by the parabolic shaped reflector  12  into a collimated main beam, which provides the focused main illumination area for the NEMA 4×2 beam pattern of the reflector assembly  10 .  
         [0044]    The ray trace diagrams of FIGS. 7 through 9 are representative of the parabolic shaped reflector  12  along the length of the arc tube  56  of the HID lamp  18 . Since the overwhelming majority of the light output from the arc tube  56  of the HID lamp  18  is emitted along the length of the arc tube  56 , the diagrams of FIGS. 7 through 9 are representative of the majority of the optical work performed by the reflector assembly  10  of the invention.  
         [0045]    Returning to FIG. 1, and  4  through  6 , since a minority of light output from the arc tube  56  of the HID lamp  18  is emitted from the ends of the arc tube  56 , the left side  58  and the right side  60  of the parabolic shaped reflector  12  are shaped to redirect the available light into the oblong shaped NEMA 4×2 beam pattern. However, also located along the left side  58  and the right side  60  of the parabolic shaped reflector  12  are a large relamping hole  62  and a lamp socket hole  64 . The relamping hole  62  is large enough to allow the HID lamp  18  to be inserted and removed through the hole for installation and maintenance of the luminaire. The socket hole  62  is necessary to attach the lamp base to the socket (not shown) for electrical connection of the lamp to power and for proper positioning of the lamp within the reflector assembly  10 . Additionally, a lamp end stabilizer (not shown) may extend through the relamping hole during normal operation of the reflector assembly  10  in order to stabilize the lamp from the vibrations of the catwalk  26 . Due to the limited optical work performed by the left side  58  and the right side  60  of the parabolic shaped reflector, the overall efficacy of the reflector assembly  10  is not greatly impacted by the relamping hole  62  or the lamp socket hole  64 .  
         [0046]    Illumination from the 102° arc of direct light  66  from the lamp if-left uncontrolled will ‘spill’ outside of the NEMA 4×2 pattern area, illuminating the adjacent, spectator seating areas  36  of the arena  22  as shown in FIG. 2. This illumination will produce glare to the spectators seated in those areas, especially from the luminaires located on the catwalk on the opposite side of the PPA due to the greater number and higher aiming angle of those luminaires.  
         [0047]    Thus, as shown in FIG. 9, the reflector assembly  10  of the present embodiment utilizes a louver assembly  14  to control direct spill light  66  from the arc tube  56  of the HID lamp  18 . The louver assembly  14  is designed such that it does not interfere with the arc of light from the arc tube  56  which is emitted into the main beam  48  of light. The louver assembly  14  must also operate around the outer bulb  68  of the HID lamp  18  and the asymmetric parabolic curves of the parabolic shaped reflector  12 . Additionally, the louver assembly  14  must not protrude beyond the pan front surface  20 , to allow for operation of the shutter system  46  described above and shown in FIG. 3.  
         [0048]    Thus, as shown in FIG. 9 the louver assembly  14  of the present embodiment has an upper group  70  of thin horizontal non-reflective louvers and a lower group  72  of thin horizontal non-reflective louvers which are, thus, parallel to the longitudinal axis of the arc tube  56 , parallel to the main beam light rays  48  reflected light from the parabolic shaped reflector  12  (FIG. 7), and parallel to the long edge of the PPA  24  (FIG. 2). This design provides control of the arc of direct light emitted by the arc tube of the HID lamp  18  along the long edge of the PPA  24 , while allowing the reflected light of the main beam  48  to be emitted from the reflector assembly  10  essentially unobstructed.  
         [0049]    The upper group  70  of louvers and the lower group  72  of louvers are also asymmetric, since the higher angle of the aiming vectors for luminaires aimed at the opposite side of the PPA  24  creates a need for more intense direct light cutoff of light from the top  40  of the parabolic reflector  12  than light emitted from the bottom  42  of the reflector  12 . Thus, as shown in FIG. 9, the upper group  70  of louvers of the shown embodiment block direct spill light  66  from the arc tube  56  in a region from about 11° above the aiming vector  32  to about 55° above the aiming vector  32 . The lower group  72  of louvers of the shown embodiment block direct spill light  66  from the arc tube  56  in a region from about 20° below the aiming vector  32  to about 55° below the aiming vector  32 .  
         [0050]    It should be noted that alternative louver designs which vary the quantity, size, and placement of the louvers could be utilized which produce similar spill light control without affecting the overall efficacy of the reflector assembly  10  and without departing from the scope of the claimed invention. It is believed that the configuration described herein, however, is optimized to block unwanted direct light from spilling beyond the bounds of the long side of the PPA  24 , whether the luminaire  28 ,  30  of FIG. 2 is aimed at the far side or the near side of the PPA  24 , while requiring the least number of louvers for manufacturing efficiency.  
         [0051]    Additionally, as shown in FIG. 1, the louver  74  assembly has vertical louvers located along the left side  58  and the right side  60  of the parabolic shaped reflector  12  for both spill light control along the short side of the NEMA 4×2 beam pattern and as a structural support for the upper group  70  and lower group  72  of horizontal louvers. In the shown embodiment, the vertical louvers  74  are formed integral with the front pan by bending a portion of the front pan  16  material, which would have otherwise been removed for creation of the oblong shaped opening, downward into the parabolic shaped reflector  12 .  
         [0052]    Further contributing to the efficacy of the embodiment of the reflector assembly  10  described herein, the material selected for the parabolic shaped reflector  12  is an aluminum material having a highly specular finish. More specifically, the preferred embodiment utilizes a reflector having a minimum 94% reflectivity with less than 15% diffuse component. One such product is sold under the trade name ANOMIRO™; however, other materials are also available. Selection of such a high efficiency material ensures that the most possible light is directed where required, and not dispersed as spill light. However, this material is available only in lighting sheets and its efficiency cannot be maintained if it is hydroformed, spun or stamped into the desired reflector geometry. The nature of these processes currently limits the reflectors formed thereby to about 86% maximum reflectivity.  
         [0053]    Therefore, the parabolic shaped reflector  12  of the described embodiment is formed by a segmenting process which involves cutting a number of pie shaped reflector sections and bending the sections at appropriate locations to approximate very closely the geometrical shape desired. Thus, the parabolic shaped reflector  12  of the described embodiment is formed from 12 sections joined to form the desired asymmetrical, oblong front reflector opening, with each section being bent in approximately 12 locations to approximate the parabolic shape desired for that section. Thus, the asymmetric parabolic shaped reflector  12  may achieve very high efficacy.  
         [0054]    The foregoing detailed description, including specific angular measurements, reflector forming techniques, materials and finishes, is primarily given for clearness of understanding. No unnecessary limitations are to be understood therefrom, for modifications will become obvious to those skilled in the art upon reading this disclosure and may be made without departing from the sprit of the invention or the scope of any appending claims.