Patent Publication Number: US-7588347-B1

Title: Lighting fixture

Description:
FIELD OF THE INVENTION 
   This invention relates to lighting fixtures for commercial and industrial applications and more particularly to high-energy-efficiency lighting fixtures. 
   BACKGROUND OF THE INVENTION 
   In view of ever-growing energy conservation and environmental concerns, fluorescent lighting fixtures are becoming the first choice for many commercial and residential lighting applications. In many commercial lighting applications where a long-life, high-output light is desired the choice is often a fixture using a high-intensity-discharge (HID), metal halide or high-pressure sodium (HPS) lamp. However, such lamps tend to exhibit high glare, heat generation, unnatural shades of light, and other inefficiencies that render them a good, but not an optimal choice for lighting large commercial spaces.  FIG. 1  shows an example of an HID fixture  100  mounted from a garage ceiling beam  102 . This example includes a single HID lamp  104  (shown in phantom) surrounded by a metallic or sturdy plastic reflector  106 . The reflector may be covered with transparent plate (not shown) to seal it or other wise protected from debris (using a grating, for example). The lamp generates a downward light as shown. In this model, a transparent annulus  110  also generates a sideways lighting effect (dashed arrows  112 . This provides a fuller lighting effect in a low-ceiling environment, as described further below. 
   One example of a large open space requiring commercial lighting is an indoor parking garage structure. In such structures lights may be operating continuously and excess heat may be problematic in underground, enclosed parking areas. Fluorescent lights present a desirable alternative in terms of their white, broad-spectrum output, cool operation and high energy efficiency. However, fluorescent lamps may exhibit lower overall light output (measured in lumens) than comparable high-intensity commercial lamps. For example, half their light is directed opposite the intended target of illumination, requiring a reflector to return this light to the target. Fluorescent lamps are also provided in long tubes that may pose challenges in focusing and distributing their light. 
   In most parking garage spaces, the ceiling height may be relatively low (for example, 8-12-foot ceiling height). Thus, fixtures that throw substantial quantities of horizontally directed light are desirable so as to avoid a spotting effect. This is an advantage with high-intensity lamps, which can be directed to throw substantial light sideways, as well as downward. In addition, traditional high-intensity fixtures for outdoor and parking area-placement are weatherproof, having durable sealed covers that keep moisture, vapor and other contaminants away from their internal wiring and components. However, fluorescent fixtures are typically open to the elements-many being fitted with an unsealed diffuser cover. 
   It is, thus, highly desirable to provide a lighting fixture that uses fluorescent tubular lamps, or another type of elongated light source, such as an LED array/strip. This elongated lighting fixture should be particularly suitable for parking areas and other enclosed structures, and afford superior light distribution (photometrics) and overall performance. Such a fixture should be easily retrofit into existing structures and exhibit performance generally similar to other high-intensity fixture types with generally lower power consumption. This fixture should be able to provide desired output using as few as two conventional fluorescent lamps or other elongated lighting sources. It should also be mountable in a pendant manner with a sealed housing to keep out moisture and contaminants. 
   SUMMARY OF THE INVENTION 
   This invention overcomes the disadvantages of the prior art by providing a lighting fixture for use in low-ceiling applications and/or outdoor environments, such as parking garages that allows for the use of more-efficient lighting sources, such as fluorescent lamps, with more-even distribution of light along the sides of the fixture so that the surrounding space is fully and efficiently illuminated. The fixture employs two elongated light sources mounted upon opposing sides, and surrounded by a pair of respective side reflectors. The side reflectors direct the light of the two light sources in a generally sideward and somewhat-downward direction. The lower portion of the side reflectors collectively define an overall wide angle and each lower portion completely overlies a respective one of the side light sources mounted above. Thus, the lower portions generally prevent predetermined light from the side light sources from being projected in a vertical or generally downward direction. A third light source can be located centrally, beneath the lower portions to provide downward light, which is further reflected generally downwardly by the wide angled lower portions. Alternatively, where only the side light sources are employed, each of the lower reflector portions can include a set of elongated slots near the center of the fixture. The slots allow a predetermined quantity of light to pass into the lower area of the reflector, and thereby in a generally downward direction. A central angled reflector can further divide and reflect the light passed through the two sets of slots. This central reflector creates the illusion of a virtual, third, bottom light source. In each embodiment, light is efficiently directed to both the sides of the fixture and beneath it to more-fully light a low-ceiling space. In various embodiments, the reflectors and light sources are mounted on the internal box of a housing constructed from metal, polymer, composite, and the like. A transparent/translucent cover is removably sealed to the housing, using an intervening perimeter gasket that ensures a weather-tight construction. 
   More particularly, in an illustrative embodiment the lighting fixture includes a housing having a widthwise dimension and an elongated dimension adapted to be mounted to a supporting structure. A light-transmitting cover is secured to a lower end of the housing with a seal provided between the housing and the cover. A light source supporting structure is operatively connected to the housing and securing a first light source and a second light source so that the first light source and the second light source each extend along the elongated dimension on each of opposing widthwise sides of the housing. A reflector assembly with a cross-section shape constructed and arranged to cover each of the first light source and the second light source with upper reflector portions, lower reflector portions and central reflector portions, the upper reflector portions and lower reflector portions respectively extending in a generally widthwise direction so as to fully overlie and extend beyond a widthwise end of each of the first light source and the second light source so that the predetermined light output from each of the first light source and the second light source is directed above a generally downward direction, and further constructed and arranged to allow predetermined light output to be discretely projected in the generally downward direction. 
   In one illustrative embodiment the lighting fixture the lower reflector portions of the lighting enclose a third lighting source, extending in the elongated dimension, which projects light discretely in the generally downward direction. In another illustrative embodiment, the lower reflector portions each include a plurality of elongated slots therealong that respectively transmit light from the first light source and the second light source into a region of the lower reflector so that the light transmitted through the slots is directed in the generally downward direction. The slots have a length generally along the widthwise dimension of between approximately ½ and 1 inch. In this two-lamp embodiment, the location of the third light source is replaced with a central divider reflector with a pair of downwardly extending reflector walls defining a cross section extending from spaced-apart locations at the lower reflector portions, adjacent to edges of the slots, to a bottommost convergence line. In either embodiment, the light sources can comprise tubular fluorescent lamps, a plurality of lamps or solid state arrays, such as LED arrays. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention description below refers to the accompanying drawings, of which: 
       FIG. 1  is, already described, is a side view of a conventional high-intensity discharge (HID) lighting fixture for use in parking garages and other generally out door areas; 
       FIG. 2  is a side cross section of a three-lamp sealed florescent lighting fixture for use in parking garages and other outdoor environments according to a prior implementation; 
       FIG. 3  is a side cross section of a three-lamp lighting fixture for use in garages and other weather-exposed environments according to an illustrative embodiment of this invention; 
       FIG. 4  is a perspective view of the three-lamp fixture of  FIG. 3 ; 
       FIG. 5  is an exploded perspective view of the three-lamp fixture of  FIG. 3 ; 
       FIG. 6  is a polar-coordinate graph of the light distribution at various viewing angles for the three-light fixture of  FIG. 3 ; 
       FIG. 7  is a side cross section of a two-lamp lighting fixture for use in garages and other weather-exposed environments according to an illustrative embodiment of this invention; 
       FIG. 8  is a perspective view of the two-lamp fixture of  FIG. 7 ; 
       FIG. 9  is an exploded perspective view of the two-lamp fixture of  FIG. 7 ; 
       FIG. 10  is a is a polar-coordinate graph of the light distribution at various viewing angles for two-lamp fixture of  FIG. 7 ; 
       FIG. 11  is a perspective view of the two-lamp fixture of  FIG. 7  showing the projection of light therefrom in each of a plurality of desired directions; and 
       FIG. 12  is a polar-coordinate graph of the light distribution at various viewing angles for the three-lamp fixture of the prior implementation of  FIG. 2 , shown for comparison. 
   

   DETAILED DESCRIPTION 
   By way of further background,  FIG. 2  details a cross-sectional view of a fluorescent lighting fixture  200  (also commonly referred to in industry as a “luminaire”) for use in low-mounting height applications, such as parking garages and other environments requiring weather and debris-resistance, according to a prior implementation. The fixture  200  can be at least three-feet in length, taken in the longitudinal or elongated direction, perpendicular to the page of the drawing (and indicated by the longitudinal axis  202 ). Its width is between approximately six and 12 inches. In general it is wider enough to effectively mount, and spread the light of the three depicted lamps ( 251 ,  253  and  255 ) in an arc of approximately 180 degrees about the axis  202 . The fixture  200  includes an upper housing  210  that encloses a fluorescent light ballast  212  of any appropriate design. The housing can be constructed from durable polymer (as shown), metal or another suitable material (for example glass-filled nylon, fiberglass or a composite). The housing  210  encloses, within its interior a sheet metal (or other material) box enclosure  220 . The box  220  acts as a sub-enclosure for the ballast  212 , and its lower end defines a support for a reflector structure  221 . The reflector structure  221  is secured to the box  220  by clips, fasteners or another attachment mechanism. The box  220  is, likewise, attached to the interior surface of the upper housing  210  by fasteners or other acceptable attachment mechanisms. 
   The exterior side walls of the housing  210  includes raised base structures  222  that can be integrally molded with the housing  210 , or can be provided as separate pieces that are secured to the housing  210  by fasteners. The raised structures  222  support spring-steel connectors  224  that extend downwardly to an inward curve  226 . The reflector structure  221  includes a pair of opposing mounting bases on each longitudinal end of the fixture that define respective flats  228 ,  230  and  232 , oriented at various angles. Conventional fluorescent lamp bases  240  are mounted on each of these flats. The lamp bases  240  can be secured by a number of different techniques. As shown, they are locked in place by unitary spring-loaded shoulders  242  that engage the side edges of a properly sized recess (i.e. a rectangular through-hole) in each flat  228 ,  230 , and  232 . While not shown, appropriate wiring can be provided between the ballast  212  and the bases  240 , as well as between the ballast  212  and an external source of electric power. The reflector structure  221  extends between opposing mounting bases on the fixture  200  and provides a series of angled facets that reflect the light of each lamp in the appropriate direction. In general, the facets of the reflector structure  221  are designed to direct the projected light of the two side lamps  251  and  255  generally in a sideways direction. The facets direct the light of the bottom lamp  253 , generally in a downward direction. As will be discussed below, the illustrative embodiments of the invention provide structures that more effectively divide the light of three or two lamps than the arrangement of the prior implementation of  FIG. 2 . As also shown, the reflector structure defines a pair of angled projections or pinnacles  250  that extend the full length of the base in the elongated/longitudinal direction (elongated axis  202 ). These pinnacles  250 , along with a reflective light or specula surface finish on the reflector structure  221  allows for reflection of light in a plurality of direction. However, in general, most light in this example is directed downwardly because at least fifty percent of each lamp&#39;s overall diameter facing directly down (vertical arrow  260 ). 
   Note, as used herein, directional terms, such as “top”, “bottom”, “upper”, “lower”, “sideward/sideways”, “vertical”, and “horizontal” should be consider as relative conventions, and not to limit the mounting orientation or structure of any described fixture. 
   To seal the light fixture  200  against encroachment by moisture, debris, pollutants and other environmental hazards, the clips  224 , and their rounded-over end segments  226  engage a lip  270  formed along each side of a transparent or translucent light cover  272 . The light cover  272  can be faceted or frosted to allow a more-diffuse transmission of light from the lamps  251 ,  253 ,  255 , or it can be relatively clear. It is constructed from glass, durable polymer or another material that allows transmission of light therethrough. When engaged as shown, the spring clips  224  bias the lip  270  against an elastomeric gasket  280  that is seated between the lip  270  and a recess  282  in the housing  210 . The gasket  270  maintains a moisture-tight seal between the housing  210  and the transparent/translucent cover  272 . In this manner, the fixture  200  of  FIG. 2  is weatherproof, making it appropriate for indoor parking garages and other applications in which are exposed to moisture, exhaust, salt, thrown-objects and other hazards. 
   As also discussed above, a disadvantage of this fixture  200  is that at least fifty percent of the cylindrical surface of each fluorescent lamp  251 ,  253 ,  255  is directed vertically downward. The underlying reflector structure  221  attempts reflect the remaining light, but the general direction of light is still essentially downward for each lamp. In low-ceiling applications, such as parking garages, it is desirable to spread light in a more horizontal/lateral/sideward fashion so that a single fixture can cover a larger area. This reduces the number of fixtures required, maximizes their individual efficiency, and therefore, reduces operating costs. 
   Accordingly, a three-lamp fixture  300  according to an illustrative embodiment is shown in  FIG. 3 . In this embodiment, the housing  310  is essentially similar to that (housing  210 ) of the fixture  200  described above. It includes a ballast  312 , spring clip supports  322  and associated spring clips  324 . The spring clips  324  curve inwardly at lower curved end segments  326  to secure a transparent or translucent light cover  330 . The cover can be clear, frosted or textured (so as to diffuse the light) as appropriate to the lighting application. The cover  330  includes a lip  332  that surrounds its perimeter. The lip  332  secures against an elastomeric gasket  334 , which itself, resides within a base  336  formed on the bottom lip of the housing  310 . 
   With further reference to  FIGS. 5 and 6 , the structure of the fixture  300  is shown and described in further detail. In general, the illustrative fixture  300  has an overall width WF of approximately 6 to 7 inches and an elongated length LF of approximately 48-49 inches and an overall housing height HF of between approximately 3 and 5 inches. These dimensions are highly variable. Notably, the fixture&#39;s lamp ballast  312  is encased within an internal box structure  340  that can be constructed from sheet metal or another acceptable material. The box structure  340  is attached to the inner surface of the housing  310  using fasteners or any other acceptable fastening technique. The bottom edge  342  of the box structure (or simply “box”)  340  supports a pair of longitudinally opposed lamp supports  510  ( FIG. 5 ), each defining a central base  350  that extends further downwardly, and divides the fixture&#39;s lower end into three separate sections. Each support  510  is attached to an opposing end of the box  340 , along the bottom edge  342 . The separate lamp sections defined by each central base  350  provide support for reflectors that extend along the entire longitudinal direction, taken along elongated axis  359 . The central base  350  includes a bottommost flattened section  352 , which extends along a plane perpendicular to the vertical direction (arrow  354  and line  357 ). A pair of angled side walls  356  of each central base  350  extend upwardly from each opposing widthwise corner of the bottommost section  352 . The angled sidewalls extend at an angle A 1  from the vertical of between approximately 5 degrees and 20 degrees. The illustrative angle A 1  is 15 degrees. The central base  350  supports each of three lamp bases  240  which connect to, and support, an end of a respective fluorescent lamp of an appropriate size, shape and wattage. In one embodiment, 48-inch-long, bi-pin-connector, T-8 lamps, with a tube diameter of 1 inch are employed in the various embodiments described herein. Other dimensions of the depicted cross-sections herein can be scaled to the diameter of the lamp. A variety of other lamp sizes, shapes, wattage ratings and connector configurations can be employed in alternate embodiments. Likewise, in alternate embodiments, fluorescent lamps can be substituted with another type of lamp having low power-consumption and high output characteristics. For example, elongated strips of LED&#39;s, arranged in arrays can be used with an appropriate power source/transformer (LED driver). This power source/driver can be located directly on the LED array circuit board, or positioned where the ballast  312  is located. Thus, as used herein the term “lamp” and/or “light source” should be taken broadly to include other types of energy-efficient lighting systems. 
   The central base  350  on each of the opposing lamp supports  510  carries three reflectors  360 ,  390  and  364 . Each reflector is constructed from a relatively thin. Light weight material such as metalized aluminum, plastic or another suitable material. The reflector can be provided with a mirrored/specular finish, a gloss or matte-white-painted finish, or any other surface finish that allows a substantial quantity of light to be reflected therefrom. As shown, the reflectors  360  and  364 , which extend somewhat horizontally/sideward from opposing widthwise sides of the central base  350 , allow the sides of the lighted area to be effectively filled with directed light. In this description, “widthwise” is taken in a direction perpendicular to the elongated vertical  354  (perpendicular axis  520  in  FIG. 4 ) The/upper top flat  370  of each reflector is generally perpendicular to the vertical  354 . The bottom/lower flat  372  of each reflector  360 ,  364  extends downwardly at an angle A 2  ( 374 ) (relative to the vertical  354 ) of approximately 110 to 130 degrees and an illustrative angle of 120 degrees. The base flat  376 , which his positioned behind each respective lamp base  240  is flush against the angled sidewall  356  of the central base  350 . Thus, the base flat  376  also extends at the approximate angle A 1  from the vertical  354 . Between the upper and lower flats  370 ,  372  and the central flat  376  on each reflector  360 ,  364 , there are a pair of intermediate flats  378  and  380 . Each intermediate flat  378 ,  380  has a respective length LF 1 , LF 2  between but approximately one-quarter inch and three-quarter inch. The intermediate flats  378 ,  380  define angles (with respect to the vertical  354 ) that are between that of the base flat (angle A 1 ) and the adjacent flats  370 ,  372  (90 degrees and angle A 2 ). Thus, the flats  378  and  380  form an incremental bend in the over all cross section of the reflectors  360  and  364 . The precise angle of each intermediate flat  378 ,  380  with respect to vertical  354  is highly variable. In general, they prevent the defining of a sharp between the central flat  376  and the adjacent upper and lower flats  370 ,  372 . In this manner the reflected light from lamps  351 ,  355  is spread more-continuously. The side reflectors  360 ,  364  attach to each opposing central base  350  using fasteners (e.g. fastener  511  in  FIG. 5 ). 
   Note that the number of flats employ to form each reflectors highly variable. In this embodiment, a pair of intermediate flats  378  and  380  is efficient to define a somewhat continuous transition between upper and lower flats  370 ,  372  and the central flat  376 . In alternate embodiments, the intermediate flats  378 ,  380  can be substituted by a curvilinear cross sections or another acceptable shape that connects the intermediate flat  376  to the upper and lower flats  370 ,  372 . 
   The lower lamp is surrounded by a widely-angled lower reflector  390 . This lower reflector  390  also extends the full elongated length (axis  359 ) includes a central flat  392  and a pair of opposing angled flats  394 . Each angled flat  394  defines an angle A 3  with respect to the vertical  354 . The angle A 3  is between approximately fifty and 70 degrees in this embodiment. The illustrative angle is approximately sixty degrees. 
   The lower reflector  390  affords a relatively widespread reflection of light from the lower lamp  353 . The reflectors  360 ,  364  and  390  in this embodiment are imperforated, fully reflective (i.e. non-translucent) units through which approximately zero light is transmitted. Thus, they reflect approximately one hundred percent of the light to which they are exposed. Moreover, the lower reflector flats  394  (and confronting side reflector flats  372 ) extend at least one to two inches in the widthwise direction beyond the widthwise ends  397  of the lamps  351 ,  355 . Each reflector, thus, provides a wide range of coverage for its respective lamp, resulting in three substantially separated reflective compartments along the elongated length of the fixture  300 . The fixture  300  thereby defines three discrete and controlled lamp regions (one below and two on opposing sides) that each fill their respective lighting area with an appropriate amount of light. In particular, a greater amount of light from the side lamps  351  and  355  is transmitted sideward, than by the arrangement of  FIG. 2  to better fill the lit space. 
   With particular reference to  FIGS. 4 and 5 , the housing  310  is adapted to be mounted in a manner similar to any conventional HID-type fixture. In this embodiment, a pair of reinforced brackets  450  are attached to the top surface of the housing fasteners, rivets or another acceptable mechanism (in this embodiment, bolts  454 ) that pass through the upper surface of the housing  310 , and thereby allow the flat, generally horizontal bases  530  of the brackets  450  to be sealed against the housing. Each bracket  450  includes an elongated slot  456  on its top surface plate  460  for receiving a threaded hanger rod, or other fastening system attached to the building&#39;s ceiling or other fixture mounting surface. A pair of folded-up wings  458  is provided along the top surface  460  of each bracket  450 . These wings can be any size and shape. In general, they help to reinforce the bracket  450 , and prevent bending of its top surface  460  under load. The bracket  450  can be constructed from relatively thin-gauge sheet steel, or similar metal (or another material as appropriate). In general the bracket  450  of this invention, with its elongated slot  456 , uniquely allows the fixture to be supported, at least in part by preexisting fixture support posts/rods. The slot also allows for variability in the fitment of the fixture with respect to new-construction, newly installed and preexisting support rods/posts so that the brackets  450  can be uniformly placed on the housings of fixtures. Alternatively, brackets can be supplied separately and custom-positioned on a housing, for example, a drill and self-tapping screws or through nuts/bolts. 
   The photometric performance of the light fixture  300  is shown by the polar-coordinate graph  600  of  FIG. 6 . The lines of the graph  600  plots sensed candela strength (in lumens) versus viewing angle between a directly downward or vertical orientation (0-degrees), a directly sideward or horizontal orientation (90 degrees), and directly upward orientation (180 degrees above the fixture). The overall candela strength per lamp is approximately 2900 lumens. As shown, five separate graph traces are depicted, and defined within the key  602 . The traces represent viewing positions with respect to the fixture that range between a position approximately aligned with the elongated axis  359  (0 degrees, or aside one of the narrow ends of the fixture  300 ) and a position perpendicular to the elongated axis (90 degrees along axis  520 —or aside the long exposed sides of the fixture). Thus, the trace  610  represents the sensed candela level at 0 degrees, the trace  620  is at 22.5 degrees, the trace  630  is at 45 degrees, the trace  640  is at 67.5 degrees, and the trace  650  is at 90 degrees (directly sideward). The candela output ranges from approximately 0 lumens (sensed for all traces at 180 degrees, where the sensor is directly over the opaque top of the housing  310 ), to a maximum of approximately 1410 lumens for the 90-degree trace  650  at 45 degrees about the elongated axis  359 . In general, the light output is strongest at all viewing angles when viewed directly aside the fixture, and weakest when viewed along the end of the fixture. Within each trace, the light output remains relatively strong and uniform and from slightly above 90 degrees (up to about 120 degrees) to directly below the fixture (0 degrees). Thus output is efficiently spread out in all directions from the lamp with the greatest output generally between about 70 degrees and 25 degrees—and is as much as 300 lumens greater than sensed at other viewing angles. This ensures that much of the light is directed sideward, to more completely fill the lighted space. 
   Before describing a further illustrative embodiment of the invention below reference is made again to  FIG. 5  in which a decorative or trademark-displaying device  560  is applied to the bottom side of the transparent/translucent cover  330 . A unitary stem  564  of the device  560  is inserted into an aperture  562  on the bottom side of the cover  330 . It is held in place by a snap-fit and/or adhesives. Its exposed portion can define any acceptable outline shape, such a circle. The device  560  can be translucent, and provided in one or more distinctive colors, at least some of which are dissimilar from the surrounding cover&#39;s shade or tone. In this manner, the cover  330  projects a distinctive, colored glowing device along its surface that attracts the viewer to the cover, but has a negligible effect on overall light transmission from the fixture. In various embodiments, such a novel device can be applied along any location on any of the fixture covers described herein. 
     FIGS. 7-9  detail a two-lamp fixture  700  according to an illustrative embodiment invention. In this embodiment, a housing  710  similar in size, shape and construction/materials to the housings  210 ,  310  described above, is provided. In general, the fixture housing  710  also includes bases  722  for spring clips  724  that include rounded-over end segments  726  for engaging a lip  732  formed on the perimeter of a transparent/translucent cover  730 , also similar to those described above. The ballast  712  is again mounted within the upper portion of the housing, within a sheet metal (or other material) box structure  740 . 
   The bottom edge  742  of the box structure  740  supports a pair of longitudinally opposed lamp supports  711  ( FIG. 9 ), each defining a central base  750  that extends further downwardly, and divides the fixture&#39;s lower end into three separate sections, two of which (the opposing sideward sections contain lamp holders  240 . In particular each support  711  is attached to an opposing end of the box  740 , along the bottom edge  742 . The separate lamp sections defined by each central base  750  provide support for reflectors that extend along the entire longitudinal direction, taken along elongated axis  709 . In this embodiment, the lamp holders  240  are mounted along a steeply downwardly angled base sections on each side that extend at an angle A 12  between approximately 5 degrees and 20 degrees. The illustrative angle A 12  is approximately 15 degrees in this embodiment. 
   The central base  750  supports a pair of side reflectors  760 ,  764  having upper flats  770  that are essentially perpendicular with respect to the vertical (arrow  754 ). The side reflectors  760 ,  764  each define a pair of upper intermediate flats  780  and  778  that join to a central flat  776 . The central flat  776  is flush against the side walls of the central base  750 . As in the above-described fixture  300 , the side reflectors  760  and  764  direct the light of their respective lamps  751 ,  755  into a somewhat downward, but generally sideways-reflected orientation. The bottom side  752  of the central base  750  is relatively flat. The bottom edges  772  of each side reflector  760 ,  764  wrap inwardly to surround the bottom section. A central divider reflector  780  extends downwardly from the flat central base section  752 . More particularly, a pair of downwardly extending reflector walls  782  each define a cross section extending from spaced-apart locations at their adjacent lower reflector portions  794 , adjacent to edges of the below-described slots  796 , to a bottommost convergence peak/line  797 . In this divider reflector  780 , each wall  782  defines an opposing angle A 22  of between approximately 24 and 34 degrees with respect to the vertical  754 . The illustrative angle A 22  is approximately 29 degrees. The bottom edges  772  of the side reflectors and central reflector  780  merge with a wide-angle lower reflector  790 . The lower reflector  790  includes opposing angled flats  794 . These flats  794  extend in opposing, generally widthwise directions at an angle A 23  with respect to vertical  754 . In this embodiment, the angle A 23  is between approximately fifty degrees and seventy degrees with an illustrative angle of sixty degrees. The combination of slots  796  and the central reflector  780  advantageously generate the image of a center light source from the projected light of the two side light sources  751 ,  755 . Thus, the overall appearance of the fixture  700  is balanced, creating the illusion of a three-lamp fixture with a “virtual” center light source. 
   Notably, the lower reflector  790  includes, adjacent to the central reflector  780 , a series of spaced-apart elongated slots  796 . The slots are better viewed, extending along the elongate/longitudinal axis  709 , in  FIGS. 8 and 9 . The slots  796  each have a widthwise length LS ( FIG. 7 ) of between approximately ½ inch and one inch. They have an elongated length ELS ( FIG. 8 ) of between approximately two inches and four inches. They are separated by smaller, unbroken segments  810  ( FIG. 8 ) along the elongated length having a length ELC between approximately ½ inch and two inches. The dimensions of the slots and the connecting segments are highly variable in alternate embodiments. In general, it is desirable to make the slots extend as long as possible along the length of the reflector  790 , without compromising the strength of the reflector by overly-shortening the connecting segments. In other words, the length of the connecting segments  810  should be minimized, while maintaining the structural integrity of the reflector assembly. In alternate embodiments, the term “slot” should be taken broadly to include a continuous opening in the reflector through which light from the sides can pass in predetermined quantities into the lower section. In such cases, the reflector ( 790 ) would be maintained in its position by alternate bracket mechanisms. 
   In this embodiment, the upper surface of each flat  794  also acts as the lower reflector flat for each side reflector  760 ,  764 . Thus, the amount of material used in the reflectors can be further minimized, while not compromising the integrity of the overall structure. Any or all reflectors can be coated on a lamp-facing side with an appropriate reflective and/or specular finish. The depicted reflectors  760 ,  764 ,  780  and  790  can be variably attached to the central supports  750 ,  752  by fasteners, or another acceptable attachment mechanism. In accordance with this embodiment, the lamps  751  and  755 , which are standard 48-inch, bi-pin, T-8 fluorescent lamps with 2900-lumen average output, provide ample side-lighting through their encapsulation by the side reflectors  760  and  764 . As discussed above, the upper flats  770  and lower flats  794  extend at least one to two inches in a widthwise direction beyond the far ends  797  of the lamps, and nearly contact the inside surface of the cover  730 . By locating the reflector slots  796 , adjacent to the central reflector  780 , combined with the angles of the central reflector, light transmitted through the slots  796  from the lamps  751 ,  755  is projected downwardly in sufficient quantity to light the area directly below, and slightly aside the fixture  700 . Thus, the fixture  700  provides desired side-lighting along with a sufficient quantity of direct-downward lighting using only two light sources, located within the area of each respective side reflector  760 ,  764 . 
   The fixture  700  can be supplied with mounting brackets  450  similar to those described above with reference to the fixture  300  (see  FIGS. 8 and 9 ). Any of the fixtures described herein can be provided with alternate brackets as appropriate to the particular mounting application. 
   The candela performance of the fixture  700  is shown in the polar-coordinate graph  1000  of  FIG. 10 . Overall, the maximum light output (in lumens) is reduced from a maximum of approximately 1400 lumens to a maximum of approximately 900 lumens relative to the three-lamp fixture  300  described in the graph  600  of  FIG. 6 . In this graph  1000 , the traces are listed in the key  1002 . Similar to the graph  600  in  FIG. 6 , the traces represent the sensed light output from directly beneath (0 degrees), to directly aside (90 degrees), to directly above (180 degrees) the fixture  700 . Each trace discretely represents a viewing position. Trace  1010  is directly toward the fixture&#39;s narrow end, in line with the axis  709  (0 degrees). Trace  1050  is directly aside the elongated side of the fixture  700  (90 degrees). Trace  1030  is at a 45-degree angle. Trace  1020  is at a 22.5-degree angle and trace  1040  is at a 67.5-degree angle. As shown, relatively sideward viewing produces sensed light output that remains in the 700 to 900-lumen range from about 110 degrees (a position above the top reflector flats (770) plane), to about 30 degrees. Output for all traces falls rapidly to zero as the angle approaches 180 degrees, directly above the housing. Output for all traces remains relatively high at over 500 lumens as the angle approaches zero degrees (directly below the fixture). Thus, the two-lamp fixture exhibits a good quantity of side-lighting performance (above approximately 30-45 degrees to the vertical), where some extra output is needed to completely fill the space, while maintaining a strong, but controlled light output in the “generally downward” direction (below approximately 30-45 degrees to the vertical). To vary the amount of directly downward light output, the width of the slots can be increased until the desired balance is achieved between downward and side lighting. Additionally, where side, lighting in a plurality of directions is desired, mounting of fixtures in the space so that some face at 90 degrees with respect to the others (e.g. mounting the fixtures so that the elongated axes  359 ,  709  on some fixtures perpendicular to the axes  359 ,  709  of others) will more effectively light the entire area. 
   Shown more graphically,  FIG. 11  details the lighting pattern of the illustrative two-lamp fixture  700 . In general, a significant portion of light (thicker solid arrows  1110 ) directed in a sideways manner. A reduced, but still desirable quantity of downward light (dashed arrows  1120 ) is transmitted over a predetermined range of angles with respect to the vertical  754 . 
   By way of comparison, the candela distribution in lumens for the prior implementation of a three-lamp fixture  200  as shown in  FIG. 2  is shown in the polar-coordinate graph  1200  in  FIG. 12 . As discussed above, this prior implementation provides no encapsulation of the side lamps  251  and  255  by separate side reflectors. Thus a large quantity of light is projected downwardly. This creates the undesirable spotting of light below the fixture as revealed by the graph  1200 . Again, the traces,  1210 ,  1220 ,  1230 ,  1240 , and  1250 , representing viewing angles from 0 (viewed on end) to 90 degrees (viewed directly aside), are defined in the graph key  1202 . All traces show significant output, in the generally downward direction, rising continuously from approximately 1000 lumens at 65 degrees to over 1900 lumens at 5 degrees. Output falls rapidly 65 degrees. Hence very little side output or upwardly angled output is provided by the fixture  200 . Unlike novel fixtures  300 ,  700 , the prior fixture  200  does not provide the needed side lighting for a low-ceiling space, such as a parking garage. 
   The foregoing has been a detailed description of illustrative embodiments of the invention. Various modifications and additions can be made without departing from the spirit and scope if this invention. Each of the various embodiments described above may be combined with other described embodiments in order to provide multiple features. Furthermore, while the foregoing describes a number of separate embodiments of the apparatus and method of the present invention, what has been described herein is merely illustrative of the application of the principles of the present invention. For example, For example, the size and shape of the housing can be varied to accommodate different shapes and sized of elongated lighting sources. As described, the light source itself (also referred to as a lamp) can be highly variable. Such light sources can project outwardly, or at a variety of angles (for example, an LED array formed in a semi-ellipsoid or semi-cylinder). As such the depiction of fluorescent lamps herein should be interpreted broadly to include other types of lighting arrangements, such as an LED array (e.g. a type of solid state lighting array). Moreover, while a single large-diameter tubular fluorescent lamp is employed in each mounting location, it expressly contemplated that a single lamp can be substituted with a plurality of discrete smaller diameter lamps, or a continuous lamp with two or more legs, having a 180-degree bend on one end. The terms “lamp” and “light source” should be taken broadly to include such multi-leg and multi-lamp configurations, as well. The mechanism by which the transparent/translucent cover is secured to the upper housing can be varied as well. Instead of clips, alternate embodiments can employ (for example) threaded fasteners, sliding components or other mechanisms to sealingly engage the cover with the housing. In addition, the mechanisms by which reflectors and lamp holders are attached to the housing are highly variable. A variety of different bracket systems that secure reflectors and lamp holders to the housing can be employed. In addition, the housing or other structures can be reinforced with further stiffening ribs, brackets, braces or other structures. Moreover, while the novel fixtures provided herein are useful in parking garages and other low-ceiling or low-fixture-mounting-height spaces, it is contemplated that the principles lamp placement and reflector construction/orientation described herein can be employed in a variety of lighting applications, including those in which the fixtures are mounted higher with respect to a ground surface. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.