Patent Abstract:
Luminaires particularly useful for ceiling mounting in either recessed or surface-mounted applications and intended for “washing” light over an adjacent wall, the “wall wash” luminaires of the invention are configured in preferred embodiments for operation with elongated lamping and particularly tubular fluorescent lamping including T5 lamps. The present luminaires are usually provided with elongated and other apertures, certain of which are often referred to as “small” apertures, conformed by shaping of at least one elongated edge thereof to minimize alternating relatively light and dark striations on adjacent walls. Luminaires according to the invention having relatively narrow elongated apertures function to transition abrupt changes in luminance imaged onto an adjacent wall by alteration of aperture opening, such as by an extension of structure from one elongated edge of such an aperture, thereby to produce a more smooth vertical light distribution over the wall.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to luminaires and particularly to luminaires intended for ceiling mounting in either recessed or surface-mounted applications for “washing” an adjacent wall with light as well as other applications. 
     2. Description of the Prior Art 
     Luminaires intended for directing light onto vertical surfaces such as walls often fail to provide a visually smooth distribution of light on the vertical surface intended to be illuminated. Such luminaires, generally referred to as “wall wash” luminaires, are typically mounted in a ceiling in proximity to the vertical surface that is to be illuminated. In providing the goal of a smooth distribution of light on a vertical surface of an adjacent wall, it is intended that visible striations or noticeably defined changes in brightness on the vertical surface be minimized or eliminated. Since the accomplishment of a smooth illumination gradient on such a vertical surface is a goal rather than a realistic expectation, it is at least intended in the art to provide an illuminance on said surface having gradations that are sufficiently gradual so as to reduce the affects of variations in brightness such as can take the form of bright or dark lines, bands, scallops and the like such as can be visually distracting. Wall wash luminaires universally employ reflective surfaces configured not only to direct light from lamping onto an adjacent vertical surface but also to smooth the light pattern on said surface. A judicious choice of reflective material as is usual in the prior art, typically diffuse or semi-specular in nature, has previously been considered desirable for smoothing of a light pattern on a vertical surface albeit at the cost of efficiency loss when considering the lumens delivered to the vertical surface by lamping of a particular power level. Diffuser lenses have also been used for similar purposes and with similar results including losses. Luminaires configured with “small apertures”, that is, small in the dimension perpendicular to the “longitudinal” dimension of the luminaire, particularly suffer from efficiency losses when reflectors employed in such luminaires are formed of diffuse or semi-specular reflective material. Luminaires with square apertures as well as other shapes can also exhibit such losses. Further, the differences in brightness between the lamping as compared to lamp “images” in the reflected material produce further difficulties in providing the quality of illumination on a vertical surface that is desired in the art when light from the lamp and from the reflector are both incident on the wall. The use of highly reflective and highly specular reflective material in such luminaires increases the efficiency of light directed onto the vertical surface, and thereby illumination levels realized on the vertical surface, and also greatly reduces differences between the brightness of light illuminating the wall directly from lamping as opposed to the brightness of light reflected from reflectors used in such luminaires. However, utilization of highly specular reflective material in such luminaires provides no panacea in intended results due to the fact that the behavior of highly specular materials in optical environments are extremely sensitive to design errors as well as manufacturing and assembly tolerances. Accordingly, the use of highly specular reflective materials as reflectors in small aperture luminaires as well as other luminaires does not necessarily produce the desired visual appearance of illumination washing a vertical surface or wall. 
     Wall wash luminaires mountable in ceilings of varying description have previously been provided in a multitude of configurations including downlighting luminaires having circular apertures such as are disclosed by Ling in U.S. Pat. No. 5,535,110 and Leadford in U.S. Pat. No. 5,800,050. Ng et al, in U.S. Pat. No. 6,350,047, and many others, also provide wall wash luminaires intended to be mounted in recessed applications in ceilings whereby at least a portion of that light generated within the luminaire is directed onto at least portions of a wall adjacent to the location wherein the luminaire is mounted within a ceiling. In luminaires of the kind just noted, lamping typically mounted in a vertical orientation is utilized and is generally not tubular fluorescent lighting of a length generally greater than approximately six to ten inches. Wall Wash luminaires employing elongated tubular fluorescent lamping such as T12, T8 and even T5 lamping presently exist as can be appreciated by reference to U.S. Pat. No. 4,564,888 to Lewin et al which discloses a substantially elongated luminaire configured with an elongated reflector for directing light onto a wall from a substantially elongated and generally rectangular aperture. Crane, in U.S. Pat. No. 5,146,393 also discloses a luminaire intended to wash an adjacent wall with light from a location recessed within a ceiling adjacent to the wall. While the apertures of the Lewin et al and Crane luminaires are not necessarily of the “small aperture” kind, the apertures of the luminaires disclosed in these two patents are rectangular and utilize elongated fluorescent lamping. While lamping-such as T5 lamping can be used in prior wall wash luminaires and even in the rectangular aperture luminaires disclosed in certain of the above-noted patents, it is to be understood that presently available wall wash luminaires have not exhibited performances approaching the goal of a visually smooth distribution of light on a vertical surface in linear wall wash configurations in luminaires using highly specular materials unless provided with a lens. It is therefore a particular intent of the present luminaire configurations to produce an acceptably smooth distribution of light on a vertical surface from a wall wash luminaire, particularly a small aperture luminaire, as can be mounted in recessed or surface-mounted applications in a ceiling at a distance from the vertical surface to be illuminated such that the cross-sectional aperture of the luminaire is small relative to the distance of the luminaire from a vertical surface that is to be illuminated. Luminaires configured according to the invention are configured to utilize highly reflective and highly specular reflective materials as reflector elements and are further configured to provide visually smooth lighting distributions on adjacent vertical surfaces such that striations and/or alternating relatively light and dark areas are reduced or visually eliminated, thereby providing a substantial advance in the art. 
     SUMMARY OF THE INVENTION 
     The invention provides in several embodiments luminaires adapted for efficient utilization of linear illumination sources such as tubular fluorescent lamps of differing type and dimension. The invention particularly intends improvement of luminaires of a kind typically referred to as “small aperture” luminaires including such luminaires intended for the “washing” of a wall or vertical surface with light generated from a location on or near a ceiling, such location being essentially adjacent to a vertical surface which is to be washed with light. The luminaires of the invention, including those luminaires often referred to as small aperture luminaires, are typically mounted in a recessed mode in a ceiling or surface-mounted to a ceiling, such ceilings typically being suspended or conventional drywall, plaster or the like. The luminaires of the invention are intended to provide a visually smooth distribution of light on a surface, particularly a vertical surface such as an adjacent wall when such luminaires are ceiling mounted. The invention further contemplates luminaires other than ceiling-mounted wall wash luminaires such as luminaires intended to direct light onto horizontal surfaces including pathways and the like. In such situations, luminaires such as bollards intended to illuminate areas adjacent such bollards can be configured to direct a smooth light distribution onto surfaces used by pedestrians as one example. The invention therefore finds utility in the general field of area lighting, pathway lighting, wall sconce uplighting, etc. 
     The invention finds particular utility in wall wash and other applications wherein linear illumination sources such as elongated tubular fluorescent lamps are employed, the invention being useful with illumination sources including T5 lamping. In luminaires configured according to the invention which utilize such lamping, the invention applies in certain embodiments to a luminaire genre such as is commonly referred to as a “small aperture” luminaire. A small aperture luminaire commonly employs elongated tubular fluorescent lamping, the aperture of such a luminaire being essentially as long as the lamping that is employed. As such, the apertures of small aperture luminaire is essentially elongated and of a length substantially equal to the length of the lamp or lamps employed for generation of light. It is therefore seen that such an aperture would typically be configured essentially as a rectangle although other shapes could be employed. In wall washing applications in particular, the essentially rectangular aperture of a luminaire configured according to the invention would have one elongated edge disposed substantially parallel to an adjacent wall which is to be washed with light, the small aperture luminaire being disposed in a ceiling adjacent to the wall or other vertical surface. The luminaire so located is provided with a reflector assembly configured to direct light reflected from lamping over at least portions of the adjacent wall, the reflector portions of the present reflector assembly being preferably formed of highly specular material with the result that lamp light imaged by the reflector assembly is effectively as bright as light from the lamp itself. In order to produce a visually smooth distribution of light on the adjacent wall, that is, a washing of the wall with light without striations or alternating relatively bright and relatively dark horizontally oriented areas, it is necessary according to the invention to configure the elongated edge of the aperture nearmost the adjacent wall in a manner to alter the vertical distance over which light from linear elements of the lamp and reflected lamp images are revealed in order to produce a smooth luminous gradient and to spread out illuminance changes over a relatively large angular zone or vertical distance on the lighted surface. The invention in several embodiments particularly contemplates the provision of structure on the “adjacent” elongated aperture edge that alters aperture geometry to cause a softening of what might otherwise be abrupt illuminance changes imaged onto the wall, thereby producing a smoother vertical distribution of light over the wall. Alteration of aperture geometry can be provided by the forming of the aforesaid adjacent aperture edge in the shape of a wedge in a preferred embodiment, thereby providing an “intrusion” into the aperture. Alternatively, the wedge shape of the adjacent aperture edge can be reversed or inverted to produce a desired result. For similar reasons, such intrusions can be configured by conforming the adjacent aperture edge to have a sawtooth edge, a sinusoidal edge, a gently rounded edge or the like over at least portions of said adjacent aperture edge, it being of greater moment to provide such an intrusion essentially at and/or near the center of said adjacent aperture edge. Apertures so configured according to the invention function particularly well with a reflector assemblies formed of highly specular material, it being possible through practice of the invention to utilize highly specular material in the formation of reflective surfaces without the concerns evident in the prior art which arise as a result of design and manufacturing errors including tolerances that cannot be controlled to a desirable degree in manufacturing and assembly processes. Luminaires configured according to the invention particularly provide wall or area washing capability with a desired visually smooth distribution of light on surfaces that are to be washed with light. 
     Accordingly, it is a primary object of the invention to provide luminaires capable of providing smooth light distributions on adjacent surfaces, such as ceiling-mounted luminaires capable of washing adjacent vertical surfaces with light, and wherein such luminaires are particularly intended to use elongated fluorescent lamping for generation of light thrown onto a surface through an elongated aperture having that lengthwise edge adjacent to the surface to be washed with light configured so as to increase the angular zone over which light from the lamping and light reflected from within the luminaire is revealed, thereby to produce a transition and spread what would otherwise be abrupt changes in luminance over a larger angular zone to reduce or effectively eliminate striations and the like in a pattern of light produced on the surface to be illuminated. 
     It is another object of the invention to provide luminaires such as are commonly referred to as “small aperture” luminaires wherein an elongated edge of such a luminaire is configured to be other than completely linear so as to produce a striation-free and relatively smooth distribution of light on an adjacent surface. 
     It is a further object of the invention to provide luminaires such as are commonly referred to as “small aperture” luminaires and which are intended for illuminating areas adjacent to said luminaires with a generally smooth distribution of light and wherein an elongated edge of such an aperture and adjacent to the area to be illuminated is caused to have at least portions thereof “intrude” into the aperture or alter the shape of the aperture in order to blend illuminance changes that are imaged onto the area and thereby provide a desired light distribution. 
     Further objects and advantages of the invention will become more readily apparent in light of the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a luminaire configured according to the invention and shown mounted in a recessed application in a ceiling seen in phantom only; 
         FIG. 2  is an exploded view of the luminaire of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the luminaire of  FIG. 1 ; 
         FIG. 4  is a diagrammatical view illustrating the shape of the aperture of the luminaire of  FIG. 1 ; 
         FIG. 5  is a diagrammatical view of another embodiment of an aperture configured according to the invention; 
         FIG. 6  is a diagrammatical view of yet another embodiment of an aperture configured according to the invention; 
         FIG. 7  is a diagrammatical view of a further embodiment of an aperture configured according to the invention; 
         FIG. 8  is a diagrammatical view of a still further embodiment of an aperture configured according to the invention; and, 
         FIG. 9  is a diagrammatical view of another aperture configured according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings and particularly to  FIGS. 1 through 4 , a luminaire configured according to a preferred embodiment of the invention is seen at  10  to comprise a housing  12  of substantially rectangular configuration, the housing  12  being formed of sheet metal or the like such as is conventional in the art. The housing  12  has a lamp  14  mounted therein in a conventional manner in juxtaposition to a reflector assembly  16  having upper and lower reflectors  18  and  20  mounted together by means of a hinge  22 . It is to be understood that the reflectors  18  and  20  can be formed as a single reflector. The housing  12  is seen to contain a ballast  24  within a compartment thereof formed generally by upper portions of the housing  12  above the upper reflector  18 . The reflector assembly  16  is hinged by means of the hinge  22  to facilitate access to the ballast  24  and other structure associated with said ballast. The hinge  22  further permits adjustment of the relative positions of the upper reflector  18  and of the lower reflector  20  in order to provide the ability to alter the distribution of light on an adjacent wall (not shown) which is to be washed with light generated by the lamp  14 . The reflective surfaces of the reflectors  18  and  20  can be shaped in the configuration of a parabola or in any other desirable configuration. 
     The luminaire  12  as particularly seen in  FIG. 1  is mounted in a recessed location within a ceiling  11  shown in phantom and is positioned in adjacent relation to a wall (not shown) which is to be washed with light as is known in the art. The luminaire  10  may be mounted within suspended ceilings or other ceiling structures such as can be formed with plasterboard and the like. As is seen in  FIG. 3 , the luminaire  10  is mounted in a suspended ceiling  13  as will be readily understood by those of skill in the art. It is to be understood that surface-mounted and pendant-mounted luminaires can also be configured according to the teachings of the invention. 
     The lamp  14  is mounted within the housing  12  in a conventional manner by means of sockets  26 , the sockets  26  being mounted to brackets  28  disposed at either end of the housing  12 , the housing  12  being essentially finished by the mounting of end plates  30  at each end thereof. Access to the interior of the housing  12  from a location at the top of the luminaire  10  is provided in a conventional manner by means of an access plate  32 , the access plate  32  having knockouts  34  to permit electrical wiring (not shown) to extend from a power source (not shown) into the interior of the housing  12  as is conventional in the art. 
     The luminaire  10  has an aperture  36  formed essentially over a lower face of the housing  12 , the aperture  36  being that “open” portion of the housing  12  through which light passes directly from the lamp  14  from the luminaire  10  and through which light reflected from the reflector assembly  16  inter alia passes to wash an adjacent wall (not shown), the direction of the wall as seen in  FIG. 3  being shown by the arrow  38 . The aperture  36  is defined by a forward edge  40  which essentially comprises an edge of a flange  42  which extends along a longitudinally disposed edge of the housing  12  essentially parallel to a wall that is to be washed with light. The forward edge  40  is essentially parallel to the lamp  14 , the lamp  14  preferably being an elongated fluorescent lamp which can take the form of conventional lamping such as T12, T8, T5 or similar lamping. Other lamping, particularly lamping of elongated configuration, can be utilized to advantage according to the teachings of the present invention. 
     An opposite longitudinal edge of the aperture  36  is defined by the terminus  44  of the lower reflector  20 , which terminus  44  can be configured to extend outwardly of the housing  12  as is best seen in  FIG. 3 . The aperture  36  is further defined by oppositely disposed side edges  46  which are edges of the respective end plates  30 . In  FIG. 3 , one of the edges  46  is shown by way of a dotted line in order to facilitate a more understandable illustration of the invention. 
     Considering  FIG. 4  in addition to  FIGS. 1 and 3 , it can be seen that the aperture  36  is substantially rectangular in conformation, the side edges  46  and that longitudinal edge provided by the terminus  44  of the lower reflector  20  defining three sides of a rectangular opening that is the aperture  36 . As can be seen in  FIG. 1  but best illustrated in  FIG. 4 , the forward edge  40  defining the remaining longitudinally-oriented side of the aperture  36  is seen to be formed in the shape of a wedge  48  which tapers from the side edges  46  to a maximum extent into the aperture  36  substantially centrally of the forward edge  40 . It is to be understood that  FIG. 4  is not shown to scale, the length of the aperture  36  being reduced by approximately one-half in relation to the length of the side edges  46  in order to emphasize the shape of the wedge  48 . In essence, the wedge  48  acts as a desirable “intrusion” into the aperture  36  and thereby shapes the aperture  36  in order to cause light directed onto an adjacent wall to be smoothly distributed and without “striations” or alternating relatively light and dark lines as is common with conventional wall wash luminaires. It is therefore a primary teaching of the invention to provide structure along a forward edge of an aperture of any one of the luminaires disclosed herein so that changes in luminance from tamping such as the lamp  14  inter alia are delayed to thereby produce a smooth distribution over a surface that is to be washed with light. Essentially, the intrusion provided by the wedge  48  into the aperture  36  as seen in  FIGS. 1 through 4  acts to increase the angular zone over which light from the lamp  14  and light imaged by the reflector assembly  16  are revealed to the wall, thereby to produce a transition and to blend out otherwise abrupt changes of luminance over a larger angular zone than would occur in the event that the forward edge  40  simply comprised a straight line edge as is conventional in the art. It is to be understood that variations in luminance can occur for a variety of reasons, among these reasons being differences in glass wall thicknesses of tamping such as the lamp  14 . Further, light reflected from a reflector, such as the reflector assembly  16  within luminaires such as are considered herein can be substantially less luminous than that light emanating directly from lamping such as the lamp  14  and passing directly through an aperture of conventional configuration. When highly specular material is used to form reflective surfaces within a luminaire of the kind referred to herein, it is even possible that reflected images can be of greater luminosity due to re-radiation of lighting flux. In such situations, design and manufacturing errors due to tolerances and the like can provide additional difficulties in controlling light directed onto a wall or other surface with desirably smooth distributions. It is to be appreciated that striations and the like are caused in applications referred to herein by the use of highly specular material in reflector formation. Abrupt changes in luminance are commonly encountered with linear sources of light and linear reflectors as are commonly used in luminaires of the kind considered herein, the sensitivity of lighting distribution to such abrupt changes in luminance occurring both from light emanating directly from the lamp and passing through an aperture and from lamp image reflected from a reflector within such a luminaire. As can thus be understood, any sudden gradation or sudden changes in the rate of gradation of light within such an aperture whether brighter or darker results in corresponding bright and dark stripes on a wall or other surface that is to be washed with light from such luminaires, these stripes being typically referred to as “striations” as referred to above. In such situations, an aperture opening formed solely of straight lines is susceptible to a less than smooth light distribution since these abrupt changes of luminance appear along the entire length of an aperture so configured at exactly the same vertical position on the lighted surface. The provision of the wedge  48  in the aperture  36  as described above results in a smoother distribution over a surface that is to be illuminated. 
     Referring further to  FIGS. 1 through 3  in particular, a trim  50  can be disposed interiorly of the housing  12  and mounted by brackets  52  for decorative purposes and also for maintaining light generated by the lamp  14  within an optical chamber defined within the luminaire  10  in association with the reflector assembly  16 . That portion of the lower reflector  20  extending outwardly of the housing  12  as noted hereinabove acts to ensure appropriate direction of light onto a surface that is to be illuminated. The lower reflector  20  can be mounted within the housing  12  by means of integral flanges  54  and  56  as is conventional in the art. The reflectors  18  and  20  are preferably formed with highly specular reflective surfaces  58  and  60  respectively, the reflectors  18  and  20  preferably being aluminum extrusions with vacuum metallized finishes comprising the surfaces  58 ,  60 , the surfaces  58  and  60  being of high specularity and high reflectance. It is to be understood that the luminaires disclosed herein are less susceptible to design and manufacturing errors such as are commonly encountered in the use of highly specular material as reflective surfaces and wherein lens structures are not provided to cover apertures. Prior luminaires of the kind referred to herein typically suffer from reduced lighting efficiency by virtue of the need to utilize diffuse or semi-specular reflective surfaces in reflector structure corresponding to the reflectors  18 ,  20  as described herein. Configuration of apertures as described herein therefore permits use of highly specular material as surfaces for reflector structure without the difficulties inherent in the prior art, thereby permitting light generated by lamping to be more efficiently utilized. 
     Referring again to  FIG. 4 , it is to be seen that an aperture such as the aperture  36  shown therein would typically have dimensions of approximately three inches along the side edges  46  and would be approximately forty-eight inches in lengthwise dimensions. It is to be appreciated that the dimensions of an aperture so configured can differ from those indicated with, for example, lengthwise dimensions being on the order of twenty-four inches with side edges such as the side edges  46  being three inches. Such dimensions accommodate commonly available lengths of tubular fluorescent lamping whether that lamping comprises single lamping or multiple lamps in an array with longitudinal axes being linearly arranged. 
     Further embodiments of the invention are provided respectively in  FIGS. 5 through 10  as being exemplary of suitable configurations of apertures that can provide the functions and advantages noted herein. Referring first to  FIG. 5 , it can be seen that a forward edge  62  of an aperture  64  can be formed essentially as the inverse of the wedge  48  of the aperture  36 . The configuration of  FIG. 5  to produce the optical transition referred to hereinabove and therefore is intended to fall within the definition of the term “intrusion” as used herein since the edge  62  “intrudes” on side portions of the aperture  64 . 
     Referring now to  FIG. 6 , a forward edge  66  of an aperture  68  configured according to a further embodiment of the invention is seen to take the form of a plurality of teeth  70 , such as in a sawtooth pattern, with the teeth  70  providing intrusions into the aperture  68  to provide the performance intended according to the invention. The teeth  70  can take the form of triangles of differing type and dimensions. 
     Referring now to  FIG. 7 , a forward edge  72  of an aperture  74  is seen to be formed as a substantially sinusoidal curve  76  with portions of the curve  76  acting as intrusions into the aperture  74 . It is to be understood that the curve  76  could take other than a sinusoidal form. 
     Referring now to  FIG. 8 , a forward edge  78  of an aperture  80  is seen to be formed arcuately at  82 , the edge  78  extending into the aperture  80  to provide the advantages herein described. The inverse shape of the edge  78  also functions to produce the performance described herein. 
     Now considering  FIG. 9 , it is to be understood that an intrusion into an aperture similar to the aperture  36  shown in  FIG. 4  is caused to occur essentially at central portions of an aperture, a forward edge  84  of an aperture  86  as seen in  FIG. 9  being formed along central portions thereof as a wedge  88 , the wedge  88  extending from portions of the edge  84  near central portions thereof rather than tapering from ends thereof as occurs with the wedge  48  of the forward edge  40  shown in  FIGS. 1 through 4 . Intrusions into apertures of luminaires as contemplated by the invention can thus be seen to be most efficiently provided along centrally disposed portions of forward edges of said apertures whether such intrusions take the form of wedges, teeth, arcuate elements or the like. The inverse shape of the edge  84  also functions to produce the performance described herein. 
     The intrusions into the apertures of luminaires as configured according to the invention are particularly seen to accommodate variations in luminance in lamping and inconsistencies in reflector structures such as are typically produced by extrusion processes. The improvements so provided are explicitly shown in the several embodiments particularly described. However, it is to be understood that the invention can be configured other than as is explicitly described herein, the scope of the invention being defined by the recitations of the appended claims.

Technology Classification (CPC): 5