Patent Publication Number: US-2023151937-A1

Title: Wall Wash Micro Lighting Fixture

Description:
FIELD OF THE INVENTION 
     The invention pertains to the field of lighting fixtures, and in particular, recessed wall wash lighting fixtures. 
     BACKGROUND OF THE INVENTION 
     A purpose of wall wash light fixture is to illuminate a typically vertical wall with a fixture installed in a typically horizontal ceiling. Often wall wash light fixtures are recessed within a ceiling such that all or a majority of the components of the light fixture are at or above the lower surface of the ceiling. 
     General desired performance characteristics for wall wash light fixtures include: light uniformity on the wall, with maximum to minimum brightness ratio of about 4:1, minimal glare in the directions perpendicular and parallel to the wall, an absences of dark bands across the top of the wall, an absence of “scalloping” on the wall between adjacent, spaced-apart wall wash fixtures, and an absence of color separation on the wall. Known wall wash fixtures do not meet all of these desired characteristics. 
     SUMMARY OF THE INVENTION 
     A purpose of the inventive wall wash micro light fixture is to illuminate a typically vertical wall with a fixture installed in a typically horizontal ceiling. The wall wash light fixture is recessed within a ceiling such that all or a majority of the components of the light fixture are at or above the lower surface of the ceiling. 
     The wall wash micro light fixture of the present design provides the aforementioned desired performance characteristics including light uniformity on the wall, minimal glare, an absence of dark bands at the top of the wall and an absence of light “scalloping.” The present design provides such performance characteristics while having a small form factor and small aperture size. 
     The inventive wall wash recessed light fixture configured according to the present design is operable to emit light through an opening in a ceiling toward a wall adjacent to the opening. The light fixture has a light engine assembly having an aperture, an LED module operable to emit light through the aperture, a lens disposed between the LED module and the aperture, and a reflector disposed between the LED module and the lens. The LED module has an optical axis passing through the aperture and substantially parallel to a longitudinal axis (Z). 
     The lens is operable to narrow a beam of light from the LED module vertically along a height of the adjacent wall, and to expand the beam horizontally along a length of the wall. The lens has a first side forming a plano-convex lens with a convex surface facing the LED module and a second side with a Fresnel lens surface facing the aperture, and the lens is aligned at an oblique angle Θ 1  relative to the optical axis of the LED module. The plano-convex lens has a principal axis aligned at the oblique angle Θ 1  relative to the optical axis, and has a center of curvature offset laterally from the optical axis. The aperture of the light engine assembly is disposed between the center of curvature and the lens. The plano-convex lens is partially cylindrical and has an axis of curvature passing through the center of curvature and perpendicular to the optical axis of the LED module. 
     The Fresnel lens surface is aligned at the oblique angle Θ 1  relative to the optical axis of the LED module and has a plurality of facets having varying slope angles that increase from a first lateral end of the lens (closest to the wall) to an opposite second lateral end. The facets of the Fresnel lens surface are aligned substantially parallel to a width axis (X) of the light engine assembly. 
     The plano-convex lens and the Fresnel lens can comprise an integrated lens or can be a composite lens with separate pieces which are optically coupled. 
     The trim element can include a kicker reflector disposed adjacent the second lateral side of the lens, with the aperture disposed between the kicker reflector and the lens. 
     The wall wash recessed light fixture can include a diffuser operable to diffuse light passing through the lens. A diffuser can be disposed adjacent the Fresnel lens surface and aligned at the oblique angle Θ 1  relative to the optical axis of the LED module. Alternatively or additionally, a diffuser can be disposed in the aperture of the light engine assembly perpendicular to the optical axis. 
     The wall wash recessed light fixture can include an enclosure with an enclosure aperture and adapted to be mounted to a ceiling structure; and the light engine assembly is configured to be mountable to the enclosure through the enclosure aperture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is perspective view, from the bottom, of a first preferred embodiment of the light fixture. 
         FIG.  1 B  is a schematic view of the light fixture of  FIG.  1    as installed. 
         FIG.  1 C  is a close-up perspective view of the light fixture of  FIG.  1    as installed. 
         FIGS.  2  and  3    are cross sectional views, from the side, of a light engine assembly of the light fixture of  FIG.  1   . 
         FIG.  4    is side view of a bottom portion of the light engine assembly of  FIG.  2   . 
         FIG.  5    is a view of the LED of the light engine assembly of  FIG.  2   . 
         FIG.  6    is bottom view of the reflector of the light engine assembly of  FIG.  2   . 
         FIG.  7    is a schematic view, from the side, of the light engine assembly of  FIG.  2   , showing the lens. 
         FIG.  8    is a perspective view of the lens, from the bottom. 
         FIG.  9    is a perspective view of the lens, from the top. 
         FIG.  10    is an exemplary light distribution curve for the light fixture of  FIG.  1   . 
         FIG.  11    is a schematic view of a preferred layout of the wall wash light fixtures in a room, adjacent a wall to be illuminated. 
         FIG.  12 A  is bottom plan view of the trim element of the light fixture of  FIG.  1   . 
         FIG.  12 B  is a side cross-sectional view trim element of the light fixture of  FIG.  1   . 
         FIG.  12 C  is a front elevational view trim element of the light fixture of  FIG.  1   . 
         FIG.  13 A  is bottom plan view of the trim element of a second preferred embodiment of the light fixture. 
         FIG.  13 B  is a side cross-sectional view trim element of  FIG.  13 A . 
         FIG.  13 C  is a front elevational view trim element of  FIG.  13 A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS.  1 - 12 C  a first preferred embodiment of the wall wash micro light fixture  10   10  is configured to emit light through an opening  15  in a ceiling  11  and toward an adjacent wall  13  of the room therebelow. The light fixture  10  can have an enclosure  12  with side walls  14 , a top (not shown), and a bottom wall  16  with an aperture  18  therethrough, for example having a diameter of about 1 inch or more. The enclosure  12  is adapted to be fastened to support structure (for example via hanger bars) above a ceiling structure (such as plaster board), and remains above the ceiling. 
     The light fixture  10  includes a light engine assembly  20  which can include an LED module  22 , a specular reflector  24 , a trim element  26 , and an aperture  90 , which can be a covered or uncovered optical aperture operable to permit the passage of light therethrough. The LED module  22  can have a base  28  with a lower portion  30  having a lower surface  32  (normally horizontal and downwardly facing). An LED  34  can be mounted to the lower surface  32  of the base  28  and is operable to emit light through the light engine assembly  20  and into the room. The LED  34  can be, for example, a 6 mm chip-on-board (COB) LED. The reflector  24  is preferably disposed around the LED  34 . The base  28  can also include an upper portion  36  having an upper surface  38  (normally horizontal and upwardly facing). An electrical connector (not shown) can be connected to the LED  34  by wires and is operable to releasably connect to a lighting driver (not shown) within the enclosure  12  to power the LED. 
     The light engine assembly  20  is preferably adapted to be removed from the enclosure  12  through the aperture  18  of the enclosure  12 , from within the room, without removing the enclosure  12  and without disturbing the ceiling. To achieve this aspect, the light fixture can include a non-removable heat sink (not shown) disposed within the enclosure  12 , and at least the LED module  22  (and permissibly other components of the light engine assembly  20 ) can have mechanical, electrical and thermal connection structures and features operable to connect to the enclosure and/or heat sink disposed therein, such as described in applicant&#39;s co-pending application for a High Output (Micro) Luminary, having Ser. No. 17/201,863, the disclosure of which is incorporated by reference herein in its entirety. 
     The trim element  26  can be connected to the base  28 , such as by one or more screws (not shown) or other means, and preferably surrounds the lower portion  30  of the base  28  and LED  34 . Portions of the lower and upper surfaces  30 ,  36  of the base  28  can form lower and upper thermal interfaces, respectively. The upper portion  36  of the base  28  can be substantially cylindrical in shape, with a substantially circular cross section and with the upper surface  38  (and thermal interface thereof) being substantially circular. For a light fixture configured for about a 1 inch diameter ceiling opening, for example, a maximal outside diameter of the upper portion  36  of the base  28  can be about 0.96 inches and the surface area of the upper thermal interface can be about 0.72 square inches (π*(diameter squared)/4). For such an application, the base  28  can have a height of about 0.9 inches between the upper and lower surfaces thereof. 
     The base  28  of the LED module  22  is preferably adapted and operable to effectively conduct heat generated by the LED  34  from the lower thermal interface to the upper thermal interface. The base  28  can be solid (or at least substantially solid) and can include (or can consist or consist essentially of) one or more materials having high thermally conductivity, such aluminum or copper, or another suitable metal or alloy, or non-metallic material. 
     As described in the aforementioned co-pending application of the applicant, the heat sink of the light fixture  10  can have a planar thermal interface which is configured for thermal connection with the upper thermal interface of the base  28  of the LED module  22 , and which is aligned with and disposed over the aperture  18  of the enclosure  12 . The heat sink is adapted and operable to receive heat generated by the LED  34  through the thermal interfaces and to dissipate such heat to ambient air. 
     The light fixture  10  can be oriented or aligned relative to mutually perpendicular axes (X,Y and Z). The light fixture  10  can have a longitudinal axis  80  parallel to the Z axis, a lateral axis  82  parallel to the Y axis, and a width axis  84  parallel to the X axis. 
     In a typical installation where the ceiling  11  is horizontal and the adjacent wall  13  is vertical, the X and Y axis (and width axis and lateral axis) are horizontal and the Z axis (and longitudinal axis) is vertical, and an X-Y plane is parallel to a plane of the ceiling  11  and perpendicular to a plane of the adjacent wall  13 , an X-Z plane is parallel to the plane of the wall  13  and perpendicular to the plane of the ceiling  11 , and a Y-Z plane is perpendicular to the planes of the ceiling  11  and wall  13 . 
     The light engine assembly  20 , and particularly the LED module (and with the reflector  24 ) has an optical axis  40  which is preferably disposed on or parallel to the longitudinal axis  80  of the light engine assembly, and, in in typical operation, the light fixture  10  and light engine assembly  20  are installed in an orientation such that both the longitudinal axis and the optical axis  40  are vertical or substantially vertical, or perpendicular to the ceiling or other structure in which the light fixture is mounted. 
     An upper portion  42  of the trim element  26  can have a substantially tubular or cylindrical shape with a corresponding circular (typically horizontal) cross section perpendicular to the optical axis  40 . A lower portion  44  of the trim element  26  can have a radially outwardly extending portion  46  on a wall-facing side  48  thereof such that the lower portion  44  has a somewhat oblong (horizontal) cross section. As described further below, this extending portion facilitates lateral light projection toward the adjacent wall surface. 
     The lower portion  44  of the trim element  26  can also include a circumferential flange  86  (e.g., a micro flange) extending radially outwardly (e.g., about ⅛-¼ in, for an about 1 inch ceiling opening) around a circumference thereof and configured to abut a lower surface of the ceiling  11  surrounding the opening  13 . 
     The light engine assembly  20  includes a lens  50  disposed below the reflector  24  which is configured to direct light emitted by the LED  34  toward the adjacent wall surface. The lens  50  includes an upper portion  52  (or barrel side) in the form of a plano-convex lens  54 , and includes a lower portion  56  (Fresnel side) in the form of a linear Fresnel lens  58 . The convex portion of the plano-convex lens  54  faces upwardly, generally toward the LED  34 , and is preferably partially cylindrical. 
     The convex surface of the plano-convex lens  54  has a center of curvature C disposed below the trim element  26  and offset laterally (Y axis) from the optical axis  40 . Since the convex surface is partially cylindrical, it has an axis of curvature A which passes through the center of curvature C. The axis of curvature A is perpendicular to the optical axis  40 , and in use is preferably typically horizontal and parallel to the adjacent wall. A radius of curvature of the convex surface can have a length of about 16.13 mm (0.635 in). 
     The plano-convex lens  54  serves and is operable to narrow the beam in one direction (vertically, along a height of the adjacent wall  13  to be illuminated) and to expand the beam in the other direction (horizontal, along a length of the wall), to achieve the desired light distributions. 
     The linear Fresnel lens  58  serves to direct light laterally toward the wall to be illuminated while having low light absorption. The Fresnel lens  58  faces downwardly, generally away from LED  34 , such that the facets or grooves  60  thereof are disposed on a bottom surface  62  of the lens  50 . A distance between the bottom surface  62  of the lens  50  and the center/axis of curvature C, A of the convex surface of the plano-convex lens  54  can be about 9.85 mm (0.388 in). 
     The lens  50  can be described as a tilted linear Fresnel lens with a convex back. The lens  50  is disposed at an oblique angle Θ 1  relative to a (typically horizontal) lateral axis  82  or plane  41  perpendicular to the optical axis  40  such that plano-convex lens  54  and the Fresnel lens  58  are likewise disposed at the oblique angle Θ 1  relative to the optical axis  40 . The oblique angle Θ 1  can preferably be an acute angle of, for example, 15 degrees. More specifically, the lens  50  (and/or the plano-convex lens  54 ) can have a plane of symmetry S (or substantial symmetry) which is generally perpendicular to the Fresnel lens  58  portion of the lens  50 , generally normal at an intersection with convex surface of the plano-convex lens  54 , and/or on which lies the center/axis of curvature C, A of the cylindrical portion of the plano-convex lens  54 . The plane of symmetry S can be disposed at the oblique angle Θ 1  relative to the optical axis  40 . 
     Alternatively, or additionally, a principal axis P of the plano-convex lens  54  (which may also be considered a principal plane) can be aligned at the oblique angle Θ 1  relative to the optical axis  40  and/or can be substantially perpendicular to the Fresnel lens  58 . 
     Due to the oblique orientation of the lens  50 , in use, a first lateral end  66  of the lens  50  is disposed higher (i.e., closer to the LED module) than a second lateral end  68  of the lens, opposite the first end, with respect to the lateral axis  82  (Y axis). In use, the first end is aligned toward the wall to be illuminated by the light fixture. 
     The lens  50  preferably extends radially outwardly to occupy the interior of the trim element  26  such that it closely abuts the interior wall  64  of the trim element  26 , such that all or substantially all of the light emitted by the light fixture into the room passes through the lens  50 . As described above, the trim element  26  can have a substantially circular cross section, as taken perpendicular to the optical axis  40 . Therefore, the lens  50 , which is at an oblique angle Θ 1  relative to the optical axis  40 , may have a substantially elliptical or oval periphery. For example, in a light fixture having an aperture of about 1 inch, the lens  50  can have a long axis of about 20.7 mm (0.815 in) and a short axis of about 19.8 mm (0.780 in) 
     The Fresnel lens  58  can include many prismatic features (facets) that have varying angles and depths. The prismatic features are designed such that a specific focal length can be achieved. For example, the focal length can be about 14 mm and a maximum depth and width of the facets can be about 1 mm. 
     The grooves  60  of the Fresnel lens  58  are preferably parallel and are aligned parallel to the width axis  86  (X axis) and/or perpendicular to the optical axis  40  and/or the principal axis P, and/or parallel to the plane of symmetry S. In use, the grooves  60  are generally horizontal and/or parallel to the wall to be illuminated. The configuration (i.e., shape) of the facets and grooves  60  of the Fresnel lens  58  can be asymmetric with respect to plane of symmetry S of the lens  50  and/or the principal axis P of the plano-convex lens  54 . In particular, a slope angle of the grooves can increase from a relatively shallow angle adjacent the first lateral end  66  of the lens  50  to a relatively steep angle adjacent the second end  68 . 
     The plano-convex lens  52  and the Fresnel lens  58  portions of the lens  50  can be a composite structure having two separate lenses, or can be one combined or integral lens. In the case of a composite lens, flat or complementary sides of the plano-convex lens  54  and the Fresnel lens  58  would preferably be in an abutting relationship, or otherwise optically coupled. The lens material can be UV stabilized polycarbonate such that will avoid yellowing under strong LED light in high temperature and high humidity environment. 
     The lens  50  can include an alignment recess  88  configured to receive a complementary alignment projection (not shown) of the trim element  26  such that lens  50  is positively aligned when inserted into the trim element, for example through the upper portion  42  thereof. 
     The light engine assembly  20  preferably can include two layers of diffusers, which can be mounted or supported by the trim element  26 . The diffusers provide improved color mixing and glare reduction and serve to direct light toward the top of the adjacent wall to be illuminated without affecting or reducing the overall light distribution on the remainder of the wall. An upper diffuser  70  can be disposed below the lens  50 , adjacent the Fresnel lens  58 . Preferably the upper diffuser  70  is disposed immediately below the lens  50  and can be in contact therewith, and can optionally be a support for the lens  50 . The upper diffuser  70  is preferably planar and aligned at the same oblique angle Θ 1  as the lens  50 . The upper diffuser  70  can comprise an ultra-thin diffusion material. 
     A lower diffuser  72  can be disposed at a bottom  74  of the trim element  26 , for example in the aperture  90  of the light engine assembly. The lower diffuser can be planar and disposed perpendicular to the optical axis  40 , such that it is generally horizontal when the light fixture  10  is in use. As can be appreciated, only the lower diffuser  72  directly is visible when in typical use. The upper diffuser  70  can be a 15 degree diffuser and the lower diffuser  72  can be a 20 degree diffuser, and other specifications are possible. Preferably, the lower diffuser  72  is removable, for example, for situations where lateral glare must be minimized. Preferably, the lower diffuser  72  is removable from within the room, below the light fixture. 
     A kicker  76  can extend downwardly from the bottom  74  of the trim element  26 . The kicker can be about ¼″ in height and preferably is substantially arcuate and extends around a portion of the trim element  26 , for example about 180 degrees around the trim element. A radially interior surface  78  of the kicker  76  is preferably parallel or substantially parallel to the optical axis  40  and at least an intermediate portion of a radially interior surface  78  of the kicker  76  can include a specular finish to enhance reflectivity, while the two end portions of the kicker  76  can have a non-specular finish. A backside (or side facing away from the adjacent wall  13 ) is preferably white such that it blends with the ceiling color to minimize the appearance of the kicker. However, the kicker is optional and can be omitted if desired for aesthetic or other purposes. 
     Preferably, the interior surface  77  of the trim element  26  includes a black specular finish to reduce glare and generate higher light output. 
     Referring to  FIG.  10   , the configuration of the light fixture  10  and, in particular, the light engine assembly  20 , provides superior light distribution for wall-wash applications. The light distribution shown in  FIG.  10    is the type of distribution needed to achieve the desired general and specific performance in the wall wash lighting application, which is described above in in the Background of the Invention. 
     Referring to  FIG.  11   , usually the required setback and spacing requirements for wall wash lighting fixtures is proportional to the size of the aperture of the fixtures. For example, in a typical layout for wall wash fixtures for typical wall heights of, for example, 8-9 feet, a series of wall wash fixtures  10 ,  10 ′ are installed in a ceiling at a set back distance of for example 2-3 feet, and are spaced laterally, parallel to the wall at a distance of, for example 18 to 24 inches. However, the even though the wall wash light fixture disclosed herein has a small aperture, the light distribution of the light fixture is superior to prior devices and allows for larger setback and/or spacing than prior devices. 
     Referring to  FIGS.  13 A- 13 C , in a second preferred embodiment of the light fixture, the trim element  126  can be configured as disclosed with respect to the first preferred embodiment but can be without a circumferential flange ( 86 ). 
     It should be understood, of course, that the specific form of the invention herein illustrated and described is intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the scope of the claimed invention.