Abstract:
A lighting assembly is provided which comprises a light fixture in combination with a support grid such as a drop ceiling t-bar. The light fixture can be configured to use a t-bar as the main form of support. The light fixture can be push-fit onto a t-bar or use a clip to join two or more portions of the light fixture to an installed t-bar. Once attached to the T-bar, the light fixture itself can provides support for a ceiling tile. Various embodiments are provided which achieve a variety of light distributions useful in typical illumination applications. Both recessed and suspended fixture types are achieved in various embodiments which are particularly well suited for LED lighting.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional patent application Ser. No. 62/099,089 titled “T-bar Lighting Assembly” filed Dec. 31, 2014. 
     
    
     BACKGROUND 
       [0002]    The invention relates to the use of a T-bar integrated with a light fixture as well as being an integral part of the suspended ceiling system for a building or other structure. In drop ceiling environments such as office space and residential homes the t-bar is a support grid that holds ceiling tiles in place in order to form a drop ceiling. 
       SUMMARY 
       [0003]    A lighting assembly is provided which comprises a light fixture in combination with a support grid such as a drop ceiling t-bar. The light fixture can be configured to use a t-bar as the main form of support. The light fixture can be push-fit onto a t-bar or use a clip to join two or more portions of the light fixture to an installed t-bar. The push fit option is a modular shape designed to fit a variety of different t-bars. Clips are designed to attach specific light fixture components to standard t-bar shapes. 
         [0004]    The light fixture can also be configured to act as a t-bar itself and provides support for a ceiling tile to rest upon. A ceiling tile resting on the t-bar can be configured to sit flat and in parallel with the other ceiling tiles. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0005]    The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: 
           [0006]      FIG. 1  is a perspective view of “embodiment a” lighting assembly. 
           [0007]      FIG. 2A  is a cross-section view of lighting assembly “embodiment a”. 
           [0008]      FIG. 2B  is a measured intensity vs. angle light distribution polar plot from lighting assembly “embodiment a”. 
           [0009]      FIG. 3  is a view of the lighting assembly “embodiment a” showing separated light fixture and t-bar. 
           [0010]      FIG. 4  is a perspective view of a lighting assembly “embodiment b” in which two halves of a light fixture housing are joined onto a t-bar by clips. 
           [0011]      FIG. 5A  is a cross-section view of a lighting assembly “embodiment b” in which two halves of a light fixture housing are joined onto a t-bar by clips. 
           [0012]      FIG. 5B  is a measured intensity vs. angle light distribution polar plot from lighting assembly “embodiment b”. 
           [0013]      FIG. 6  is a cross-section view of a partially disassembled “embodiment b” lighting assembly. 
           [0014]      FIG. 7  is a perspective view of a partially disassembled “embodiment b” lighting assembly. 
           [0015]      FIG. 8A  shows a perspective view of a direct lit lighting assembly “embodiment c”. 
           [0016]      FIG. 8B  is a measured light distribution polar plot of the “embodiment c” lighting assembly of  FIG. 8A . 
           [0017]      FIG. 9A  shows a cross-section view of an edge lit lighting assembly “embodiment d” with a single light guide edge lit from two opposing sides. 
           [0018]      FIG. 9B  is a measured light distribution polar plot of the “embodiment d” lighting assembly of  FIG. 9A . 
           [0019]      FIG. 10A  shows a cross-section view of an edge lit lighting assembly “embodiment e” with angled light guides. 
           [0020]      FIG. 10B  is a measured light distribution polar plot of the “embodiment e” lighting assembly of  FIG. 10A . 
           [0021]      FIG. 11A  shows a cross-section view of an edge lit lighting assembly “embodiment f” with two edge lit light guide, each lit from the center edge. 
           [0022]      FIG. 11 b    is a measured light distribution polar plot of the “embodiment f” lighting assembly of  FIG. 11A . 
           [0023]      FIG. 12  is a perspective view of an asymmetric lighting assembly “embodiment g” with a single edge lit light guide. 
           [0024]      FIG. 13A  is a cross-section view of lighting assembly “embodiment g” with a single edge lit light guide. 
           [0025]      FIG. 13B  is a measured light distribution polar plot of the embodiment lighting assembly “embodiment g” of  FIG. 13A . 
           [0026]      FIG. 14  is a cross-section view of “embodiment g” light guide having a light diffusing volume and light directing features. 
           [0027]      FIG. 15  is a cross-section view of lighting assembly “embodiment h”, with suspended light fixture. 
           [0028]      FIG. 16  is an underneath perspective view of an example t-bar lighting assembly installation from within a room looking up at the ceiling. 
           [0029]      FIG. 17  is an overhead perspective view of a t-bar lighting assembly from above a t-bar grid within a ceiling cavity. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  is a perspective view of lighting assembly “embodiment a”. A LED board  10 A, which serves as a light source, and light guide  12 A have been inserted into the housing, extrusion  16   a . The conformal shape of the extrusion  16   a  mates with and is held in place by the t-bar  14   a.  In this manner, a light fixture (everything in  FIG. 1  except the t-bar  14   a ), can be mounted onto a t-bar  14   a  without the use of fasteners. 
         [0031]      FIG. 2A  is a cross-section view of lighting assembly “embodiment a”. The housing, extrusion  16   a , is mated with and supported by the t-bar  14   a.  This fixture uses an edge lit lighting configuration wherein light from the LEDs  11  on the LED board  10 A is input into the edge of the light guide  12 A and the output face of the light guide becomes the light emitting surface  13 A of the fixture. In a typical embodiment the inside surface of the extrusion  16   a  will have an optically reflective surface such as a white paint to enhance optical efficiency of the lighting assembly. 
         [0032]    “Embodiment a” is a recessed embodiment wherein the housing rests on the t-bar and is mounted flush with a ceiling tile  17   a  that is supported by a ledge  19   a  on the edge of the housing.  15   a  is an electrical connector through which electrical power is distributed to the LED board from a power source such as an LED driver which could be mounted onto the lighting assembly housing or located remotely and connected by wiring. 
         [0033]      FIG. 3  is a view of the lighting assembly “embodiment a” wherein the light fixture  21  is shown separated from the t-bar  14   a.  This view illustrates how the extrusion  16   a  mimics the shape of the t-bar to create a conformal flush fit. During installation the light fixture  21  attaches to and is supported by the t-bar  14   a.    
         [0034]      FIG. 4  is a perspective view of a lighting assembly “embodiment b” wherein the housing is comprised of two extrusions  16   b  and  18 B which are joined to the t-bar  14   b  by use of a clip  20   b . For an assembled fixture that is 1′ long for example, two clips  20   b  could be used to attach two extrusions together. Here, each extrusion  16   b  and  18 B is fully assembled into light fixture halves then attached at an installation site to an opposing extrusion using clips  20   b.  For installation, ceiling tile on each side of the assembly can be is cut to mount onto the extrusion ledge  19 B. 
         [0035]      FIG. 5A  is a cross-section view of a lighting assembly “embodiment b” wherein the housing is comprised of two extrusions  16   b  and  18 B which are joined to the t-bar  14   b  by use of a clip  20   b .  15 B is an electrical connector through which electrical power is distributed to the LED board from a power source such as an LED driver which could be mounted onto the lighting assembly housing or located remotely and connected by wiring. 
         [0036]      FIG. 6  and  FIG. 7  are views of a partially disassembled “embodiment b” lighting assembly which show the separate sections that are assembled into the finished lighting assembly; the two light fixture halves formed from extrusion  16   b  and  18 B, clip  20   b,  and t-bar  14   b.  The clip  20   b  contains small grooves on it to allow for a tight locking fit. 
         [0037]    Lighting assembly “embodiment c” of  FIG. 8A  is a direct lit configuration which provides a light distribution with peak intensity normal to the fixture. Two halves of the light fixture, extrusion  16   c  and extrusion  18   c,  are joined onto the t-bar  14   c,  by clips  20   c.  LEDs  11  populate each LED board  10   c  from which light is emitted and dispersed into the reflective chamber  23   c  before exiting the lighting assembly through a diffuser lens  22   c.  Ledges  19   c  on both sides of the housing provide a resting place for ceiling tile. In addition to scattering light, a diffusion lens may be used in both direct lit and edge lit optical systems to reduce glare if it contains light directing surface features. Examples include but are not limited to geometric shapes such as half spheres, pyramids, truncated pyramids, lenticulars, and linear prisms. 
         [0038]    Lighting assembly “embodiment d” of  FIG. 9A . contains a single light guide  12   d  lit from two opposing edges by LEDs  11   d  mounted on LED boards  10   c  and provides a wide angle lobed light distribution similar to the “embodiment a” of  FIG. 2  but with more light normal to the fixture. The extrusion  16   d  serves as a housing which has a t-bar shaped section that conforms to the shape of the t-bar  14   d;  the two mating together to hold the assembly in place upon the t-bar  14   d.  Ledges  19   d  provide support for ceiling tile and power is supplied via electrical connecters  15   d.    
         [0039]    Lighting assembly “embodiment e” of  FIG. 10A  has two light guides  12   e,  each lit from the inside edge by LEDs  11   e  and tilted upward which produces a light distribution with even peak intensity over the range ±30° from normal as seen in  FIG. 10B . The tilted light guides  12   e  provide for a design in which the side of the extrusion  16   e  acts as a reflector and baffle in narrowing the light distribution and preventing glare. 
         [0040]    The lighting assembly “embodiment f” of  FIG. 11A  contains two light guides  12   f  each lit from the inside edge by LEDs  11   f  and shaped with flared edges that provide an extreme wide angle light distribution with 2 major lobes at ±90° from normal and a weaker minor lobe normal to the fixture. “Embodiment f” is a configuration which is not recessed within the ceiling but rather the significant portion of the housing extrusion  16   f  is suspended below the ceiling tile  17   f  which is supported by the ledge  19   f.  The clip  20   f  hold the housing extrusion together on the t-bar  14   f.    
         [0041]      FIG. 12  is a perspective view of asymmetric lighting assembly “embodiment g” with a single edge lit light guide. The housing extrusion  16   g  mates with the t-bar  14   g  which holds it in place.  FIG. 13A  is a cross-section view of lighting assembly “embodiment g” which details the configuration. 
         [0042]      FIG. 13A  is a cross-section view of lighting assembly “embodiment g” with a single edge lit light guide. Both the fixture mechanical design and the light output distribution in  FIG. 13B  polar plot of intensity vs. angle are asymmetric making this embodiment optimal for applications such as wall washing, wall grazing, and cove lighting. The ledge  19   g  of the housing extrusion  16   g  supports ceiling tile  17   g  in a recessed ceiling fit. Light from LEDs  11   g  on the LED board  10   g  is input into the light guide  12   g  and then propagates through the diffusing lens  22   g  before exiting the lighting assembly. The diffusing lens  22   g  is slightly angled with respect to the light guide to provide some offset distance near the input side to improve the spatial uniformity of light distribution but closer to the light guide  12   h  near the opposing edge to increase optical efficiency. Alternatively, the diffusing lens  22   g  could be a component with light directing surface features to reduce glare and/or change light distribution patterns.  FIG. 14  illustrates optical detail of the “embodiment g” light guide  12   g  which is primarily polymethyl methacrylate (PMMA) but contains a &lt;2% concentration of polymer microbeads  25  having a refractive index differing from that of the bulk PMMA, thus producing a volumetric diffuser and inducing some light scattering and helping to out couple light from the light guide. The light guide  12   g  also consists of light directing surface features  27  in the specific form of linear ridges located on the output face which act to produce light outcoupling and the specific light distribution seen if  FIG. 13B . As an alternative to polymer microbeads for producing volumetric diffusion, other micro-regions of differing refractive index could be utilized to induce light scattering. Examples include white reflective powders such as TiO2 or micro-regions of differing refractive index formed by immiscible blending of polymer materials. 
         [0043]      FIG. 15  is a cross-section view of lighting assembly “embodiment h” in which the light fixture portion of the assembly is suspended below the ceiling tile  17   h  by means of an extended housing. Alternatively, the bottom portion of the housing could be suspended by cable connected to the upper portion. The housing  16   h  is mated to the t-bar  14   h  to hold the lighting assembly in place. A ledge  19   h  supports ceiling tile  17   h.  Light from LEDs  11  enters the input edge of the light guide and is propagated within the light guide with some light exiting bottom, top, and side of the housing  16   h.  Portions of light exiting through the top and side exit through though the top aperature  30   h  and side aperature  32   h  respectively. In this way a suspended direct/indirect light fixture integrated with a ceiling t-bar can be achieved. The multiple paths of light propagation are illustrated in  FIG. 15  with arrows. 
         [0044]      FIG. 2B ,  FIG. 5B ,  FIG. 8B ,  FIG. 9B ,  FIG. 10B ,  FIG. 11 b   , and  FIG. 13B  show measured intensity vs. angle light distribution polar plots of embodiment lighting assemblies of  FIG. 2A ,  FIG. 5A ,  FIG. 8A ,  FIG. 9A ,  FIG. 10A ,  FIG. 11A , and  FIG. 13B  respectively and illustrate some of the wide range of light distributions possible with various embodiment configurations. The two light guides in the embodiment of  FIG. 2A , each lit from the outside edge, provide a fairly wide light distribution with higher intensity lobes centered at approximately ±60° from normal (straight down for a ceiling mounted fixture). 
         [0045]    The embodiment of  FIG. 5A  has two light guides, each lit from the inside edge and tilted to narrow the light distribution and provide higher intensity lobes at approximately ±40° from normal (straight down for a ceiling mounted fixture). A light distributions such as that shown in  FIG. 5B  is commonly referred to as bat wing light distribution and is considered very desirable in many illumination applications where the illuminance field projected onto a flat surface from an overhead light fixture is optimally uniform in intensity. The lobes in the light distribution facilitate this by projecting more light off axis from the light fixture to compensate for the greater distance needed to reach the illuminated surface at angles away from normal directly below the fixture. 
         [0046]    Embodiments “b” and “e” shown in  FIG. 5A / 5 B and  FIG. 10A / 10 B illustrate that changing the orientation of light guides changes the output light distribution. By providing means for tilting light guides within the lighting assembly, a lighting assembly of adjustable light distribution can be produced. Furthermore, addition of electronics capable of receiving a control signal and an electromechanical motor can be used to remotely adjust the light distribution. When mounted into a room ceiling, embodiment lighting assemblies can provide adjustment of light distribution without noticeable change from an observer within the room. 
         [0047]    In general, embodiments of have been shown to provide a wide variety of non-lambertian light distributions that are typically valued in illumination applications. 
         [0048]      FIG. 16  is an underneath perspective view of an example t-bar lighting assembly installation from within a room looking up at the ceiling. A t-bar lighting assembly  34  is mounted onto a t-bar  14  flush with the ceiling tile  17 . 
         [0049]      FIG. 17  is an overhead perspective view of a t-bar lighting assembly from above a t-bar grid within a ceiling cavity. A t-bar lighting assembly  34  is mounted onto a t-bar grid (mounting t-bar not visible but adjacent t-bar  14  shown). An optional suspension cable is shown which can be used for extra support and is required by building code in some installation situations. 
       LIST OF NUMERICAL REFERENCES 
     Suffix a-h Added in Detailed Description Section to Indicate Specific Embodiment 
       [0000]    
       
           10  LED board 
           11  LED 
           12  light guide 
           13  light emitting surface 
           14  t-bar 
           15  electrical connector 
           16  extrusion/housing 
           17  ceiling tile 
           18  extrusion 
           19  ledge (of housing/extrusion) 
           20  clip a 
           21  light fixture 
           22  diffusing lens 
           23  reflective cavity 
           25  polymer microbeads 
           27  light directing surface features 
           30  top aperature 
           32  side aperature 
           34  t-bar lighting assembly 
           35  suspension cable