Patent Publication Number: US-11649938-B2

Title: Thin profile surface mount lighting apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of application Ser. No. 16/881,686. Application Ser. No. 16/881,686 was filed on May 22, 2020 and is titled “Thin Profile Surface Mount Lighting Apparatus.” application Ser. No. 16/881,686 was filed as a continuation application of application Ser. No. 16/653,497. Application Ser. No. 16/653,497 was filed on Oct. 15, 2019 and is titled, “Thin Profile Surface Mount Lighting Apparatus.” Application Ser. No. 16/653,497 was filed as a continuation of application Ser. No. 16/016,040. Application Ser. No. 16/016,040 was filed on Jun. 22, 2018 and is titled, “Thin Profile Surface Mount Lighting Apparatus.” Application Ser. No. 16/016,040 was filed as a continuation-in-part of Design Application No. 29/648,046 under 35 U.S.C. § 120. Design Application No. 29/648,046 was filed on May 17, 2018 and is titled “Light Fixture.” application Ser. No. 16/016,040 also claimed the benefit, under 35 U.S.C. § 119(e), of U.S. Provisional Application No. 62/523,640, which was filed on Jun. 22, 2017 and is titled “Surface Mounted Ceiling Lamp;” and U.S. Provisional Application No. 62/552,126, which was filed on Aug. 30, 2017 and is titled “Surface Mounted Ceiling Lamp.” Priority is claimed to each of the aforementioned applications and each of the aforementioned applications is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Some conventional surface mount LED downlights may be coupled to a junction box disposed behind a ceiling and may be employed in new construction or retrofit architectural projects. One such example is the “Disk Light” provided by Commercial Electric and manufactured by Cree (manufacturer model number CE-JB6-650L-27K-E26). The Disk Light can be installed in an existing recessed can or a four-inch junction box and includes a semi recessed lens. The Commercial Electric Disk Light may be used indoors and in an outdoor enclosed setting, and is generally intended for kitchens, hallways, bathrooms, closets, laundry, porches and garage work rooms. Another example is the Halo Surface Mount LED Downlight (SMD) series, which are low-profile surface mount luminaires designed for installation in many 3½″ and 4″ square, octagon, or round junction boxes. 
     SUMMARY 
     Various inventive concepts disclosed herein relate generally to a thin surface mount type of luminaire, wherein “thin” refers to the protruding portion of the luminaire below the line of the ceiling, for example. In various implementations, the luminaire can be installed from below the ceiling by a twist lock mechanism or by clips into a junction box that is installed in the ceiling. Some implementations include a test switch that is accessible from the portion of the luminaire that protrudes below the ceiling line. The lens of some implementations combines a total internal reflection lens with a conical structure buried at its center. In other implementations, the luminaire includes a plurality of light sources distributed evenly across a light producing portion of the luminaire. In such implementations, the light sources can comprise LEDs. 
     In sum, one inventive implementation is directed to an LED lighting apparatus, comprising: a housing comprising at least one sidewall having a front facing edge and a back facing edge positioned adjacent to a ceiling when the LED lighting apparatus is installed in an opening of the ceiling, wherein a depth of the at least one sidewall of the housing, between the front facing edge and the back facing edge, is less than one inch such that the apparatus does not visibly appear to protrude substantially from a surface of the ceiling when the apparatus is installed in the opening of the ceiling; an LED board coupled to the housing, the LED board comprising a plurality of LEDs; and a lens coupled to the housing, the lens having a back side facing the LED board and a front side opposite to the back side, wherein the front side of the lens provides a downward facing surface when the LED lighting apparatus is installed in the opening of the ceiling, the lens being disposed with respect to the LED board such that the plurality of the LEDs illuminate the back side of the lens. A first spacing of the plurality of the LEDs on the LED board causes resulting light from the downward facing surface of the lens to be substantially uniform during operation of the apparatus. The front side of the lens, providing the downward facing surface when the LED lighting apparatus is installed in the opening in the ceiling, is essentially flush with the front facing edge of the at least one sidewall of the housing. 
     Another inventive implementation is directed to an LED lighting apparatus, comprising: a housing; an LED board coupled to the housing, the LED board comprising a plurality of LEDs; and a lens coupled to the housing, the lens having a back side facing the LED board and a front side opposite to the back side, wherein the front side of the lens provides a downward facing surface when the LED lighting apparatus is installed in an opening of a ceiling, the lens being disposed with respect to the LED board such that the plurality of the LEDs illuminate the back side of the lens. A first spacing of the plurality of the LEDs on the LED board causes resulting light from the downward facing surface of the lens to be substantially uniform during operation of the apparatus. 
     Another inventive implementation is directed to a thin profile surface mount LED lighting apparatus, comprising: a housing comprising at least one sidewall having a front facing edge and a back facing edge positioned adjacent to a ceiling when the LED lighting apparatus is installed in an opening of the ceiling, wherein a depth of the at least one sidewall of the housing, between the front facing edge and the back facing edge, is less than one inch; an LED board coupled to the housing, the LED board comprising a plurality of LEDs; and a lens coupled to the housing, the lens having a back side facing the LED board, a front side opposite to the back side and an outer edge, wherein the front side of the lens provides a downward facing surface when the LED lighting apparatus is installed in the opening of the ceiling, the lens being disposed with respect to the LED board such that the plurality of the LEDs illuminate the back side of the lens. The front facing edge of the at least one sidewall forms a perimeter around the outer edge of the lens. The front side of the lens, providing the downward facing surface when the LED lighting apparatus is installed in the opening in the ceiling, is essentially flush with the front facing edge of the at least one sidewall of the housing forming the perimeter around the outer edge of the lens. The perimeter around the outer edge of the lens is significantly thin so as not to extend significantly beyond the outer edge of the lens. 
     It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The skilled artisan will understand that the drawings primarily are for illustrative purposes and are not intended to limit the scope of the inventive subject matter described herein. The drawings are not necessarily to scale; in some instances, various aspects of the inventive subject matter disclosed herein may be shown exaggerated or enlarged in the drawings to facilitate an understanding of different features. In the drawings, like reference characters generally refer to like features (e.g., functionally similar and/or structurally similar elements). 
         FIG.  1    is an assembly drawing of an example luminaire according to some inventive implementations. 
         FIGS.  2 A,  2 B, and  2 C  illustrate various aspects of a lens in the assembly of  FIG.  1   , according to some inventive implementations. 
         FIGS.  3 A and  3 B  illustrate various aspects of a conical structure of the lens of  FIGS.  2 A through  2 C , according to some inventive implementations. 
         FIGS.  4 A and  4 B  illustrate aspects of mounting a luminaire in a junction box, according to some inventive implementations. 
         FIG.  5    is an assembly drawing of another example luminaire according to some inventive implementations. 
         FIG.  6    illustrates various emergency aspects of the example luminaire of  FIG.  5    according to some inventive implementations. 
         FIG.  7    is an assembly drawing of another example luminaire according to some implementations. 
         FIG.  8 A  illustrates an example circular LED board that can be included in a luminaire such as that illustrated in  FIG.  7   , according to some inventive implementations. 
         FIG.  8 B  illustrates an example rectangular LED board that can be included in a luminaire according to some inventive implementations. 
         FIGS.  9 A and  9 B  illustrate example aspects of installing a luminaire such as that shown in  FIG.  7    into a junction box in a ceiling, according to some inventive implementations. 
         FIG.  9 C  is a partial side cross-sectional view of the luminaire of  FIG.  7   , illustrating an arrangement of an LED board and a lens disposed in a housing and example dimensions relating to same, according to some inventive implementations. 
         FIG.  10 A  is a side view of a luminaire similar to that shown in  FIG.  7   , according to some inventive implementations. 
         FIG.  10 B  is a front view (or downward facing view) of the luminaire shown in  FIG.  10 A . 
         FIG.  10 C  is a back view (or upward facing view) of the luminaire shown in  FIG.  10 A . 
         FIG.  10 D  is a back (or top) perspective view of the luminaire shown in  FIG.  10 A . 
         FIG.  10 E  is a front (or bottom) exploded perspective view of the luminaire shown in  FIG.  10 A . 
         FIG.  11 A  is a side view of a luminaire similar to that shown in  FIG.  7   , according to some inventive implementations, which includes a test button similar to that shown in  FIG.  5   . 
         FIG.  11 B  is a front view (or downward facing view) of the luminaire shown in  FIG.  11 A . 
         FIG.  11 C  is a back view (or upward facing view) of the luminaire shown in  FIG.  11 A . 
         FIG.  11 D  is a back (or top) perspective view of the luminaire shown in  FIG.  11 A . 
         FIG.  11 E  is a front (or bottom) exploded perspective view of the luminaire shown in  FIG.  11 A . 
         FIG.  12 A  is a front (or bottom) side perspective view of a rectangular-shaped luminaire according to some inventive implementations. 
         FIG.  12 B  is a back (or top) side perspective view of the luminaire of  FIG.  12 A  according to some inventive implementations. 
     
    
    
     DETAILED DESCRIPTION 
     Following below are more detailed descriptions of various concepts related to, and implementations of, inventive thin profile surface mount lighting apparatus. It should be appreciated that various concepts introduced above and discussed in greater detail below may be implemented in numerous ways. Examples of specific implementations and applications are provided primarily for illustrative purposes so as to enable those skilled in the art to practice the implementations and alternatives apparent to those skilled in the art. 
     The figures and examples below are not meant to limit the scope of the present implementations to a single embodiment, but other implementations are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present implementations can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present implementations are described, and detailed descriptions of other portions of such known components are omitted so as not to obscure the present implementations. In the present specification, an implementation showing a singular component should not be considered limiting; rather, the present disclosure is intended to encompass other implementations including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. 
     According to certain aspects, the present applicants have recognized that it would be desirable to have a low cost but aesthetically pleasing and efficient LED downlight that is, or appears to be, surface mounted to a ceiling, and which includes a thin profile and uniform lighting distribution. 
     In fulfillment of these and other aspects,  FIG.  1    is an assembly drawing of an example luminaire according to some implementations. 
     As shown, luminaire  100  is comprised of a housing  102  having an integrally formed flange portion  116  and fins  122 . As further shown, luminaire  100  also includes driver  104 , reflector  106 , lens  108 , cone  110 , light source  112  and adapter bracket  114 . As will be described in more detail below, the luminaire  100  is designed to be positioned behind a ceiling or a wall such that the flange portion  116  of housing  102  extends outside a hole in the ceiling or wall (not shown) and rests flush against the exposed surface of the ceiling or wall. As such, the flange portion  116 , when assembled together with lens  108 , helps the luminaire  100  appear to be “surface-mounted” on the ceiling or wall, although it is not actually mounted on the surface. 
     The driver  104 , as will be described below in more detail below, is mounted within driver module cover  124  and contained inside the housing  102  behind reflector  106 , lens  108  and cone  110 . The lens  108  is attached to the flange portion  116  by a twist and lock mechanism built into the outer periphery of lens  108  and inner surface of flange portion  116  as will be described in more detail below. The lens  108  thus completely fills the opening defined by flange portion  116 , and thus further helps the luminaire  100  appear to be mounted on the surface of the ceiling or wall. Despite these appearances however, the luminaire is not designed to be directly mounted to the surface of the ceiling or wall. Rather, the adapter bracket  114  allows the luminaire  100  to be installed within a junction box (not shown, for example via a twist and lock mechanism or a friction fit mechanism), the junction box being already installed within the ceiling or wall as described in more detail below. The housing  102  can be secured to bracket  114  by screws  118  and clips  120 . 
     Housing  102 , including integrally formed flange portion  116  and fins  122 , may be composed of any thermally conductive material so as to help cool the luminaire during operation of light source  112 . For example, housing  102  including integrally formed flange portion  116  and fins  122  may be comprised of injection molded thermally conductive plastic. In other implementations, housing  102 , flange portion  116  and/or fins  122  may be made of aluminum alloys, copper, copper-tungsten pseudoalloy, AlSiC (silicon carbide in aluminum matrix), Dymalloy (diamond in copper-silver alloy matrix), E-Material (beryllium oxide in beryllium matrix), and/or other thermally conductive plastics or ceramics. 
     Driver  104  is an electronic circuit or device that supplies and/or regulates electrical energy to the light source  112  and thus powers the light source  112  to emit light. The driver  104  may be any type of power supply circuit, including one that includes power converters, rectifiers, power transistors and the like for delivering an appropriate alternating current (AC) or a direct current (DC) voltage to the light source  112 . Upon receiving electricity, the driver  104  may regulate current or voltage to supply a stable voltage or current within the operating parameters of the light source  112 . In implementations, the driver  104  receives an input current from an electrical power wiring network of the building or structure in which the luminaire  100  is installed and may drop the voltage of the input current to an acceptable level for the light source  112  (e.g., from 120V-277V to 36V-48V). In these and other implementations, ground wire  130 , attached to housing  102  by screw  132 , is electrically connected to the electrical power ground and wires  135  are electrically connected to a wiring network (e.g., the main house voltage of a building or other transformed voltage) and delivers power to the driver  104 . 
     The light source  112  may be any electro-optical device or combination of devices for emitting light. For example, the light source  112  may have one or more light emitting diodes (LEDs, such as an XLamp LED from Cree), organic light-emitting diode (OLEDs), or polymer light-emitting diode (PLEDs). The light source  112  receives electricity from the driver  104 , as described above, such that the light source  112  can emit a controlled beam of light toward cone  110  and lens  108 , and thus into a room or surrounding area of the luminaire  100  (when installed behind a ceiling or wall) as will be described in more detail below. 
     Driver module cover  124  in implementations may be made of heat resistant or insulating plastic, for example plastic comprising materials selected from a group consisting of semi-crystalline polyamides, polyamide alloys, polycarbonate, polymers, minerals, glass, carbon, steel fibers, etc. In these and other implementations, insulator  124  may be formed by injection molding, extrusion or other means and dimensioned in accordance with driver  104 , which is held into place inside insulator  124  via clips  126 . In the illustrated embodiment, driver module cover  124  is attached to housing  102  by screws  128 , which in turn aligns light source  112  with an opening in reflector  106  and thus an optical path between light source  112 , lens  108  and cone  110  as will become more apparent from the descriptions below. 
     Example aspects of lens  108  and cone  110  according to implementations are shown in  FIGS.  2 A and  2 B  which provide side and cross-sectional views, respectively.  FIG.  2 C  also provides a cross-sectional view of aspects of an operation of lens  108  and cone  110  together with light source  112  and reflector  106  when assembled and aligned together as designed. As shown in  FIGS.  2 A and  2 B , the lens according to the present implementations is unusual. When assembled for operation according to implementations, it combines a total internal reflection lens  108  with a reflective conical structure  110  buried at its center. In implementations, cone  110  is sized and dimensioned to be held into place in a corresponding center depression  204  of lens  108  with a friction fit. In other implementations, cone  110  is held into place by an adhesive or other suitable means. In still other implementations, lens  108  and cone  110  are integrally formed together from a single unitary material, with the upper surface of cone  110  being machined or otherwise formed in the center of lens  108 . 
     As further shown in  FIG.  2 C , according to operational aspects of an assembled luminaire  100 , the light from light source  112  is projected toward the center of the lens and is mostly reflected by the cone  110  into the lens  108 . From there it undergoes further total internal reflections within the lens forcing the light to travel downwards and out the exit side of the lens  108 . Under normal conditions, the spot on the lens covered by the cone  110  would be dark because all the light would be reflected. According to the present implementations, however, the reflective surface of the cone  110  is not completely reflective. Rather, it is configured to allow about 10% of the light to pass through as will be described in more detail below. This prevents a dark spot from appearing at the exit side of lens  108  in the center portion occupied by the cone  110 . It should be further noted that the total internal reflection features of lens  108  and the partially transmissive features of cone  110  allows for a uniform amount of light to be distributed across the entire surface of the exit side of lens  108 , which starkly contrasts with conventional approaches, such as those having light sources arranged at a periphery of a lens. Still further, the arrangement of lens  108  and cone  110  allow for the use of only a single light source  112 , which enables a low-cost design as opposed to other approaches requiring multiple light sources. 
     According to further aspects of some implementations, when assembled for operation together with reflector  106 , any light from light source  112  that is reflected by cone  110  but which escapes from lens  108  back toward light source  112  is further reflected downward and back out the exit side of lens  108 , thus increasing the operational lighting efficiency of light source  112 . 
     Lens  108  may be made of any optically transmissive material, including glass and hard plastics. For example, lens  108  may be comprised of polycarbonate material. In one embodiment, the lens  108  also provides a protective barrier for the light source  112  and shields the light source  112  from moisture or inclement weather. As further shown in  FIG.  2 A , an embodiment of lens  108  includes twist and lock groove  202  formed on the outer periphery of lens  108 . As such, lens  108  may be sized and shaped to be locked into position into flange portion  116  of housing  102 , thereby covering the main opening at the bottom of the housing  102  and providing the shielding advantages as mentioned above. Moreover, the twist and lock mechanism allows for lens  108  to be removed from below a ceiling even when the luminaire  100  is installed, thereby allowing for components of luminaire  100  to be accessed for test, inspection, removal, replacement, etc., without having to remove the luminaire  100  from behind the ceiling or wall. 
     Reflector  106  may be made of any reflective material, or any material having a reflective coating. In implementations, reflector  106  is comprised of highly reflective (e.g. 98%) Valar 2.0 BRDF. In these and other implementations, reflector  106  is separately formed from lens  108  and held into place within housing  102  when lens  108  is twist and locked into flange portion  116 . 
       FIGS.  3 A and  3 B  illustrate example aspects of cone  110  according to implementations in more detail, providing top and cross-sectional views of cone  110 , respectively. 
     In the illustrated implementations, cone  110  is made of a thermoplastic material such as polycarbonate, having a base portion  302  and cone portion  304 . As shown, cone portion  304  is formed so as to extend at an angle of about 45 degrees from base portion  302 . Cone  110  includes bottom surface  306 , side surface  308  and cone surface  310 . With reference to  FIG.  2   , when assembled together with lens  108 , the bottom surface  306  abuts with a bottom portion of depression  204  in lens  108 , while side surface abuts with a side portion of depression  204  in lens  108 . In implementations, cone surface  310  is treated to cause light from light source  112  to reflect towards and into lens  108 , while allowing some light to enter cone  110  and exit through bottom surface  306 . Accordingly, bottom surface  306  is preferably treated in these and other implementations to allow for light to be transmitted through surface  306  and toward an exit side of lens  108 . In non-limiting example implementations, cone surface  310  is vacuum metalized (e.g. aluminum) to be 90% reflective and 10% transmissive, and possibly further coated with a coating such as SiO, SiO 2  or organic coatings having silicates. In these and other implementations, surface  306  and surface  308  are both surface treated with a texturing specification such as LDK-1002, however such texturing is not necessary in all implementations. 
       FIG.  4 A  illustrates aspects of how the present implementations provide aesthetically pleasing surface mounted appearances when luminaire  100  is used as a downlight in a ceiling. 
     Housing  102  is secured to junction box  402  via adapter  114  and a corresponding adapter ring  416 , as will be described in more detail below. Junction box  402  is mounted above an opening of ceiling  404  and can be secured to a ceiling by two or more hanger arms  406 . When housing  102  is thus secured to junction box  402 , flange portion  116  is flush against the surface of ceiling  404 , and flange portion  116  (as well as lens  108 ) is the only portion of the luminaire  100  that extends outward from the surface of ceiling  404 . According to aspects, flange portion  116  is thin, for example less than an inch, such that luminaire  100  does not visibly appear to protrude substantially from the surface of ceiling  404 . such that luminaire  100  does not visibly appear to protrude substantially from the surface of ceiling  404   
     In implementations, junction box  402  may be made of galvanized steel, injection molded plastic, aluminum or ceramic. Junction box  402  may be fire-resistant in that it has a fire rating of up to two hours without any need for modification, where the fire rating is described in the National Electrical Code (NEC) and by the Underwriters Laboratories (UL) such as specified in UL 263 Standard for Fire Tests of Building Construction and Materials. In other implementations, luminaire  100  may be attached to a standard 4.times.4 electrical junction box, which may or may not be fire rated. 
       FIG.  4 B  shows how adapter bracket  114  and adapter ring  416  are coupled together in a twist and lock fashion, thus allowing luminaire  100  to be easily mounted to junction box  402 . As shown, slot portions  420  of structures on adapter ring  416  are dimensioned to receive corresponding structures on adapter bracket  114 , which structures are then fixedly coupled to adapter ring  416  when the adapter  114  and adapter ring  416  are twisted clockwise with respect to each other. Example twist and lock mechanisms that are suitable for practice with the present implementations include those described in U.S. Patent Publ. No. 2016/0348860. By virtue of such mechanisms, luminaire  100  may be easily mounted, accessed, serviced, tested and possibly replaced from below ceiling  404 . 
       FIG.  5    is an assembly drawing of another example luminaire  500  according to implementations. 
     As shown in this example, luminaire  500  includes many of the same components as luminaire  100 , and so repeated descriptions thereof are not included here. Meanwhile, luminaire  500  further includes test button  502  and button housing  504 . The button housing  504  in this example is mounted to the external surface of flange portion  116  of housing  102  via clip  120  and screws  506 . Test button  502  can be attached to an electrical wire (not shown) and electrical signal source and can include any electrical and mechanical components so that, when test button  502  is depressed, an electrical signal is provided on the attached electrical wire. Many possible examples of such components are known to those skilled in the art, so further details thereof will be omitted here for sake of clarity of the invention. 
       FIG.  6    illustrates example emergency aspects of luminaire  500 . In this example, luminaire  500  is attached to a junction box  402  behind a ceiling  404  as described above in connection with  FIGS.  4 A and  4 B . As such, when luminaire  500  is so attached, button  502 , by virtue of being attached to flange portion  116  of housing  102 , is accessible from below ceiling  404 . As further illustrated, when button  502  is pressed, an electrical signal is sent to power switch  602 , which causes power to the luminaire  500  (e.g. via one or more wires  630 ) to be switched from regular power source  604  to an emergency power source  606 . For example, regular power source  604  can be an electrical power wiring network of the building or structure in which the luminaire  500  is installed. In these and other implementations, emergency power source  606  can be a backup power supply including one or more batteries and power conditioning electronics. If the emergency power source  606  is sufficient, light from luminaire  500  will be produced, thereby allowing personnel to verify emergency power source  606  without having to remove luminaire  500  or otherwise gain direct access to emergency power source  600 . 
     It should be noted that the arrangement of elements  602 ,  604  and  606  with respect to junction box  402  and luminaire  500  shown in  FIG.  6    is for illustration purposes only and non-limiting to the present implementations. Many other arrangements are possible, as will be appreciated by those skilled in the art. 
       FIG.  7    is an assembly drawing of another example luminaire  700  according to some implementations pursuant to the concepts disclosed herein. 
     As shown in this example, luminaire  700  includes some of the same components as luminaire  100 , and so repeated descriptions thereof are not included here. Meanwhile, differently from luminaire  100 , luminaire  700  includes driver module cover  704  which can house a driver such as module  104  described above (although a driver  104  is not explicitly shown in  FIG.  7   , it should be appreciated that a driver may be included in some implementations based on  FIG.  7   , as discussed elsewhere herein in connection with other figures). not shown). A light source housing  708 , similar in some respects to the flange portion  116  of the housing  102  shown in  FIG.  1   , houses an LED board  710  and lens  712 , which are mounted in housing  708  using screws  714  and friction fit clips  716 , respectively. Light source housing  708  is further attached to driver module cover  704  using screws  702 . 
     Driver module cover  704  and/or light source housing  708  according to implementations may be made of thermally conducting material, for example plastic comprising materials selected from a group consisting of semi-crystalline polyamides, polyamide alloys, polymers, minerals, glass, and carbon, or other materials such as carbon fiber, aluminum, steel, etc. In these and other implementations, insulator  704  and/or housing  708  may be formed by injection molding, extrusion or other means and dimensioned in accordance with driver  104  and LED board  710 , respectively. It should be noted that although light source housing  708  is shown as having a round shape in this example, that this is not limiting, and many other shapes are possible such as squares, rectangles, ovals, etc. (e.g., as discussed further below in connection with  FIGS.  8 B,  12 A and  12 B )). 
     LED board  710  comprises a plurality of LEDs and an example will be described in more detail below. Lens  712  may be made of any optically transmissive material, including glass and hard plastics. For example, lens  712  may be comprised of polycarbonate material, such as Covestro Makrolon® (e.g., see www.plastics.covestro.com/en/Products/Makrolon). In implementations, lens  712  causes light from LEDs on LED board  710  to be distributed evenly across its downward facing surface by at least one of two approaches. In a first approach, the spacing of the LEDs is controlled so as to cause the resulting light to be uniform. In a second approach, lens  712  is formed using a plastic that includes additives that result in a milky white diffusive polymer. 
     More generally, in one implementation based on  FIG.  7    (as well as features from other figures described herein), an LED lighting apparatus  700  comprises a housing  708 , an LED board  710  coupled to the housing, and a lens  712  coupled to the housing. The lens has a back side  712 B facing the LED board, a front side  712 F opposite to the back side, and an outer edge  712 E. The front side  712 F of the lens provides a downward facing surface when the LED lighting apparatus is installed in an opening of a ceiling, and the lens is disposed with respect to the LED board such that multiple LEDs disposed on the LED board illuminate the back side of the lens. 
     With reference for the moment to  FIG.  9 B , which shows a bottom or down-facing perspective view of the lighting apparatus  700  of  FIG.  7    as it is installed in a junction box  902 , the housing  708  of the lighting apparatus  700  comprises a sidewall  718  having a front facing edge  720  and a back facing edge  722  positioned adjacent to a ceiling when the LED lighting apparatus is installed in an opening of the ceiling. In one example implementation, a depth  724  of the sidewall  718 , between the front facing edge  720  and the back facing edge  722 , is less than one inch such that the apparatus does not visibly appear to protrude substantially from a surface of the ceiling when the apparatus is installed in an opening of the ceiling. In one aspect, the front side  712 F of the lens, providing the downward facing surface when the LED lighting apparatus is installed in the opening in the ceiling, is essentially flush with the front facing edge  720  of the sidewall  718  of the housing  708 . In another aspect, the front facing edge  720  of the sidewall  718  forms a perimeter around the outer edge  712 E of the lens, wherein the perimeter around the outer edge of the lens is significantly thin so as not to extend significantly beyond the outer edge of the lens. In the foregoing manners, the lighting apparatus  700  has an appreciably thin profile (e.g., installed depth from the ceiling of less than one inch, and significantly thin perimeter around the outer edge of the lens) to provide an aesthetically pleasing architectural lighting component. 
       FIG.  9 C  is a partial side cross-sectional view of the luminaire of  FIGS.  7  and  9 B , illustrating an arrangement of the LED board  710  and the lens  712  disposed in the housing  708 , and example dimensions relating to same, according to some inventive implementations. As shown in  FIG.  9 C , the outer edge  712 E of the lens  712 , when installed in the housing  708 , is disposed in a rabbet  719  of the sidewall  718  of the housing that runs along the front facing edge  720  of the sidewall  718 , such that an edge thickness  726  of the front facing edge  720  is smaller than a sidewall thickness  727  of the sidewall  718 . In various examples, sidewall  718  may have a thickness  727  of less than 10 millimeters, in some examples less than 5 millimeters, and in other examples less than 3 millimeters. In other examples the front facing edge  720 , forming the perimeter around the outer edge of the lens, may have a thickness  726  of less than two millimeters, and in some examples less than 1.5 millimeters. In one specific implementation, the thickness  726  is 1.2 millimeters and the thickness  727  is 2.1 millimeters. 
     As also shown in  FIG.  9 C , the housing  708  has a depth  724  between the front facing edge  720  and the back facing edge  722  of the sidewall  718 , which in some inventive implementations is less than one inch, as discussed above. In another aspect, a lens thickness  736  of the lens  712  may be on the order of approximately 3 millimeters. In some implementations, a spacing  732  between the LED board  710  and the lens  712  may be particularly selected to cause the resulting light  750  from the downward facing surface of the lens (e.g., see  FIG.  7   ) to be substantially uniform during operation of the apparatus. In yet another aspect, this spacing  732  may be approximately or equal to 8 millimeters. 
       FIG.  8 A  illustrates an example circular LED board  710  that can be included in a luminaire such as that illustrated in  FIG.  7    according to some inventive implementations, and  FIG.  8 B  illustrates an example rectangular LED board  710 B that can be included in a luminaire according to other inventive implementations (e.g., as discussed further below in connection with  FIGS.  12 A and  12 B ). As a general premise for both of the LED boards shown respectively in  FIGS.  8 A and  8 B , a spacing of the multiple LEDs  802  on the LED board causes the resulting light  750  from the downward facing surface of the lens (see  FIG.  7   ) to be substantially uniform during operation of the apparatus. In another aspect, both the spacing of the LEDs  802  on the LED board, and the spacing  732  between the LED board  710  and the lens  712 , contribute toward a substantially uniform distribution of the resulting light from the downward facing surface of the lens. In yet another aspect, the spacing of the LEDs  802  on the LED board, the spacing  732  between the LED board  710  and the lens  712 , and the thickness  736  of the lens respectively contribute toward a substantially uniform distribution of the resulting light. In yet another aspect, the spacing of the LEDs on the LED board, the spacing  732  between the LED board  710  and the lens  712 , the thickness  736  of the lens, and the type of material used in the lens (e.g., a milky white polycarbonate) respectively contribute toward a substantially uniform distribution of the resulting light. 
     In some inventive implementations, the LEDs are distributed uniformly on the LED board and spaced apart almost identically. With reference to  FIG.  8 A , the plurality of LEDs  802  are arranged on the LED board  710  as a plurality of concentric rings  804 . In one aspect, a distance  806  between any two adjacent concentric rings of the plurality of concentric rings is the same or approximately the same. As shown in  FIG.  8 A , at least a first ring  804 A of the plurality of concentric rings comprises a first group  802 A of the plurality of LEDs, and respective LEDs of the first group are spaced substantially evenly around the first ring  804 A. In some examples (e.g., as shown in  FIG.  8 A ) each ring of the plurality of concentric rings may comprise a different group of the plurality of LEDs, and respective LEDs of each different group are spaced substantially evenly around a corresponding ring of the plurality of concentric rings. In one example, an LED-to-LED spacing of the plurality of LEDs on the LED board is in a range of from approximately 7.5 millimeters to 8.5 millimeters. In another example, a circular LED board  710  has a total of 165 LEDs  802 . 
     With reference to  FIG.  8 B , the plurality of LEDs  802  on the rectangular LED board  710 B are arranged substantially uniformly across an entire surface or substantially the entire surface of the LED board. In one example, an LED-to-LED distance between neighboring LEDs of the plurality of LEDs is in a range of from approximately 7.5 millimeters to 8.5 millimeters; in one example, a horizontal distance  844  between horizontally neighboring LEDS is 7.5 millimeters, and a vertical distance  842  between vertically neighboring LEDS is 8.1 millimeters. As also shown in  FIG.  8 B , the LED board  710 B may also include one or more electrical traces terminating in electrical pads  850 , which may be used, for example, in connection with the test button embodiments discussed above in connection with  FIGS.  5  and  6   , and discussed further below in connection with  FIGS.  11 A-E . 
     It should be noted that the number and spacing of LEDs  802  on the circular or rectangular LED boards shown in  FIGS.  8 A and  8 B  can depend on factors such as the amount of lumens produced by the LEDs, the type of lens  712 , the desired overall light intensity of luminaire  700 , etc. In other implementations, an excessive amount of lumens than necessary is produced by the LEDs. Each of LEDs  802  can be implemented by, for example an XLamp LED from Cree, OLEDs, or PLEDs. 
       FIGS.  9 A and  9 B  illustrate aspects of how easily luminaire  700  according to implementations can be installed in an opening of a ceiling, for example. 
     As shown in  FIG.  9 A , first adapter ring  114  is attached to a junction box  902  using screws  904 . The adapter ring  114  may include one or more cutouts  906  to facilitate coupling of the luminaire/lighting apparatus to the adapter ring, as discussed below in connection with  FIG.  9 B . The junction box  902  can be already installed above an opening in the ceiling. Although a standard 4×4 junction box is shown in  FIG.  9 A , it should be apparent that many other types of junction boxes can be used, such as a type of junction box similar to junction box  402  described above. 
     Next as shown in  FIG.  9 B , operating power can be connected to luminaire  700  using wires and connectors in the junction box  902  (not shown). Then luminaire  700  can be snapped into adapter ring  114  and held into place by friction fit clips  706 . In one example, the friction fit clips  706  snap fit into the one or more cutouts  906  off the adapter ring  114 . It should be noted that junction box  902  is preferably installed and positioned above the ceiling line such that, when luminaire  700  is snapped in place as described herein, light source housing  708  of luminaire  700  appears to be surface mounted to the ceiling, although luminaire  700  is actually held in place by clips  706  and adapter ring  114 . Many other alternatives to friction fit clips are possible, such as spring clips, magnets, etc. 
       FIG.  10 A  is a side view of a luminaire similar to that shown in  FIG.  7   , according to some inventive implementations. The luminaire  700 A is substantially similar in multiple respects to the luminaire described above in connection with  FIGS.  7  through  9   . In one different aspect, the driver module cover  704  may include multiple fins  740  which, in some implementations, may facilitate heat dissipation from the luminaire. As shown in  FIG.  10 A , a ground wire  730  may be coupled to one or both of the housing  708  or the adapter ring  714 , and operating power may be coupled to the luminaire via wires  735 , to provide for a substantially uniform distribution of resulting light  750  from the luminaire during operation.  FIG.  10 B  is a front view (or downward facing view) of the luminaire shown in  FIG.  10 A , showing the appreciably thin perimeter formed by the front facing edge  720  of the sidewall  718  of the housing (e.g., having a thickness  726  on the order of less than 10 millimeters, or less than five millimeters, or less than three millimeters, or less than two millimeters, or less than 1.5 millimeters).  FIG.  10 C  is a back view (or upward facing view) of the luminaire shown in  FIG.  10 A , while  FIG.  10 D  is a back (or top) perspective view of the luminaire shown in  FIG.  10 A  and  FIG.  10 E  is a front (or bottom) exploded perspective view of the luminaire shown in  FIG.  10 A . 
     It should be noted that other implementations of luminaire  700  can include a test button such as described above in connection with  FIGS.  5  and  6   , for example attached to light source housing  708  and connected to electrical wires as described above. In particular, the luminaire may comprise a test button, coupled to the at least one sidewall of the housing and at least one electrical wire, to provide an electrical signal on the at least one electrical wire upon activation of the test button. To this end,  FIG.  11 A  is a side view of a luminaire similar to that shown in  FIG.  7   , according to some inventive implementations, which includes a test button similar to that shown in  FIG.  5   .  FIG.  11 B  is a front view (or downward facing view) of the luminaire shown in  FIG.  11 A ,  FIG.  11 C  is a back view (or upward facing view) of the luminaire shown in  FIG.  11 A ,  FIG.  11 D  is a back (or top) perspective view of the luminaire shown in  FIG.  11 A , and  FIG.  11 E  is a front (or bottom) exploded perspective view of the luminaire shown in  FIG.  11 A . 
       FIG.  12 A  is a front (or bottom) side perspective view of a rectangular-shaped luminaire  700 C according to some inventive implementations, and  FIG.  12 B  is a back (or top) side perspective view of the luminaire of  FIG.  12 A  according to some inventive implementations. The luminaire shown in  FIGS.  12 A and  12 B  may employ the rectangular LED board  710 B as shown and discussed above in connection with  FIG.  8 B . In other aspects, the luminaire  700 C may share one or more features or attributes as discussed above in connection with the circular luminaires; for example, the housing  708 C of the luminaire may have a depth  724  of sidewalls  718  on the order of less than one inch, and a perimeter thickness  726  of the front facing edge  720  of the housing sidewalls, constituting a perimeter around the front face  712 F of the lens  112 , may be on the order of less than 10 millimeters, or less than 5 millimeters, or less than 3 millimeters, or less than 2 millimeters, or less than 1.5 millimeters. 
     Although the present implementations have been particularly described with reference to preferred ones thereof, it should be readily apparent to those of ordinary skill in the art that changes and modifications in the form and details may be made without departing from the spirit and scope of the present disclosure. It is intended that the appended claims encompass such changes and modifications. 
     CONCLUSION 
     Those skilled in the relevant arts will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations may depend upon the specific application or applications for which the inventive teachings is/are used. It is to be understood that the foregoing implementations are presented primarily by way of example and that, within the scope of the appended claims and equivalents thereto, inventive implementations may be practiced otherwise than as specifically described and claimed. Inventive implementations of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure. 
     Also, the technology described herein may be embodied as a method. The acts performed as part of the method may be ordered in any suitable way. Accordingly, implementations may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative implementations. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law. 
     As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc. 
     In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.