Patent Publication Number: US-11022259-B2

Title: Lighting module with separated light source and power supply circuit board

Description:
This application is a continuation application (CON) of and claims priority to U.S. application Ser. No. 15/167,682, filed on May 27, 2016, entitled “LIGHTING MODULE FOR RECESSED LIGHTING SYSTEMS,” which in turn claims priority to and the benefit of U.S. Provisional Application No. 62/168,510, filed on May 29, 2015, entitled “RECESSED LIGHTING SYSTEM WITH PACKAGING OF POWER SUPPLY CIRCUITRY AND OPTICS,” each of which applications is incorporated herein by reference in its entirety. 
     An embodiment of the invention relates to a recessed lighting system with improved packaging of power supply circuitry, light source, and optics. Other embodiments are also described. 
    
    
     BACKGROUND 
     Recessed lighting fixtures are typically installed or mounted into an opening in a ceiling or a wall. Modern recessed lighting fixtures generally consist of a trim, an LED-based light source module, an electronic power supply or driver circuit, and a legacy incandescent “can” in which the light source module and driver circuit are housed. The can and a junction box are mounted to a frame or platform, which in turn is attached to the internal structural member that is behind the wall, via hangar bars. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment of the invention in this disclosure are not necessarily to the same embodiment, and they mean at least one. Also, in the interest of conciseness and reducing the total number of figures, a given figure may be used to illustrate the features of more than one embodiment of the invention, and not all elements in the figure may be required for a given embodiment. 
         FIG. 1  shows an exploded view of a lighting module for recessed lighting systems, according to one embodiment of the invention. 
         FIG. 2  shows a side cross-section view of the embodiment if  FIG. 1 . 
         FIG. 3  shows a perspective view of the embodiment of  FIG. 1 . 
         FIG. 4  shows the lighting module installed as part of an example recessed lighting system. 
         FIG. 5  is an exploded view of a lighting module in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Several embodiments are described with reference to the appended drawings. While numerous details are set forth, it is understood that some embodiments of the invention may be practiced without these details. In other instances, well-known circuits, structures, and techniques have not been shown in detail so as not to obscure the understanding of this description. 
     An embodiment of the recessed lighting system described here is shown in a section view in  FIG. 4 . The system serves to illuminate a room, and is located behind a ceiling or a wall  31  of the room. The system has a lighting module whose housing  2  has been installed, for this particular example only, within a junction box  34  that is secured to joists of the building, behind the wall  31 , by a pair of hanger bars  37   a ,  37   b . Electrical wires  13  that are behind the wall  31  serve to bring mains electricity power into the housing  2  of the lighting module, through the rear end of the housing  2 . In this example, the wires  13  are routed through a knockout  33  of the junction box  34 . The recessed lighting system in this example also includes a trim  35  that is affixed to front end of the housing  2  of the lighting module. The trim  35  covers the exposed edge of the ceiling or wall  31  where an opening is formed for light to emerge from the front end of the housing  2 . Other applications of the lighting module include its installation within a legacy incandescent can or other enclosure, and the use of attachment mechanisms other than the hanger bars  37   a ,  37   b  to secure the system to other building structural members. 
       FIG. 1  shows an exploded view of the lighting module, in accordance with an embodiment of the invention. Not shown are the trim and the mechanism by which the recessed lighting system can be installed behind a wall or ceiling—such aspects may be entirely conventional as discussed above in connection with the example of  FIG. 4 , e.g. through the use of a legacy incandescent can and platform with hangar bars, or other suitable attachment mechanism. In one embodiment, the lighting module has a housing  2 , a power supply circuit board  3 , a light source  4 , a light source holder  5 , an optic  6 , a retaining ring  7 , a cover  8 , and one or more screws  9 . Not all of these components however are necessary for every embodiment of the invention, as discussed below. The housing  2  may be composed of any thermally conductive material, e.g., 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 thermally conductive plastics or ceramics. The housing  2  is generally cylindrical with an open rear end and an open front end that are defined at opposite ends of a sidewall  22  that forms a closed loop as shown (surrounding an interior cavity). Note however that while  FIG. 1  shows the sidewall  22  as having a circular cross-section, other shapes are possible including elliptical and polygonal. The exterior or outside surface of the sidewall  22  may include features that improve a heat sink function, such as fins  23  that may entirely surround the housing  2  as shown. These fins  23  are passive components that serve to cool the housing  2  and any nearby heat producing or heat sensitive components such as the power supply circuit board  3 , the light source  4  and the optic  6 . The fins  23  may be integrally formed, e.g., manufactured by being cast into the housing  2 . 
     As also seen in the cross-section view of the module in  FIG. 2 , the interior cavity of the housing  2  is divided, in a longitudinal direction (up/down), into two chambers or portions, namely a rear or top cavity  11  that is directly above a front or bottom cavity  12 , by a partition  10  that extends in a lateral direction (left/right) joining a left portion of the sidewall  22  to a right portion thereof. The top cavity  11  extends to the open rear end, while the bottom cavity extends to the open front end of the housing  2 . Inside the top cavity  11  there is a power supply circuit board  3  that has an input, which is connected to a number of electrical wires  13  (e.g., at least a pair) which emerge from the housing  2  and serve to deliver mains electricity power. The wires  13  serve to deliver mains electricity power, for example 120V/240 VAC power, to the power supply input of the power supply circuit board  3 . The power supply circuit board  3  also has a power supply output. A number of electrical wires  16  (e.g., at least a pair) are connected at one end to the power supply output, and at another other end to the light source  4 , and in between those ends the wires  16  are routed through an opening (not shown) in the partition  10 . 
     In one embodiment, once the power supply circuit board  3  is positioned inside the top cavity  11  through the open rear end of the housing  2 , the cover  8  may be placed on top of the sidewall  22 , to thereby completely enclose the top cavity  11  (with the power supply circuit board  3  inside.) The cover  8  may be a plate that is shaped to entirely cover the open rear end of the housing. In one embodiment the cover  8  is attached to the housing  2 , by being directly fastened to the island  17  which may be viewed as an extension of the housing  2 , as shown in  FIG. 2 . In that case, the cover  8  may be entirely solid except for one or more screw hole openings  28  (two are shown, only as an example) and a wire opening  14 . The screws  9 , respectively, are inserted through the openings  28  for securing the cover  8  to the top of the island  17  (although other fasteners or other mechanisms that serve to retain the cover  8  in the closed position as shown can be alternatively used, including an arrangement that only requires one screw for example.) The electrical wires  13  are routed through the opening  14 , from one end of their connections at the power supply circuit board  3  inside the top cavity  11  to another end that is outside of the housing  2  and connected to a power source (e.g. building electrical power grid.) Also, in the case where the cover  8  is to be relied upon as a further heat sink element of the lighting module, a number fins  23  may be formed on the outside (or top) face of the cover  8  to enhance the heat sink function. 
     As shown in  FIG. 2 , the partition  10  serves as a physical barrier between a) the power supply circuit board  3  and b) the light source  4  and the optic  6 . In the example shown, the partition  10  is not entirely flat or horizontal, but instead has a central portion from which the rest slopes downward as shown. In one embodiment, the partition  10  is entirely solid and completely isolates the top cavity  11  from the bottom cavity  12  except for an opening (not shown) through which the wires  16  pass (and which carry electrical power from an output of the power supply circuit board  3  to the light source  4 .) This provides a fire barrier within the hole that is formed in the ceiling or wall (for the recessed lighting system), between the room and the building space between walls and ceilings, which is a typical requirement with recessed lighting systems that need to comply with building and safety codes/regulations. In addition, the partition  10  may reduce the risk of electrical shock when a user is reaching into the housing  2  through the open front end, because any conductors in the power supply circuit board  3  that carry for example 120/240 Vac are shielded against by the partition  10 . 
     In one embodiment, the island  17  is provided to enhance the heat sink function of the lighting module and to secure the cover  8  to the housing  2 . The island  17  is joined to, and protrudes or rises into the top cavity  11  from, the rear face of the partition  10  (as shown.) The island  17  may have a variety of shapes (e.g., circular cylinder, polygon cylinder, oval cylinder, etc.). In one embodiment (as shown in  FIG. 1 ), the island  17  is a circular cylinder with a flat top, and that is received (height-wise or lengthwise) into and extends past a face-to-face opening  18  of the power supply circuit board  3 . The face-to-face opening  18  may be a hole that has been cut through the opposing faces of the board  3 , resulting in a structure that looks like a washer. The island  17  has one or more screw holes  19  in its top that are to be aligned with the openings  28  in the cover  8 , to receive one or more screws  9  (or other fasteners), respectively, to fasten the cover  8  to the island  17 . Other ways of fastening the cover  8  to the partition  10  may be possible. 
     In one embodiment, the island  17  may be formed integrally with the partition  10 , e.g., as a single cast metal piece, and wherein the periphery of the partition  10  may be attached, e.g., bonded, to the inside surface of the sidewall  22 . Alternatively, the partition  10  and the island  17  may both be integrally formed with the sidewall  22 , as a single-piece housing  2  (e.g., as a single cast metal piece.) The island  17  may be located at the center of the housing  2  as shown, or at the common center axis of the housing  2  (which center axis is shared by the open rear end and by the open front end of the housing  2 .) The island  17  may serve to enhance the heat sink function of the lighting module, by conducting the heat that has been generated by the power supply circuit board  3  and/or by the light source  4 , through the partition  10  and then outward to the sidewall  22 . In addition, in one embodiment, the island  17  is tall enough so that its top abuts the bottom face of the cover  8 , so that the island  17  may perform heat transfer directly to the cover  8 , e.g., through a thermal paste layer that joins or is directly sandwiched between the top (or top surface) of the island  17  and the inside (or bottom) face of the cover  8 . 
     The power supply circuit board  3  has the needed light source driver circuit components installed thereon, that are designed to ensure that the appropriate voltage and current are fed to the light source  4  to enable the emission of light by one or more light emitting elements of the light source  4 . The components of the driver circuit may be installed on both the top and bottom faces of the board  3  as shown. The driver circuit draws and converts power through the wires  13 , and then supplies its output power through the wires  16 , to the light source  4  (and thus powers the light source  4  to emit light.) The driver may be any type of electrical power supply circuit, including power supplies that deliver an alternating current (AC) or a direct current (DC) voltage to the light source  4 . For example, the driver may drop the voltage of its input power to an acceptable, safe for a human touch level in its output power, for operating the light source  4  (e.g., from 120V-277Vac to 36 Vdc-48 Vdc). The output power may be delivered to the light source  4  through a removable connector, a permanent connector, or soldered leads, at the power supply circuit board  3  and on a carrier or substrate of the light source  4 . 
     As shown in  FIG. 1 , the power supply circuit board  3  has a face-to-face opening  18  therein that may be entirely surrounded by the driver circuit components of the printed circuit board  3  (as opposed to being located at the edge or periphery of the board  13 ). In one embodiment, the opening  18  is shaped and sized so that when the island  17  is passed through it, the fit between the side surface of the island  17  and the inner edge of the board  13  along the opening  18  prevents the board  3  from moving laterally (left/right), inside the housing  2 , to thereby prevent the outer edge of the board (along the periphery) from touching the inside surface of the sidewall  22 . 
     In one embodiment, where the cover  8  is to be used to close off the open rear end of the housing  2 , at least two electrically insulating spacers (not shown) may be mounted to the top face of the power supply circuit board  3 . Another two or more electrically insulating spacers (not shown) may be mounted to the bottom face of the board  3 . The cover  8  can then be installed over the open rear end and secured to housing  2 , resulting in the spacers being compressed between the partition  10  at one end and the cover  8  at another end, which fixes the height position (in the up/down direction) of the board  3  within the upper cavity  11  of the housing  2 , at a desired height between the partition  10  and the cover  8 . 
     Another embodiment of the lighting module is shown in the exploded view of  FIG. 5  in which all of the elements shown may be similar to those in  FIG. 1  and in  FIG. 2 , except for the addition of a cup  41 . In this embodiment, there may be a gap between the side surface or sidewall of the island  17  and the inner edge of the power supply circuit board  13  that defines the opening  18  which could allow the board  3  to move around inside the housing so as to possibly touch the sidewall  22 , the partition  10 , or the cover  8  (if the latter is being used.) The cup  41  is provided to limit such movement of the board  3 , both longitudinally (up/down) as well as laterally (left/right or sideways.) The cup  41  may be made of an electrically insulating material, such as plastic or polycarbonate, which may serve to insulate the board  3  from the housing  2  and the cover  8 , especially when the latter are made of a conductive material such as a metal (e.g., as a cast, aluminum piece.) The outside height of the cup  41  may be less than the height of the sidewall  22  that is between the top surface of the partition  10  and the top of the sidewall  22 , so that the cup  41  can fit entirely inside the upper cavity  11  of the housing  2  (in the orientation shown.) The inside width of the cup  41  may be the same as or slightly greater than the outer width of the board  3 , so as to allow the board  3  to be inserted into the cup  41  through its mouth (in the orientation shown in  FIG. 5 .) At least two separate openings may be formed in the base of the cup  41 , namely one through which the wires  13  are passed, and another opening  42  that is large enough for the island  17  to be inserted therein (in the height direction as shown.) For example, the opening  42  may have the same shape and be about the same size as the opening  18  in the board  3 . The opening  42  is located in the base of the cup  41  so that when the board  3  is inserted into the cup  41  the opening  18  of the board  3  is aligned with the opening  42 . 
     The wall of the cup  41  has a snap lock (or snap fit) mechanism formed therein, to retain the board  3  in position. For example, at least two flaps  44  may be formed in the wall and that are positioned in the same plane but at different radial positions about the center longitudinal axis of the cup  41 . As an example, each flap  44  may be formed as a partial, generally rectangular or square cut out portion of the wall such that the flap  44  remains connected with the wall on one of its sides while its other three sides are not. The flap  44  as formed is angled inward, i.e. towards the center longitudinal axis of the cup. As the board  3  is inserted into the cup (in the orientation shown), its top face at its outer periphery pushes against and pivots the flap  44  outward until the outer periphery clears the flap  44 , at which point the flap  44  “pops” back (inward) and over the bottom face of the board  3 . The flap  44  then stays in that inward position, by virtue of being made of a semi-rigid material for example, thereby holding the board  3  fixed in the height direction (up/down direction) between the flap  44  and the base of the cup  41 . The cup  41  with the board  3  held therein is then inserted “upside down” into the upper cavity  11 , in the orientation shown, through the open rear end of the housing  2 , until for example the brim of the cup  41  lands on the top face of the partition  10 . In one embodiment, the flaps  44  are positioned at a height such that the tallest electronic circuit components that are mounted onto the bottom face of the board  3  do not touch the top face of the partition  10 , when the cup  41  has been inserted into the housing  2  to the full extent. In one embodiment, the height of the cup  41  may be defined so that when the brim of the cup is resting against the partition  10 , the outside of the base of the cup is only slightly below the top of the island  17 . This allows the cover  8  to then be placed into position covering the open rear end of the housing  2 , with the bottom face of the cover  8  being joined to the top of the island  17  (e.g., through a layer of thermal paste) to promote heat transfer between the island  17  and the cover  8 , and then secured in that position by installing the screw  9  (through the cover  8  and into its corresponding hole  19  in the island  7 .) 
     In yet another embodiment, the island  17  is not provided. In that case, to secure the cover  8  to the housing  2 , a snap lock mechanism, a thread type, or a twist and lock mechanism may be provided on the sidewall  22  of the housing  2  (while a complementary portion is provided on the cover  8 .) In that case, the cup  41  (which serves as an insulator and holder for the board  3 ) would not need to have the opening  42  in it. Also, the power supply circuit board  3  would not have to have the opening  18  in it. The board  3  could still be held inside the cup  41  in the manner described above (e.g., using the flaps  44 ), and the cup  41  could still be held by compression between the cover  8  and the partition  10 . In that case, centering of the board  3  inside the upper cavity  11  would depend on centering the cup  41 , by for example making the cup  41  to have just the right width to fit inside the upper cavity  11  while lightly abutting the inside surface of the sidewall  22 . 
     Assembly of the lighting module (as shown in  FIG. 1  or in  FIG. 5 ) may continue with inserting the light source  4  into the bottom cavity  12 , through the open front end of the housing  2 . The light source  4  may be composed of a carrier or substrate on the bottom face of which one or more light emitting devices are installed. The light emitting devices may be any electro-optical device, or combination of different electro-optical devices, for emitting visible light to illuminate a room, whose required voltage levels are “safe” even if any of their exposed terminals come into incidental contact with a human. For example, the light emitting devices may be “low voltage” light emitting diode (LED) elements, e.g., LED devices, organic LED (OLED) devices, and polymer LED (PLED) devices. In some embodiments, the light source  4  may have multiple LED elements connected in series, yet is still deemed a low voltage LED-based light source. The light source  4  receives electricity from the board  13 , as described above, such that the light source  4  may emit a controlled beam of light into a room or surrounding area. The driver circuitry (in the power supply circuit board  3 ) is designed to ensure that the appropriate voltage and current are fed to the light source  4 . In one embodiment, light emitted by the light source  4  through the open front end of the housing, to illuminate a room, is produced only by light emitting diode (LED) elements of the light source  4  that require input power at less than 50 Volts. 
     The light source  4  may be attached to the partition  10  by being held or captured between a light source holder  5  and a portion of the bottom face of the partition  10 , which portion may be directly underneath the island  17  as shown. An indented region may be formed on the back face of the holder  5 , as best seen in  FIG. 1 , into which the light source  4  is fitted as shown, so as to limit the compression forces that may be imparted on the carrier of the light source  4  (as it is sandwiched between the holder  5  and the bottom face of the partition  10 .) A layer of thermal paste may be applied directly to the portion of the bottom face of the partition  10  or to the top face of the carrier of the light source  4 , so as to enhance heat transfer from the light source  4  to the island  17 . The light source holder  5  may be affixed to the partition  10  using screws or other fasteners, a snap lock mechanism, a twist and lock mechanism, or glue. In the example shown here, screws can be inserted through the two holes  26  in the holder  5  which are aligned with the two holes  20 , respectively, in the partition  10 . The light source holder  5  has an opening  21  that is positioned inward of the holes  26 , and through which light from the emitting devices will emerge (and then enter the room through the optic  6  that is secured to the housing  2  in front of the holder  5 .) The light source holder  5  may also have an open portion (that may be shared with the opening  21 ) through which the proximal ends of the wires  16  can be electrically connected (e.g., soldered) to electrical terminals that are exposed on the bottom face of the carrier of the light source  4 . The carrier has wire traces (not shown) that route electrical power from the terminals to the one or more light emitting devices that are installed on the bottom face of the carrier. The distal ends of the wires  16  are electrically connected to the outputs of the power supply circuit board  3 . There may be an opening (not shown) in the partition  10  through which the electrical wires  16  are led, from their electrical connection at the light source  4  (in the bottom cavity  12  of the housing  2 ), to their electrical connection at the power supply circuit board  3  that is in the top cavity  11 . 
     The housing  2  also has a flange or lip  24  that may extend laterally outward from the sidewall  22  and surrounds the open front end of the housing  2  as shown. The lip  24  includes features that serve to couple the housing  2  to a trim (not shown), especially via a twist and lock mechanism that does not require the use of separate tools or other devices. The trim may have features that that are complementary to the features of the lip  24  shown in  FIG. 2 , that form the twist and lock mechanism. The twist and lock mechanism features may include a groove or slot  29  on the lip  24  of the housing  2 , which is designed to produce a friction fit against corresponding or mating structures of the trim, to create a twist-and-lock friction connection. In other embodiments, however, the trim may be coupled to the housing  2  using a resin (a permanent attachment), clips, screws, bolts, or clamps. In one embodiment, different diameter trims may be capable of being coupled to the housing  2 . The size and design of the trims may depend on the size of the ceiling or wall hole behind which the recessed lighting system is to be fitted, to conceal the exposed wall or ceiling edge that defines the hole. The recessed lighting system may include two or more trims of different sizes to cover ceiling or wall openings of different sizes. The trim may need to meet the aesthetic demands of the consumer. The trim may be made of aluminum plastic polymers, alloys, copper, copper-tungsten pseudoalloy, AlSiC (silicon carbide in aluminum matrix), Dymalloy (diamond in copper-silver alloy matrix), and E-Material (beryllium oxide in beryllium matrix). 
     Still referring to the housing  2 , the lip  24  of the housing  2  may also have one or more fastener openings  25  formed therein that allow the housing  2  to be attached to a junction box (e.g., an octagonal junction box) or another suitable enclosure, using screws or other suitable fasteners. The top end of the housing  2  (where the cover  8  has been attached) may be inserted into the junction box while the one or more openings  25  of the lip  24  are aligned with corresponding screw holes of the junction box, and then screws can be inserted into the openings  25  and screw holes of the junction box to fasten the housing  2  to the junction box. 
     As shown in  FIG. 1 , the recessed lighting system may include an optic  6  that is positioned in the optical path of the emitted light from the light source  4 , and may adjust the way light emitted by the light source  4  is directed into or focused inside the room in which the system is installed. In one embodiment, the optic  6  may be a separate piece, i.e., separate from the housing  2  and separate from a retaining ring  7  which is used to attached the optic  6  to the housing  2  (as described further below.) The optic  6  includes a reflector portion as shown, that has a closed, curved surface which is ring-like or annular, with a central opening that is aligned with the light source  4 . The rear face of the reflector portion along its inner periphery may abut the bottom (or front) face of the light source holder  5 . The reflector portion may be formed of any fire retardant material, including steel, aluminum, metal alloy, calcium silicate, or other similar materials. The reflector portion may be formed to redirect the emitted light and can have any shape that serves this purpose. For example, the shortest path along the closed, curved surface of the reflector portion between its inner periphery (that defines the central opening) and its outer periphery may be a straight line or it may be a curved line (e.g., a elliptic curve, a parabolic curve, circular curve. The front surface of the reflector portion (facing the room) which lies between the inner and outer peripheries may be coated with a reflective material or include one or more reflecting elements that assist in the adjustment of light emitted by the light source  4 . For example, the reflective portion may be coated with a shiny enamel or include one or more mirrors or retroreflectors or a microcellular polyethylene terephthalate (MCPET) material to adjust the path of the light emitted by the light source  4 . 
     In one embodiment, a lens/filter  27  which may be a lens only, a filter only, or a combination of the two, is attached to the outer periphery of the reflector portion—see also  FIG. 3 . The lens/filter  27  may serve as a protective barrier for the light source  4 , and may shield the light source  4  from moisture or inclement weather. The lens/filter  27  also adjusts the emitted light that illuminates the room, via focusing and/or diffusion for example. The lens/filter  27  may be made of any at least partially transparent material, including glass and hard plastics. The reflector portion and the attached lens/filter  27  may form a single, indivisible unit of the optic  6 . In one embodiment, the optic  6  may be interchangeable so that an adjustable light spread can be had in the field, by detaching the retaining ring  7  and then replacing the optic  6  with a different one. Different instances of the optic  6  may be produced, where each instance has a different combination of the lens/filter  27  and the reflector portion, so as to change the spread, angle, or other optical characteristics associated with the optic  6 . The optic  6  may also have adjustable alignment features in which the orientation or position of the reflector portion or the lens/filter  27  can be changed in the field. 
     As shown in  FIG. 1  and in  FIG. 2  (and also in  FIG. 5 ), the retaining ring  7  is attached to the housing  2 , at the open front end of the housing  2 , so as to hold or retain the optic  6  within the bottom cavity  12  of the housing  2 . The mechanism for attaching the retaining ring  7  to the housing may be a twist and lock mechanism, with complementary features of the twist and lock mechanism being formed on a) the outside of the ring  7 , such as a boss  30  as shown in  FIG. 1 , and b) the portion of the inside surface of the housing  2  that is next to the extended lip portion  24 , as best seen in  FIG. 2 . In this manner, the ring  7 , and thus the optic  6 , may be installed into and removed from the housing  2  without requiring any tools. In one embodiment, where otherwise the optic  6  might, in one embodiment, fall out of the housing  2  due to gravity alone). 
     While certain embodiments of the lighting module have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that the invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. The description is thus to be regarded as illustrative instead of limiting.