Abstract:
A recessed lighting unit for mounting to a ceiling or a wall is provided. The recessed lighting unit includes an interface module having a through-duct. The through-duct may be coupled to a wire connector assembly to secure an electrical wire to the interface module and allow the electrical wire to reach a light source module. The wire connector assembly may be twisted and locked to the interface module without the use of tools. The lighting trim may be snapped on to an interface module through the use of a flexible retainer ring. The lighting trim may also be twisted and locked to an interface module without the use of tools. The present invention provides for a reduced set of components while ensuring adaptability and easy installation of lighting units. Other embodiments are also described and claimed.

Description:
FIELD 
       [0001]    An embodiment of the invention relates to a recessed lighting unit that is mounted behind a ceiling or a wall via its interface module. Other embodiments are also described. 
       BACKGROUND 
       [0002]    Recessed lighting units are typically installed or mounted to a structural member of a dwelling behind a ceiling or a wall. Recessed lighting units generally consist of various components of different shapes and sizes. For example, different styles of trims and light source modules may be used to accommodate different needs of consumers. 
         [0003]    Although current recessed lighting units come in a variety of shapes and sizes, switching between different components can be tedious and cumbersome. In particular, current systems require the removal of numerous screws and fasteners to change a single component of the system, such as a trim. Thus, there is a need for a lighting system that enables efficient interchangeability between different components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    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. 
           [0005]      FIG. 1  shows a side view of a recessed lighting unit and its components positioned partly inside a ceiling or a wall, including an interface module, lighting trim, heat sink, wire connector assembly, electrical wires, power source, and flexible conduit according to one embodiment. 
           [0006]      FIG. 2  shows a cross-section view of a recessed lighting unit and its components positioned partly inside a ceiling or a wall, including an interface module, lighting trim, heat sink, and light source module, according to one embodiment. 
           [0007]      FIG. 3  shows a perspective view of the interface module according to one embodiment. 
           [0008]      FIG. 4  shows an overhead view of the interface module according to one embodiment. 
           [0009]      FIG. 5  shows a side view of the interface module according to one embodiment. 
           [0010]      FIG. 6  shows a perspective view of an interface module according to another embodiment. 
           [0011]      FIG. 7  shows an overhead view of the interface module according to another embodiment. 
           [0012]      FIG. 8 a    shows a side view of the interface module according to another embodiment. 
           [0013]      FIG. 8 b    shows a cross section view of the interface module according to another embodiment. 
           [0014]      FIG. 9  shows two perspective views of female component of a wire connector assembly according to one embodiment. 
           [0015]      FIG. 10  shows a cross-section view of the female component of a wire connector assembly according to one embodiment. 
           [0016]      FIG. 11  shows two perspective views of a male component of the wire connector assembly according to one embodiment. 
           [0017]      FIG. 12  shows a cross section view of the wire connector assembly according to one embodiment. 
           [0018]      FIG. 13  shows two perspective views of a two-piece female component of a wire connector assembly according to another embodiment. 
           [0019]      FIG. 14  shows two cross-section views of a two-piece female component of a wire connector assembly according to another embodiment. 
           [0020]      FIG. 15  shows two perspective views of a male component of the wire connector assembly according to another embodiment. 
           [0021]      FIG. 16  shows a cross section view of the wire connector assembly according to another embodiment. 
           [0022]      FIG. 17  shows a side view of the male component of the wire connector assembly according to another embodiment. 
           [0023]      FIG. 18  shows a cross section view of a snap-on lighting trim assembly and its components, including an interface module, lighting trim, flexible retainer ring, and a reflector. 
           [0024]      FIG. 19  an overhead view, a side view, and a perspective view of a flexible retainer ring according to one embodiment. 
           [0025]      FIG. 20  shows a side view of a lighting trim with a recessed base and a retaining edge, according to one embodiment. 
           [0026]      FIG. 21  shows a side view of a lighting trim with a recessed base and a notch, according to another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Several embodiments are described with reference to the appended drawings are now explained. 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. 
         [0028]    A recessed lighting unit  1  is disclosed.  FIG. 1  shows a side view of one embodiment of a recessed lighting unit  1  that is positioned on a ceiling or wall  2  to provide light into a room. The recessed lighting unit  1  may have an interface module in the form of a housing  3  that is coupled to a lighting trim  4 , heat sink  5 , and a wire connector assembly  6  that is engaged to a through-duct  7  of the housing  3 . The lighting trim  4  of the recessed lighting unit  1  may cover the exposed edge of an opening or hole in the ceiling or wall  2 . The lighting trim  4  helps the recessed lighting unit  1  to appear seamlessly integrated into the ceiling or wall  2 . The housing  3  may be formed so that it may be coupled to lighting trims  4  of different sizes. The housing  3  serves to house a light source module  10  (shown in  FIG. 2 ) while allowing light from the light source module  10  to be emitted into a room through the opening in the ceiling or wall  2 . 
         [0029]      FIG. 1  also shows a magnified cross-section view of an electrical wire  8   a  which may be connected to a power source  9  that provides electricity. The power source  9  (which may include an electronic power supply circuit) is designed to ensure that the appropriate voltage and current are fed to the light source module  10  to enable the emission of light by the one or more light sources within the light source module  10 . In one embodiment, an AC to DC power conversion module with a 120 Volt AC input may be used whose input is connected to the AC wiring that is between the walls  2  or between a ceiling  2  and a floor in a dwelling (not shown). In one embodiment, the AC to DC power conversion module can be integrated as part of the light source module  10 . 
         [0030]    The electrical wire  8   a  may be surrounded by a flexible conduit  11 . There may be one or more insulating layers in between the electrical wire  8   a  and the flexible conduit  11 . The electrical wire  8   a  may be led through the flexible conduit  11  and attached to one or more electrical contacts at the end of the flexible conduit  11 . In one embodiment, flexible conduit  11  with electrical wire  8   a  may be a coaxial cable with one or more electrical contacts attached to its end, forming a coaxial connector  56   a.    
         [0031]    The flexible conduit  11  with one or more electrical contacts that forms a coaxial connector  56   a  may be engaged to the wire connector assembly  6  (which may have a female component  22  and a male component  23 , discussed in further detail below). A top end of the wire connector assembly  6  may have an electrical wire  8   b  attached to a coaxial connector  56   b . The electrical wire  8   b  may be surrounded by an insulating layer. The electrical wire  8   b  may be connected to the light source module  10  located inside the housing  3 . The electrical wire  8   b  may be led from the light source module  10  through a hollow interior of the wire connector assembly  6  and through the through-duct  7  of the housing  3 . When the flexible conduit  11  is engaged or coupled to wire connector assembly  6 , the electrical contacts of both electrical wires  8   a  and  8   b  would come into contact as the coaxial connectors  56   a  and  56   b  are engaged. The electrical contact of the electrical wire  8   a  attached to the flexible conduit  11  may be male or female, as long as it is complementary to the electrical contact of the electrical wire  8   b  attached to the wire connector assembly  6 . 
         [0032]      FIG. 2  shows a cross-section view of the recessed lighting unit  1  that is positioned on a ceiling or wall  2 . The recessed lighting unit  1  has a housing  3 , lighting trim  4 , heat sink  5 , and light source module  10 . The light source module  10  may include any electro-optical device or combination of devices for emitting light. For example, the light source module  10  may have as a single light source a light emitting diode (LED), organic light-emitting diode (OLED), or polymer light-emitting diode (PLED) installed on a carrier structure (e.g., a printed circuit board or flex circuit). In some embodiments, the light source module  10  may have multiple light sources (e.g., LEDs, OLEDs, and/or PLEDs). The light source module  10  receives electricity from a power source  9  such that the light source module  10  may emit a controlled beam of light into a room or a surrounding area. In one embodiment, the light source module  10  may include a set of electrical leads positioned in its carrier structure, for receiving electricity from the power source  9  via electrical contacts. The electrical leads of the light source module  10  may be soldering points that are traditionally coupling areas for electrical wires  8   b  that are directly soldered to the light source module  10  and directly connect the light source module  10  with the power source  9 . The light source module  10  may be surrounded by a light reflector  55  (shown in  FIG. 18 ) to direct the beam of light in the desired direction. 
         [0033]      FIGS. 3-5  show a perspective view, an overhead view, and a side view of one embodiment of an interface module in the form of a housing  3 . As shown in  FIG. 3 , the interface module is a housing  3  in which a top opening  12  and a bottom opening  13  are formed in an outer surface  14  of the housing  3 , wherein the top  12  and bottom  13  openings are open to a cavity  15 . Cavity  15  is defined in part by an inner surface  16  of the housing  3 . One or more screw holes  17  may be positioned on the housing  3  so that they are accessible through the top opening  12  or bottom opening  13 , which may receive screws for attaching a heat sink  5 , for example, to the housing  3 . 
         [0034]      FIG. 3  also shows the housing  3  having a through-duct  7  formed thereon, which may allow connection of an electrical wire  8   a  from a power source  9  located outside of the housing  3  to an electrical wire  8   b  connected to a light source module  10  located inside of the housing  3 . Connection of electrical wires  8   a  and  8   b  may be accomplished via a wire connector assembly  6  as described above. Through-duct  7  may be engaged to a wire connector assembly  6 , i.e. a male component  23  and female component  22  (in embodiments where there is no female component  22 , as described below, the male component  23  may be referred to as a wire connector  23 ). Thus, the through-duct  7  allows the flexible conduit  11  to be secured to the housing  3  through a wire connector assembly  6 . As shown in  FIG. 5 , the through-duct  7  has a first through-duct opening  18  in the outer surface  14  that leads to a second through-duct opening  19  in the inner surface  16 . The through-duct  7  forms a pathway between the first through-duct opening  18  in the outer surface  14  and the second through-duct opening  19  in the inner surface  16 . In one embodiment, the through-duct  7  may have an upper portion  20  and a lower portion  21 , between the first through-duct opening  18  and the second through-duct opening  19 . As shown in  FIG. 3  and  FIG. 5 , an embodiment of the housing  3  may have a lower portion  21  that forms an elbow between the upper portion  20  and the second through-duct opening  19 . In another embodiment, the pathway of the through-duct  7  need not have an elbow, and may be shaped to form a right circular cylinder, an oblique circular cylinder, or a polygonal tube. The pathway may have one or more bends. In the case of a right circular cylinder, the cylinder would be oriented horizontally relative to the housing  3 . In that case, it follows that the wire connector assembly  6  would also be positioned horizontally. Where the through-duct  7  is shaped as an oblique circular cylinder, shape of the wire connector assembly  6  may conform to the shape of the through-duct  7 . 
         [0035]      FIGS. 3, 4 and 5  show an embodiment where the through-duct  7  forms a bulge or protrusion that extends outwardly. However, it is not necessary to have a bulge or protrusion formed on the outer surface  14  in order to form through-duct  7 . In another embodiment, outer surface  14  may be made with increased thickness so that through-duct  7  is subsumed by the outer surface  14 , allowing for a smooth or uninterrupted outer surface  14  without a bulge or protrusion. In another embodiment, outer surface  14  may have a greater circumference so that the through-duct  7  is formed inside of the circumference. In these embodiments, the shape of the interior of through-duct  7 , with its upper portion  20  and lower portion  21 , may remain the same. 
         [0036]    In one embodiment, as shown in  FIG. 3 , the first through-duct opening  18  and the upper portion  20  may be completely or partially enclosed. Also, top opening  12  may be completely or partially enclosed.  FIG. 3  shows an embodiment where the first through-duct opening  18  and the upper portion  20  are partially enclosed.  FIG. 3  also shows an embodiment where the top opening  12  and the first through-duct opening  18  are contiguous with each other. In another embodiment, the top opening  12  and the first through-duct opening  18  need not be contiguous with each other. The first through-duct opening  18  need not have the same height as the top opening  12 . The first through-duct opening  18  may be higher or lower than the top opening  12 , and may have an angle. Also, the through-duct  7  need not be strictly vertical at the upper portion  20  and may be formed at an angle. 
         [0037]      FIGS. 6-8   b  show another embodiment of housing  3 . For example,  FIG. 6  shows the through-duct  7  having a first through-duct opening  18  in the outer surface  14  that leads to a second through-duct opening  19  in the inner surface  16  (as shown in  FIG. 8 b   ).  FIG. 8 b    also shows the through-duct  7  having an upper portion  20  and a lower portion  21 , between the first through-duct opening  18  and the second through-duct opening  19 . The lower portion  21  may form an elbow between the upper portion  20  and the second through-duct opening  19 . However, as described above, through-duct  7  need not have an elbow, and may be shaped to form a right circular cylinder, an oblique circular cylinder, or a polygonal tube. In this embodiment, the first through-duct opening  18  is completely enclosed. The top opening  12  is interrupted by the first through-duct opening  18  and through-duct  7 , but the top opening  12  and the first through-duct opening  18  are not contiguous with each other like the embodiment shown in  FIGS. 3-5 . 
         [0038]    As described above, the through-duct  7  may provide a pathway for the electrical wire  8   b  that is led from the light source module  10  inside of the cavity  15  of the housing  3  to connect with electrical wire  8   a  led from the power source  9 . The connection of the electrical wires  8   a  and  8   b  are secured to the housing  3  by the wire connector assembly  6  being engaged to the through-duct  7 . The wire connector assembly  6  may have a female component  22  ( FIGS. 9 and 10 ) and a male component  23  ( FIGS. 11 and 12 ). The female component  22  and male component  23  form a twist and lock mechanism where the male component  23  is inserted into the female component  22  and twisted into a locked position. The first through-duct opening  18  is shaped so that it is capable of having the female component  22  of the wire connector assembly  6  positioned inside upper portion  20 . The female component  22  may be keyed into upper portion  20  so that the female component  22  does not easily fall out of the upper portion  20 . The female component  22  may also be attached to the upper portion  20  by glue, screws, snapping mechanism, and the like. Once the female component  22  is positioned inside the upper portion  20 , the male component  23  can be engaged to the female component  22 . 
         [0039]      FIG. 9  shows two perspective views of female component  22 .  FIG. 10  shows a cross section view of female component  22 . The female component  22  of a wire connector assembly  6  has an exterior surface  24 , an interior surface  25 , a top opening  27 , and a bottom opening  28 .  FIG. 12  shows a cross-section view of the wire connector assembly  6  with the female component  22  and male component  23  engaged in a locked position through a twist and lock mechanism. The twist and lock mechanism is formed by the female component  22  having one or more locking engagements  26  formed on the interior surface  25  that are shaped to engage one or more locking members  30  formed on an exterior surface of the male component  23 . The male component  23  and female component are locked when the male component  23  is inserted into the female component  22  and turned about its longitudinal axis into a locked position. The locking member  30  and locking engagement  26  may have a variety of shapes, as long as they are formed to engage each other to form a locking mechanism. 
         [0040]    The female component  22  may have one or more retaining surfaces  31  that abut one or more retaining lips  32  of a male component  23  of the wire connector assembly  6  when the male component  23  of the wire connector assembly  6  inserted into the female component  22  and is turned about its longitudinal axis into a locked position. The one or more retaining surfaces  31  may abut one or more of retaining lips  32  of the male component  23  of the wire connector assembly  6  when one or more of the locking engagements  26  are engaged to one or more of locking members  30 . The one or more retaining surfaces  31  need not always be in direct contact with the one or more retaining lips  32 . There may be a small gap in between the retaining surface  31  and retaining lip  32 . While there may be a small gap, when the male component  23  is pulled upwards while in a locked position, the retaining lip  32  would contact the retaining surface  32  and prevent the male component  23  from being pulled out. In order to pull out the male component  23 , one must twist the male component  23  to unlock it from the female component  22  by twisting it longitudinally into an unlocked position. 
         [0041]      FIG. 11  shows two perspective views of the male component  23  of the wire connector assembly  6 , according to one embodiment. The male component  23  of the wire connector assembly  6  has a top end with an opening  29  and a bottom end with an opening  33 , and a hollow interior  34  running longitudinally from the top end to the bottom end. While not shown in  FIG. 11 , there may be an electrical wire  8   b  attached to the top opening  29  of the male component  23  that forms a coaxial connector  56   b , as described above. The male component  23  has one or more retaining lips  32  that extend outwardly from the bottom end. The male component  23  also has a grip section  35  formed on the exterior surface of the male component  23  of the wire connector assembly  6  between the top end and the bottom end. The grip section  35  may have one or more knurls  36  that provide friction for a user to twist the male component  23  by hand without the need for tools. While the use of knurls  36  is one way to provide friction, knurls  36  are not absolutely necessary, as there are other ways of providing friction. The grip section  35  may have ridges, sawtooth surface, or the like, that provide friction for a user&#39;s fingers. The male component  23  has one or more locking members  30  on the lower exterior surface  40  of the male component  23  of the wire connector assembly  6  between the grip section  35  and the bottom end. The locking members  30 , as explained above, may engage to locking engagements  26  of the female component  22 . 
         [0042]    Once the bottom end of the male component  23  is inserted into a top opening  27  of the female component  22  so that the retaining lips  32  pass beyond the bottom end of the female component  22 , the male component  23  may be twisted by hand by gripping the grip section  35 . Because the retaining lips  32  of the male component  23  must pass beyond the bottom end of the female component  22  (as shown in  FIG. 12 ), it is preferred that there be free space below the bottom end of the female component  22  inside the through-duct  7 . This free space allows the retaining lips  32  of the male component  23  to turn freely inside the through-duct  7  when the male component  23  is turned about its longitudinal axis. Once turned, one or more locking members  30  on the male component  23  engage one or more locking engagements  26 . Also, one or more retaining lips  32  of the male component  23  abuts one or more retaining surfaces  31  at the bottom end of the female component  22 . For example, when the male component  23  is inserted into the top opening  27  of the female component  22  and is turned clockwise or counterclockwise approximately 90 degrees, the one or more retaining lips  32  abut the one or more retaining surfaces  31 . This prevents the male component  23  from falling out or pulled out of the female component  22  once the wire connector assembly  6  is in locked position. As stated above, the one or more retaining surfaces  31  need not always be in direct contact with the one or more retaining lips  32 . 
         [0043]    In another embodiment (not shown in the figures), the need for a separate female component  22  may be eliminated by providing for the same or similar features of the female component  22  on the upper portion  20  of the though-duct  7  itself In this embodiment, the male component  23  may simply be referred to as a wire connector  23 . Like the female component  22 , upper portion  20  may have one or more locking engagements  26  formed on the interior surface  25  of the upper portion  20  that are shaped to engage one or more locking members  30  formed on an exterior surface of the wire connector  23  when the wire connector  23  is inserted into the upper portion  20  and turned about its longitudinal axis into a locked position. The upper portion  20  may have one or more retaining surfaces  31  that abut one or more retaining lips  32  of the wire connector  23  when the wire connector  23  is inserted into the upper portion  20  and is turned about its longitudinal axis into a locked position. The one or more retaining surfaces  31  may abut one or more of retaining lips  32  of the wire connector  23  when one or more of the locking engagements  26  are engaged to one or more of locking members  30 . Within the upper portion  20  of the through-duct  7 , there may be free space below the retaining surface  31  of the upper portion  20  of the through-duct  7 . The free space allows for the one or more retaining lips  32  of the wire connector  23  to turn freely inside the through-duct  7  when the wire connector  23  is turned about its longitudinal axis. 
         [0044]      FIGS. 13-17  show another embodiment of wire connector assembly  6  having a female component  22  and male component  23 .  FIGS. 13-14  show another embodiment of female component  22 , where the one or more retaining surfaces  31  that abut one or more retaining lips  32  of the male component  23  (shown in  FIGS. 15 and 16 ) are not at the bottom end of the female component  22 . Instead, the one or more retaining surfaces  31  are positioned below the top opening  27  within the female component  22 . In addition, a gap  37  is within the interior of the female component  22  below the one or more retaining surfaces  31 , which provides free space for the retaining lips  32  to move within the female component  22 . The top opening  27  of the female component  22  may be elongated in shape to allow the one or more retaining lips  32  to pass through the top opening  27 . In this embodiment, the female component here does not have locking engagements  26  as shown in the embodiment depicted in  FIGS. 9 and 10 . As shown in  FIGS. 13 and 14 , the female component  22  may be made from two separate pieces  22   a  and  22   b  that can be combined into a single piece  22 . Female component  22  (pieces  22   a  and  22   b ) may be held together by a snapping mechanism, glue, or the like. 
         [0045]      FIG. 15  shows a male component  23  that corresponds to the female component  22  shown in  FIGS. 13-14 . The one or more retaining lips  32  are not at the bottom end of the male component  23 , but in between the grip section  35  and the bottom end. In addition, the male component  23  does not have locking members  30  in between the grip section  35  and the bottom end of the male component  23 . In other respects, the male component  23  shown in  FIG. 15  is similar to that shown in  FIG. 11 . 
         [0046]      FIG. 16  shows a cross section view of wire connector assembly  6  with the male component  23  (shown in  FIG. 15 ) inserted into the female component  22  (shown in  FIGS. 13 and 14 ) and placed in a locked position. When the bottom end of the male component  23  is inserted into the top opening  27  of the female component  22 , the one or more retaining lips  32  of the male component  23  passes below the one or more retaining surfaces  31  of the female component  22 . Below the retaining surface  31 , the female component  22  has a gap  37  that provides sufficient space for the one or more retaining lips  32  of the male component  23  to turn freely inside the female component  22  when the male component  23  is turned about its longitudinal axis. Once the one or more retaining lips  32  of the male component  23  pass below the one or more retaining surfaces  31  of the female component  22  into the gap  37  and the male component  23  is turned about its longitudinal axis, the one or more retaining lips  32  of the male component  23  abuts one or more retaining surfaces  31 . For example, when the male component  23  is inserted into the top opening  27  of the female component  22  and is turned clockwise or counterclockwise approximately 90 degrees, the one or more retaining lips  32  abut the one or more retaining surfaces  31 . In this locked position, the male component  23  cannot be easily pulled out of the female component  22 . As mentioned above, in the embodiment shown in  FIGS. 13-17 , the female component  22  does not have one or more locking engagements  26  and the male component  23  does not have one or more locking members  30 . 
         [0047]    The upper exterior surface  39  of the male component  23  (or wire connector  23 ) may have multiple rounded threading bumps  38  that may be threaded into a flexible conduit  11 . The flexible conduit  11  may have threads on its interior surface that have a corresponding pitch in relation to the rounded threading bumps  38 .  FIG. 17  shows a side view of the male component  23  or wire connector  23  according to one embodiment. In between the top end of the wire connector  29  and grip section  35 , there are multiple rounded threading bumps  38  on the upper exterior surface  39  of the wire connector  23 . As shown in  FIG. 17 , in one embodiment, a first set  41 ( a, b, c ) of rounded threading bumps  38  are positioned longitudinally along the upper exterior surface  39  of the wire connector  23 . There is also a second set  42 ( a, b, c ) of rounded threading bumps  38  positioned longitudinally along the exterior surface  39  of the wire connector  23 . The number of threading bumps may vary. The rounded threading bumps  38  of the first set  41  and the second set  42  are on opposite sides of a longitudinal cross section plane of the wire connector  23 . The longitudinal distance between one rounded threading bump  41   a  and the next rounded threading bump  41   b , for example, of the first set  41  represents a pitch distance of a thread. Similarly, the longitudinal distance between one rounded threading bump  42   a  and the next rounded threading bump  42   b  of the second set  42  represents a pitch distance of a thread. The height difference between the rounded threading bumps  38  of the first set  41  and the second set  42  is half of the pitch distance. This allows the wire connector  23  or male component  23  to be twisted into a flexible conduit  11  that has threads of a corresponding pitch distance. The embodiment shown in  FIG. 11  may have the same arrangement of threading bumps. In another embodiment, as shown in  FIG. 1 , there may be multiple subsets of two threading bumps (instead of one threading bump) that conform to the thread on the interior surface of the flexible conduit  11 . 
         [0048]    A snap-on lighting trim assembly for a recessed lighting unit  1  is also disclosed.  FIG. 18  shows a cross section view of the snap-on lighting trim assembly including a housing  3 , flexible retainer ring  43 , a reflector  55 , heat sink  5 , and a lighting trim  4 . The housing  3  in which a top opening  12  and a bottom opening  13  are open to a cavity  15 . The cavity  15  may be defined in part by an inner surface  16  of a vertical sidewall of the housing  3 , wherein at least a portion of the inner surface  16  is cylindrical. Near the bottom portion of the housing  3 , there is an indentation  48  along the circumference of a horizontal cross-section plane of the inner surface  16 . The indentation  48  is capable of having a flexible retainer ring  43  positioned therein. 
         [0049]      FIG. 19  shows an overhead view, a side view, and a perspective view of a flexible retainer ring  43  according to one embodiment. The flexible retainer ring  43  is a part of a snap-on lighting trim assembly. The flexible retainer ring  43  is used for coupling a lighting trim  4  to an interface module housing  3  without the need for screws, adhesives, or tools. The flexible retainer ring  43  has alternating arcuate sections  44  and linear sections  45 , and two arcuate ends  46 , wherein the flexible retainer ring  43  generally forms an incomplete circle on a plane. The flexible retainer ring  31  may be resilient and made of metal or polymer. The flexible retainer ring  43  is positioned inside the indentation  48  of the housing  3  before the lighting trim  4  is engaged. 
         [0050]      FIG. 20  shows a side view of the lighting trim  4  of the snap-on lighting trim assembly according to one embodiment. The lighting trim  4  has a recessed base  49  that forms a closed curve, wherein an external surface of the recessed base  49  has a retaining edge  50  extending radially outward along a circumference of a horizontal cross-section plane of the recessed base  49 . While the flexible retainer ring  43  is positioned in the indentation  48  of the housing  3 , the recessed base  49  of the lighting trim  4  is inserted into the bottom opening  13  of the housing  3 . The flexible retainer ring  43  bends to allow the recessed base  49  into the bottom opening  13  until the retaining edge  50  passes the flexible retainer ring  43 . Because the flexible retainer ring  43  may be resilient, the linear sections  45  may approximately return to its original shape and contact the retaining edge  50  at its bottom, and prevent the lighting trim  4  from being pulled out of the housing  3 . It is understood that the flexible retainer ring  43  need not return to its exact original shape while holding the lighting trim  4  in place. No tools are required to engage the lighting trim  4  to the housing  3 . 
         [0051]    In another embodiment, there may be a lighting trim assembly  1  with a twist and lock mechanism.  FIG. 21  shows a side view of one embodiment of lighting trim  4 . Lighting trim  4  may have a recessed base  49  that has a notch  51  with a vertical opening portion  52  and a horizontal opening portion  53 . As shown in  FIG. 8 a   , housing  3  may have a side tab  54  extending outwardly from the exterior surface of the housing  3  that is shaped to engage a notch  51  on a lighting trim  4 . The lighting trim  4  is capable of being engaged to the housing  3  by inserting the side tab  54  into the vertical opening portion  52  and twisting the lighting trim  4  so that the side tab  54  is inserted into the horizontal opening portion  53  into a locked position.  FIG. 1  shows a lighting trim assembly  1  with the lighting trim  4  engaged to a housing  3  with the twist and lock mechanism in a locked position. 
         [0052]    While certain embodiments 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.