Abstract:
A modular system of LED lighting provides for the use of LED lighting modules that are connectable using a interconnect module that provides structural rigidity. The LED lighting modules provide a sealed connection between adjoining LED modules, allowing their use under environmental conditions that may involve transient exposure to liquids such as water. Variants of the module allow using interconnect modules that allow flexible connections where rigidity is of less concern. Mounting features integrated into the interconnect modules allow mounting the interconnected lighting units to an installation site as desired.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to the field of lighting systems utilizing light emitting diodes (“LEDs”), and in particular to a modular system for connecting lighting modules. 
       BACKGROUND ART 
       [0002]    Luminescent lighting displays, such as cabinet and flat panel signs, billboards, storefront awnings, and the like, often utilize illuminated signage fixtures commonly referred to as “channel letters” to produce a variety of lighting effects. Such channel letters typically comprise one or more channels, with internal light sources, each channel being shaped as a letter, number, design, or a combination thereof, and each generally having a rigid, translucent plastic cover. The term “lighting displays” also includes architectural lighting, interior lighting for homes and businesses, and other applications where it is desirable to provide evenly bright, long-lasting lighting with low power requirements. 
         [0003]    The common light sources, such as fluorescent lamps, halogen lamps, gaseous discharge xenon lamps, neon lights, and the like, have been used in such lighting displays and fixtures, such as channel letters, for illuminated signs. These types of light sources typically convert a significant portion of the power or energy consumed into heat that may be difficult to dissipate from a sealed display, and may damage electronic circuitry contained therein, or may be inappropriate for temperature-controlled environments. In addition, these lamps consume significant amounts of power, and typically require large power supplies or transformers. Some of these lamps and power supplies also generate substantial electromagnetic emissions, which may interfere with radio communications and thus can be problematic in certain applications and locations. Finally, these light sources may have a relatively short operational life, necessitating frequent replacement. 
         [0004]    As a result of these known problems with traditional lighting sources, there are many potential areas of application in luminescent lighting displays for LEDs. This is because LED systems, among other advantages, enable creation of a lighting display that: (1) is far more durable than present sources in common use; (2) is modular and, therefore, more adaptable; (3) has a long life span; (4) is portable; (5) operates in damp conditions; (6) uses lower voltage, producing a light display that is much safer to use, install, service and less expensive to operate; (7) generates less heat; and (8) is more durable than glass-based lamps. 
         [0005]    Some potential uses for LED lighting have been limited because of various problems, including a need for rigidity in the LED modular lighting unit and environmental conditions such as possible transient exposure to liquids. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0006]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of apparatus and methods consistent with the present invention and, together with the detailed description, serve to explain advantages and principles consistent with the invention. In the drawings, 
           [0007]      FIG. 1  is a perspective view of a modular system of LED modules and rigid and flexible interconnects according to one embodiment. 
           [0008]      FIG. 2  is a perspective view of a portion of the modular system of  FIG. 1  with only the rigid interconnect, illustrating an end of one of the LED modules according to one embodiment. 
           [0009]      FIG. 3  is a perspective view of a portion of an LED module and an interconnect according to one embodiment. 
           [0010]      FIG. 4  is a perspective view of LED modules, an interconnect, and an end cap according to one embodiment. 
           [0011]      FIG. 5  is a sectional view of an interconnect connecting two LED modules according to one embodiment. 
           [0012]      FIG. 6  is a perspective view of an LED module according to one embodiment. 
           [0013]      FIG. 7  is a side view of an LED module according to one embodiment. 
           [0014]      FIG. 8  is a cross-sectional view of the LED module of  FIG. 7 . 
           [0015]      FIG. 9  is a perspective view of a modular system of LED modules and rigid and flexible interconnects according to another embodiment. 
           [0016]      FIG. 10  is a perspective view of a portion of the modular system of  FIG. 9  with only the rigid interconnect, illustrating an end of one of the LED modules according to one embodiment. 
           [0017]      FIG. 11  is a perspective view of a portion of an LED module and an interconnect according to one embodiment. 
           [0018]      FIG. 12  is a perspective view of LED modules, an interconnect, and an end cap according to one embodiment. 
           [0019]      FIG. 13  is a sectional view of an interconnect connecting two LED modules according to one embodiment. 
           [0020]      FIG. 14  is a perspective view of an LED module according to one embodiment. 
           [0021]      FIG. 15  is a side view of an LED module according to one embodiment. 
           [0022]      FIG. 16  is a cross-sectional view of the LED module of  FIG. 15 . 
           [0023]      FIG. 17  is a top and bottom view of the interconnect of  FIG. 9 . 
           [0024]      FIG. 18  is another perspective view of the modular system of  FIG. 9 . 
           [0025]      FIG. 19  is a bottom perspective view of the module system of  FIG. 18 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without these specific details. In other instances, structure and devices are shown in block diagram form in order to avoid obscuring the invention. References to numbers without subscripts or suffixes are understood to reference all instance of subscripts and suffixes corresponding to the referenced number. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment. 
         [0027]      FIG. 1  is a perspective view illustrating a modular system  100  of LED lighting modules and interconnects according to one embodiment. As illustrated in  FIG. 1 , two LED modular lighting units  110  are connected by an interconnect  120  that both provides electrical conductivity between two LED modular lighting units  110  and provides rigidity to the connected LED modular lighting units  110 . In some embodiments, as many as  16  LED modular lighting units  110  may be connected in a rigid string of LED modular lighting units. In addition, the interconnect  120  may seal an interconnection area so that the interconnection between the LED modular lighting units  110  prevents ingress of dust and is water tight for up to for temporary immersion in up to 1 m of water and carries an Ingress Protection Rating of IP 67. 
         [0028]    Also illustrated in  FIG. 1  is a flexible interconnect  130  formed of a one-sided interconnect  132  and a one-sided interconnect  134  connected by a flexible cable  136  that provides electrical conductivity between an LED modular lighting unit  110  connected to interconnect  132  and another LED modular lighting unit  110  (not shown) connected to interconnect  134 . Thus, the system of LED modular lighting units  110  and interconnects  120  and  130  provides a designer of a lighting installation with the ability to link together LED modular lighting units  110  in both rigid and flexible configurations. One of the one-sided interconnects  132  and  134  may provide a circuit board and female connector for connecting with a male connector of the LED modular lighting unit  110  and the other of the one-sided interconnects  132  and  134  provides a circuit board and male connector for connecting with a female connector of the LED modular lighting unit  110 . The interconnects  132  and  134  are otherwise configured as portions of the full interconnect  120  and are not otherwise described herein. 
         [0029]    Although only a straight line rigid interconnect  120  is illustrated in  FIG. 1 , rigid interconnect  120  could be formed with angular connections to allow rigid interconnections at any desired angle. In such an angular interconnect, instead of the LED modular lighting units  110  directly interconnecting as in the straight line interconnect  120  illustrated in  FIG. 1 , the LED modular lighting units  110  interconnect with circuit boards in each and of the angular rigid interconnect which are electrically connected with each other. 
         [0030]    The interconnect  120  and the interconnects  132  and  134  may be formed of any desired material, such as a polycarbonate material. In one embodiment, the interconnect  120  and interconnects  132 / 134  are formed by injection molding. A central portion of the interconnect  120  is a generally round overmolded housing into which male and female ends of the LED modular lighting units  110  are inserted to form a sealed connection between the LED modular lighting units  110 . In one embodiment, the interconnect  120  is formed of a material having a hardness of at least Review70 durometer to provide sufficient stiffness for the interconnected LED modular lighting units  110 . Although illustrated as generally round or cylindrical in shape in  FIG. 1 , other shapes could be used as desired. 
         [0031]    Connectivity to a power source may be provided by a pigtail unit that plugs into one end of a LED modular lighting unit  110 , an interconnect  120 , or one of the split units  132 / 134  and which is connected to a power source. Alternatively, a power supply may (not shown) be used with one of the split units  132 / 134  formed as part of the power supply unit. 
         [0032]    Additional details are illustrated in the perspective view of  FIG. 2 . To provide secure insertion of the LED modular lighting units  110  into the interconnect  120 , snap fittings  210  (as illustrated holes) may be provided in the interconnect  120  to mate with snap fittings  610  ( FIG. 6 ) on the LED modular lighting units  110  so that upon full insertion of the LED modular lighting unit  110  into the interconnect  120 , the snap fittings  210  and  610  engage for removable but secure connection. A female end connector of the LED modular lighting unit  110  is illustrated in  FIG. 2 . A similar male end connector is formed on the opposite and of the LED modular lighting unit  110  but is not visible in  FIG. 2 , because it is inserted into the interconnect  120 . 
         [0033]    In one embodiment, illustrated in  FIG. 3 , the interconnect  120  may be configured for mounting to another surface (not shown), such as a wall. In one embodiment, the mounting feature includes a slot  310  formed in one end of a base of the interconnect  120 , providing an opening for inserting a screw or other type of fastener  320  through the slot  310  for attaching the interconnect  120 , and thereby that portion of the modular system  100 , to the other surface. In such an embodiment, the bottom portion of the interconnect  120  preferably has a flat surface for mounting flush against the other surface. In some embodiments, instead of using a fastener to hold the interconnect  120  to another surface, adhesives or any other desired way of connecting the interconnect to the other surface may be used. As illustrated in  FIG. 3 , when the mounting screw  320  is used to attach the interconnect  120  to an external surface, once the LED modular lighting units  110  are inserted into and connected through the interconnect  120 , the mounting screw or other fastener  320  is hidden from view and not accessible. 
         [0034]      FIG. 4  illustrates an end cap  410  that may be used at an end of a string of LED modular lighting units  110 . The end cap  410  snaps on to the LED modular lighting unit  110  as described above and provides a covering for the male or female connectors of the LED modular lighting unit  110 . As illustrated in  FIG. 4 , in one embodiment a mounting tab  420  similar to that provided in the interconnect  120  may be provided in the end cap  410  for mounting that end of the string of LED modular lighting units  110  to another surface. The end cap  410  is generally formed as a closed half of the full interconnect  120  and is not otherwise described herein. 
         [0035]      FIG. 5  is a sectional view of two LED modular lighting units  110  connected through an interconnect  120  according to one embodiment. As illustrated, each LED modular lighting unit  110  includes a heat sink  530  that is mounted to a circuit board  580  on which are mounted any desired number of LEDs  510  and any other driving circuitry necessary for the LED modular lighting unit  110 . A lens  520  may cover the LEDs  510 , typically snapping or otherwise being removably fixed into a housing for the circuit board  580  and LEDs  510 . The lens  520  may vary based upon any desired lighting throw. 
         [0036]    As illustrated in  FIG. 5 , a bottom portion  560  of the interconnect  120  extends partially along an underside of the LED modular lighting unit  110 , providing rigidity of the interconnection. In addition, an annular portion  570  is formed at the middle of the interconnect  120  to receive the male ( 540 ) and female ( 550 ) connectors of the LED modular lighting units  110  and provide a seal for the connection between those two connectors. The male connector  540  has a gasket  545 , typically an O-ring, to seal with the annular portion  570 . Similarly, the female connector  550  as a gasket  555  to seal with the annular portion  570 . 
         [0037]    Although illustrated in  FIG. 5  only extending along the bottom of the LED modular lighting units  110 , the bottom portion  560  typically extends up and around at least a portion of the side of the LED modular lighting units  110  to provide stability and rigidity in 2 dimensions, as well as to provide the snap fittings for ensuring the LED modular lighting units  110  stay connected to the interconnect  120 . In applications in which a water seal is not needed, the gaskets  545  and  555  may be omitted if desired, but the annular portion  570  would remain to continue to give structural support to the connection and provide rigidity. In some embodiments, instead of mounting the gaskets  545  and  555  in the connectors  540  and  550 , gaskets or other sealing elements may be disposed with the annular portion  570 . 
         [0038]      FIG. 6  is a perspective view of an LED modular lighting unit  110  according to one embodiment. The LED modular lighting unit  110  provides male ( 620 ) and female ( 220 ) connectors at opposite ends of the LED modular lighting unit  110 . Projections  610  are snap fittings intended to engage with the snap fittings  210  of the interconnect  120 , to ensure that the LED modular lighting unit  110  is firmly held in the interconnect  120 . Although as illustrated, projections  610  are formed on the LED modular lighting unit  110  and holes  210  are formed in the interconnect  120 , embodiments can use projections on the interconnect  120  and holes on the LED modular lighting unit  110  the same purpose. Alternate techniques known to the art for holding two objects together may be used. For example, straps or other physical connectors may be provided and attached to a portion of the LED modular lighting units  110  for preventing them from disconnecting from the interconnect  120  instead of the snap fittings  210  and  610 . The placement of the snap fittings  210  and  610  is illustrative and by way of example only, and other placements of those fittings may be used as desired. 
         [0039]      FIG. 7  is a side sectional view of an LED modular lighting unit  110  according to one embodiment. A male electrical connector  710  extends outward from the male connector  620 , and an opening  720  provides access to a female electrical connector for providing electrical connections to the circuit board  580  and LEDs  510 . Any desired type of male and female electrical connectors may be used. In one embodiment, instead of using electrical connectors embedded in the ends of the LED modular lighting unit  110  as illustrated herein, the end connectors  620  and  220  may simply provide structural stability and rigidity by mating with the annular portion  570  of the interconnect  120 , and other techniques for electrically connecting adjoining LED modular lighting units  110  may be used, such as using an external wire connector (not shown) between the LED modular lighting units  110 . 
         [0040]    As illustrated in  FIG. 7 , the heat sink  530  extends nearly to the end of the LED modular lighting unit  110  to engage with the interconnect  120  for providing structural stability and rigidity, as well as to provide adequate heat conduction from LEDs  510  at the ends of the LED modular lighting unit  110 . In some embodiments, the heatsink  530  may not extend as far towards the end of the LED modular lighting unit  110  as illustrated, and thermoplastic or other material used for the housing of the LED modular lighting unit  110  may engage with the bottom portion  560  of the interconnect  120  to provide structural stability and rigidity. 
         [0041]      FIG. 8  is a cross-sectional end view of the LED modular lighting unit  110  of  FIG. 7  along line  8 - 8 . As illustrated in  FIG. 8 , the heatsink  530  includes a body  820  mounted on the underside of the circuit board  580  and a plurality of fins  810  for conducting heat generated by the LEDs  510  and other electrical components away from the circuit board  580 . The heatsink body  820  is mounted with the circuit board  580  and a housing  830  that is overmolded or otherwise formed to hold those elements. In one embodiment, the lens  520  is configured to snap into the housing  830 , but may be attached to the housing  830  in any desired fashion and in some embodiments may be omitted altogether. In some embodiments, the fins  810  may be omitted, and other techniques for dispersing heat away from the circuit board  580 , such as vent holes in the housing  830  may be provided, as desired. 
         [0042]      FIG. 9  is a perspective view illustrating a modular system  100  of LED modular lighting units and interconnects according to another embodiment that uses metal interconnects instead of plastic interconnects for greater strength. As illustrated in  FIG. 9 , two LED modular lighting units  910  are connected by an interconnect  920  that both provides electrical conductivity between two LED modular lighting units  910  and provides rigidity to the connected LED modular lighting units  910 . Any number of LED modular lighting units  110  may be connected in a rigid string of LED modular lighting units. In addition, the LED modular lighting units  910  may seal an interconnection area between the LED modular lighting unit  910  so that the interconnection between the LED modular lighting units  910  prevents ingress of dust and is water tight for up to for temporary immersion. In one embodiment, the seal provides protection in up to 1 m of water and carries an Ingress Protection Rating of IP 67. 
         [0043]    Also illustrated in  FIG. 9  is a flexible interconnect  930  formed of a one-sided interconnect  932  and a one-sided interconnect  934  connected by a flexible cable  936  that provides electrical conductivity between an LED modular lighting unit  910  connected to interconnect  932  and another LED modular lighting unit  910  (not shown) connected to interconnect  934 . Thus, the system of LED modular lighting units  910  and interconnects  920  and  930  provides a designer of a lighting installation with the ability to link together LED modular lighting units  910  in both rigid and flexible configurations. One of the one-sided interconnects  932  and  934  may provide a circuit board and female connector for connecting with a male connector of the LED modular lighting unit  910  and the other of the one-sided interconnects  932  and  934  provides a circuit board and male connector for connecting with a female connector of the LED modular lighting unit  910 . The interconnects  932  and  934  are otherwise configured as portions of the full interconnect  920  and are not otherwise described herein. 
         [0044]    Although only a straight line rigid interconnect  920  is illustrated in  FIG. 9 , rigid interconnect  920  could be formed with angular connections to allow rigid interconnections at any desired angle. In such an angular interconnect, instead of the LED modular lighting units  110  directly interconnecting as in the straight line interconnect  920  illustrated in  FIG. 9 , the LED modular lighting units  910  may interconnect with circuit boards in each and of the angular rigid interconnect which are electrically connected with each other. 
         [0045]    The interconnect  920  and the interconnects  932  and  934  may be formed of any desired material, such as aluminum. Although plastic interconnects  920  may be used, metallic interconnects  920  are preferred to provide greater strength and resistance to breakage. As shown in more detail in  FIG. 17 , a base portion of the interconnect  920  is a generally flat structure configured for insertion into the male and female ends of the LED modular lighting units  910  to form a latched connection between the LED modular lighting units  910 . Other shape of the interconnects  920  may be used to correspond to the shapes of the LED modular lighting units  910 . 
         [0046]    Connectivity to a power source may be provided by a pigtail unit that plugs into one end of a LED modular lighting unit  910 , an interconnect  920 , or one of the split units  932 / 934  and which is connected to a power source. Alternatively, a power supply may (not shown) be used with one of the split units  932 / 934  formed as part of the power supply unit. 
         [0047]    Additional details are illustrated in the perspective view of  FIG. 10 . To provide secure insertion of the interconnect  920  into the LED modular lighting units  910 , flexible tabs  1010  may be provided in the interconnect  920  to mate with slots  1530  ( FIG. 15 ) on the LED modular lighting units  910  so that upon full insertion of the interconnect  920  into the LED modular lighting unit  910 , the flexible tabs  1010  and slots  1530  engage for removable but secure connection. A male end connector of the LED modular lighting unit  910  is illustrated in  FIG. 10 . A similar female end connector is formed on the opposite and of the LED modular lighting unit  910  but is not visible in  FIG. 10 , because it is inserted into the interconnect  120 . 
         [0048]    In one embodiment, illustrated in  FIG. 11 , the interconnect  920  may be configured for mounting to another surface (not shown), such as a wall. In one embodiment, the mounting feature includes a hole formed near one end of a base of the interconnect  920 , providing an opening for inserting a screw or other type of fastener  1110  through the hole for attaching the interconnect  920 , and thereby that portion of the modular system  900 , to the other surface. In such an embodiment, the bottom portion of the interconnect  920  preferably has a flat surface for mounting flush against the other surface. In some embodiments, instead of using a fastener to hold the interconnect  920  to another surface, adhesives or any other desired way of connecting the interconnect to the other surface may be used. As illustrated in  FIG. 11 , when the mounting screw  1110  is used to attach the interconnect  920  to an external surface, once the LED modular lighting units  910  are connected through the interconnect  920 , the mounting screw or other fastener  1110  is hidden from view and not accessible. 
         [0049]    By providing LED modular lighting units and interconnects as disclosed above, a modular system can provide rigid and/or flexible connection of any desired length and configuration. Although as illustrated herein, the LED modular lighting units  110  and  910  are all of the same size, embodiments may provide LED modular lighting units of different sizes that can be mixed or matched to fit the desired configuration of the composite lighting unit. Because the electrical connections are sealed, the units may be immersed in water or other liquids for temporary periods. The modular system may be used in all types of lighting applications, including signage, cove lighting, accent lighting, task lighting, and case lighting. 
         [0050]      FIG. 12  illustrates an end cap unit  1210  that may be used at an end of a string of LED modular lighting units  910 . The end cap unit  1210  engages with the LED modular lighting unit  910  as described above and provides a covering for the male or female connectors of the LED modular lighting unit  910 . A cover portion  1220  may be formed on the end cap unit  1210  to cover the electrical connector of the LED modular lighting unit  910 . The cover portion  1220  may be formed of any desired material, such as a thermoplastic material, and may include a circuit board (not shown) to complete the electrical circuit across the electrical connectors of the LED modular lighting unit  910 . As illustrated in  FIG. 12 , the end cap unit  1210  may also provide a mounting hole  1230  or other capability for mounting the end cap unit  1210  to a surface. The end cap unit  1210  is generally formed as a half of the full interconnect  120  and is not otherwise described herein. 
         [0051]      FIG. 13  is a sectional view of two LED modular lighting units  910  connected through an interconnect  920  according to one embodiment. As illustrated, each LED modular lighting unit  910  includes a heat sink  1330  that is mounted to a circuit board  1380  on which are mounted any desired number of LEDs  1310  and any other driving circuitry necessary for the LED modular lighting unit  910 . A lens  1320  may cover the LEDs  1310 , typically snapping or otherwise being removably fixed into a housing for the circuit board  1380  and LEDs  1310 . The lens  1320  may vary based upon any desired lighting throw. 
         [0052]    As illustrated in  FIG. 13 , a bottom portion  1360  of the interconnect  920  extends partially along and engages with an the heat sink  1330  of the LED modular lighting unit  910 , providing rigidity of the interconnection. Unlike the embodiment of  FIGS. 1-8 , an annular portion  1370  is formed as part of or as an attachment to an end of one of the interconnected LED modular lighting units  910  to receive the male ( 1340 ) and female ( 1350 ) connectors of the LED modular lighting units  910  and provide a seal for the connection between those two connectors. The male connector  1340  in one embodiment has an area of flexible wickers  1355  to seal with the annular portion  1370 . The annular portion  1370  is typically formed of a thermoplastic material, which may be the same as or different from that of the thermoplastic material used on the rest of the LED modular lighting units  910 . Other techniques for sealing the electrical connectors with the annular portion, such as gaskets or O-rings, may be used as desired. 
         [0053]    Although illustrated in  FIG. 5  as attached to the female connector  1350  of the LED modular lighting unit  910 , the annular portion  1370  may be attached to either male or female connectors as desired. In one embodiment, the annular portion  1370  is removable and may be attached to the male or female connectors  1340 / 1350  before joining the LED modular lighting units  910 . 
         [0054]    Although illustrated in  FIG. 13  only extending along the bottom of the LED modular lighting units  910 , the bottom portion  1360  typically engages with a portion of the underside of the LED modular lighting units  910  to provide stability and rigidity in 2 dimensions, as well as to provide the flexible fittings for ensuring the LED modular lighting units  910  stay connected to the interconnect  920 . In applications in which a water seal is not needed, the annular portion  1370  may be omitted. In some embodiments, instead of or in addition to forming flexible wickers  1355  on the electrical connectors  1340 / 1350 , flexible wickers may be formed on an interior surface of the annular portion  1370 . 
         [0055]      FIG. 14  is a perspective view of an LED modular lighting unit  910  according to one embodiment. The LED modular lighting unit  910  provides male and female connectors at opposite ends of the LED modular lighting unit  910 . A housing  1410 , typically of a thermoplastic material, is disposed about the circuit board  1380  (not visible in  FIG. 14 ) and a portion of the lens  1320  that covers the LEDs  1310  (not visible in  FIG. 14 ). The housing  1410  typically snaps onto or it otherwise removably fixed over the circuit board  1380  and lens  1320 . 
         [0056]      FIG. 15  is a side sectional view of an LED modular lighting unit  910  according to one embodiment. A male electrical connector  1510  extends outward from the male connector  1350 , and an opening  1520  provides access to a female electrical connector for providing electrical connections to the circuit board  1380  and LEDs  1310 . Any desired type of male and female electrical connectors may be used. In one embodiment, instead of using electrical connectors embedded in the ends of the LED modular lighting unit  910  as illustrated herein, other techniques for electrically connecting adjoining LED modular lighting units  110  may be used, such as using an external wire connector (not shown) between the LED modular lighting units  910 . 
         [0057]    As illustrated in  FIG. 15 , the heat sink  1330  extends nearly to the end of the LED modular lighting unit  910  to engage with the interconnect  920  for providing structural stability and rigidity, as well as to provide adequate heat conduction from LEDs  1310  at the ends of the LED modular lighting unit  910 . A slot  1530  is configured to engage with tabs on the interconnect  920 , removably locking the interconnect  920  in place to resist disengagement until the tab is removed from the slot  1530 . In one embodiment, one slot  1530  is disposed on one side of the heat sink  1330  and a second slot  1530  is disposed on a second side of the heat sink  1330 , for connecting with interconnects  920  engaged with each end of the heat sink  1330 ; however, embodiments may form both slots  1530  on the same side if desired. 
         [0058]      FIG. 16  is a cross-sectional end view of the LED modular lighting unit  910  of  FIG. 15  along line  16 - 16 . As illustrated in  FIG. 16 , the heat sink  1330  includes a body  1620  mounted on the underside of the circuit board  1380  and a plurality of fins  1610  for conducting heat generated by the LEDs  1310  and other electrical components away from the circuit board  1380 . The heat sink body  1620  is mounted with the circuit board  1380  and the housing  1410  that is overmolded or otherwise formed to hold those elements. In one embodiment, the lens  1320  is configured to snap into the housing  1410 , but may be attached to the housing  1410  in any desired fashion and in some embodiments may be omitted altogether. Channels  1630  are formed on either side of the body  1620  to engage the base of the interconnect  920 , providing a rigid connection between the LED modular lighting unit  910  and the interconnect  920 . 
         [0059]      FIG. 17  is a top and bottom view of the interconnect  920  according to one embodiment. A base portion  1710 , typically formed of aluminum, is generally flat, corresponding to the generally flat shape of the heat sink  1330 . At both ends of the base portion  1710  flexible tabs  1730  and  1740  are positioned for engaging with the slots  1530  formed in the heat sink  1330 , preventing disengagement of the interconnect  920  from the LED modular lighting unit  910  without disengaging the tabs  1730  and  1740  from the slots  1530 . The tabs  1730  and  1740  are typically of a spring steel, but may be formed of any desired material. The tabs  1730  and  1740  are attached to the base portion  1710  in one embodiment by the use of holes  1752  and pins  1750 , such as PEM® SPOTFAST® fasteners. (PEM and SPOTFAST are registered trademarks of PEM Management, Inc.) Any desired technique for attaching the tabs  1730  and  1740  to the base portion  1710  may be used, including welding or any other type of bonding. In one embodiment, tab  1730  is oriented in an opposite direction from tab  1740 , with each engaging an opposite slot  1530  on the heat sink  1330 . Other embodiments may orient both tabs  1730  and  1740  in the same direction. 
         [0060]    Foam pads  1720  may be placed on the top side of the base portion, to engage with an underside of the heat sink  1330  to improve the connection between the interconnect  920  and the LED modular lighting unit  910 . Mounting holes  1760  in one embodiment are formed in the base portion  1710  to allow mounting the interconnect  920  to a surface. Although four mounting holes  1760  are illustrated in  FIG. 17 , any number of mounting holes  1760  may be used. The interconnect  920  may be of any desired length. 
         [0061]    As illustrated in  FIG. 17 , rails  1770  are formed on both sides of the base portion  1710 , configured to engage the channels  1630  of the heat sink  1330 , providing rigid interconnection of the interconnect  920  with the LED modular lighting unit  910 . In another embodiment, channels may be formed on the base portion  1710  for engagement with rails on the heat sink  1330 . 
         [0062]      FIGS. 18 and 19  are perspective views of the top and bottom of LED modular lighting units  910  and interconnects  920  in various stages of interconnection, ranging from initial insertion, partial connection, and fully engaged. In this example, two of the interconnects are two-way interconnects  920  and one is a one-way interconnect  932  for a flexible connection. 
         [0063]    It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention therefore should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.