Patent Publication Number: US-9423116-B2

Title: LED lamp and modular lighting system

Description:
BACKGROUND 
     Light emitting diode (LED) lighting systems are becoming more prevalent as replacements for older lighting systems. LED systems are an example of solid state lighting (SSL) and have advantages over traditional lighting solutions such as incandescent and fluorescent lighting because they use less energy, are more durable, operate longer, can be combined in multi-color arrays that can be controlled to deliver virtually any color light, and generally contain no lead or mercury. A solid-state lighting system may take the form of a lighting unit, light fixture, light bulb, or a “lamp.” 
     An LED lighting system may include, for example, a packaged light emitting device including one or more light emitting diodes (LEDs), which may include inorganic LEDs, which may include semiconductor layers forming p-n junctions and/or organic LEDs (OLEDs), which may include organic light emission layers. Light perceived as white or near-white may be generated by a combination of red, green, and blue (“RGB”) LEDs. Output color of such a device may be altered by separately adjusting supply of current to the red, green, and blue LEDs. Another method for generating white or near-white light is by using a lumiphor such as a phosphor. Still another approach for producing white light is to stimulate phosphors or dyes of multiple colors with an LED source. Many other approaches can be taken. 
     SUMMARY OF THE INVENTION 
     In some embodiments, a lighting system comprises a lamp where the lamp comprises an enclosure that is at least partially optically transmissive. At least one LED is located in the enclosure and is operable to emit light through the enclosure when energized through an electrical path. The lamp also comprises a first electrical connector for connecting the electrical path to a power source and a second electrical connector configured to connect the electrical path to a second lamp. 
     The enclosure may comprise a base made of a thermally conductive material where the base is thermally coupled to the at least one LED. A plurality of LEDs may extend for substantially the length of the base. The enclosure may comprise an optically transmissive lens. The lens may be connected to the base where the base may comprise a first channel and a second channel for receiving a first edge and a second edge of the lens, respectively. The at least one LED may be mounted on a LED board that provides physical support for the at least one LED and forms part of the electrical path. The LED board may comprise a FR4 board. The LED board may be mounted on the base. The first electrical connector may comprise a power cord. The first electrical connector may be configured to connect to a second lamp. The first electrical connector and the second electrical connector may comprise one of a male plug and a female plug. The second electrical connector may comprise a cable that extends from the lamp and terminates in one of a male plug and a female plug. A second lamp may comprise a third connector configured to connect to the second connector. The third connector may comprise one of a male and female plug connected to the second lamp by a flexible cable. The lamp may abut the second lamp when the third connector is connected to the second connector. A bracket may be provided for connecting the lamp to the second lamp. The third connector and the second connector may be located inside one of the lamp and the second lamp. The third connector and the second connector may be located inside of an end cap of one of the lamp and the second lamp where a section of the end cap may be removable to provide access to the third connector and the second connector. The lamp may comprise a base and a bracket releasably connected to the base where the bracket comprises a mounting mechanism for mounting the bracket to a support surface. The enclosure may comprise an optically transmissive lens and a base where the at least one LED is mounted on a LED board and a portion of the lens holds the LED board against the base. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view showing an embodiment of a LED lamp of the invention. 
         FIG. 2  is a side view of the LED lamp of  FIG. 1 . 
         FIG. 3  is a partial exploded view of the LED lamp of  FIG. 1 . 
         FIG. 4  is a partial perspective view of the LED lamp of  FIG. 1  in a first position. 
         FIGS. 5 and 6  are perspective views of one embodiment of the top section of the end cap used in the LED lamp of  FIG. 1 . 
         FIGS. 7 and 8  are perspective views of a second embodiment of the top section of the end cap used in the LED lamp of  FIG. 1 . 
         FIG. 9  is a partial perspective section view of the LED lamp of  FIG. 1 . 
         FIG. 10  is a top view showing two LED lamps connected together. 
         FIG. 11  is a partial perspective section view of the LED lamp of  FIG. 1 . 
         FIG. 12  is a section view of the LED lamp of  FIG. 1 . 
         FIGS. 13-16  are perspective views showing embodiments of a mounting bracket used with the lamp of  FIG. 1 . 
         FIG. 17  is a partial perspective view showing an embodiment of an electrical connector used with the lamp of  FIG. 1 . 
         FIG. 18  is a perspective view of two lamps shown in a partially connected position. 
         FIG. 19  is a perspective view of two lamps shown in an electrically connected position. 
         FIG. 20  is a side view showing two LED lamps connected together. 
         FIG. 21  is a perspective view showing two LED lamps connected together. 
         FIG. 22  is a perspective view showing two LED lamps connected together in a second embodiment. 
         FIGS. 23-27  schematically illustrate embodiments of the electrical connections for the lamp. 
         FIG. 28  is a section view of the lamp of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Moreover, the various aspects of the embodiments as described herein may be used in combination with any other aspects of the embodiments as described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element such as a layer, region or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” or “top” or “bottom” may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Unless otherwise expressly stated, comparative, quantitative terms such as “less” and “greater”, are intended to encompass the concept of equality. As an example, “less” can mean not only “less” in the strictest mathematical sense, but also, “less than or equal to.” 
     The terms “LED” and “LED device” as used herein may refer to any solid-state light emitter. The terms “solid state light emitter” or “solid state emitter” may include a light emitting diode, laser diode, organic light emitting diode, and/or other semiconductor device which includes one or more semiconductor layers, which may include silicon, silicon carbide, gallium nitride and/or other semiconductor materials, a substrate which may include sapphire, silicon, silicon carbide and/or other microelectronic substrates, and one or more contact layers which may include metal and/or other conductive materials. A solid-state lighting device produces light (ultraviolet, visible, or infrared) by exciting electrons across the band gap between a conduction band and a valence band of a semiconductor active (light-emitting) layer, with the electron transition generating light at a wavelength that depends on the band gap. Thus, the color (wavelength) of the light emitted by a solid-state emitter depends on the materials of the active layers thereof. In various embodiments, solid-state light emitters may have peak wavelengths in the visible range and/or be used in combination with lumiphoric materials having peak wavelengths in the visible range. Multiple solid state light emitters and/or multiple lumiphoric materials (i.e., in combination with at least one solid state light emitter) may be used in a single device, such as to produce light perceived as white or near white in character. In certain embodiments, the aggregated output of multiple solid-state light emitters and/or lumiphoric materials may generate white light. 
     Solid state light emitters may be used individually or in combination with one or more lumiphoric materials (e.g., phosphors, scintillators, lumiphoric inks) and/or optical elements to generate light at a peak wavelength, or of at least one desired perceived color (including combinations of colors that may be perceived as white). Inclusion of lumiphoric (also called ‘luminescent’) materials in lighting devices as described herein may be accomplished by direct coating on solid state light emitter, adding such materials to encapsulants, adding such materials to lenses, by embedding or dispersing such materials within lumiphor support elements, and/or coating such materials on lumiphor support elements. Other materials, such as light scattering elements (e.g., particles) and/or index matching materials, may be associated with a lumiphor, a lumiphor binding medium, or a lumiphor support element that may be spatially segregated from a solid state emitter. 
     Linear lights such as fluorescent lights may comprise a fluorescent tube releasably mounted in a fixture that may be mounted on a ceiling or other structure. One use of linear lights is as down and/or up lighting in commercial fixtures where the light is mounted in a rack or other merchandise display to illuminate displayed merchandise. Such linear lights may also be used in non-commercial applications such as a down light mounted under a kitchen cabinet, for example, to provide down lighting on a counter or other surface. Linear lights are used in a variety of applications to provide down lighting, up lighting, and/or accent lighting in a variety of applications. Because LED based solid state lamps use less energy, are more durable, operate longer, can be combined in multi-color arrays that can be controlled to deliver virtually any color light, and generally contain no lead or mercury the conversion to, or replacement of linear lighting systems such as fluorescent lighting systems with LED lighting systems is desired. “Linear light” as used herein means a lamp having an illuminated enclosure that has a significantly longer length than width. For example the linear light of the invention may be approximately 1-3 inches in width with a length of between approximately 12-80 inches. 
     In one embodiment the LED lamp  1  comprises a base  10 . The base  10  may be made of a thermally conductive material such that it functions as a heat sink to dissipate heat from the LED assembly. The base  10  may be made of a rigid material to support the LED assembly  30  and lens  50 . In some embodiments the base  10  may be made of extruded aluminum. While aluminum may be used, other rigid, thermally conductive materials and manufacturing processes may be used to form the base  10 . The base  10  defines a support surface for the LED assembly  30  that may be comprised of a pair of planar support surfaces such as flanges  12  that support the longitudinal edges of the LED assembly  30  along the length thereof. The spaced flanges  12  may be used as the support surface in embodiments where the LED assembly  30  comprises a generally rigid substrate that is capable of spanning the flanges  12  and physically supporting the LEDs  32 . In one embodiment the flanges  12  extend for the length of the LED assembly  30 ; however, the flanges  12  may extend for less than the entire length of the LED assembly provided that they adequately support and retain the LED assembly  30 . For example, gaps may be provided in the flanges  12  while still adequately supporting the LED assembly. The flanges  12  face one another to create a planar support for receiving and supporting the LED assembly  30 . The LED assembly  30  may be thermally coupled to the base  10  such that heat generated by the LEDs  32  is transferred to the base  10  via the LED board  34  and is dissipated to the ambient environment by the base  10 . The thermal couple between the LED board  34  and base  10  may be provided by providing surface to surface contact between the board  34  and the base  10 . In other embodiments thermally conductive layers may be provided between the base  10  and the board  34 . For example, thermal adhesive may be used to attach the board  34  to the base  10 . In some embodiments the support surface may comprise a planar member that extends across the entire width of the LED assembly rather than two spaced flanges  12 . 
     The flanges  12  are supported on side walls  14  that extend generally perpendicularly from a bottom wall  16 . A cross member  18  may be provided between the side walls  14  to provide structural rigidity to the base  10  such that the base  10  does not flex or bend and to define a wire way  101  for containing the lamp electronics  102 , such as the power supply and other electronics, and wiring as shown in  FIG. 28 . 
     The side walls  14  define grooves  20  that extend for the length of, or for a portion of the length of, the base  10 . The grooves  20  may be engaged by mounting brackets  40  for securing the lamp to a surface. Different embodiments of the mounting bracket  40  may be used for different mounting applications. Referring to  FIG. 13  in one embodiment the mounting bracket  40  comprises a base plate  42  that extends for approximately the width of the base  10 . At least one engagement member  44  extends from each end of the base plate  42  for releasably engaging the side walls  14  of the base  10  such that the lamp may be secured to the bracket  40 . In one embodiment the engagement members  44  comprise resilient tabs  46  that extend from the base plate  42  and that are shaped and dimensioned to engage the grooves  20  formed on the side walls  14  of base  10 . Each tab  46  includes a protrusion  48  that is shaped and dimensioned to fit into grooves  20  to mechanically lock the base  10  to the brackets  40 . The tabs  46  may be resiliently mounted relative to the base plate  42  such that the tabs  46  may flex to releasably engage the base  10 . The tabs  46  may be arranged in opposed pairs to clamp the base  10  therebetween. While two tabs  46  are shown on each end of the bracket  40  a greater or fewer number of tabs may be used. The base plate  40  and tabs  46  may be formed of a single piece of deformable, resilient material such as steel where the resiliency of the material is used to create the bias force of the tabs  46  against the base  10 . In other embodiments the tabs may be formed of separate members that are mounted to the base plate at a hinges and that are biased into engagement with the base by separate springs. 
     The tabs  46  may be formed with flared ends that create angled camming surfaces  49  where the surfaces  49  are oriented such that the base  10  may be centered between and pushed against the camming surfaces  49  to flex the tabs  46  and allow the base  10  to be inserted between the opposing tabs  46 . When the force on the tabs  46  is released, such as when the protrusions  48  on the tabs  46  are aligned with the grooves  20 , the tabs  46  return toward the undeformed position to create a gripping force on the base  10  sufficient to hold the lamp  1  in the brackets  40 . The use of elongated grooves  20  and resilient tabs  46  allow the brackets  40  to be located at any position along the length of the base  10 . The base  10  may also be slid relative to the brackets  40  to allow adjustment of the position of the lamp relative to the brackets  40  after the base  10  is mounted in the brackets  40 . Typically a plurality of brackets  40  may be used to support a lamp depending upon the length and weight of the lamp. 
     In the embodiment of  FIG. 13  bracket  40  comprises a pair of mounting flanges  50  that comprise apertures  52  for receiving fasteners such as screws that may be used to secure the bracket  40  to a support surface. The mounting flanges  50  extend from the plate  42  such that apertures  52  are disposed to either side of the lamp  1  where the apertures  52  are accessible when the lamp  1  is mounted in the bracket  40 . While circular apertures for receiving separate fasteners such as screws are shown, the mounting apertures  52  may comprise various shaped and sized apertures, slots, channels or the like for receiving any type of fastener. Moreover, the flanges  50  may comprise mounting mechanisms other than apertures if desired. For example, the mounting mechanisms may comprise male or female engagement members that engage separate female or male brackets that are mounted to the support surface. Other mechanisms such as adhesive, hook and loop fasteners or the like may also be used. 
       FIG. 14  shows an alternate embodiment for the mounting bracket where the mounting flanges  50  are angled relative to the plate  42  to define a plane that is disposed at an angle relative to the lamp such that when the flanges  50  are mounted on a support surface the base plate  42  and the lamp  1  are mounted at an angle relative to the support surface.  FIG. 15  shows an alternate embodiment for the mounting bracket where the mounting flanges  50  extend from the sides of the base plate  42  rather than from the ends of the base plate such that the mounting flanges  50  are hidden from view after the lamp is mounted on the brackets  40 . In this embodiment the brackets  40  are mounted to the support surface before the lamp  1  is installed in the brackets  40 .  FIG. 16  shows another alternate embodiment for the mounting bracket  40  where the mounting flange  50  extends from the end of the base plate  42  but is disposed at approximately a 90 degree angle relative to the base plate  42  such that the mounting flange  50  extends along one side wall  14  and the lamp is oriented at a 90 degree angle relative to the support surface. Other arrangements of the bracket may also be provided. 
     The LED lamp  1  comprises an LED assembly  30  that may be supported by and secured to the base  10 . The LED assembly  30  may comprise a plurality of LEDs or LED packages  32  that are mounted on LED board  34  and that extend the length of, or substantially the length of, the base  20  to create a desired light pattern. The LEDs  32  may be arranged such that the light pattern extends the length of, or for a substantial portion of the length of, the lamp and is similar in length to a traditional fluorescent bulb. While in one embodiment the LEDs  32  extend in a line for substantially the entire length of the base  10 , the LEDs  32  may be arranged in other patterns and may extend for less than substantially the entire length of the base if desired. For example, the LEDs may be disposed along the edges of the LED board  34  and directed toward the middle of the lamp. The LEDs may be directed into a waveguide. The LEDs  32  may be mounted on a LED board  34  that provides physical support for the LEDs  32  and provides an electrical path for providing electrical power to the LEDs. The electrical path provides power to the LEDs and may comprise the power source, board  34  and lamp electronics  102 . In one embodiment the board  34  comprises an FR4 board. In an FR4 board circuitry  103  may be etched into a copper layer of the board where the circuitry comprises a portion of the electrical path to the LEDs  32 . In other embodiments the board may comprise a MCPCB, lead frame or other suitable mounting substrate for the LEDs. The board may also comprise a flex circuit. Because a flex circuit is inherently flexible the flex circuit may be supported on a rigid substrate if needed. The board  34  may comprise the electrical circuitry  103  and components that form part of the electrical path to the LEDs  32 . With embodiments of the invention, the term “electrical path” can be used to refer to the entire electrical path to the LED array, including an intervening power supply disposed between the electrical connection that would otherwise provide power directly to the LEDs and the LED array, or it may be used to refer to the connection between the mains and all the electronics in the lamp, including the power supply. The term may also be used to refer to the connection between the power supply and the LED array. 
     The LEDs  32  may be provided in a variety of patterns and may include a wide variety of different types and colors of LEDs to produce light in a wide variety of colors and/or light patterns. In some embodiments LEDs as disclosed herein may include one or more light affecting elements (including light transmissive, light-absorptive, light reflective and/or lumiphoric materials) formed on, over or around at least one solid state light emitter. In one embodiment for a 48 inch lamp twenty two LEDs may be used arranged in-line and having a 2 inch spacing between LEDs. The LEDs may comprise XT-E LEDs manufactured and sold by CREE Inc. In some embodiments the LED board  34  may comprise a plurality of fixtures electrically interconnected to make LED board  34 . In one embodiment each fixture is 15 W, 1700 Lm, 125 mA @ 120V. Other LEDs and/or combinations of LEDs may be used depending on the desired characteristics of the emitted light. For example, in some embodiments, the LEDs may be center mounted with greater side emitting optical profiles such as CREE XPQ LEDs. In some embodiments a prismatic lens or parabolic reflectors may be used to create a desired light distribution. 
     The base  10  and LED assembly  30  may be made of, or covered in, a light reflective material, such as MCPET, white optic, reflective film or paint or the like, to reflect light from these components into mixing chamber  51 . The entire base  10  and/or board  34  may be made of, or covered in, a reflective material or portions of the base and/or board may be made of reflective material. For example, portions of the base and/or board that may be exposed to the emitted light may be made of, or covered in, a reflective material. 
     A lens  50  may be connected to the base  10  to cover the LED assembly  30  and create a mixing chamber  51  for the light emitted from the LEDs  32 . The light is mixed in the chamber  51  and is emitted from the lamp through the lens  50 . The lens  50  may diffuse the light to provide a uniform, diffuse, color mixed light pattern. The lens  50  may be made of molded plastic or other material and may be provided with a light diffusing layer. In the drawings the lens is shown as transparent to better illustrate the internal components of the lamp; however, in actual use the lens may be diffusive such that it is light transmissive but not necessarily transparent. The light diffusing layer may be provided by etching, application of a coating or film, by the translucent or semitransparent material of the lens, by forming an irregular surface pattern during formation of the lens or by other methods. In some embodiments the lens  50  has a round or circular cross-sectional shape, however, the lens may have other shapes including a flattened circular shape or oval, a faceted shape, a rectilinear, square or rectangular shape or other suitable shape. 
     The lens  50  extends substantially the length of the base  10  to cover the LEDs  32 . In some embodiments, the longitudinal edges  50   a ,  50   b  of the lens  50  are provided with inwardly facing lips or projections  52  and  54  that may be received in outwardly facing longitudinal C-channels  56 ,  58  formed along the side walls  14  of the base  10 . The channels  56 ,  58  may be formed by a portion of walls  14  and outwardly facing angled members  59 . The lens  50  and projections  52 ,  54  may be formed as one piece such as of molded plastic. In some embodiments, the base  10  may be formed of extruded, stamped or rolled metal where the channels  56 ,  58  are formed as one-piece with the base; however, the base may be made as separate components secured together to form the completed base. The projections  52 ,  54  are inserted into the channels  56 ,  58  and mechanically engage the members  59  to retain the lens  50  on the base  10 . The projections  52 ,  54  may be slid into the channels  56 ,  58  from the end of the base  10 . If the lens  50  is made of an elastic material, such as molded plastic, the projections  52 ,  54  may also be inserted into the channels  56 ,  58  by inserting a first projection  52  into one of the channels  56  and deforming the lens to insert the opposite projection  54  into the opposite channel  58 . The lens  50  may then be released such that the lens elastically returns to its original shape where the projections  52 ,  54  are forced into the opposed channels  56 ,  58 . 
     The lens  50  comprises a second set of inwardly facing flanges  55 ,  57  that are spaced from the projections  52 ,  54 , respectively, to trap the outwardly facing members  59 . The flanges  55 ,  57  are dimensioned such that when the lens  50  is secured to the base  10  the flanges  55 ,  57  engage the top surface of the board  34  to clamp the board  34  between the flanges  55 ,  57  and the flanges  12 . 
     End caps  60  may be provided at the opposite ends of the lens  50  and base  10  to close the interior mixing chamber  51  of LED lamp  1  and to support the electrical connectors for connecting the LEDs to a power source. The end caps  60 , base  10  and lens  50  together define an enclosure that retains the LEDs  32 . The enclosure is partially optically transmissive through the lens  50 . 
     Each end cap  60  comprises an internal chamber  62  defined by a bottom section  61  and a top section  63  dimensioned and shaped to closely receive the base  10 , and lens  50 . The bottom section  61  is formed with protrusions  76  that engage the grooves  20  formed in the base  10 . To secure the bottom section  61  of the end cap  60  to the base  10 , the bottom section  61  may be slid over the base such that the protrusions  76  slide into grooves  20  and the bottom wall  16  of base  10  rests on the bottom wall  65  of end cap  60 . The bottom section  61  further comprises apertures  78  for receiving fasteners  80  such as screws that engage mating holes  82  formed in the base  10 . 
     In one embodiment the top section  63  is provided with two deformable locking members  64  that engage the base  10  such that the top section  63  may be removed from the lamp. The locking members  64  are made of resilient material and have a first end connected to the top section  63  and an engagement member  66  at the free end that engage channels  56 ,  58  formed on the base  10 . The locking members  64  may be deformed by the base  10  as the top section is attached to the bottom section  61 . To facilitate the deformation of the locking members  64  the ends of the locking members  64  are formed with angled camming surfaces  65  that are engaged by the camming surfaces  59  as the top section  63  is mounted on the bottom section. When the engagement members  66  are aligned with channels  56 ,  58 , the locking members  64  return to the undeformed locking position such that the engagement members  66  are biased into engagement with the base  10 . The engagement of the engagement members  66  with the side walls  14  of the base  10  secures the top section  63  of end cap  60  to the base  10 . The locking members  64  are located in recesses  74  formed in the bottom section  61  to fix the lateral position of the top section  63  relative to the bottom section  61 . Other arrangements of snap-fit connectors may be used. For example a fewer or greater number of locking members  64  may be used. The deformable locking members may be formed on the base  10  and apertures or other mating receptacles may be formed on the end caps. Rather than using deformable resilient members the locking members may comprise rigid members that are biased to the locking position by separate springs. While use of a snap-fit connector provides a simple assembly method that does not require additional tools, assembly steps or fasteners, the top section  63  may be connected to the bottom section  61  using other connection mechanisms such as separate fasteners, or the like. 
     Referring to  FIGS. 5 and 6  the end wall  83  of the top section  63  defines an aperture  92  for receiving an electrical connector of the lamp. In one embodiment the top section  63  is formed with a slotted aperture  94  for receiving the internal wiring of the lamp such that an electrical connector may be extended to the outside of the lamp with the wiring to the connector passing through the slot  94 . Referring to  FIGS. 7 and 8  in a second embodiment the top section  63   a  comprises an aperture  92  where the aperture is round aperture  96  formed in end wall  83  that receives a cable  98  that connects to the electrical path of the lamp (See, for example,  FIG. 17 ). The cable  98  may be held in a strain relief collar or grommet  100  secured in the aperture  96 . The choice of top section  63 ,  63   a  is selected based on the type of connector used to connect to the electronics of the lamp as will be described. 
     The lamp of the invention may be used as part of a modular system allowing multiple lamps to be connected together to create a linear light of varying length. In one embodiment the lamp has a length and a diameter suitable for use as a replacement for existing linear lights such as fluorescent tubes. For example, in one common application the lamp may have a length of approximately 48 inches that is sized to replace a 48 inch light fixture. While a specific length has been described it will be appreciated that the lamp may be made in any suitable length including standard and non-standard lengths. For example, the lamp may be made in a one foot length, a two foot length, a three foot length or other lengths including significantly longer lengths. Moreover, a single installation may use lamps of varying lengths. 
     In one embodiment, as shown in  FIGS. 17 and 23  lamp  1  may comprise a power cable  98  that extends from the exterior of the lamp through aperture  96  in the end cap  60  and into the wire way  101  formed in base  10  between bottom wall  16  and cross member  18 . The power cable  98  may contain wires for providing both sides of the current and a ground wire. The power cable  98  is connected to lamp electronics  102  that may be located in the wire way  101 . The lamp electronics  102  are contained in the wire way  102  and may comprise a board or boards, such as a circuit board, on which the power supply and other electrical components are mounted. The power cable  98  is electrically coupled to the lamp electronics  102  for carrying both sides of the critical current to the lamp. The power cable  98  may terminate in a plug or other connector  104  that may be inserted into a mating outlet that is connected to a power source  99 . Alternatively the connector  104  may comprise a hard wire connection to power source  99 . The power cable  98  forms a part of the electrical path for powering the LEDs. The electrical path may also include the lamp electronics  102 , conductors  105  from the lamp electronics  102  to the LED board  34  and conductors  103  on the LED board to the LEDs  32 . In some embodiments, where plural lamps are connected to one another such that power is provided from one lamp to an additional lamp or lamps, one lamp may have the driver and the appropriate current is supplied to all of the LEDs in all of the Lamps from the lamp with the driver while in other embodiment each lamp may comprise a driver such that each lamp receives the same power from the power source. 
     Referring to  FIGS. 18-20 and 23 , in some embodiments the electrical current from power cable  98  is also provided to an electrical connector  110  via wires  112 . The electrical path may also include electrical connector  110  and wires  112 . The electrical current may be provided through the lamp electronics  102  where the lamp electronics and wiring  112  are connected in series (shown in  FIG. 23 ) or the current may be provided to connector  110  in parallel with the lamp electronics  102  where power cable  98  is electrically coupled to wires  112  (shown in  FIG. 27 ). Connector  110  is located in compartment  115  in base  10  underneath the top section  63  of end cap  60  where it may be stored out of sight when not in use. Connector  110  may comprise one of a male or female electrical plug configured to mate with a connector  114  that comprises a corresponding female or male plug on a second lamp  1   a  to complete an electrical path between the plugs. The second connector  114  is connected to the lamp electronics  102  of the second lamp  1   a  by wiring such that electrical current provided from the first lamp may be used to power the second lamp via the coupling of electrical connectors  110 ,  114  ( FIG. 24 ). Connector  110  may be provided with a releasable locking member  111  that engages mating locking member  113  on connector  114 . 
     To connect lamp  1  in series with a second lamp  1   a , the top section  63  of end cap  60  is removed on both lamps  1  and  1   a  to reveal connectors  110  and  114 . The top sections  63  are removed by flexing locking members  64  to disengage the locking members from the base. The connector  110  is extended to the exterior of lamp  1  and is electrically coupled to connector  114  in compartment  115  of lamp  1   a . Wires  112  are made of a sufficient length to allow the connector  110  to extend outside of the end cap  60 . The top sections  63  are mounted on the bottom sections  61  of both lamps  1  and  1   a . The top sections  63  are mounted by forcing the locking members  64  over angled camming surfaces  59  such that the locking members  64  deform and engage channels  56  and  58  on the base  10 . The wiring  112  is extended through slots  94  such that the wiring extends between the lamps  1  and  1   a  and the connectors  110 ,  112  are located in the end cap of one of lamps  1  and  1   a . The second lamp  1   a  is connected to the first lamp  1  such that current may be delivered from lamp  1  to lamp  1   a . In this embodiment the lamps  1  and  1   a  are intended to be mounted in an end to end abutting relationship where the lamps are arranged in a linear path. The wires  112  are covered by the end caps because the walls  83  of the end caps  60  of the adjacent lamps  1  and  1   a  abut or are closely adjacent to one another. “Abut” as used herein means that the end caps are physically touching or are in very close proximity to one another such that the wires  112  extending between the lamps  1  and  1   a  are not exposed or accessible. 
     The second lamp  1   a  may be provided with a first connector  110  at its opposite end such that the second lamp  1   a  may be connected to a third lamp as described above such that current is carried from the first lamp to the second lamp and from the second lamp to a third lamp or additional lamps. This arrangement may be repeated for a plurality of lamps to create a modular, expandable linear lighting system. Different lamps may be provided with the different types of connectors as needed to complete the system. For example, one lamp may be provided with a first connector  104  and power cable  98  for connecting to a source of power  99  and a first connector  110  for connecting to additional lamps ( FIG. 23 ). Intermediate lamps may comprise one of the first connector  110  and the second connector  114  ( FIG. 24 ) such that these lamps may be connected in series with one another. A third configuration of the lamp may be provided only with a first connector  110  ( FIG. 26 ) for connecting to one lamp such that this lamp functions as the end lamp in a series of interconnected lamps. In another configuration one lamp may be provided with a first connector  104  and power cable  98  ( FIG. 25 ) where this lamp connects to a source of power but is not intended to be connected to another lamp. In some embodiments all of the lamps may include at least two connectors. The various mechanisms for making the electrical connections to and from the lamps may be used in various combinations. 
     With use of the first connector  110  and the second connector  114 , as described above, the lamps are intended to be connected in a relatively straight line in an abutting relationship where the end of one lamp physically contacts or is closely adjacent to the end of the adjacent lamp. In some embodiments a bracket  120  may be used to mechanically connect adjacent lamps together. Referring to  FIGS. 19-21  the bracket  120  may have a construction similar to the mounting brackets  40  where a base plate  122  is dimensioned to span two lamps  1 ,  1   a . In one embodiment the base plate  122  is dimensioned to extend across and beyond the two abutting end caps. A pair of tabs  124  is provided on each side of the base plate  122 , the tabs  124  being positioned to engage the grooves  20  in the base  10 , as previously described with respect to tabs  44 , just beyond the internal edges of the end caps  60 . The two end caps  60  are trapped between the tabs  124  such that the lamps  1 ,  1   a  may not be separated from one another without removing the bracket  120 . 
     In some embodiments it may be desirable to connect a plurality of lamps  1 ,  1   a  together in series as previously described while allowing the lamps to be oriented relative to one another in other than a straight line. Referring to  FIG. 22  the first connector  110  may be mounted at the end of a flexible electrical connector  130  having a sufficient length such that the connected lamps  1 ,  1   a  may be spaced from one another such that the lamps are not abutting. The lamps  1  and  1   a  may be oriented relative to one another in other than a straight line by flexing connector  130 . The flexible connector  130  may comprise wires  112  having a connector  110 ,  114  at the end thereof where the wires extend a distance from one of the lamps  1 ,  1   a  that allow the wires to flex to allow the lamps  1 ,  1   a  to be oriented at any angle relative to one another. It may be desirable or required to encase the wires  112  such as by using an electrically insulated cable  132  because the electrical wires  112  would otherwise be exposed to the ambient environment. Other insulating devices such as conduit, flexible metal cables or the like may also be used to encase the wiring. As used herein “cable” means a flexible electrical connection that may be exposed to the ambient environment and that allows two interconnected lamps to be oriented at angles relative to one another by flexing the cable. Because the cable  132  may be too large to fit through the slots  94  formed in the end caps  60 , a second end cap top section  63   a  may be used that has an aperture  96  large enough to receive the cable. A strain relief grommet  100  may be used to line the aperture. Use of the flexible connection between adjacent lamps  1 ,  1   a  allows the lamps to be disposed relative to one another in other than a straight line. 
     To assemble the lamp of the invention, an LED board  34  is populated with LEDs  32 . The LED board  34  is located on the flanges  12  of the base  10  such that the board  34  is supported by the base  10 . In addition to supporting the board  34  the base  10  may also function as a heat sink to dissipate heat generated by the LEDs  32  to the ambient environment. The lamp electronics  102  are located in wireway  101  and the electrical path  105  from the board  34  to the power supply  102  is completed. The appropriate electrical connectors  104 ,  110 ,  114  are connected to the electrical path using wires  114  and/or power cable  98 . The lens  50  is mounted to the base  10  by inserting the flanges  52 ,  54  of the lens into the mating C-channels  56 ,  58  on the base  10 . The flanges may be slid into the C-channels or the lens may be deformed and snap-fit into the C-channels. The flanges  55 ,  57  of the lens  50  are engaged with the board  34  to hold the LED board  34  against the flanges  12 . The first and second end caps  60  may be mounted to the base  10  with the electrical connectors contained in the end caps as previously described. Plural lamps may be connected together to create a lighting system during installation of the lamps on site. 
     Although specific embodiments have been shown and described herein, those of ordinary skill in the art appreciate that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiments shown and that the invention has other applications in other environments. This application is intended to cover any adaptations or variations of the present invention. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described herein.