Patent Publication Number: US-9897302-B2

Title: Flat LED lamp assembly

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation patent application that hereby claims priority to U.S. patent application Ser. No. 13/546,959, filed Jul. 1, 2012, titled FLAT LED ASSEMBLY, which is a Continuation-In-Part patent application of and claims priority to U.S. patent application Ser. No. 13/370,277, filed Feb. 9, 2012, titled FLAT LED LAMP ASSEMBLY, which claims priority to U.S. Provisional Patent Application No. 61/441,239 filed Feb. 9, 2011, and titled FLAT LED LAMP ASSEMBLY, all of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present invention are directed to lamp assemblies, and more particularly to LED-based lamp assemblies. 
     BACKGROUND 
     Conventional light bulbs and lamps experience significant drawbacks. High Intensity Discharge (HID) bulbs, such as Mercury vapor, high-pressure Sodium, metal halide and other high-intensity bulbs such as halogen, high-powered compact fluorescent, etc., produce high intensity light, but the bulbs typically generate a significant amount of heat, have a limited useful life, are susceptible to damage from fairly rough handling, and can be expensive. Some HID bulbs also contain mercury, such as Mercury vapor and compact fluorescents. The HID and high-intensity bulbs also typically produce light in a spherical pattern, such that a significant portion of the generated light from the bulb is blocked or disrupted by the fixtures into which these bulbs are installed. Conventional HID bulbs typically include a mogul base that screw into a mogul base socket in the light fixture. Conventional non-HID bulbs or lamp used to replace HID bulbs, such as fluorescent bulbs or LED lamps, typically require rewiring of the ballast or reconfiguration of the fixture&#39;s socket to receive the replacement bulb or lamp. This reconfiguration of the fixture can be time consuming labor intensive, and expensive. 
     Flat LED retro-fit lamp kits have been developed to provide improved efficiency and lighting characteristics. The conventional flat retro-fit lamps, however, typically require a fitting that mates with the light fixture so as to insure that the flat lamp is properly oriented relative to the fixture when installed. Accordingly, light fixtures that include a mogul base socket or other receptacles for HID bulbs typically have to be modified or removed and it is necessary to rewire the fixture and to remove existing ballasts and/or head fixtures with a compatible receptacle for the flat LED lamp. This retrofit process is also time consuming, labor intensive, and expensive. 
     Conventional incandescent light bulbs also suffer from significant drawbacks. Typical incandescent medium base light bulbs are extremely inefficient, relatively fragile, very susceptible to damage or breakage, and have fairly short useful lives. In addition, government regulations are phasing out incandescent light bulbs, including many of the medium base incandescent light bulbs sold in the residential markets. Accordingly, such medium base incandescent light bulbs will not be available in their current state and there is no guarantee that the modified hybrid incandescent light bulbs will be as efficient, provide for lower heat output or an equal light output, and there is a significant need for a lamp that overcomes the drawbacks of the conventional or the new hybrid bulbs. 
     SUMMARY 
     The present invention provides a flat LED-based lamp assembly that overcomes drawbacks experienced in the prior art and provides other benefits. One of the advantages of the claimed invention is a more efficient utilization and conservation of energy resources. At least one embodiment provides a flat LED lamp assembly having a plurality of LED lights on a circuit bed and one or more heat sinks attached to the circuit bed. A constant current driver is connected to the circuit bed and is configured to dissipate the igniter or start-up voltage used with conventional HID style light fixtures, thereby eliminating the need to bypass conventional ballast systems. The lamp assembly has a cylindrical base, such as a threaded mogul base, medium base, or other threaded lamp base. The base has a spring loaded tip that defines one of the electrical connection points with the socket of the receiving light fixture. The spring loaded tip is configured so the flat LED lamp can be rotated relative to the fixture after electrical connection is made between the tip and the fixture&#39;s socket. The spring loaded tip also acts as a tensioner to provide improved frictional engagement between the base and the socket of the fixture. The lamp assembly also has a “quick disconnect” feature separating the LED Driver circuitry from the LED circuit bed and the heat sink device. This quick disconnect feature allows for easy interchange of circuit beds/heat sink arrangements without having to replace the driver and base. The disconnect feature allows for other LED circuit bed and heat sink device assemblies to be interchanged, for example, when increased lumens or luminous lux is required. 
     In one embodiment, an LED-based lamp assembly has a driver assembly with a base portion rotatably engageable with a socket portion of a light fixture to make a first electrical contact with the light fixture. The driver assembly has an electrically conductive tip portion coupled to the base portion. The tip portion engages the socket portion to make a second electrical contact with the light fixture. The tip portion is retractable relative to the base portion and can retract when in electrical contact with the light fixture&#39;s socket portion. A lamp housing assembly is operably connected to the driver assembly. The lamp housing assembly has a lamp housing connected to the driver assembly, and the lamp housing has electrical contacts that operatively connected to electrical contacts on the driver assembly. The lamp housing is coupled to at least one substrate having at least one LED light thereon. The substrate is connected to, or is an integral part of, a heat sink configured to carry heat away from the substrate and/or LED light. The lamp housing assembly is rotatable relative to the light fixture to adjust the angular position of the light source while maintaining the first and second electrical contacts between the driver assembly and the socket portion. 
     In another embodiment, an LED-based light fixture assembly has a light fixture coupleable to a power source and that has a threaded socket portion. A driver assembly has a threaded base portion that screws into the threaded socket portion. The driver assembly has an electrically conductive, retractable tip portion coupled to the base portion and positioned to electrically engage the socket portion when the base portion is being screwed into the socket portion. The tip portion is retractable relative to the base portion after the tip portion electrically engages the socket portion and before the base portion is fully screwed into the socket portion. A lamp housing assembly is electrically connected to the driver assembly. The lamp housing assembly has a heat sink with a plurality of fins, and at least one LED substrate is mounted to the heat sink and has at least one LED light thereon. Alternately, the LED substrate and the heat sink may be one and the same. An air flow device is adjacent to the heat sink and is operable to move air over the heat sink. The heat sink is configured to carry heat away from the LED substrate and/or the LED light. The LED light source and the heat sink are rotatable as a unit relative to the light fixture to adjust the angular position of the light source while maintaining electrical engagement between the tip portion and the socket portion. 
     Another embodiment provides a lamp assembly for use with a light fixture having a socket. The lamp assembly comprises a driver assembly having a threaded base portion that screws into the socket. The driver assembly has an electrically conductive, retractable tip portion coupled to the base portion and positioned to electrically engage the socket when the base portion is being screwed into the socket portion. The tip portion is retractable relative to the base portion and can retract after the tip portion electrically engages the socket portion and before the base portion is fully screwed into the socket. The driver assembly has a driver housing with a first connection member spaced apart from the threaded base portion. A lamp housing assembly is removeably and electrically connected to the driver assembly. The lamp housing assembly has a lamp housing with a second connection member that releasably mates with the first connection member. The lamp housing is connected to a heat sink with an LED substrate mounted to the heat sink, wherein the LED substrate has a plurality of LED lights thereon. Alternately, the LED substrate and the heat sink may be one and the same. The LED substrate and heat sink are rotatable as a unit relative to the light fixture to adjust the angular position of the LED chip board while maintaining electrical engagement between the tip portion and the socket. 
     Another embodiment provides an LED-based lamp assembly comprising a driver assembly having a base portion rotatably engageable with a socket portion of a light fixture to make a first electrical contact with the light fixture. The driver assembly has an electrically conductive tip portion coupled to the base portion. The tip portion is engageable with the socket portion to make a second electrical contact with the light fixture. A lamp housing assembly is connected to the driver assembly and has a lamp housing connected to the driver assembly. The lamp housing has second electrical contacts operatively connected to the first electrical contacts. A heat sink is coupled to the lamp housing. The heat sink has a support portion and a plurality of fins coupled to the support portion. The fins form air columns between adjacent fins, and the support portion has a plurality of first apertures in communication with the air columns. The lamp housing assembly has at least one LED substrate having a plurality of second apertures therethrough and at least one LED light thereon. The LED substrate is connected to the support portion of the heat sink and the second apertures are aligned with the first apertures and aligned with the air columns. The lamp housing assembly has a fan adjacent to the heat sink with the heat sink positioned between the fan and the LED substrate. The fan is positioned to move air through the air columns in the heat sink and through the plurality of first and second apertures to move a flow of heated air away from the LED substrate. The lamp housing assembly can be rotatable relative to the light fixture to adjust the angular position of the LED substrate while maintaining the first and second electrical contacts between the driver assembly and the socket portion. 
     Another embodiment provides an LED-based light fixture assembly having a light fixture coupleable to a power source and having a threaded socket portion. A driver assembly has a threaded base portion that screws into the threaded socket portion. The driver assembly has an electrically conductive, tip portion coupled to the base portion and positioned to electrically engage the socket portion when the base portion is being screwed into the socket portion. A lamp housing assembly is electrically connected to the driver assembly and has a heat sink with a plurality of fins and a support portion adjacent to the fins. The support portion has a plurality of first apertures therethrough. At least one LED chip board is mounted to the heat sink, and the LED chip board has at least one LED light thereon and has a plurality of second apertures therethrough. The second apertures are coaxially aligned with the first apertures to allow airflow to pass through the support portion and through the LED chip board. The lamp housing has an air flow device adjacent to the heat sink and operable to move air over the heat sink and through the plurality of first and second apertures. The fan is configured to move the airflow away from the LED chip board in a direction of illumination of the LED light. The LED chip board and heat sink can be rotatable as a unit relative to the light fixture to adjust the angular position of the LED chip board while maintaining electrical engagement between the tip portion and the socket portion. 
     Yet another embodiment provides a lamp assembly for use with a light fixture having a socket. The lamp assembly has a driver assembly with a threaded base portion that screws into the socket. The driver assembly has an electrically conductive tip portion coupled to the base portion and positioned to electrically engage the socket when the base portion is being screwed into the socket portion. The driver assembly has driver housing with a first connection member spaced apart from the threaded base portion. A lamp housing assembly is removeably and electrically connected to the driver assembly. The lamp housing assembly has a lamp housing with a second connection member that releasably mates with the first connection member. The lamp housing is connected to a heat sink and an LED chip board mounted to the heat sink, wherein the LED chip board has a plurality of LED lights thereon and a plurality of first apertures therethrough. The heat sink has a support portion coupled to the LED chip board, and the support portion has a plurality of second apertures therethrough. The second apertures are in axial alignment with the first apertures. The lamp housing assembly has an airflow device positioned to move airflow over the heat sink and through the first and second apertures to carry heat away from the LED chip board during operation of the lamp assembly. The LED chip board and heat sink can be rotatable as a unit relative to the light fixture to adjust the angular position of the LED chip board while maintaining electrical engagement between the tip portion and the socket. 
     Another embodiment provides an LED-based lamp assembly for use with a light fixture having a socket portion. The lamp assembly includes a driver assembly having a base portion rotatably engageable with the socket portion to make a first electrical contact with the light fixture. The base portion is coupled to a driver housing and the driver assembly has an electrically conductive tip portion coupled to the base portion. The tip portion is engageable with the socket portion to make a second electrical contact with the light fixture wherein the tip portion and driver housing are moveable relative to each other when the tip portion is in the second electrical contact with the socket portion. The driver assembly includes first electrical contacts. The lamp assembly includes a lamp housing assembly operably connected to the driver assembly. The lamp housing assembly includes second electrical contacts operatively connected to the first electrical contacts of the driver assembly. The lamp housing assembly is coupled to at least one LED substrate having at least one LED light thereon. The LED substrate is connected to a heat sink configured to carry heat away from the LED substrate. The lamp assembly includes at least one fan electrically connected to the driver assembly and oriented to move air across the heat sink when activated. 
     Yet another embodiment provides an LED-based lamp assembly for use with a light fixture having a socket portion. The lamp assembly includes a driver assembly having a driver and a driver housing containing the driver. The lamp assembly further includes a base portion connected to the driver housing and electrically coupled to the driver assembly. The base portion includes an electrically conductive first threaded portion coupled to the driver assembly and rotatably engageable with the socket portion to make a first electrical contact with the light fixture. The base portion includes an electrically conductive tip portion electrically coupled to the driver assembly and electrically isolated from the first threaded portion. The tip portion is engageable with the socket portion to make a second electrical contact with the light fixture. The base and the driver assembly are moveable relative to each other when the tip portion is in the second electrical contact with the socket portion. The driver assembly includes first electrical contacts. The lamp assembly includes a lamp housing assembly operably connected to the driver assembly. The lamp housing assembly includes second electrical contacts operatively connected to the first electrical contacts of the driver assembly. The lamp housing assembly includes at least one LED substrate with at least one LED light thereon with the LED substrate being operatively coupled to the driver. The lamp assembly includes a heat sink connected to the lamp housing assembly and thermally coupled to the at least one LED substrate and configured to carry heat away from the LED substrate. The lamp assembly includes at least one fan electrically connected to the driver assembly and oriented to move air across the heat sink when activated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a light fixture with an LED-based lamp assembly in accordance with an embodiment of the present invention. 
         FIG. 2  is a bottom isometric view of an LED-based lamp assembly in accordance with an embodiment of the present invention. 
         FIG. 3  is a top isometric view of the assembly of  FIG. 2 . 
         FIG. 4  is a partially exploded bottom isometric view of the assembly of  FIG. 2 . 
         FIGS. 5A-5E  include a bottom plan view, a top plan view, a side elevation view, a front elevation view and a rear elevation view of the assembly of  FIG. 2 . 
         FIG. 6  is another bottom isometric view of the LED-based lamp assembly of  FIG. 2 . 
         FIG. 7  is a top isometric view of the assembly of  FIG. 6 . 
         FIG. 8  is an isometric view of an LED-based lamp assembly in accordance with another embodiment. 
         FIG. 9  is an elevation view of portions of the driver assembly and light housing assembly of  FIG. 8 . 
         FIGS. 10 and 11  are bottom and top isometric views of an LED-based lamp assembly in accordance with another embodiment. 
         FIGS. 12A-12D  include a bottom plan view, a top plan view, a side elevation view, and a front elevation view of the assembly of  FIG. 10 . 
         FIG. 13  is a partially exploded isometric view of the LED-based lamp assembly of  FIG. 10 . 
         FIGS. 14 and 15  are other bottom and top isometric views of the LED-based lamp assembly of  FIG. 10 . 
         FIG. 16  is a rear bottom isometric view of an LED-based lamp assembly in accordance with another embodiment. 
         FIG. 17  is a partially exploded bottom isometric view of the lamp assembly of  FIG. 16 . 
         FIG. 18  is an exploded rear isometric view of the lamp assembly of  FIG. 17 . 
         FIG. 19  is an enlarged partial front isometric view of the lamp assembly of  FIG. 16  with a portion of the lamp housing not shown. 
         FIGS. 20A and 20B  are enlarged front isometric views of the driver housing of the assembly of  FIG. 16 , with internal circuitry not shown in  FIG. 20A  for purposes of clarity. 
         FIG. 21  is a partial exploded isometric view of the heat sink and two LED chip boards, shown removed from the assembly of  FIG. 16 . 
         FIG. 22  is an end view of a heat sink in accordance with another embodiment shown removed from the assembly of  FIG. 16 . 
         FIGS. 23 and 24  are partially exploded isometric views of a heat sink and LED chip boards in accordance with another embodiment. 
         FIG. 25  is an exploded bottom isometric view of an LED-based lamp assembly in accordance with another embodiment. 
         FIG. 26  is an exploded bottom isometric view of an LED-based lamp assembly in accordance with yet another embodiment. 
         FIG. 27  is a top isometric view of the lamp assembly of  FIG. 26 . 
         FIG. 28  is a plan view of a heat sink of an LED-based lamp assembly of another embodiment. 
         FIGS. 29 and 30  are side and end elevation views of the heat sink of  FIG. 28 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure describes Light Emitting Diode (LED)-based lamp assemblies in accordance with certain embodiments of the present invention. Several specific details of the invention are set forth in the following description and the Figures to provide a thorough understanding of certain embodiments of the invention. One skilled in the art, however, will understand that the present invention may have additional embodiments, and that other embodiments of the invention may be practiced without several of the specific features described below. 
       FIG. 1  is an isometric view of a light fixture  1  with an LED-based lamp assembly in accordance with an embodiment of the present invention. The light fixture is connected to an electricity source, such that the light fixture  1  provides electricity to the lamp assembly  10 . As seen in  FIGS. 2-7 , the flat LED-based lamp assembly  10  of the illustrated embodiment has a lamp housing assembly  11  that includes a lamp housing  12 , LED chip board(s)  14 , LED lights  16 , and a heat sink  22 . The lamp housing  12  carries the heat sink  22 , and one or more LED chip boards  14 , which include one or more LED lights  16 , are coupled to the heat sink  22 . In the illustrated embodiment, the lamp housing  12  is a substantially flat, rectangular frame that defines an open interior area  15 . The lamp housing  12  includes a shoulder portion  17  that extends radially inwardly toward the interior area  15  so as to define a support surface connected to the perimeter portion of the heat sink  22 . The heat sink  22  is securely bonded or otherwise attached to the lamp housing  12  at the shoulder portion  17 . Accordingly, a flat bottom surface  18  of the heat sink  22  extends across the lamp housing&#39;s open interior area  15 . 
     In the illustrated embodiment, the LED chip boards  14 , each of which includes a plurality of spaced apart LED lights  16 , are attached to the flat bottom surface  18  of the heat sink  22  so that heat generated by the LED chip boards  14  and/or the LED lights  16 , can be drawn away and dissipated by the heat sink  22 . The LED chip board  14  in the illustrated embodiment is a conventional printed circuit board, although other embodiments can use other suitable structures that carry the LED lights  16 , including, as an example, a SinkPAD™ product from SinkPAD Corporation of Placentia, Calif. In the illustrated embodiment, the LED chip board  14  spans across the lamp housing&#39;s interior area  15  and ends of the LED chip boards  14  are connected to the interior surface of the lamp housing  12 . Alternately, the LED chip board may be an integral part of the heat sink member, with the LED lights being mounted directly onto the heat sink. 
     In the illustrated embodiment, two LED chip boards  14  are attached to the heat sink  22 , although other embodiments can include one or more than two LED chip boards  14  operatively coupled to the heat sink  22 , and each LED chip board  14  can have one or a plurality of LED lights  16  operatively disposed on the LED chip board. In at least one embodiment, the lamp housing  12  can be made of, as an example, a cast plastic, and the LED chip board(s)  14  with the LED lights  16  thereon can be adhered to a heat sink of aluminum, ceramic or other heat-dissipating material and then to the cast plastic. In other embodiments, other suitable materials can be used. In one embodiment, the LED chip boards  14  can be adhered directly to the back of the heat sink  22  using a thermally conductive adhesive, such as a high temperature thermally conductive epoxy. In addition, the entire lamp housing assembly  11  can be potted for exterior use. In yet another embodiment, the lamp housing assembly  11  can be coated with a thin film of sealant material that protects the components of the assembly without substantially decreasing heat transfer to and from the heat sink  22 . For example, one embodiment can use a very thin Florine-based polymer film coating to help protect the features of the lamp housing assembly. 
     The LED chip boards  14  are mechanically and electrically connected to the lamp housing  12 , such that electricity is provided to the LED lights  16  via the LED chip boards  14 . The LED lights  16  and the LED chip boards  14  are positioned on the heat sink&#39;s planar bottom surface  18  in a selected orientation to provide the desired lighting characteristics from the lamp assembly  10 . While the illustrated embodiment provides the LED chip boards  14  and LED lights  16  on the planar bottom surface  18 , in other embodiments, the bottom surface  18  may have selected sloped or contoured surfaces so as to selectively orient or aim the LED lights  16  on the LED chip boards  14 . 
     The heat sink  22  is configured to dissipate heat generated from the LED lights  16  and the LED chip boards  14 . The heat sink  22  of the illustrated embodiment has a plurality of fins  24  extending away from the bottom surface  18  generally opposite each of the LED chip boards  14 . Other embodiments can have heat sinks with other configurations of the fins or other heat dissipating elements. The heat sink  22  may be made of aluminum, aluminum alloy, ceramic, ceramic-based materials, or any other suitable heat-dissipating material. Further, the illustrated embodiment has a unitary heat sink  22  with integral heat dissipating elements, although other embodiments can include multiple heat sinks or other arrangements of head dissipating elements positioned in selected locations relative to the LED chip board(s)  14  to carry heat away from the LED chip board(s)  14  and LED lights  16  during operation. 
     The lamp housing assembly  11  is removeabley connected to a driver assembly  28 , such that when the lamp housing assembly  11  is in an installed position on the driver assembly  28 , the lamp housing assembly  11  is mechanically and electrically connected to the driver assembly, as discussed in greater detail below. The driver assembly  28  of the illustrated embodiment has a driver housing  30  that contains and/or supports a constant current device  32 , such as an LED driver integrated circuit (IC) or the like. The constant current device  32  is operatively coupled to the LED chip board  14  and LED lights  16  via an interlocking member  26  on the lamp housing (discussed below). The constant current device  32  is configured to allow the flat LED lamp assembly to be used in any current ballast type fixture or voltage input level from, for example, 85 v to 480 v. In one embodiment, the driver housing  30  may be cast from plastic or other suitable material and may include two or more cavities that will be potted for exterior and wet location uses and appropriately sealed with glue, sonic welding of the housing structures or other suitable protective closure. 
     As indicated above, the flat LED lamp assembly  10  is configured to as a replacement or retrofit light element for existing light fixtures, such as HID bulbs with a threaded mogul base. The conventional HID light fixtures typically have ballasts or other configurations that provide a high voltage start-up surge that is needed to “ignite” or otherwise energized the HID bulb. The driver assembly  28  of the present flat LED lamp assembly  10  is provided with the constant current device  32  that is configured to automatically discharge any high voltage start-up surge produced by the HID ballast in the HID light fixture. Accordingly, the lamp assembly  10  can be screwed into a mogul base socket of a conventional HID light fixture, and the constant current device  32  accommodates the HID ballasts without having to retrofit or rewire the light fixture  1  ( FIG. 1 ). Although the illustrated embodiment is discussed as having a threaded mogul base for use in a light fixture having a mogul socket, it is to be understood that the lamp assembly in accordance with the present disclosure can include a medium base or a threaded base having a different size (including a standard size as well as custom sizes) for use with a light fixture having a corresponding sized socket. 
     In one embodiment, the constant current device  32  is configured with input power conditioning that allows the lamp to be used with existing supply voltage and ballast infrastructure, dissipating ignition pulses from the ballast and providing conditioned power to the constant-current driver circuitry. Conditioned power supplied to the driver circuitry may be either AC or DC as required. Voltage rectification, power factor correction, and dissipation of ignition pulses may each or all be done with either passive or active components. As an example of passive components, a simple clamping diode may be used to dissipate the ignition pulses. 
     As seen in  FIG. 4 , lamp housing assembly  11  has an interlocking member  26  connected to the lamp housing  12 , and the interlocking member included a pair of electrical contacts  34  electrically coupled to the LED chip board  14  and the LED lights  16 . The interlocking member  26  is configured to releasably connect to a receiving portion  40  of the driver housing  30  to provide an electrical connection between the components. 
     In the illustrated embodiment, the interlocking member  26  project rearwardly from a rear wall of the lamp housing  12 , and the interlocking member has a “bow-tie” shape with a pair of electrical contacts  34  on the rear surface of the member. These electrical contacts  34  are electrically connected to the LED chip boards  14  and the LED lights  16 . This bow-tie shaped interlocking member  26  fits into a similarly shaped aperture  35  in a receiving portion  40  of the driver housing ( FIG. 5D ). In the illustrated embodiment, when the lamp housing assembly is in the installed position, the bow-tie shaped interlocking member  26  is oriented at an approximately 90-degree offset from the aperture  35  in the driver housing&#39;s receiving portion  40 . Accordingly, the interlocking member  26  can fit into the aperture  35  when the lamp housing assembly is rotated 90-degrees from the installed position. 
     In one example, the flat lamp housing assembly  11  is substantially horizontal when in the installed position. The lamp housing assembly  11  can be removeabley connected to the driver housing assembly  28  by orienting the lamp housing assembly  11  vertically, so the bow-tie shaped interlocking member  26  is aligned with the bow-tie shaped aperture  35  in the driver housing&#39;s receiving portion  40 . The interlocking member  26  is positioned in the driver housing  30  through the aperture  35 , and the lamp housing assembly  11  is then rotated 90-degrees relative to the driver housing  30  so that the interlocking member is 90-degrees misaligned with the aperture  35 . Accordingly, the interlocking member  26  is releasably locked to the driver housing  30  when in the installed position, but can be quickly disconnected upon rotating the lamp housing assembly 90-degrees relative to the driver housing  30 . 
     In one embodiment illustrated in  FIGS. 8 and 9 , the lamp housing assembly  11  and the driver housing  30  are configured so the interlocking member  26  will only fit into the aperture  35  when the lamp housing assembly  11  is in a particular orientation relative to the driver housing. In the illustrated embodiment, the aperture  35  in the forward wall of the driver housing  30  has a keyway  70  on one side of the aperture  35 . The interlocking member  26  has a similarly shaped key member  72  on one end of the member. This keyway  70  and key  72  configuration requires the lamp housing assembly  11  be oriented so the key  72  will pass through the keyway  70  as the lamp housing assembly is being connected to the driver housing, thereby insuring proper positioning of the lamp housing assembly  11 . 
     After the interlocking member  26  is inserted into the aperture  35 , the lamp housing is rotated 90-degrees in one direction (i.e., clockwise) to lock the lamp housing assembly in the installed position. In the embodiment shown in  FIG. 9 , the keyway  70  in the driver housing  30  is configured with rotational stops  74  that restrict the direction and extent of rotation of the interlocking member  26  within the driver housing. In the illustrated embodiment, the keyway  70  is configured with rotation stops  74  that allow the interlocking member  26  to rotate only in the clockwise direction and through a range of approximately 90-degrees when the interlocking member is first inserted into the aperture  35  for movement toward the installed position. The keyway  70 , the key  72 , and the rotation stops  74  are positioned to insure that the lamp housing assembly  11  properly and operatively connects to the driver assembly  28 . This arrangement also insures that proper electrical connection between the components is established, so as to avoid inverting the connections and creating a reverse polarity situation between the components. When the lamp housing assembly  11  is operatively connected to the driver assembly  28  and in the installed position, the entire LED-based lamp assembly  10  will rotate clockwise to screw into and mate with the internal threads of a conventional mogul base socket. The engagement between the lamp housing assembly  11  and the driver assembly is sufficiently secure so that the entire LED-based lamp assembly  10  can be rotated counterclockwise as a unit to unscrew the assembly from the conventional mogul base socket without rotating the lamp housing assembly away from the installed position. 
     As indicated above, the interlocking member  26  has the electrical contacts  34  on its rear face, and the electrical contacts  34  are configured to engage mating electrical contacts  36  in the receiving portion  40  of the driver housing  30  when the lamp housing assembly  11  is in the installed position. As best seen in  FIG. 9 , the electrical contacts  36  are positioned in the driver housing  30  relative to the aperture  35 , so that when the lamp housing&#39;s interlocking member  26  is in an installed position in the receiving portion, the electrical contacts  34  and  36  are electrically connected to each other. When the lamp housing assembly  11  is rotated away from the installed position, the interconnect member  26  and its electrical contacts  34  move out of engagement with the driver housing&#39;s electrical contacts  36 , and terminate the electrical connection between the driver assembly  28  and the LED chip boards  14  and the LED lights  16 . This arrangement of the bow-tie shaped interconnect member  26  and the driver assembly&#39;s housing  30  provides the quick connect/disconnect arrangement between the components while insuring that proper alignment and electrical connection will be established when in the installed position. Other embodiments may have other configurations to provide the quick connect/disconnect interface between the components. 
     This quick disconnect feature allows an entire lamp housing assembly  11  (with the lamp housing  12 , LED chip boards  14 , the LED lights  16 , and the heat sink  22 ) to be disconnected from the driver assembly  28  while the driver assembly  28  remains in place in the light fixture. Accordingly, a user can remove and replace one lamp housing assembly  11  and install a new lamp housing assembly without having to remove or change the driver assembly  28  in the light fixture  1 . Changing of the lamp housing assembly  11  can be done if, as an example, LED lights need to be replaced, or if different lumens or luminous lux is desired. The quick disconnect also allows one style of lamp housing assembly  11 , such as a horizontal assembly, to be easily and quickly replaced with another style of lamp housing assembly, such as a T-device usable for High Bay or vertical facing light fixtures. When the lamp housing assembly  11  is fully engaged, it is securely “locked” in place in the driver assembly  28  and the electrical contacts between the components will be fully engaged and energized. 
     The lamp assembly  10  of the illustrated embodiment has the base  50  connected to the driver housing  30 . In the illustrated embodiment, the base  50  is a threaded mogul base configured to screw into and mate with the internal threads of a conventional mogul base socket  51  of the light fixture  1  ( FIG. 1 ). While the lamp assembly  10  of the illustrated embodiment is described as having a mogul base, other embodiments of the lamp assembly can include a medium base, or other base configurations that can be used with conventional or custom light fixtures without having to rewire, rework, or retrofit the light fixture. 
     In the illustrated embodiment, the base  50  has a metal, substantially cylindrical threaded sleeve  52  fixedly attached to a mating portion  54  of the driver housing  28 . The sleeve  52  is configured to operatively connect to an electrical contact in the socket  51  so as to establish one of the electrical contact points between the light assembly  10  and the light fixture  1 . The base  50  also includes a biased, electrically conductive, retractable tip  56  that defines the second electrical contact point with another electrically conductive portion in the socket  51 . The retractable tip  56  is slidably disposed in a receptacle  58  in an electrically insulated separator  57  the distal portion  60  of the driver housing  28 . Accordingly, the insulated separator  57  is disposed between the retractable tip  56  and the outer metal threaded sleeve  52 . The metal mogul threaded sleeve  52  can be cast into porcelain that forms part of the driver housing  30 . The retractable tip  56  is slidably retained in the distal portion of the driver housing  30  by a radially extending flange  61  on the proximal end of the tip that overlaps with a slight rim or flange  59  formed in the housing at the entrance to the receptacle  58 . In other embodiments, other retention configurations between the tip  56  and the driver housing  30  can be used. 
     An electrically conductive, contact tension spring  62  is positioned in the receptacle  58  and biases the retractable tip  56  toward an extended position away from the driver housing  28 . The spring  62  and the retractable tip  56  are electrically coupled to the constant current drive  32 , such that when the mogul base  50  is screwed into the mogul base socket of the fixture, the retractable tip  56  makes electrical contact with the fixture  1  ( FIG. 1 ). 
     The retractable tip  56  compresses the spring  62  and moves axially into the receptacle  58  as the base  50  is screwed further into the socket after the tip  56  makes initial contact with the fixture&#39;s socket. The spring  62  biases the tip  56  against the electrical contact in the fixture&#39;s socket. The spring  62  also acts as a tensioner to keep the male threads of the sleeve  52  in firm engagement with the threads of the fixture&#39;s socket, thereby providing improved frictional engagement between the lamp assembly  10  and the fixture. While the illustrated embodiment uses a spring  62 , such as an electrically conductive contact tension spring, other embodiments can use other springs or other biasing members to urge the tip  56  away from the distal end of the driver housing  30  and to enhance the frictional retention of the lamp assembly  10  in the light fixture  1  ( FIG. 1 ). 
     This retractability of the tip  56  also ensures that the flat lamp can rotate to a desired or proper orientation within the fixture after electrical contact has been made between the retractable tip and the end of the socket in the light fixture. In the illustrated embodiment, the retractable tip  56  and the spring  62  are configured to retract so that the lamp assembly  10  can be rotated up to one full turn (360°) relative to the light fixture after the retractable tip  56  makes initial electrical contact with the bottom of the fixture&#39;s socket. During this additional rotation, the mogul base  50  screws further into the socket and the tip  56  is retracted and the spring  62  is compressed. Accordingly, the lamp assembly  10  can be screwed into the light fixture  1  ( FIG. 1 ), and after electrical connection is initially established, the lamp assembly  10  can be further rotated within the light fixture until the lamp housing assembly  11  is properly oriented within the light fixture no matter which point the male threads on the mogul engage with the female receiver threads. 
       FIG. 10-15  are isometric and elevation views of an LED-based lamp assembly  100  in accordance with another embodiment. In this alternate embodiment, lamp assembly  100  is generally similar to the lamp assembly  10  discussed above, except for the primary features described below. The lamp housing assembly  11  of the illustrated embodiment defines a flat assembly that is substantially perpendicular to the longitudinal axis of the driver assembly  28 . The lamp housing assembly  11  has a spacer  105  coupled to the heat sink  22  on the top of the lamp housing  12 . The spacer  105  can be connected directly to the heat sink  22 , or the spacer can extend through an aperture in the heat sink and attach directly to the lamp housing  12 . 
     The other end of the spacer  105  away from the lamp housing  12  includes an interlocking contact member  26  that releasably connects to the driver housing  30  in a quick connect/disconnect fashion as described above. In one embodiment, the interlocking contact member  26  has the same bow-tie shape as in the embodiment discussed above, such that the end of the spacer can releasably connect with the driver assembly  28  of the embodiment discussed above. In another embodiment, an articulateable portion can be provided at or near the distal end of the spacer  105  that would allow the lamp housing  12  to rotate from a perpendicular position relative to the spacer to angled positions through in substantially any number of infinite degrees to a fully parallel position relative to the spacer  105  in some HID light fixture housings. Accordingly, the driver assembly and the lamp housing assembly of the embodiments of  FIGS. 2-7 ,  FIGS. 8-10 , and  FIGS. 11-16  can be interchangeable. 
       FIG. 16  is a rear bottom isometric view of an LED-based lamp assembly  140  in accordance with another embodiment, and  FIGS. 17 and 18  are exploded bottom isometric views of the lamp assembly  140 . The lamp assembly  140  has a lamp housing assembly  142  with a lamp housing  144  and LED chip boards  146  attached to a flat bottom surface  148  ( FIG. 18 ) of a heat sink  150 . The lamp housing assembly  142  is removeably connected to a driver assembly  156 , discussed in greater detail below. 
     The lamp housing assembly  142  and driver assembly  156  are generally similar to the lamp housing assembly  11  and driver assembly  28 , respectively, discussed above, except for the primary differences discussed below. As best seen in  FIGS. 17 and 18 , the lamp housing assembly  142  has top and bottom frame portions  152  and  154  that connect to the heat sink  150  and the LED chip boards  146 . The lamp housing assembly  142  releasably connects to the driver assembly  156  with a male interlocking member  158  that mates with a shaped female aperture  160 , similar to the interlocking member  26  and shaped aperture  35  discussed above. In the illustrated embodiment, the shaped female aperture  160 , however, is formed in the top and bottom frames  152  and  154  of the lamp housing assembly  142 , and the shaped male interlocking member  158  is projecting from the driver housing  162  of the driver assembly  156 . While the shaped female aperture  160  is formed by the top and bottom frame portions  152  and  154 , other embodiments can provide the aperture in only one of the top or bottom frame portions. 
     In the illustrated embodiment, the top frame portion  152  has a rear fan housing portion  164  that projects away from the bottom frame portion  154  and is positioned adjacent to the back end of the heat sink  150 . The rear fan housing portion  164  is a partially hollow structure that contains a pair of fans  166  adjacent to the back end of the heat sink  150 . The fans  166 , when activated, are positioned to blow a flow of air directly into and through the heat sink  150  to facilitate heat removal from the fins  168  of the heat sink  150  during operation of the lamp assembly  140 . In the illustrated embodiment, the fans  166  can be highly efficient, electric, sealed, dust resistant fans, such as fans provided by Sunon® (i.e., Sunonwealth Electric Machine Industry Company, Ltd). Other embodiments can use fans from other manufacturers. While the illustrated embodiment uses two fans  166  carried by the top frame portion  152 , other embodiments may use one fan or more than two fans depending upon, as an example, the thermal characteristics of the lamp assembly  140 . 
     The fans  166  are electrically connected to an interface board  170  positioned in the lamp housing adjacent to the rear fan housing portion  164  and adjacent to the shaped female aperture  160 . The interface board  170  of the illustrated embodiment is captured between the top and bottom frame portions  152  and  154 . The interface board  170  receives power through or from the circuitry in the driver assembly  156  when the driver assembly is attached to the lamp housing assembly. The interface board  170  of the illustrated embodiment has electrical connectors  172  project partially in the shaped female aperture  160  and positioned to engage and electrically connect to mating electrical connectors on the male interlocking member  158  when the driver assembly is in the installed position as discussed above (with the male interlocking member in a 90-degrees misaligned orientation relative to the shaped female aperture  160 ). The electrical connectors  172  are shown in  FIG. 18  as being a pair of pins, although other connectors can be used in other embodiments. 
       FIG. 19  is an isometric view of the lamp assembly  140  without the bottom frame portion  154  of the lamp housing  144  shown to illustrate the interface board  170  in position relative to the top frame portion  152 , the driver assembly  156 , and the LED chip boards  146 . The interface board  170  is also electrically connected to the fans  166  ( FIG. 18 ), such that electricity is provided through the electrical connectors  172 , through the interface board to each fan  160 . The interface board  170  also includes electrical spring clips  174  coupled to the electrical connectors and positioned to electrically engage connector pads  176  on the LED chip boards  146 . These spring clips  174  maintain electrical contact with the LED chip boards to provide electricity to the LED lights  16  when the driver assembly  156  is in the light fixture  1  ( FIG. 1 ) and is connected to the lamp housing assembly  142 . The interface board  170  can include electrical components, such as control circuitry, between the electrical connectors  172  and the spring clips  174  and/or the connector pads to control electricity flow in the lamp housing assembly  142 . 
       FIGS. 20A and 20B  are enlarged front isometric views of the driver assembly  156  separated from the lamp housing assembly  142  of  FIG. 16 . The driver housing  162  has a housing body  178  that contains internal driver circuitry  181  ( FIG. 20B ), and a front plate  180  that carries the male interlocking member  158  is attached to the housing body  178  to close off the interior area  184  of the driver housing  162 . In the illustrated embodiment, the front plate  180  is removeably fastened to the housing body  178  with fasteners  182 , such that the front plate can be removed to access the internal driver circuitry when if or when needed. The front plate  180  has a pair of air flow apertures  186  that align with the fans  166  ( FIG. 18 ) when the driver assembly  156  and the lamp housing assembly  142  are engaged and in the installed position. The rear wall  183  of the housing body  178  also has a pair of rear apertures  185  generally aligned with the fan apertures  186  in the front plate  180 . The rear apertures  185  allow air to be drawn by the fans  166  into and through the housing&#39;s interior area  184 , through the fan apertures  186  in the front plate  180 , through the fans  166 , and get pushed through the heat sink  150 . 
     The front plate  180  in the illustrated embodiment is integrally attached to the male interlocking member  158 . As seen in  FIG. 20 , the male interlocking member  158  has a pair of curved channels  188  shaped and positioned to receive the pins forming the electrical connectors  172 . These curved channels  188  are shaped to allow the lamp housing assembly  142  to rotate the 90 degrees during the installation or removal process while maintaining electrical contact between the driver assembly and the lamp housing assembly  142 . The curved channels  188  are connected to electrical elements that, in turn are connected to wires  190  extending through the housings interior area  184  and into the base assembly  191  attached to the rear wall  183  of the driver housing  178 . 
     As best seen in  FIGS. 18 and 20A , the base assembly  191  of the illustrated embodiment has a hollow base portion  192  integrally connected to the housing&#39;s rear wall  183 . The wires  190  extending through the interior area  184  also extend rearwardly through the hollow base portion  192 . In the illustrated embodiment, the hollow base portion  192  includes internal fins  194  extending radially inwardly so as to define divided chambers  195  within the hollow base portion  192 . These divided chambers  195  can receive the individual wires  190  extending therethrough to help keep the wires separated and spaced apart from each other within the driver housing  162 , thereby helping to maintain wire management therein. These divided chambers also help keep the wires separated near the rear ends where the wires connect to the electrical contact portions of the base. 
     The hollow base portion  192  is sized to receive the threaded sleeve  52 , which electrically connects to at least one of the wires  190  that extends through one of the divided chambers. As discussed above, the sleeve  52  operatively connected to one of the electrical contact points between the light assembly and the light fixture  1  ( FIG. 1 ). The hollow base portion  192  also receives therein a retractable tip assembly  196 . In the illustrated embodiment, the retractable tip assembly  196  has a sleeve  198  that extends into the rear portion of the hollow base portion  192 . The sleeve  198  can include one or more slots  199  that align with and receive the internal fins  194  in the base portion, so that the internal fins engage and firmly hold the sleeve in axial alignment within the base portion. When the sleeve  198  is positioned in the base portion, the sleeve works with the internal fins to fully separate and isolate the divided chambers  195  from each other. 
     The sleeve  198  is a hollow component that slidably receives a biased, electrically conductive retractable tip  200  that defines the second electrical contact point with another electrically conductive portion of the socket  51  of the light fixture  1  ( FIG. 1 ). The sleeve  198  also contains the biasing member, such as a spring  202 , that urges the retractable tip  200  rearwardly away from the base toward an extended position. The forward portion of the retractable tip  200  is captured within the sleeve  198  and is electrically connected to at least one wire  190  extending into the front end of the sleeve. Accordingly, this wire  190  connected to the retractable tip is physically and electrically isolated from the other wire  190  that extends through one of the divided chambers and is electrically connected to the electrically conductive threaded sleeve  52 . The biased retractable tip  200  is configured to compress the spring  202  and move axially into the hollow base portion  192 , similar to the arrangement discussed above. Accordingly, the retractable tip  200  makes electrical contact with the light fixture&#39;s socket, and the spring  202  biases the tip  200  against the fixture&#39;s electrical contact. The spring  202  also acts as a tensioner to keep the threads of the sleeve  52  in firm engagement with the mating threads in the light fixture&#39;s socket. This retractable tip arrangement also allows the lamp assembly  140  to rotate relative to the light fixture to rotationally position the lamp housing assembly  142  in a desired or proper orientation as discussed above. 
       FIG. 21  is a partial exploded isometric view of the heat sink  150  and two LED chip boards  146 , shown removed from the assembly of  FIG. 16 . The base  204  of the heat sink  150  has ridges  206  that define channels  208  that receive the LED chip boards  146 , so the chip boards are held in proper alignment directly on the heat sink&#39;s base  204 . In the illustrated embodiment, the ridges  206  have substantially the same thickness as the LED chip boards  146  so the chip boards are effectively recessed and flush with the surface of the heat sink ridges  206 . In the illustrated embodiment, the base  204  has a plurality of apertures  210  aligned with the plurality of apertures  211  in the LED chip boards  146 . These apertures  210  and  211 , and the LED lights  16 , are also axially aligned with air columns  212  defined by the space between contoured fins  168  of the heat sink  150 . In the illustrated embodiment, the contoured fins  168  are generally aligned with the edge portion of the LED lights, so that the fins  168  can efficiently conduct heat away from the LED light  16  and the area of the LED chip board  146  carrying the LED light  16 . The contoured fins  168  provide for an increased surface area in the heat sink from which to dissipate heat generated by the LED lights  16  and chip boards  146 . 
     As seen in  FIGS. 18 and 19 , the air columns  212  between the contoured fins  168  extending longitudinally along the full length of the heat sink  150 , and the entrance to the air columns  212  are immediately adjacent to the fans  166 . Accordingly, the fans  166  drive airflow directly into the heat sink&#39;s air columns  212  and over surface of the fins  168 , thereby efficiently drawing heat away from the LED chip boards  146  and keeping the heat of the lamp assembly  140  to a minimum. The heat sink  150  is configured to very efficiently and effectively draw heat away from the LED chip boards  146  during operation of the lamp assembly, such that the fans  166  may not be needed in some environments or operating conditions. In some embodiments, the lamp assembly can be provided without the fans  166  adjacent to the heat sink  150 . 
     The heat sink  150  of the illustrated embodiment is a unitary member with the fins  168  integrally connected at one end to the base  204  and integrally connected at the other end to a top portion  216 . The base  204  and top portion  216  are also connected to side walls  218  extending therebetween and generally parallel to the fins  168 . 
       FIG. 22  is an end view of a heat sink  219  in accordance with another embodiment. The heat sink  219  has contoured fins  220  projecting away from the base  222 . The contoured fins  220  each include a plurality of longitudinal ridges  224  that increase the surface area of the fins  220  and that are substantially parallel to the airflow direction through the heat sink  219  during operation of the lamp assembly  140 . The heat sink  219  also has a removable top portion  226  connected to top edges  228  of the sidewalls  230 . The sidewalls  230  of the illustrated embodiment have external support ribs  231  configured to engage the bottom frame portion  154  of the lamp housing  144  ( FIG. 18 ) to support the heat sink on the frame portion. The heat sink&#39;s top portion  226  also has a plurality of channels  232  that removeably receive top edges  234  of the contoured fins  220 . The channels  232  substantially restrain the fins from lateral movement relative to the base  222 . This removable top portion  226  can be configured to decrease the cost and/or complexity of manufacturing the heat sink  219 . 
       FIGS. 23 and 24  are partially exploded isometric views of a heat sink  236  in accordance with another embodiment. The illustrated heat sink  236  has a base  204  that supports the LED chip boards  146  similar to the heat sinks  150  and  219  of  FIGS. 21 and 22 . The base  204  includes a plurality of apertures  210  ( FIG. 24 ) aligned with the air columns  212  defined by the space between the contoured fins  220 , such that the apertures  210  do not interfere with the fins  220  connected to and projecting away from the base  204 . The LED lights  16  ( FIG. 24 ) are also aligned with the air columns  212 . The apertures  210  are coaxially aligned with the apertures  211  in the LED chip boards  146 . 
     The top portion  238  of the heat sink  236  of the illustrated embodiment has a pair of apertures  240  ( FIG. 23 ) each shaped and sized to receive a fan  242  therein. The fans  242  are positioned to blow air into the air columns  212  of the heat sink, thereby creating airflow over the fins  220 . The airflow also flows through the apertures  210  and  211  in the heat sink&#39;s base  204  and the LED chip boards  146 , respectively, thereby pushing air away from the lights  16  in the direction of illumination. In one embodiment, the heat sink  236  is mounted in the lamp housing  142  ( FIG. 16 ) and a portion of the lamp housing  142  can define one or more end structures immediately adjacent to one or both ends of the heat sink  236 . The end structures, such as end caps, can block airflow from exiting the air columns  212 , thereby driving the airflow through the apertures in the base  204  and the LED chip boards  146 . The end caps can be configured to allow for some air to move laterally out of the air columns so as to selectively control the airflow out the ends of the heat sink  236  as well as the airflow passing through the apertures  210  and  211  in the base  204  and LED chip boards  146 . 
     The heat sink  236  can include a wire chase to protect and route wires from the fans  242  to a power source for the fans, such as the interface board  170  in the lamp housing  14  ( FIGS. 16 and 17 ). In the illustrated embodiment, portions of the fins  220  are shaped to form a recess that receives the fans  242 . This recessed arrangement can provide a flush fit for the fans  242  in the top portion of the heat sink. In other embodiments, the fans  242  may not be fully or partially recessed in the heat sink  236 . The heat sink&#39;s top portion  238  of the illustrated embodiment is removably attached to the sidewalls  228 , similar to the heat sink  236  of  FIG. 22 . In other embodiments, the top portion  238  can be integrally connected to the sidewalls and to the contoured fins, similar to the heat sink configuration of  FIG. 21 . 
     The illustrated embodiment shows two fans  242 , such as electric, sealed, dust resistant fans made by Sunon®, mounted in the top portion  238  of the heat sink  236 . Other embodiments can include a single fan mounted in the heat sink  236 , and yet other embodiments can include more than two fans mounted to the heat sink  236  to drive air through the heat sink and through the LED chip boards  146 . This airflow through the heat sink  236 , the base  204 , and the LED chip boards  146  provides a more efficient thermally dynamic coefficient of heat removal from the chip boards  146  at least in part by creating increased turbulent air flow over an increased surface area allowing the heat drawn from the LED chip boards  146  to be expelled downward away from the heat sink  236 , the base panel  204  and the LED chip boards  146 . This results in increasing the assembly&#39;s thermal efficiency and substantially lowering the thermal temperature of the heat sink  236 , the LED chip boards  146 , and the lights  16 , which results in extending the working life of LED chip boards  146 . This configuration also drives heat in the direction of illumination. 
     When the lamps are positioned in or adjacent to a ceiling structure of a building space and facing downwardly, the downward flow of heated air and can also greatly reduce the thermal stratification/de-stratification that can occur in large rooms, such as warehouses, hangars, large box stores (e.g., Costco), auditoriums, large greenhouses, etc. Accordingly, the lamp assemblies allow the HVAC systems to better or more efficiently balance the inner-environment space and even out environmental temperatures, thereby reducing the number of ceiling fans in new installations and possibly allow removal in existing spaces where ceiling fans are currently installed. Embodiments of the lamp assemblies provide additional benefits, including a substantial weight reduction compared to conventional lamps that include ballast (which can weigh approximately 9-12 lbs., a capacitor, an igniter, and the associated wiring. In at least one embodiment, a lamp assembly for a hi-bay light fixture can provide a weight savings of approximately 11-14 lbs per fixture. In a large building that has approximately 400 hi-bay light fixtures, the lamp assemblies of the present disclosure can provide a reduction of ceiling weight of well over 2 tons. Such a weigh savings can be significant for the structural design for new construction due to a potential reduction of roof load. 
       FIGS. 25-27  are isometric views of an LED-based lamp assembly  300  in accordance other embodiments. The lamp assembly  300  has a substantially circular LED chip board assembly  302  that includes a plurality of LED lights  304  disposed in a selected pattern. The LED chip board assembly  302  is attached to a circular base panel  306  of a heat sink  308 . The heat sink  308  has a plurality of radially extending fins  310  connected to and projecting away from the base panel  306 . The heat sink  308  also has a plurality of mounting portions  312  projecting away from the base panel  306  and oriented substantially parallel to the fins  310 . 
     The top edges of the fins  310  and the mounting portions  312  of the illustrated embodiment are substantially coplanar and support a fan  316  coaxially aligned with the heat sink  308  and the LED chip board assembly  302 . The fan  316  is configured to push airflow downwardly along the fins and through the heat sink  308  to help draw heat from the LED chip board assembly  302  away from the heat sink fins  310 . In at least one embodiment, the base panel  306  of the heat sink  308  can have apertures formed therethrough to allows some of the airflow from the fan  316  to flow directly to the LED chip board assembly  302 . The fan  316  of the illustrated embodiment can be a sealed, dust resistant, non-bearing, magnetic levitation fan from Sunon® that can provide air flow of approximately 116 cfm. Other embodiments can use other fans or have other airflow performance characteristics to help keep the LED chip board assembly  302  and other components during operation of the lamp assembly. 
     The fan  316  is operably connected to a driver housing assembly  320 . In the illustrated embodiment, the fan  316  is mounted to a driver housing assembly  320  by fasteners  322  that extend through the corners of the driver housing  324 , through corners of the fan  316 , and extend into and threadably engage the mounting portions  312  of the heat sink  308 . Other embodiments can use other fastening techniques for securing the fan  316  between the driver housing  324  and the heat sink  308 . In other embodiments, the lamp assembly  300  can be provided without the fan  308 , such that the driver housing  324  can be secured directly to the heat sink. 
     The driver housing  324  has a removable top plate  326  that provides access into the interior area of the driver housing. The top plate  326  is integrally connected to a hollow base portion  192  of a base assembly  191 . The base assembly  191  has a configuration substantially as discussed above with the internal fins  194  defining the divided chambers  195  in the hollow base portion  192 , the threaded sleeve  52 , and the retractable tip assembly  196  to operatively and removably connect the lamp assembly  300  to the light fixture  1  ( FIG. 1 ). 
       FIG. 26  illustrates an alternate embodiment wherein the circular base panel  306  of the heat sink  308  includes a plurality of apertures  330  axially aligned with spaces between the radially extending fins  310 . The LED chip board assembly  302  also includes a plurality of apertures  332  aligned with the apertures  330  of the base panel  306  such that airflow from the fan  316  can move axially over the fins  310  and through the aligned apertures  330  and  332 , thereby driving air through the LED chip board assembly  302  to carry heat away from the PCB chip board and the associated LED lights  304 . In at least one embodiment the LED chip board assembly  302  can be a standard metal core board constructed of Aluminum or other such thermal-advantaged metal or can be a SinkPad® metal core board of various type metals. 
     In at least one embodiment, the LED chip board assembly  302  can be an integral component of the heat sink  308 . For example, the LED chip board  302  can include integrated circuits and associated components printed or applied directly onto the base panel  306  of the heat sink  308 , such that an additional conventional printed circuit board is not attached or otherwise fixed to a separate base panel of the heat sink. In this alternate embodiment, the air passageways carrying heated air away from the heat sink  308  can be provided in the base panel onto which the integrated circuitry and lights and associated components are mounted. In yet other embodiments, the LED chip board can be formed by other dynamic LED chip board arrangements, such as CarbAl®, a nano-level product combining carbon and aluminum. 
     In the illustrated embodiment, the LED chip board assembly  302  has an equal number of thru-holes that provide an exact match to the number of thru-holes in base panel  306 . The LED chip board assembly  302  also has a plurality of fastener holes  336  that align and match a plurality of fastener holes  338  in the base panel  306  a plurality of fasteners  340 , special thread-forming screws, extend through the fastener holes  336  and  338  to fasten the LED chip board assembly  302  directly to the base panel  306 . In other embodiments the heat sink  308  and the LED chip board assembly  302  can include a registration means, such as notches, lines, or a non-symmetrical shape, that ensure the LED chip board assembly  302  will be properly positioned and registered on the circular base panel  306  with the apertures  330  and  332  in axial alignment. 
     The apertures  330  and  332  in the base panel  306  and LED chip board assembly  302  can vary in diameter and position relative to the LED lights  304  so as to provide selective airflow and a direct cooling effect on the LED chip board assembly  302 . The apertures  330  in the base panel  306  are positioned to align with the spaces between the fins  310  so that the apertures do not interfere with the fins  310 . In addition, the apertures in the base panel and/or the LED chip board assembly  302  are positioned so as to not interfere with the LED lights  304  while allowing the air flow to draw heat away the integrated circuits, the lights, and associated components. 
     Similar to the embodiment discussed above in connection with  FIGS. 23 and 24 , this configuration with the aligned apertures  330  and  332  in the heat sink  308  and LED chip board assembly  302  provides an increased thermal advantage by allowing air from the fan  316  to pass downward along the fins  310 , through the heat sink&#39;s base panel  306  and the LED chip board assembly  302 , thereby drawing and pushing the heat away from the LED chips  304  in the direction of illumination. The result is a more efficient thermally dynamic coefficient of heat removal from the LED chip board assembly  302  via the increased turbulence over a greater surface area, which substantially lowers the thermal temperature of the heat sink  304 , LED chip board assembly  302  and associated LED lights  304 , and which extends the working life of the LED chip board assembly  304 . This configuration is also very effective at greatly reducing the weight of the light fixtures as well as reducing the thermal stratification/de-stratification that can occur in large rooms, such as warehouses, hangars, large box stores (e.g., Costco), auditoriums, large greenhouses, etc., as discussed above. 
       FIG. 28  is a plan view of a heat sink of an LED-based lamp assembly of another embodiment.  FIGS. 29 and 30  are side and end elevation views of the heat sink of  FIG. 29 . In at least one embodiment, the LED lamp assembly  10  includes an improved heat sink  122  that has a base plate  124  that mounts to the lamp housing as discussed above. The heat sink  122  includes a plurality of heat dissipating fins or towers  126  projecting from the base plate  124 . The base plate  124  and the towers  126  are made from Aluminum, Aluminum alloy, or other suitable material. As seen in  FIGS. 29 and 30 , a plurality of holes  128  extend through the top portions of the towers  126 . The holes  128  in the illustrated embodiment are substantially parallel to the base plate  124 . Other embodiments can have the holes in other locations or orientations. The holes  128  act to increase the effective surface area of the heat sink  122 , thereby increasing its heat-dissipating effectiveness. In one embodiment, the towers  126  can also have holes  130  therein perpendicular to the base plate  124 , such that a portion of the tower  126  is hollow. This hollow or partially hollow construction can also increase the effective surface area of the heat sink  122 . 
     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the invention. Additionally, aspects of the invention described in the context of particular embodiments or examples may be combined or eliminated in other embodiments. Although advantages associated with certain embodiments of the invention have been described in the context of those embodiments, other embodiments may also exhibit such advantages. Additionally, not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.