Abstract:
There is described an LED lighting system comprising: at least one light emitting diode (LED); a heat sink thermally connected to the at least one LED for dissipating heat generated by the at least one LED; an electrical connector for electrically connecting the LED lighting system to a power source; and a thermal insulating connector having a first end connected to the heat sink and a second end connected to the electrical connector, the thermal connector comprising a chamber adapted to receive an electronic circuit therein, the electronic circuit being operatively connected to the at least one LED and the electrical connector.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 61/309,998, filed on Mar. 3, 2010, the contents of which are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to the field of LED lighting systems, and particularly to thermal protection of electronic circuitry in LED lighting systems. 
       BACKGROUND 
       [0003]    Light emitting diode (LED) lighting systems usually include a heat sink in order to cool heat generating LEDs. A heat sink cools the device by absorbing and dissipating generated heat and is made of a thermal conductive material. The transfer of heat is improved by providing the heat sink with a specific shape, intended to create greater surface area and an improved thermal flow. 
         [0004]    When LED lighting systems comprise embedded electronic circuitry, such as an electrical power converter circuit, the electronic circuitry is usually positioned in a cavity inside the heat sink. As a result, the electronic circuitry can be exposed to a high temperature environment when the LEDs are in operation, which can damage or shorten the lifetime of an electronic circuit. 
         [0005]    Therefore, there is a need for thermally protecting embedded electronic circuitry in an LED lighting system. 
       SUMMARY 
       [0006]    According to a first broad aspect, there is provided an LED lighting system comprising: at least one light emitting diode (LED); a heat sink thermally connected to the at least one LED for dissipating heat generated by the at least one LED; an electrical connector for electrically connecting the LED lighting system to a power source; and a thermal insulating connector having a first end connected to the heat sink and a second end connected to the electrical connector, the thermal connector comprising a chamber adapted to receive an electronic circuit therein, the electronic circuit being operatively connected to the at least one LED and the electrical connector. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
           [0008]      FIG. 1  is an exploded view of an LED lighting system comprising electronic circuitry embedded in a thermal connector, in accordance with an embodiment; 
           [0009]      FIG. 2  is a top view of the thermal connector of the  FIG. 1 ; 
           [0010]      FIG. 3  is a front view of a T-shaped thermal connector provided with a chamber in the upper portion of the connector, in accordance with an embodiment; 
           [0011]      FIG. 4  is a front view of a T-shaped thermal connector provided with a chamber in the lower portion of the connector, in accordance with an embodiment; 
           [0012]      FIG. 5   a  is a front view of a bayonet-type electrical connector, in accordance with an embodiment; 
           [0013]      FIG. 5   b  is a front view of a GU-type electrical connector, in accordance with an embodiment; and 
           [0014]      FIG. 5   c  is a front view of an MR-type electrical connector, in accordance with an embodiment. 
       
    
    
       [0015]    It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
       DETAILED DESCRIPTION 
       [0016]      FIG. 1  illustrates one embodiment of an LED lighting system  10  which comprises an LED board  12 , a heat sink  14 , an embedded electronics circuit  16 , a thermal insulating connector  18 , and an electrical connector  20 . The LED board  12  has a plurality of LEDs  22  positioned on its top surface. The LED board  12  also comprises electrical connections on its top surface to electrically connect the LED  22  to a source of power. The heat sink  14  is designed to receive the LED board  12  on its top surface and the heat radiating fins  24  are designed to remove the heat generated by the LEDs  22  from the LED board  12 . Any mechanical means can be used to removably or permanently attach the LED board to the top surface of the heat sink  14 . For example, screws can be used to removably secure the LED board  12 . Alternatively, the LED board  12  can be welded to the heat sink  14  in order to be permanently attached thereto. The LED board  12  can also be bonded to the heat sink  14  by thermal tape which increases the thermal communication between the LED board  12  and the heat sink  14  and increases the cooling of the LED board  12 . Alternatively, a thermal paste can be used to bond the LED board  12  to the heat sink  14 . A thermal conductive plate made of heat conductive material such as graphite, for example, can also be inserted between the LED board  12  and the heat sink  14  in order to improve the heat transfer between the two. 
         [0017]    The thermal connector  18  has a chamber  28  of which the shape and size are adapted to receive the circuit  16 . The thermal connector  18  is made of any thermal insulating material such as plastic, polycarbonate, or the like. A cover  26  also made of a thermal insulating material is used to seal the chamber  28  once the circuit is inserted into the chamber  28 . The thermal connector  18  and the thermal cover  26  protects the enclosed circuit  26  from the heat emitted by the heat sink  14 . The cover  26  is provided with at least one hole  42  so that electrical cables  30  and  32  connect the circuit  16  to the LEDs  22  of the LED board  12 , as illustrated in  FIGS. 1 and 2 . 
         [0018]    Once the circuit  16  is enclosed in the chamber  28  and the cover  26  is positioned on top of the thermal connector  18 , the thermal connector  18  is attached to the heat sink  14  and the electrical connector  20 . The thermal connector  18  is provided with a thread  38  on its upper outer surface. The heat sink comprises a threaded aperture on its lower inner surface. The dimensions of the aperture are adapted to receive the thermal connector  18  for threading into the heat sink  14 . The thermal connector  18  also comprises a second thread  40  on its lower outer surface. The electrical connector  20  comprises a threaded aperture of which the thread corresponds to the second thread  40  of the thermal connector  18 . The thermal connector  18  is then screwed into the electrical connector  20 . 
         [0019]    The circuit  16  is connected to the electrical connector  20  via cables  34  and  36 . The bottom part of the thermal connector  18  is provided with at least one aperture adapted to receive the cables  34  and  36 . The electrical base connector  20  receives electric power from an external power source and transmits it to the LEDs  22  via cables  30 ,  32 ,  34 , and  36 , and the circuit  16 . 
         [0020]    While the present description refers to four LEDs  22 , it should be understood that the LED lighting system  10  can comprise one or more LEDs. The LEDs can be white LEDs or colored LEDs. The system  10  can be an RGB system comprising red, green, and blue LEDs in order to produce a white light. 
         [0021]    In one embodiment, the thermal insulating material is also an electrical insulating material. As a result, the thermal connector  18  and the cover  26  form an electrical insulating barrier protecting the enclosed circuit  16 . 
         [0022]    In one embodiment, the circuit  16  is fixedly attached in the chamber  28  using screws or clamps, for example. Alternatively, any adhesive can be used to attach the circuit  16  in the chamber  28 . It should be understood that any mechanical means can be used to removably or permanently secure the circuit  16  in the chamber  28 . 
         [0023]    The circuit  16  can be any type of embedded circuit used in LED lighting systems, such as an electric circuit, an electronic circuit, a microprocessor, and the like. The circuit  16  can be an electrical power converter for converting a 110V ac input into a 12V dc output, for example. Electronic controllers represent another example of embedded circuit  16 . For example, the circuit  16  can be a DMX network protocol controller, a dimmer circuit, etc. 
         [0024]    While the chamber  28  extends from the top surface of the thermal connector  18 , it should be understood that the chamber could be located elsewhere within the connector  18 . For example, the chamber  28  could be located in the lower portion of the connector  18  and connected to the bottom surface of the thermal connector  18 . 
         [0025]    In one embodiment, a lens or lens assembly is positioned on top of LED board  12 . The lens can be secured to the heat sink using any mechanical means such as clamps, screws, etc. 
         [0026]    While the thermal connector  18  is attached to the bottom surface of the heat sink  14 , it should be understood that the thermal connector  18  could be secured on another surface of the heat sink  14 , such as on the lateral outer surface. 
         [0027]    Any mechanical means can be used for fastening the thermal connector  18  to the heat sink  14  and the electrical connector  20 . For example, the thermal connector  18  can be screwed to the heat sink  14 , and the thermal connector  18  and the electrical connector  20  are secured together via a bayonet mechanism. The bayonet mechanism comprises pins located on the lateral outer surface of the thermal connector  18 . The pins are inserted into slots present on the lateral surface of the electrical connector  20 . A spring present in the electrical connector  20  can be used to apply a clamping force. Alternatively, an adhesive can be used for securing the thermal connector  18  to the heat sink  14  and the electrical connector  20 . In this case, the bottom surface of the heat sink  14  and the top surface of the electrical connector  20  can be planar surfaces with no hole and the thermal connector is glued to these surfaces. 
         [0028]    While  FIG. 1  refers to a cylindrical thermal connector  18 , it should be understood that the thermal connector can have any shape.  FIG. 3  illustrates one embodiment of a T-shaped thermal connector  50  having a first section  52  and a second section  54 . The dimensions of the first section  52  are adapted to the dimensions of the circuit  56  while the size of the second section  54  is adapted to that of the electrical connector to which the thermal connector  50  is to be secured. The connector  50  comprises a chamber  58  in the first section for receiving the electronic circuit  56 . A cover  60  closes the chamber  58  and protects the circuit  56  from the heat emitted by the heat sink to which the first section  52  of the thermal connector  52  is secured. The cover is provided with an aperture  62  to allow an electrical cable to connect the circuit  56  to the LEDs. The thermal connector  50  is provided with an aperture  64  which connects the chamber  58  to the bottom surface of the second section  54  and which allows electrical cables to connect the circuit  56  to the electrical connector. 
         [0029]      FIG. 4  illustrates another embodiment of a T-shaped connector  70  having a top section  72  and a bottom section  74 . The bottom section  74  is provided with a chamber in which an electronic circuit  78  is inserted. As the thermal connector  70  comprises no cover, the chamber  76  is laid opened. The circuit  78  can be fixedly attached within the chamber  76 . Alternatively, the tension in the electrical cables which connect the circuit  78  to the LEDs  22  is sufficient to maintain the circuit  78  in position within the chamber  76 . 
         [0030]    In one embodiment, the thermal insulating connector  70  is provided with a cover adapted to enclose the circuit  78  within the chamber  76 . 
         [0031]    In one embodiment, the LED lighting system  10  is a retrofit lighting system which can be connected to already existing electrical installations. For example, the LED lighting system  10  can be a retrofit lamp used in replacement of a usual light bulb. Light bulbs require a 110V-240V ac electrical current and therefore the electrical installations that receive the light bulb are adapted to provide a 110V-240V ac electrical current to the light bulb. If an LED lighting system is used as a retrofit light bulb, the voltage is converted since LEDs usually require a dc voltage. In this case, the embedded circuit can be an electrical power converter for converting a 110V-240V ac input into a 12V dc output, for example. 
         [0032]    It should be understood that the LED lighting system can be any type of lamp, such as a mirrored reflected (MR) lamp or a parabolic aluminized reflector (PAR) lamp, for example. 
         [0033]    While the electrical connector  20  illustrated in  FIG. 1  is an Edison screw type connector,  FIGS. 5   a - c  illustrate other types of electrical connectors that can be used in the LED lighting system.  FIG. 5   a  illustrates a bayonet-type electrical connector while  FIGS. 5   b  and  5   c  illustrate a GU-type electrical connector and an MR-type electrical connector, respectively. 
         [0034]    The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.