Abstract:
An LED device has an LED assembly connected to or abutting a heat sink, the heat sink connected to a cooling bridge and optionally enclosed within insulated connector end caps and crossover end caps and within a reflector cover and side cover. The cooling bridge conducts heat to the heat sink away from the reflector cover, and side cover, where the heat may be removed by a circulating coolant. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 C.F.R. §1.72(b).

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 (e) to, and hereby incorporates by reference, U.S. Provisional Application No. 61/372,060, filed Aug. 9, 2010. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to light-emitting diodes and, in particular, this invention relates to a method for cooling a device using light-emitting diodes being used to generate and direct radiation. 
         [0004]    2. Background 
         [0005]    While LEDs represent a significant improvement in generating radiation for industrial uses, such as UV-polymerizing printing inks and coatings, these devices nonetheless produce significant amounts of heat. Unless dissipated or removed from LED-utilizing devices, the heat can distort any reflective surface and can significantly damage the LEDs themselves. There is then a need for an efficient and structurally straightforward design for removing unwanted heat from LED-utilizing devices. 
       SUMMARY OF THE INVENTION 
       [0006]    This invention substantially meets the aforementioned needs of the industry by providing an LED device with a straightforward, yet efficient structure for removing heat from an operating LED device. 
         [0007]    There is provided an LED device, the LED device including an LED assembly, a plurality of cooling bridges, a heat sink, a reflector cover, a side cover, a reflector, and connector and crossover end caps. The LED assembly may include a plurality of LED chips. The cooling bridges may be attached to or abut the heat sink. The reflector may be positioned by the reflector cover to direct radiation from the LED assembly. The connector and crossover end caps may include an electrically or thermally insulating material. 
         [0008]    There is also provided a method of manufacturing an LED device, the method including 1) attaching a plurality of cooling bridges to a water rail, the water rail having a pair of axially formed channels; 2) positioning a reflector to direct radiation emitting from the LED chips; and 4) attaching a connection end cap and a crossover end cap to the water rail so as to form a fluidic circuit. 
         [0009]    There is still yet formed a method of cooling an LED device, the LED device having an LED array, a reflector directing radiation emitted from the LED array, a water rail attached to, or abutting, the LED array, the water rail also attached to or abutting the cooling bridge, the method comprising circulating a coolant within axial channels formed in the water rail. 
         [0010]    These and other features of this invention will become apparent from the description which follows, when considered in view of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of one embodiment of the insulated LED device of this invention. 
           [0012]      FIG. 2  is an exploded view of the insulated LED device of  FIG. 1 . 
           [0013]      FIG. 3  is a side view of the insulated LED device of  FIG. 1 . 
           [0014]      FIG. 4  is a cross section taken along line A-A of  FIG. 3 . 
       
    
    
       [0015]    It is understood that the above-described figures are only illustrative of the present invention and are not contemplated to limit the scope thereof. 
       DETAILED DESCRIPTION 
       [0016]    Unless otherwise defined, all 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. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 
         [0017]    Any references to such relative terms as front and back, right and left, top and bottom, upper and lower, horizontal and vertical, or the like, are intended for convenience of description and are not intended to limit the present invention or its components to any one positional or spatial orientation. Dimensions of the components in the attached figures may vary with a potential design and the intended use of an embodiment of the invention without departing from the scope of the invention. 
         [0018]    Each of the additional features and methods disclosed herein may be utilized separately or in conjunction with other features and methods to provide improved devices of this invention and methods for making and using the same. Representative examples of the teachings of the present invention, which examples utilize many of these additional features and methods in conjunction, will now be described in detail with reference to the drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Therefore, only combinations of features and methods disclosed in the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative and preferred embodiments of the invention. 
         [0019]    One embodiment of an insulated LED device of this invention is depicted in the figures at  100 , and includes a light engine such as an LED assembly  102 , a plurality of cooling bridges  104 , a heat sink, such as a water rail  106 , a reflector cover  108 , a side cover  110 , a connection end cap assembly  112 , and a crossover end cap assembly  114 . A person of ordinary skill in the art will readily recognize that the LED assembly  102  contains a plurality of LED chips  122  supported on a copper plate  124 . Several configurations and materials for the LED assembly  102  may be present in the contemplated invention. 
         [0020]    In the embodiment depicted, the water rail  106  may be made from a thermally conductive material, such as aluminum. However, a person of ordinary skill in the art would readily recognize other acceptable materials for manufacturing the present water rail. When connected to the LED assembly  102  and the water rail  106 , the plurality of cooling bridges  104  serve to conduct heat away from the LED assembly  102  and to position the LED assembly  102  so as to direct radiation being emitted from the present LED assembly. A plurality of finned channels  132 ,  134  may be axially defined in the water rail  106 . Fins  136 ,  138 , formed adjacent respective channels  132 ,  134 , increase surface area of the water rail  106  adjacent the channels  132 ,  134 , thereby more efficiently extracting heat from the water rail  106  when a coolant is circulated through the channels  132 ,  134 . The coolant thusly circulated may be a liquid or a gas. Suitable liquids include water, polyethylene glycol-water solutions, liquefied nitrogen, and the like. Suitable gases include cooled atmospheric air. 
         [0021]    A terminal block  144  may be used to jumper each light engine segment together, or to group light engines to allow one or more of the light engines to be controlled separately of the others, and may be attached to an underside of the cooling bridge and/or to the reflector cover. Terminal blocks allow for thermally and electrically insulated connections between light engines and external power sources. 
         [0022]    The reflector cover  108  has an outer portion  150  and inner lobes  152  extending from the outer portion  150 . The outer portion  150 , at a channel  153  attaches to a lip structure  154 , the lip structure  154  forming an axial slot  155 . A slot  156  is formed at a lower portion of the outer portion  150 . Another slot  160  is formed opening inboard at a lower location of the outer portion  150 . The slots  155 ,  156  are positioned so as to accommodate a reflector  162 . The reflector  162  is maintained at a desired position and configuration by being marginally disposed within the slots  155 ,  156  and by abutting the lobes  152 . 
         [0023]    The side cover  110  attaches to or contacts the water rail  106  at a channel  170 . The side cover  110  terminates upwardly at an extension  172  and terminates downwardly at a slot  174 . The extension  172  disposes within the slot  158  of the reflector cover  108 . However, a person of ordinary skill in the art would recognize that extension  172  and slot  158  could be present on respective reflector cover  108  and side cover  110 . The slot  174  of the side cover  110  and the slot  160  of the reflector cover  108  cooperate to accommodate and position a window  180 . 
         [0024]    The window  180  may be selected from materials allowing desired radiation wavelengths to pass therethrough, such as an acrylic or other material readily known to a person of ordinary skill in the art. 
         [0025]    The connection end cap assembly  112  has a connection end cap  190  and a connection insulator block  192 . The connection end cap  190  is secured to, and positions, the reflector and side covers  108 ,  110 . The connection insulator block  192  is made of an electrically insulative material such as an acetyl polymer, Delran™ being one suitable material. However a person of ordinary skill in the art will readily recognize that other suitable materials may be used as well. Fittings  194  may attach to the connection insulator block  192  so as to connect to sources of coolant and to provide ingress and egress of coolant to the water rail  106 . It is recognized that the fittings  194  will vary according to the coolant being used and conditions under which the water rail  106  is cooled and maintained. 
         [0026]    The crossover end cap assembly  114  includes a crossover end cap  200  and a connection insulator block  202 . The crossover end cap  200  defines a slot  204 , which accommodates and positions the connection insulator block  202 . The connection insulator block may be made from Delran™ or another suitably insulating material as described about with respect to the insulator block  192 . The connection insulator block  202  defines a slot  206  which is dimensioned and positioned so as to direct coolant egressing from one of the channels  132 ,  134  to the other of the channels, thereby providing and completing a coolant circuit for the LED device  100  of this invention. Fluid-tight seals may be facilitated by the presence of O-rings (not shown) at each of the openings of the channels  132 , 134 . One function of the insulator block is that the remainder of the instant LED device, aside from the LED assembly  102 , cooling bridge  104 , water rail  106 , and reflector and side covers  108 ,  110 , is not cooled, thereby more efficiently cooling the components of this invention needing to be maintained at a desired temperature. 
         [0027]    An optional conduit  206  may contain electrical wires providing electricity to the LED assembly  102 . The conduit  206 , if present, may provide support and anchorage to the LED device  100  as well. While not shown, a person of ordinary skill in the art will recognize that a coolant supply apparatus may be operably present to provide and receive circulating coolant to and from the water rail  106 . The coolant supply apparatus would vary depending on, for example, the coolant used and desired coolant temperatures and flow rates. 
         [0028]    Thermal contacts  220 ,  222 ,  224  from the respective reflector cover  108 , side cover  110 , and water rail  106  are accomplished by abutting contact between these features and the cooling bridge  104 . A percentage of radiated energy, such as heat, is absorbed by the irradiated extrusions (covers  106 ,  108 ) and reflector  162 , which results in unwanted heating of these outer extrusions. The cooling bridge  104  of this invention thusly provides a path for the unwanted heat to be conducted from the reflector cover  108  and side cover  110  through the cooling bridge  106  to the water rail  106 , which is a heat sink, thus lowering the temperature of the outer extrusions. 
         [0029]    The cooling bridges  104  also provide uniform optical alignment between the radiation source (LED chips  122 ) and the reflector  162  by precisely tying the extrusions supporting the reflector  162  to the water rail  106  in several places along the length of the LED device  100  of this invention. 
         [0030]    One suitable LED assembly has a plurality of LED chips  102  mounted to a heat-tolerant and electrically insulative resin such as an amorphous thermoplastic polyethermide. One suitable such polyethermide is Ultem® (SABIC Innovative Plastics). The heat-tolerant resin is mounted or bonded to a thermally conductive, but electrically insulative resin such as SARCON®, which is bonded or connected to a thermally and electrically conductive plate  124  such as copper or aluminum. 
         [0031]    In addition to those disclosed above, other suitable polymers or synthetic resins are disclosed and described in the Handbook of Plastics, Elastomers, and Composites, Third Edition, Charles a Harper, Editor-in-Chief, McGraw-Hill New York (1996), which is hereby incorporated by reference in its entirety. 
         [0032]    A person of ordinary skill in the art will readily appreciate that individual components shown on various embodiments of the present invention are interchangeable to some extent and may be added or interchanged on other embodiments without departing from the spirit and scope of this invention. 
         [0033]    Because numerous modifications of this invention may be made without departing from the spirit thereof, the scope of the invention is not to be limited to the embodiments illustrated and described. Rather, the scope of the invention is to be determined by the appended claims and their equivalents.