Abstract:
Disclosed herein is a replacement light for a fluorescent tube usable in a fluorescent fixture. The light includes a housing having a first end and a second end opposite the first end. A support structure is disposed within the housing. At least one LED is positioned within the housing and is arranged on the support structure. A first seal has at least one aperture and is disposed within the first end of the housing. The first seal is configured to conform to an inner circumference of the first end of the housing. At least one electrical connector extends through the at least one aperture is and connectable to the fluorescent fixture.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 61/108,345, filed Oct. 24, 2008, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates in general to LED replacements for fluorescent lights. 
       BACKGROUND 
       [0003]    LED-based lights shaped to replace conventional fluorescent tubes have appeared in recent years. Typically, such lights include a hollow tube with two end caps, one at each longitudinal end of the tube. The end caps generally include molded plastic cup-shaped bodies that slide over the ends of the tube to secure the end caps to the tube. End caps can seal ends of the tube to prevent contaminants from interfering with operation of the light. Additionally, each end cap can include one or more pins for compatibility with standard fluorescent fixtures. For example, many end caps carry two pins for compatibility with fixtures designed to receive standard-sized tubes, such as T5, T8, or T12 tubes. 
       SUMMARY 
       [0004]    Embodiments of a replacement light for a fluorescent tube usable in a fluorescent fixture are disclosed herein. In one such embodiment, the light includes a housing having a first end and a second end opposite the first end. A support structure is disposed within the housing. At least one LED is positioned within the housing and is arranged on the support structure. A first seal has at least one aperture and is disposed within the first end of the housing. The first seal is configured to conform to an inner circumference of the first end of the housing. At least one electrical connector extends through the at least one aperture is and connectable to the fluorescent fixture. 
         [0005]    In another such embodiment, the light includes a housing having a first end and a second end opposite the first end. A support structure is disposed within the housing. At least one LED is positioned within the housing and arranged on the support structure. Sealing means for replacing a conventional end cap are disposed within the first end of the housing. 
         [0006]    Embodiments of a method of manufacturing a seal for a fluorescent tube replacement light containing at least one LED are also disclosed herein. In one such embodiment, the method includes providing a housing having a first end and a second end opposite the first end. A hardenable material is introduced to at least the first end of the housing. The hardenable material is hardened such that it conforms to an inner circumference of the first end. 
         [0007]    These and other embodiments will be described in additional detail hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a cross-section of an example of a light tube according to one embodiment of the present invention; 
           [0009]      FIG. 2  is a perspective view of an example of the end cap replacing seal of  FIG. 1 ; 
           [0010]      FIG. 3  is a perspective view of material being poured into a housing to form an end cap replacing seal; and 
           [0011]      FIG. 4  is an exploded side view of an end cap replacing seal being inserted into a housing. 
       
    
    
     DESCRIPTION 
       [0012]    Examples of LED-based lights including end cap replacing seals for use instead of plastic cup-shaped end caps and other types of end caps are discussed below with reference to  FIGS. 1-4 .  FIG. 1  illustrates a light  10  sized for placement in a fixture  12  designed to receive standard-sized tubes. The fixture  12  can be, for example, of the type for accepting a T5, T8, T12 or any other suitable tube. Alternatively, the fixture  12  can be of the type for accepting another light, such as a halogen light or an incandescent bulb. 
         [0013]    The light  10 , as shown in  FIG. 1 , includes a tubular housing  14 , a circuit board  16 , multiple LEDs  20 , and two end cap replacing seals  22 . The tubular housing  14  defines a through-bore  17 . The housing  14  can be made from polycarbonate, acrylic, glass or another light transmitting material (i.e., the housing  14  can be transparent or translucent). For example, a translucent housing  14  can be made from a composite, such as polycarbonate with particles of a light refracting material interspersed in the polycarbonate. While the illustrated housing  14  is cylindrical, housing having a square, triangular, polygonal, or other cross sectional shape can alternatively be used. Similarly, while the illustrated housing  14  is linear, housing having an alternative shape, e.g., a U-shape or a circular shape can alternatively be used. Additionally, the housing  14  need not be a single piece as shown in  FIG. 1 . Instead, another example of a housing can be formed by attaching multiple individual parts, not all of which need be light transmitting. For example, a housing formed by attaching multiple individual parts can include an opaque lower portion and a lens or other transparent cover attached to the lower portion to cover the LEDs  20 . The housing  14  as shown in  FIG. 1  can be manufactured to include light diffusing or refracting properties, such as by surface roughening or applying a diffusing film to the housing  14 . For compatibility with the fixture  12  as discussed above, the housing  14  can have a length such that the light  10  is approximately 48″ long, and the housing  14  can have a 0.625″, 1.0″, or 1.5″ diameter. Of course, housing  14  can have other suitable dimensions. Additionally, the housing  14  can define a groove  15  for slidably receiving the circuit board  16 . 
         [0014]    The circuit board  16 , as illustrated in  FIG. 1 , is an elongate printed circuit board. Multiple circuit board sections can be, for example, joined by bridge connectors to create the circuit board  16 . The circuit board  16  is slidably engaged with the groove  15  of the housing  14 , though the circuit board  16  can alternatively be clipped, adhered, snap- or friction-fit, screwed or otherwise connected to the housing  14 . For example, the circuit board  16  can be mounted on a heat sink that is attached to the housing  14 . As another example, the circuit board  16  can be secured by the seals  22  as is discussed below in greater detail. Also, other types of circuit boards may be used, such as a metal core circuit board. Or, instead of a circuit board  16 , other types of electrical connections (e.g., wires) can be used to electrically connect the LEDs  20  to a power source. Additional electrical components, such as a rectifier and filter, can also be mounted on the circuit board  16 . 
         [0015]    The LEDs  20  can be surface-mount devices of a type available from Nichia, though other types of LEDs can alternatively be used. For example, although surface-mounted LEDs  20  are shown, one or more organic LEDs can be used in place of or in addition thereto. The LEDs  20  can be mounted to the circuit board  16  by solder, a snap-fit connection, or other means. The LEDs  20  can produce white light. However, LEDs that produce blue light, ultra-violet light or other wavelengths of light can be used in place of white light emitting LEDs  20 . 
         [0016]    The number of LEDs  20  can be a function of the desired power of the light  10  and the power of the LEDs  20 . For a 48″ light, such as the light  10 , the number of LEDs  20  can vary from about five to four hundred such that the light  10  outputs approximately 500 to 3,000 lumens. However, a different number of LEDs  20  can alternatively be used, and the light  10  can output a different amount of lumens. The LEDs  20  can be evenly spaced along the circuit board  16 , and the spacing of the LEDs  20  can be determined based on, for example, the light distribution of each LED  20  and the number of LEDs  20 . 
         [0017]    As shown in  FIG. 1 , the seals  22  can be positioned in opposing ends of the housing  14  (i.e., in opposing ends of the through-bore  17  defined by the housing  14 ). The seals  22  can be made from a variety of materials, such as an epoxy or other resin-based substance, rubber, cork, gel, concrete, glass, clay, wax, a polymer, silicone, or another material. The seals  22  can prevent the unintended entry of objects to the interior of the housing  14 . The seals  22  can also perform additional functions as described below. 
         [0018]    Each seal  22  can have a perimeter  22   a  shaped to conform to an inner circumference of the housing  14 . As such, each seal  22  can have a perimeter  22   a  substantially identical to an inner circumference of the housing  14  such that the seal  22  can plug an end of the housing  14 . For example, each seal  22  can be generally disc-shaped if the housing  14  is cylindrical. Alternatively, the seals  22  can be shaped to contact only portions of the inner circumference of the housing  14  when fit into ends of the housing  14 . Thus, while the seals  22  can serve to prevent the unintended entry of an object to the interior of the housing  14 , the seals  22  need not necessarily be air-tight or water-tight. 
         [0019]    The thickness of the seals  22  (i.e., the distance that each seal  22  extends longitudinally from an end of the housing  14  toward a center of the housing  14 ) can be based on multiple factors. A large thickness can allow the seals  22  to strengthen the housing  14 , can be more securely engaged with the housing  14 , and/or can enhance the ability of the seals  22  to prevent unintended entry of an object to the interior of the housing  14 . However, a seal  22  with a large thickness can require more material to produce, can be more difficult to install in the housing  14 , and can limit the length of the housing  14  through which light can be produced. These factors, among others, can be considered to determine a proper seal shape. Additionally, the seals  22  can protrude from ends of the housing  14  (i.e., the seals  22  need not be fully contained within the housing  14  or flush with ends of the housing  14 ). 
         [0020]    Each seal  22  can also define two apertures  24   a  and  24   b  to allow pins  26   a  and  26   b  to communicate between the socket  12  and circuit board  16 . The apertures  24   a  and  24   b  can be circular, with diameters as large as or larger than diameters of the pins  26   a  and  26   b . However, apertures  24   a  and  24   b  can have alternative shapes, such as shapes that allow the pins  26   a  and  26   b  to pass through the seal  22 . The apertures  24   a  and  24   b  can also physically support the pins  26   a  and  26   b . For example, each seal  22  can hold the pins  26   a  and  26   b  in position via a friction fit between the apertures  24   a  and  24   b  and the pins  26   a  and  26   b , respectively. If the seals  22  are made from a material that is not electrically insulating, a rubber O-ring or other insulator can be included between the seal  22  and the pins  26   a  and  26   b.    
         [0021]    The pins  26   a  and  26   b  can physically and electrically connect the light  10  to the fixture  12 . The pins  26   a  and  26   b  can be the sole physical connection between the light  10  and the fixture  12 , though ends of the housing  14  and/or portions of the seals  22  can also contact the fixture  12 . The pins  26   a  and  26   b  can be directly electrically connected to the circuit board  16  as shown in  FIG. 1  to provide power to the LEDs  20  from the fixture  12 , or the pins  26   a  and  26   b  can be coupled to another structure that in turn is electrically connected to the circuit board  16 . Of the four total pins  26   a  and  26   b , two of the total four pins  26   a  and  26   b  can be “dummy pins” that do not provide an electrical connection. Alternatively, instead of pairs of pins  26   a  and  26   b , other types of electrical connectors depending on the type of fixture  12  can extend through the seals  22  or otherwise past the seals  22  into the housing  14 . For example, a single pin can be used instead of two pins  26   a  and  26   b  for compatibility with a single pin fixture. Alternatively, three of the four total pins  26   a  and  26   b  can be “dummy pins” that do not provide an electrical connection, thereby permitting only one of the pins to electrically connect with the fixture  12 . 
         [0022]    A variety of methods can be used to manufacture the seals  22 . In a first example, the seals  22  are formed from a liquefied or viscous material that is introduced to the housing  14 , and then hardened in the position shown in  FIG. 1 . The liquefied or viscous material can be an epoxy prior to setting or mixing with a hardener, concrete prior to hardening, a polymer heated to above its melting point, melted wax, or another liquefied or viscous material. Several different processes can be used to form the seals  22  from the liquefied or viscous material depending on the characteristics of the material. For example, as shown in  FIG. 3 , the circuit board  16  can be engaged with the housing  14 , and one end of the housing  14  can be sealed with a non-stick mat  28  or other structure while liquefied material  23  is poured into the top of the bore  17  of the housing  14 . The seal  22  can be formed when the material  23  dries or cures, and the apertures  24   a  and  24   b  can be drilled in the seal  22  for the insertion of pins  26   a  and  26   b . However, prior to inserting the pins  26   a  and  26   b  into the apertures  24   a  and  24   b , the housing  14  can be rotated 180° and the seal  22  forming process can be repeated at the other end by pouring liquefied material  23  through one of the apertures  24   a  or  24   b . Finally, the pins  26   a  and  26   b  can be inserted into the apertures  24   a  and  24   b  in each seal  22  and electrically connected to the circuit board  16 . Alternatively, the circuit board  16  can be supported without being attached to the housing  14  during the seal  22  forming process, in which case the seals  22 , once hardened or cured, can each define a groove  22   b  as shown in  FIG. 2  for receiving and/or securing the circuit board  16 . 
         [0023]    As another example of manufacturing the seals  22 , the housing  14  can be inserted into a pool of liquefied or viscous material, and the material can be allowed to harden to form the seal  22 . The insertion can occur with the pins  26   a  and  26   b  already coupled to the housing  14  such that the seals  22  are formed to include apertures  24   a  and  24   b  without drilling, in which case sleeves can be installed over the portions of the pins  26   a  and  26   b  that engage the fixture  12  during insertion of the housing  14  into the pool of material in order to avoid getting material on the pins  26   a  and  26   b.    
         [0024]    If the material is too viscous to be poured into the housing  14 , the material can be packed into an end of the housing  14 . For example, pliable clay can be packed in an end of the housing  14  and then be allowed to dry, or silicone sealant can be applied in the end of the housing  14 . 
         [0025]    In yet another example, seals  28  as shown in  FIG. 4  can be shaped prior to insertion into the housing  14 . For example, each seal  28  can be made from an elastic material such as rubber or cork, and each seal  28  can shaped to have a perimeter  28   a  transitioning from slightly smaller than an inner circumference of the housing  14  to slightly larger than the inner circumference of the housing  14 , allowing the seal  28  to be press fit into the housing  14  as shown in  FIG. 4 . If made from a less elastic material, each seal  28  can be shaped to have a perimeter slightly smaller than an inner circumference of the housing and a rubber O-ring or similar elastic strip can circumscribe the seal  28 . By using O-rings, the seals  28  can be inserted into the housing  14  without substantially deforming the seals  28 . Also, each seal  28  can define a groove  28   b  for receiving and/or securing the circuit board  16  similar to the groove  22   b  in the seal  22 . 
         [0026]    Also, regardless of the elasticity of the seals  28 , installation of the seals  28  can include inserting the pins  26   a  and  26   b  through the apertures  24   a  and  24   b  in the seals  28  prior to the pins  26   a  and  26   b  being physically attached to the circuit board  16 . For example, the pins  26   a  and  26   b  can be coupled by flexible wires to the circuit board  16 , then inserted into the apertures  24   a  and  24   b  of the seals  28 , and then the seals  28  can be press-fit into the housing  14 . As another example, the pins  26   a  and  26   b  can be coupled to the circuit board  16  with the circuit board  16  disconnected from the housing  14 . The pins  26   a  and  26   b  can then be inserted into the apertures  24   a  and  24   b . Then, the circuit board  16  can be slid into the housing  14  until the seal  28  is press-fit into the housing  14 , in which case the circuit board  16  is supported by the seals  28  instead of directly by the housing  14 . 
         [0027]    Additionally, structures other than seals  22  or seals  28  can be used instead of plastic end caps. For example, tape can be applied over ends of the housing  14 , or the housing  14  can be formed of a solid rod that is drilled to accommodate pins  26   a  and  26   b  without end caps. 
         [0028]    The above-described embodiments have been described in order to allow easy understanding of the invention and do not limit the invention. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structure as is permitted under the law.