Abstract:
Embodiments of the invention relate generally to lighting devices and, more particularly, to lighting devices having tubular housings containing light emitting devices on a circuit board, as well as housings for such lighting devices. In one embodiment, the invention provides a lighting device comprising: a circuit board including a light emitting device; and an elongate substantially tubular housing for enclosing the circuit board, the tubular housing including: a substantially circular interior; a support shelf extending across the substantially circular interior to support the circuit board; and a circuit board restraining member restraining the circuit board to the support shelf.

Description:
BACKGROUND OF THE INVENTION 
     Embodiments of the invention relate generally to lighting devices and, more particularly, to lighting devices having tubular housings containing light emitting devices on a circuit board, as well as housings for such lighting devices. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, the invention provides a lighting device comprising: a circuit board including a light emitting device; and an elongate substantially tubular housing for enclosing the circuit board, the tubular housing including: a substantially circular interior; a support shelf extending across the substantially circular interior to support the circuit board; and a circuit board restraining member restraining the circuit board to the support shelf. 
     In another embodiment, the invention provides a lighting device comprising: a circuit board including a light emitting device; and an elongate substantially tubular housing for enclosing the circuit board, the tubular housing including: a substantially circular interior; a first support member extending inward from the substantially circular interior to support the circuit board; a second support member extending inward from the substantially circular interior to support the circuit board, the second support member being positioned substantially opposite the first support member; and at least one circuit board restraining member restraining the circuit board against at least one of the first and second support members. 
     In still another embodiment, the invention provides an elongate tubular housing for enclosing a lighting device, the elongate tubular housing including: a substantially circular interior; a support shelf extending across the substantially circular interior to support a lighting device circuit board; and a circuit board restraining member restraining a circuit board against the support shelf. 
     In yet another embodiment, the invention provides an elongate tubular housing for enclosing a lighting device, the elongate tubular housing including: a substantially circular interior; a first support member extending inward from the substantially circular interior to support the circuit board; a second support member extending inward from the substantially circular interior to support the circuit board, the second support member being positioned substantially opposite the first support member; and at least one circuit board restraining member restraining a circuit board against at least one of the first and second support members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which: 
         FIGS. 1-13  show cross-sectional views of lighting devices and lighting device housings according to various embodiments of the invention. 
         FIGS. 14-15  show perspective views of lighting device housings according to an embodiment of the invention. 
     
    
    
     It is noted that the drawings of the invention are not to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings,  FIG. 1  shows a cross-sectional view of a housing  100  and circuit board  182  including a light emitting device  188 . Circuit board  182  includes an upper surface  184 , to which light emitting device  188  is affixed, and a lower surface  186 . Methods and techniques for physically and electrically connecting light emitting device  188  to circuit board  182  are known in the art and will not be described in detail here for the sake of brevity. As will be recognized by one skilled in the art, circuit board  182  may include associated circuitry, such as driver circuitry. 
     In some embodiments of the invention, light emitting device  188  is a light emitting diode (LED). In other embodiments, light emitting device  188  may comprise an incandescent or fluorescent lighting device. Together, a housing and a circuit board including a light emitting device comprise a lighting device according to an embodiment of the invention. 
     Housing  100  is substantially circular in cross-sectional shape, having a first portion  110  and a second portion  130 . Each of first portion  110  and second portion  130  includes a substantially circular outer surface  112 ,  132  and a substantially circular inner surface  114 ,  134 . First portion  110  may comprise a polycarbonate, such as, for example, the thermoplastic polycarbonate LEXAN 153 resin (SABIC Innovative Plastics) or the polycarbonate/ABS material CYCOLOY (SABIC Innovative Plastics). In such embodiments, the thermoplastic polycarbonate may be opaque. 
     In some embodiments of the invention, the material of first portion  110  is thermally-conductive. In such embodiments, first portion  110  may act to absorb and then dissipate heat generated by light emitting device  188 , circuit board  182 , and/or their associated circuitry. Such heat-dissipating properties may be imparted by the material of first portion  110  itself or, according to some embodiments of the invention, by a separate thermally-conductive material, such as aluminum, copper, steel, or alloys thereof, embedded within the material of first portion  110 . 
     Second portion  130  preferably comprises a transparent or translucent material, such as a polycarbonate, an acrylic, or a glass. In some embodiments of the invention, the material of second portion  130  comprises LEXAN resin SLX2531T (SABIC Innovative Plastics). The material of second portion  130  may include, as a coating or integrated material, a UV-resistant material and/or a material capable of diffusing light produced by light emitting device  188 . 
     First portion  110  and second portion  130  are preferably formed simultaneously or substantially simultaneously. For example, first portion  110  and second portion  130  may be co-extruded, such that each is formed at the same time from different materials. Such simultaneous or substantially simultaneous formation permits the manufacture of a seamless joint between first portion  110  and second portion  130  that is impervious to water and atmosphere under typical operating conditions, such as normal atmospheric pressure. 
     As shown in  FIGS. 1 and 2 , first portion  110  includes a support shelf  120  extending across the substantially circular inner surface  114 . Support shelf  120  divides an interior of housing  100  into a first cavity  122  and a second cavity  124 . As shown in  FIG. 2 , one or more channels  126  may be provided in support shelf  120 , thereby connecting first cavity  122  and second cavity  124 . Such channels  126  may be useful, for example, where first cavity  122  is used as a conduit raceway, such that connections may be made between electrical wires within first cavity  122  and circuit board  182 . 
     Second portion  130  includes a first restraining member  136  and a second restraining member  138 . First and second restraining members  136 ,  138  act to restrain circuit board  182  against an upper surface  118  of support shelf  120 , as shown in  FIG. 2 . Specifically, as shown in  FIGS. 1 and 2 , first and second restraining members  136 ,  138  are a pair of tabs operable to exert a downward force upon upper surface  184  of circuit board  182 , securing lower surface  186  of circuit board  182  against upper surface  118  of support shelf  120 . The application of a downward force upon circuit board  182  acts to maintain contact between upper surface  118  of support shelf  120  and lower surface  186  of circuit board  182 . In embodiment in which the material of first portion  110  is thermally-conductive, this serves to improve the transfer of heat from circuit board  182  to support shelf  120  of first portion  110 . 
       FIG. 3  shows a cross-sectional view of a housing  300  according to another embodiment of the invention. Rather than a support shelf, as in  FIGS. 1 and 2 , first portion  310  includes a pair of support members  326 ,  328 , which support a portion of a lower surface  386  of circuit board  382 . As such, first and second cavities  322 ,  324  are defined by circuit board  382 . In an embodiment such as that shown in  FIG. 3 , first cavity  322  may be employed as a conduit raceway without the need for channels ( 126  in  FIG. 2 ) to electrically connect electrical wires within the conduit raceway to circuit board  382 . 
     Restraining members  336 ,  338  of second portion  330  together form a pair of slots or channels in which circuit board  382  may be held. As shown in  FIG. 3 , restraining members  336 ,  338  are substantially straight and shaped similar to the pair of support members  326 ,  328 , although other arrangements are possible, of course. For example,  FIG. 4  shows a cross-sectional view of a housing  400  according to yet another embodiment of the invention. Here, restraining members  436 ,  438  are curved in shape, similar to the embodiments shown in  FIGS. 1 and 2 .  FIG. 5  shows a cross-sectional view of a housing  500  according to still another embodiment of the invention. Here, first portion  510  includes a support shelf  520  and restraining members  536 ,  538  are substantially straight, as shown in  FIG. 3 . 
     In  FIG. 6 , a stiffening member  650  has been added to first portion  610 . According to some embodiments of the invention, stiffening member  650  is thermally-conductive. For example, stiffening member  650  may comprise or include aluminum, copper, or alloys thereof. As shown in  FIG. 6 , stiffening member  650  includes a radial portion  656  extending substantially through support shelf  620  and a pair of arcuate portions  652 ,  654  within first portion  610 . In the embodiment of  FIG. 6 , radial portion  656  also serves to ensure that support shelf  620  remains substantially flat as first portion  610  is formed. For example, where first portion  610  is an extruded polycarbonate, radial portion  656  of stiffening member  650  helps ensure that support shelf  620  does not droop or otherwise deform in such a manner that contact with circuit board  682  cannot be uniformly maintained. 
     Other arrangements of stiffening members are possible, of course. For example, in  FIG. 7 , stiffening member  750  includes an arcuate portion  752  extending through substantially all of first portion  710  and a pair of radial portions  756 ,  757  within support shelf  720 . 
       FIGS. 8 and 9  show cross-sectional views of other embodiments of the invention, each with still other arrangements of the stiffening members. In  FIG. 8 , stiffening member  850  includes an arcuate portion  852  extending substantially through all of first portion  810  and a pair of radial portions  856 ,  857 , each extending through support shelf  820  in a hairpin arrangement. In  FIG. 9 , stiffening member  950  includes an arcuate portion  952  extending through substantially all of first portion  910  and a pair of radial portions  956 ,  957 , each extending partially into support shelf  920  in hairpin arrangements. 
       FIGS. 10-12  show first portions  1050 ,  1150 ,  1250  of housings according to still other embodiments of the invention. Each shows, respectively, a radial portion  1056 ,  1156 ,  1256  of stiffening member  1050 ,  1150 ,  1250  disposed along an upper surface  1018 ,  1118 ,  1218  of support shelf  1020 ,  1120 ,  1220 . In  FIG. 12 , an arcuate portion  1252  of stiffening member  1250  is similarly disposed along inner surface  1214  of first portion  1210 . 
       FIG. 13  shows housing  1300  according to another embodiment of the invention. Here, radial portion  1356  of stiffening member  1350  acts directly as a support shelf. In the embodiment shown in  FIG. 13 , arcuate portions  1352 ,  1354  of stiffening member  1350  meet and are disposed along an inner surface of first portion  1310 , such that first cavity  1322  is lined by stiffening member  1350 . 
       FIG. 14  shows a perspective view of a pair of elongate housings  100 ,  200  according to an embodiment of the invention. As described above, each housing comprises a first portion  110 ,  210  and a second portion  130 ,  230 , respectively. As shown above with respect to  FIGS. 1 and 2 , a circuit board  182  having one or more light emitting devices  188  may be inserted into each housing  100 ,  200  and electrically connected. Housings  100 ,  200  may then be physically connected, as shown in  FIG. 15 , for example, using a tubular joint or fitting  190 . Fitting  190  may also enable the electrical connection of housings  100 ,  200 , such that a continuous electrical connection may be established and maintained between circuit boards within each housing  100 ,  200 . In some embodiments of the invention, fitting  190  provides a substantially waterproof seal between housings  100 ,  200 . Similarly, although not shown in  FIG. 15 , but as would be apparent to one skilled in the art, a similar end cap or boot may be affixed to either or both ends of housings  100 ,  200  so joined. In some embodiments, fitting  190  or such an end cap or boot may include a conduit or similar device for enclosing an electrical supply wire to the circuit boards within housings  100 ,  200 . 
     Fitting  190  and/or such an end cap or boot may be formed from any number of materials, both rigid and flexible. Suitable materials include, for example, and without limitation, polyvinyl chloride (PVC), rubber, silicone, neoprene, polycarbonate, and nylon. Other materials may also be employed, depending upon the particular application to which the housing will be put, as will be apparent to one skilled in the art. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any related or incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.