LED unit for installation in a post-top luminaire

An LED unit is provided with a plurality of LED panels each having a support surface supporting at least one LED. The LED unit may be provided with a frame that may support the LED panels and the arrangement of the LED panels may be movable between a symmetric and an asymmetric configuration.

CROSS-REFERENCE TO RELATED DOCUMENTS

Not Applicable.

TECHNICAL FIELD

This invention pertains to a LED unit for installation in a post top luminaire.

BACKGROUND

Outdoor post-top luminaires typically include a base, such as a post or other support, which supports a fitter. The fitter supports a globe that encloses a light source such as an incandescent or HID bulb. The globe may be designed with refractive surfaces, prismatic surfaces and the like to help achieve a desired light distribution from the post-top luminaire. Furthermore, a reflective shield may be included within the globe to redirect some light from the light source and help achieve a desired light distribution pattern.

DETAILED DESCRIPTION

Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention and that other alternative mechanical configurations are possible.

Referring now to the Figures, wherein like numerals refer to like parts, and in particular toFIG. 1throughFIG. 5where an embodiment of an LED unit10is shown. InFIG. 1LED unit10is shown installed in a post-top luminaire. The post-top luminaire includes a support base or pole6which is coupled to and supports a fitter4. The fitter4supports a globe2, shown inFIG. 1exploded away from fitter4. The globe2may be sealably retained by fitter4, forming an optical chamber substantially sealed from the external environment. Globe2may be designed to help achieve a given light distribution pattern and may be provided with a refractive surface, prismatic surface, and/or reflectors, among other items, if desired for a particular light distribution. The post-top luminaire ofFIG. 1is provided for exemplary purposes and as made apparent from the present description, LED unit10may be used with or adapted for use with a variety of post-top luminaires having varied support, fitter, and/or globe configurations, among other things. For example, globe2may include a separable roof portion. The roof portion may be removably sealed to the globe and the globe may be removably or fixedly sealed to the fitter4.

LED unit10has an LED driver cover72that may be removably affixed to the fitter4and that may cover at least one LED driver74. InFIG. 1andFIG. 2, four vertically oriented elongated LED panels40are depicted disposed above the LED driver cover72in a generally V-shaped arrangement coupled to a pair of symmetric and asymmetric frames22. The generally V-shaped arrangement of LED panels40inFIG. 1andFIG. 2provides for asymmetric light distribution from LED unit10. The particular asymmetric distribution depicted provides for asymmetric distribution wherein a substantial majority of light output from LED unit10is directed within a range of one-hundred and eighty degrees to provide directional lighting from the LED unit10and reduce any backlighting. InFIG. 4andFIG. 5, four LED panels140are depicted in a generally square shaped arrangement coupled to the symmetric and asymmetric frames22. The generally square shaped arrangement of the LED panels140inFIG. 4andFIG. 5provides for symmetric light distribution from LED unit10.

Each LED panel40inFIG. 1andFIG. 2is provided with a lens46that covers a single centrally aligned recessed pocket having a printed circuit board with at least one LED attached thereto. In alternative configurations the recessed pocket may be non-centrally aligned. Each LED panel40shown inFIG. 4andFIG. 5has a support surface with three recessed pockets42. With particular reference toFIG. 4, at least one LED printed circuit board, such as LED printed circuit boards44, may be received in each recessed pocket42and secured in recessed pocket by, for example, screws45. In some embodiments LED printed circuit boards44may be a metal core circuit board and have seven or ten one-watt Luxeon Rebel LEDs coupled thereto. In alternative configurations differing numbers of LEDs may be used as well as printed circuit boards of differing material. A thermal interface material may optionally be interposed between LED printed circuit board44and the support surface of the LED panel40. In some embodiments the thermal interface material may include a thermal pad such as an eGRAF HITHERM HT-1220 thermal pad manufactured GrafTech. In alternative configurations other thermal interface materials may optionally be used such as, but not limited to, thermal grease or thermal paste. A lens46may then be placed over LED printed circuit boards44and seal each recessed pocket42in such a manner as to achieve appropriate ingress protection rating qualifications if desired. In some embodiments each lens46may be affixed using a high temperature silicone and achieve an ingress protection rating of IP 66. In some embodiments the high temperature silicone may be Dow Corning 733 Glass and Metal Sealant. One or more apertures may also be provided through portions of LED panel40to enable wiring to extend from one or more LED drivers74to any LED printed circuit board44. Such apertures may likewise be sealed with high temperature silicone to achieve appropriate ingress rating qualifications.

As depicted inFIG. 4, less than all of recessed pockets42may be provided with a LED printed circuit board. This allows for a manufacturer and/or user to use the same LED panel40with a variable amount of LED printed circuit boards44in order to provide flexibility in luminous output and/or light distribution from LED unit10. For example, as shown inFIG. 4, only one recessed site42may be provided with a LED printed circuit board44and covered with a lens46. Alternatively, each recessed site42may be provided with a LED printed circuit board and covered with a lens46, providing for a higher luminosity LED unit10. In other embodiments of LED unit10, a support surface for LEDs may be provided without recessed sites42or with a greater or lesser number of recessed sites42, and/or with larger or smaller recessed sites42that may accommodate variable sized or variable numbers of printed circuit boards. For example, as shown inFIG. 1, only a single centrally located recessed site may be provided and covered with a lens46and the area on either side of the recessed site may be non-recessed.

Extending rearward from each support surface of each LED panel40is a heatsink148having a plurality of curved heat fins that extend rearward and away from the support surface of each LED panel40. In the depicted embodiments LED support surface and LED heatsink148are formed as an integral piece, which can be made, for example, by a casting from aluminum or an aluminum alloy such as a 356 Hadco Modified aluminum alloy. Heatsink148is in thermal connectivity with recessed sites42and any LED printed circuit boards44received by recessed sites42and helps dissipate heat generated by any LED printed circuit board44.

With particular reference toFIG. 3, one embodiment of the symmetric and asymmetric frame22is described in more detail. The frame22has six tabs23,24,25,26,27, and28. The tabs23,24,25,26,27, and28are arranged generally in the shape of an isosceles right angle triangle, with tabs23and24arranged along a first leg, tabs25and26arranged along a second leg, and tabs27and28arranged along a hypotenuse. Each tab23,24,25,26,27, and28has a corresponding receptacle23a,24a,25a,26a,27a, and28atherethrough. An opening29extends through the frame22and has two securing apertures29aand29bon either side for attachment of the frame22to a support base76. The depicted frame22is formed from a single piece of sheet metal and the tabs, receptacles, and apertures cut and formed from the single piece of sheet metal.

In the asymmetric LED panel arrangement ofFIG. 1andFIG. 2two of the LED panels40have common orientations that are offset approximately ninety degrees from the other two LED panels40that also have common orientations. In the symmetric LED panel arrangement ofFIG. 4andFIG. 5, each of the LED panels40has a unique orientation that is offset approximately ninety degrees from two other LED panels40and is offset approximately one-hundred and eighty degrees from one other LED panel40. In the asymmetric arrangement, LED panels40are connected to tabs23,24,25, and26. In the symmetric arrangement the LED panels40are coupled to tabs24,25,27, and28. To change from a symmetric to an asymmetric configuration in this embodiment of frames22involves uncoupling two LED panels40from tabs23and26and coupling the two uncoupled LED panels40to tabs27and28.

Each LED panel40is held in place by screws21that are inserted through apertures in a front face of each LED panel40and received in one of the receptacles23a,24a,25a,26a,27a, or28aof symmetric and asymmetric frames22. The screws21associated with any one LED panel40may be loosened to allow for movement of each LED panel40to another location on symmetric and asymmetric frame22or to remove each LED panel40from LED unit10if desired. One or more LED panels40may be removed to alter the distribution pattern and/or luminous intensity of LED unit10and may be removed by a user or prior to packaging. The ability to selectively detach and reattach each LED panel to desired connection areas on frames22provides an easily customizable LED unit10providing for flexibility in light distribution and luminosity. While a screw21extending through a corresponding aperture of each LED panel40and received in one of the receptacles23a-28ahas been described, one skilled in the art will recognize that other fasteners and other mechanical affixation methods may be used in some embodiments to removably attach each LED panel40to a given location on the frame22. For example, prongs, fasteners, latches and/or structure extending from one or more frames22may interface with corresponding structure on LED panels40. Also, this interchangeably includes prongs, fasteners, latches, and/or structure extending from LED panels40that correspond with structure on one or more frames22. Also, although one embodiment of LED unit10has been described as having both a top and a bottom frame22with specific structure, one skilled in the art will recognize that other frame configurations, including singular frame configurations, may properly support LED panels40. Also, although a specific symmetric and asymmetric arrangement of LED panels40have been described, one skilled in the art will recognize that other symmetric and asymmetric arrangements may be used as desired for particular light distributions and outputs.

Each LED panel40may be individually adjusted to a given orientation on symmetric and asymmetric frames22at the factory or by a user, allowing for symmetric and asymmetric distribution patterns from LED unit10that may be selectively adjusted as desired. Reflective shields may be used, but are not needed with LED unit10, as LED panels40may be oriented on frames22to direct light away from a given area in order to achieve asymmetric light distribution. LED unit10may be used in retrofit applications if desired and LED panels40may be configured in a symmetric or asymmetric distribution pattern to replicate a previously existing distribution pattern, or create a new distribution pattern, while interfacing with the same preexisting globe of the post-top luminaire. In some embodiments LED unit10may be used to replace an incandescent light source or a metal halide light source.

A support base76may support the bottom frame22and is coupled to LED driver cover72, which covers three LED drivers74. In other embodiments only one LED driver, two LED drivers, or more than three LED drivers may be provided. Frame support base76may be interchanged at the factory or by a user with a frame support base of a differing height to permit vertical adjustment of the LED panels40in order to appropriately position LED unit10within a globe of a particular post-top luminaire. The depicted LED driver cover72is a Twistlock ballast cover manufactured by Hadco from die cast aluminum and is designed to rotatably engage corresponding structure extending from the top of a fitter of a post-top luminaire and be locked in place with a spring clip. The depicted LED driver cover72and LED unit10provide for tool-less installation of LED unit10. However, as understood in the art, other driver covers may be utilized to appropriately isolate LED drivers, such as LED drivers74. LED drivers74may be placed in electrical communication with one another and contain a terminal block or other connection for electrically coupling LED drivers74with power from a power source. In some embodiments LED drivers74may be one or more drivers manufactured by Magtech, part number LP1025-36-00700. In some embodiments LED drivers74may be one or more drivers manufactured by OSRAM, part number OT25-120-277-700E.

Referring now toFIG. 6andFIG. 7, the depicted embodiment of heatsink148is described in more detail. Heatsink148has a plurality of arcuate heat fins154a-e,155a-e,164a-e, and165a-eflanking each side of a channel156that extends longitudinally along the entire length of heatsink148. In some embodiments LED heatsink148may be sand casted from an aluminum alloy such as a 356 Hadco Modified aluminum alloy. In the depicted embodiment channel156is centrally aligned and includes bosses157,158,159,167,168, and169that extend partially into channel156. Bosses157,158,159,167,168, and169may receive corresponding screws or other fasteners that are used to secure printed circuit boards within recessed sites142. Fasteners that are used to secure printed circuit boards within recessed sites142may also or alternatively be received in bosses that are completely or partially contained within any or all of arcuate heat fins154a-e,155a-e,164a-e, and165a-e.

The arcuate heat fins154a-e,155a-e,164a-e, and165a-eextend from proximal central channel156toward the longitudinal periphery of heatsink148and are oriented to efficiently dissipate heat from heatsink148when heatsink148is oriented vertically, horizontally, or at an angle between horizontal and vertical. Each arcuate heat fin154a-e,155a-e,164a-e, and165a-ehas a first end located proximal central channel156and a second end located proximal a trough adjacent a ridge173that extends longitudinally proximal the longitudinal periphery of the heatsink148.

Heatsink148may be divided latitudinally into a first portion and a second portion in some embodiments. In the depicted embodiment pie shaped heat fins160and161divide heatsink148into a first and second portion and define a latitudinal dividing region. Each arcuate heat fin154a-e,155a-e,164a-e, and165a-eis oriented such that the interior face of each arcuate heat fin154a-e,155a-e,164a-e, and165a-egenerally faces toward the dividing region generally defined by pie shaped heat fins160and161and generally faces away from channel156. Also, the second end of each arcuate heat fin154a-e,155a-e,164a-e, and165a-eis more distal the dividing region and channel156than the first end of each arcuate heat fin and the exterior face of each arcuate heat fin generally faces toward channel156. As a result of the shape and orientation of the heat fins, the amount of heat that becomes trapped in between the heat fins and reabsorbed is reduced.

When oriented in a non-horizontal direction, heat dissipation is further optimized by heatsink148as a result of natural convection. For example, assuming heat fins152and153are located at a higher vertical position than heat fins162and163, hot air, exemplarily designated by Arrows H inFIG. 7, is forced outward and away from heatsink148. Cooling air, exemplarily designated by Arrows C inFIG. 7, is drawn toward the heatsink from the surrounding environment. Central channel156provides a path for communication of air between heat fins, exemplarily designated by the unlabeled arrows extending through central channel156, and further aids in heat removal and natural convection. The shape and orientation of the heat fins in the depicted embodiment aids natural convection by forcing heat outward and away from heatsink148while drawing in cooling air and reduces reabsorption of heat by the heat fins of heatsink148. The shape of the heat fins also provides additional surface area for improved convection. In some embodiments an apparatus such as a fan may be used in conjunction with heatsink148for forced convection.

In the depicted embodiment of heatsink148each arcuate heat fin154a-e,155a-e,164a-e, and165a-eis a curved segment of a circle and has a corresponding arcuate heat fin that also forms a curved segment of the same circle. Also, in the depicted embodiment each arcuate heat fin154a-e,155a-e,164a-e, and165a-ehas a mirror imaged heat fin located on the opposite side of channel156that also has a corresponding arcuate heat fin that also forms a segment of the same circle. For example, arcuate heat fins155aand165aform a segment of the same circle and may generally circulate air between one another, potentially increasing the convective current. Opposite arcuate heat fins155aand165aare arcuate heat fins154aand164a, which form a segment of a circle that is the same radius of the segment of the circle formed by arcuate heat fins155aand165a. Also, arcuate heat fins155eand165eform a segment of the same circle, which is much larger than the circle partially formed by arcuate heat fins155aand165a. In other words, arcuate heat fins155eand165ehave a more gradual curvature than arcuate heat fins155aand165a.

In the depicted embodiment of heatsink148, the curvature of heat fins154a-e,155a-e,164a-e, and165a-ebecomes more gradual the farther away from pie shaped heat fins160and161it is located, such that each heat fin progressively forms a segment of a larger circle. Heat fins152,153,162, and163are not segments of a circle, but do aid in the convective process and help dissipate heat away from, and draw cooling air into, heatsink148. Also, although the interior facing portion of arcuate heat fins152,153,162, and163is formed from two nearly linear portions, it still has a generally arcuate overall shape. Extending along the longitudinal peripheries of heatsink148is a ridge portion173, which sits atop a trough and may be provided for additional surface area for dissipation of heat.

Although heatsink148has been illustrated and described in detail, it should not be limited to the precise forms disclosed and obviously many modifications and variations to heatsink148are possible in light of the teachings herein. For example, in some embodiments some or all arcuate heat fins may not form a segment of a circle, but may instead be otherwise arcuate. Also, for example, in some embodiments some or all arcuate heat fins may not be provided with a corresponding mirror imaged heat fin on an opposite side of a channel and/or an opposite side of a dividing region. Also, for example, in some embodiments where a dividing region is present, the dividing region may not have any heat fins such as pie shaped heat fins160and161. Also, for example, in some embodiments heat fins may have one or more faces formed from multiple linear segments and still be generally arcuate in shape. Although heatsink148has been described in conjunction with a LED unit10, one skilled in the art will readily recognize its uses are not limited to such. Also, one skilled in the art will recognize that alternative embodiments of LED unit10may utilize alternative heatsinks, such as heatsinks with a plurality of linear and parallel fins, or may be provided without a heatsink if desired.

The foregoing description has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is understood that while certain forms of the invention have been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims and allowable functional equivalents thereof.