Abstract:
A modular luminaire which uses LED light sources. The basic frame comprises two end pieces compressed together by through bolts. At least one elongated heat sink is compressed between the end pieces. Each heat sink may bear a plurality of LEDs mounted on a printed circuit board which may have an integral metallic backplate, and is installed on one of the heat sinks with a layer of heat conductive grease therebetween. The heat sinks have fins projecting in three directions, the fourth direction being accounted for by the LEDs, and are rotatable about their longitudinal axes to adjust direction of light propagation. The heat sinks are arrayed in an arc, so that the outside heat sinks shield observers from direct glare from opposed heat sinks. Heat sinks may be extruded to form cooling fins and slots which may receive fasteners such as screws.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the filing date under 35 USC 119(a) of Chinese Patent Application No. 200820203225.7, filed Nov. 11, 2008, the contents of which are incorporated herein by reference. This application is also related to HEAT SINK FOR MODULAR LED FLOOD LIGHT, application Ser. No. 12/420,332 filed Apr. 8, 2009 now abandoned. This application is also related to LENS FOR LIGHT EMITTING DIODES MOUNTED ON A HEAT SINK, application Ser. No. 12/420,352 filed Apr. 8, 2009 now U.S. Pat. No. 7,633,684. This application claims priority to and incorporates by reference application Ser. No. 12/420,314 filed Apr. 8, 2009 now U.S. Pat. No. 8,061,869 titled MODULAR LED FLOOD LIGHT. All applications are of common ownership with the present invention. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to illumination, and more particularly to a flood light having modular construction. 
       BACKGROUND OF THE INVENTION 
       [0003]    Lights for illuminating large areas such as roads, parking lots, fields, and the like have long been provided. Lighting technology for such lights has progressed from incandescent to specialized high powered types such as sodium vapor and mercury vapor. However, it has become desirable to utilize more efficient light sources, as efficiency relates to units of light output per unit of electrical input. 
         [0004]    Light emitting diodes (hereinafter LEDs) are among the most efficient types of light sources commercially available today. LEDs enjoy not only relatively high efficiency, but offer long life and relatively uncomplicated construction. LEDs have progressed to the point where white light producing LEDs could be employed in many applications. 
         [0005]    Luminaires are typically produced in models each of which is designed to provide a predetermined amount of light, to have a specific predetermined construction or design, to project light in a predetermined pattern and in a predetermined quantity. Therefore, many different models must be made available so that the most suitable design may be selected for any given application. This leads to the situation that many different models must be designed, produced, and stocked, and replacement parts be made available for each model. While this situation offers great versatility in providing varieties of luminaires, such convenience comes at economic cost. 
         [0006]    It would be desirable to offer different models having diverse outputs while minimizing the cost of luminaires of each model or capacity. 
         [0007]    A need exists for mass producing high intensity flood lamps using white LEDs in many light output capacities, so that individual luminaires employing LEDs may compete with established high intensity luminaires. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention addresses the above stated need by providing a design for luminaires which utilize LEDs which lends itself to producing many different output configurations and capacities while using a common core of components for construction of such luminaires. In one aspect, the present invention contemplates a modular design for LED using luminaires which is readily adjustable as to light source layout in two orthogonal directions. In another aspect of the invention, a luminaire may be assembled from a minimum number of component parts. According to a further aspect of the invention, a significant LED bearing component may be fabricated as an extrusion of indefinite length, which is readily cut to a desired length. 
         [0009]    The LED bearing component carries a plurality of LEDs arranged serially. This component serves as a structural support for LEDs and their associated printed circuit boards and lenses, and also as a heat sink. For brevity, the LED bearing component will be referred to as a heat sink, it being understood that the functions described above and others are also satisfied by the heat sinks. 
         [0010]    The length of each heat sink determines the length of the overall light source. Width of the light source may be established by selecting a desired number of heat sinks and mounting them parallel to one another. 
         [0011]    The heat sinks may be mounted between two end pieces. These end pieces are compressed together by a plurality of through bolts. The overall length of the support for the heat sinks may be varied by simply selecting through bolts of appropriate lengths. 
         [0012]    One of the end pieces accommodates an integral clamp, which allows the luminaire to be mounted to a pole. The clamp accommodates many different dimensions and configurations of poles, so that the novel luminaire need not require careful coordination with any one design or model of pole. 
         [0013]    The end pieces are somewhat arcuate, so that the pattern of LEDs mounted thereto is that of a curved plane. This both allows for advantageous projection of light in overlapping beams, and also provides an inherent glare suppression feature for protecting observers at a distance from the luminaire. Overlapping beams of light assure illumination coverage even in the event that one or several LEDs fail. 
         [0014]    Electrical components serving the individual LEDs may be mounted to the luminaire in a way that avoids interfering with heat dissipation through the heat sinks. 
         [0015]    It is therefore an object of the invention to provide a design for a luminaire which utilizes LEDs which is both modular and also readily adjustable as to dimensions of the array of individual LEDs. 
         [0016]    It is an object of the invention to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes. 
         [0017]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
           [0019]      FIG. 1  is a top perspective view of a modular luminaire according to at least one aspect of the invention. 
           [0020]      FIG. 2  is an exploded top perspective view of  FIG. 1 . 
           [0021]      FIG. 3  is an exploded top perspective detail view of components seen at the center of  FIG. 1 . 
           [0022]      FIG. 4  is a top perspective detail view of the lowermost component of  FIG. 3 . 
           [0023]      FIG. 5  is a diagrammatic representation of possible positions and adjustments to the direction of projection of light from LEDs, according to a further aspect of the invention. 
           [0024]      FIG. 6  is a top perspective view of an individual lens which may be representative of lenses which are shown along the upper right of  FIG. 3 . 
           [0025]      FIG. 7  is similar to  FIG. 6 , but shows a slightly different configuration of the subject lens. 
           [0026]      FIG. 8  is an exaggerated, diagrammatic end elevational view of the components of  FIG. 3 , shown assembled. 
           [0027]      FIG. 9  is a diagrammatic plan view showing details of an electrical distribution scheme which may be used in the invention. 
           [0028]      FIG. 10  is an exploded bottom perspective view of the modular luminaire of  FIG. 1 . 
           [0029]      FIG. 11  is a diagrammatic end elevational view of lighting elements of the novel modular luminaire, symbolically showing a light projection pattern. 
           [0030]      FIG. 12  is an environmental side elevational view of light projection from the novel modular luminaire with the modular luminaire mounted on a pole above the ground. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  of the drawings shows a modular luminaire  10  according to at least one aspect of the invention. The modular luminaire  10  is of a type which may be used as a street light, for example. The modular luminaire  10  may comprise a plurality of LEDs  12  (not all of which are individually called out by reference numeral) arranged along and ultimately supported by heat sinks  14  (see  FIG. 2 ). The heat sinks  14  are suspended between a proximal end piece  16  and a distal end piece  18 , which are in turn compressed towards one another and against the heat sinks  14  by through bolts  20 . The through bolts  20  extend from the proximal end piece  16  to the distal end piece  18  and unite the proximal end piece  16  and the distal end piece  18 , while drawing the proximal end piece  16  towards the distal end piece  18  while entrapping each one of the heat sinks  14  between the proximal end piece  16  and the distal end piece  18 . 
         [0032]    The component parts of the modular luminaire  10  are better seen in the exploded view of  FIG. 2 , to which attention is directed. Two yoke type brackets  22  are mounted to the modular luminaire  10  by passing the central two through bolts  20  through eyes  24  formed at the two ends of each bracket  22 . Each bracket  22  thereby spans two through bolts  20 . 
         [0033]    A power converter  26  which converts AC power to DC power may be fastened to the brackets  22 . It should be noted that the brackets  22  and the power converter  26 , although close to the heat sinks  14 , are out of contact with the heat sinks  14 , so that heat dissipation from the heat sinks is not unduly obstructed. 
         [0034]      FIG. 3  shows components of an individual heat sink  14 . A plurality of LEDs  12  is mounted on printed circuit boards  28  (not all of which are individually called out by reference numeral) in conventional fashion. Each LED  12  may have its own individual or dedicated printed circuit board such as a printed circuit board  28 , or alternatively, one printed circuit board may serve more than one LED  12 . The printed circuit boards  28  may be mounted to the heat sink  14  using screws  31  (not all of which are individually called out by reference numeral), with further mounting details to be described hereinafter. A lens  30  (not all of which are individually called out by reference numeral) is provided to cover each LED  12 . Each lens  30  may be dedicated to one LED  12 , so that there may be a one-to-one relationship between LEDs  12  and lenses  30 . This relationship contributes to modularity of the modular luminaire  10  in that for any number of LEDs  12  accommodated by any heat sink  14 , a corresponding number of lenses  30  may be used. Customization of length of the lens, such as cutting to a length or molding lenses  30  to specific lengths, is not necessary. 
         [0035]    Each heat sink  14  may be said to have a proximal end  34 , a distal end  36 , and a length defined therebetween, although designation as proximal or distal in this case is only a semantic convenience. For example, the proximal end  34  may be that engaged and supported by the proximal end piece  16 , while the distal end  36  may be that supported by the distal end piece  18 . The LEDs  12  are located between the proximal end  34  and the distal end  36 , and may for example be ordered in straight rows. Of course, other arrays of LEDs  12  on each heat sink  14  are possible. 
         [0036]    Because the modular luminaire  10  may be employed outdoors, seals are provided to exclude water and dust from the vicinity of the LEDs  12  and the circuit boards  28 . For example, lateral sealing may be provided by seals such as silicone strip seals  32 . Respective proximal and distal ends  34 ,  36  of each heat sink  14  may be sealed respectively by gaskets  38  which may be secured in place by respective end plates  40 . It should be made clear that the terms “proximal” and “distal”, as applied to the heat sinks  14 , are merely for semantic purposes. The end plates  40  may be secured to the heat sink  14  by screws  42 . Protective barriers  44  may be provided to close the end of a row of lenses  30  should the latter leave a gap between the lenses  30  and the gasket  38 . 
         [0037]      FIG. 4  shows a heat sink  14  isolated from its associated seals, such as the seals  32  and the gaskets  28 , LEDs  12 , and printed circuit boards  28  is shown in  FIG. 4 . The heat sink  14  is seen to have lateral cooling fins  46 ,  48  and top cooling fins  50 . The lateral cooling fins  46  may project in a direction represented by the arrow  52 . The lateral cooling fins  48  may project in a direction represented by the arrow  54 . The bottom cooling fins  50  may project in a direction represented by the arrow  56 . The directions of the arrows  52 ,  54 ,  56  may be arranged such that each direction is perpendicular to an adjacent direction. Alternatively stated, a right angle A may exist between any two adjacent ones of the directions indicated by the arrows  52 ,  54 ,  56 . However, it is not necessary that perpendicularity be present. It is desired that the cooling fins  46 ,  48 ,  50  face in three substantially different directions outwardly away from the central axis  58 . 
         [0038]    As employed herein, orientational terms such as top and bottom will be understood to refer to the orientations depicted in the referenced drawing figures. Therefore, orientational terms must be understood to provide semantic basis for purposes of description, and do not limit the invention or its component parts in any particular way. This also holds true as to designation of the fins  50  as being at the bottom of their associated heat sink  14 . The location of the fins  50  may change due because a modular luminaire such as the luminaire  10  may be mounted in any orientation. 
         [0039]    It will be seen that all of the fins are longitudinally oriented in that they are parallel to the central longitudinal axis  58  of the heat sink  14 . Also formed in the heat sink  14  is a plurality of fastener thread receiving channels  60 ,  62 ,  64 ,  66 , which extend along the length of their associated heat sink  14 . Screws  42  (see  FIG. 3 ) which may be self-tapping screws, or which may otherwise be sufficiently robust as to thread to the fastener thread receiving channels  60 ,  62 ,  64 ,  66  may be employed without the necessity of drilling and tapping screw holes. It will be appreciated that both the fins  46 ,  48 ,  50  and also the fastener thread receiving channels  60 ,  62 ,  64 ,  66  may be advantageously and inexpensively formed for example by an extrusion process, although other fabrication methods such as casting or injection molding could be employed if desired. 
         [0040]      FIG. 4  also shows a mounting surface  68  for mounting the printed circuit boards  28  and fastener holes  70  for receiving fasteners to secure the printed circuit boards  28  to the heat sink  14 . 
         [0041]    A fastener hole  72  is formed at the central longitudinal axis  58  of the heat sink  14 . The location of the fastener hole  72  enables angular adjustment of heat sinks  14  and hence of LEDs. Referring to  FIG. 5 , five representative heat sinks  14 A,  14 B,  14 C,  14 D,  14 E are shown. These heat sinks  14 A,  14 B,  14 C,  14 D,  14 E may be structural and functional counterparts to the heat sinks  14  described priorly, for example. The heat sinks  14 A,  14 B,  14 C,  14 D,  14 E are angularly adjustable about their respective central longitudinal axes  58 A,  58 B,  58 C,  58 D,  58 E. Representative angular adjustment of the heat sinks  14 A,  14 B,  14 D,  14 E is depicted, showing one position in solid lines and an alternative position in broken lines. Considering the heat sink  14 A as an example, the directions of the center line of light propagation is indicated by the arrows B and C. The center heat sink  14 C could be angularly adjusted if the resulting asymmetry of light projection were deemed not objectionable. 
         [0042]    The proximal end piece  16  and the distal end piece  18  may be dimensioned and configured to hold the heat sinks  14  in the arcuate array depicted in  FIGS. 1 ,  2 , and  5 . The arcuate array is seen when the heat sinks, such as the heat sinks  14 A,  14 B,  14 D,  14 E are viewed from their ends, as depicted in  FIG. 5 , and with the heat sinks oriented parallel to one another, as seen in  FIGS. 1 and 2 . In conclusion, centering of the fasteners such as the screws  74  (not all of the screws are called out by reference numeral) (see  FIG. 1 ) for securing heat sinks  14  to the proximal end piece  16  and the distal end piece  18  within their respective heat sinks  14  enables each heat sink  14  to be angularly adjusted as to its mounting position by threading its fastening screw  74  into its respective centered fastener thread receiving channel  72  and rotating the heat sink  14  about its longitudinal axis  58  prior to tightening the through bolts  20 . 
         [0043]    The lenses  30  of the LEDs  12  are configured to project rectangular light beams. Because of this, uniform overlapping of light beams from the many LEDs  12  can be achieved. This results in more even lighting at the environmental surface (not shown) which is being illuminated. 
         [0044]      FIGS. 6 and 7  show alternative possible configurations of lenses  30  which may project rectangular light beams from their associated LEDs  12 . In  FIG. 6 , a lens  30 A has a generally planar rectangular base  82  and a curved raised portion  84 . The curved raised portion  84  may display curvature according to profile lines  86 ,  88 , which are hypothetical entities superimposed over the lens  30 A only to illustrate the nature of the curvature along two orthogonal axes. 
         [0045]      FIG. 7  shows a generally similar lens  30 B, the difference being a flat facet  90  formed at the apex of the curved surface  92  which apart from the flat facet  90  corresponds to the curved surface  84  of  FIG. 6 . 
         [0046]      FIG. 8  shows further details of how an LED  12  and its associated printed circuit board  28  are mounted on a heat sink  14 . LEDs  12  are mounted to their associated printed circuit boards  28  in conventional fashion. Each circuit board  28  may comprise an electrically insulative layer  76  on which conductive circuitry (not shown) is printed. Each circuit board  28  may comprise a metallic backing plate  78  which is integrated therewith. Each printed circuit board  28  may be mounted on a heat sink  14 , with a layer of heat conductive grease  80  placed between the printed circuit board  28  and its associated heat sink  14 . 
         [0047]      FIG. 9  shows an arrangement wherein the circuitry of the modular luminaire  10  is arranged to supply the LEDs  12  of each one of the heat sinks  14  individually from the power converter  26 . This is accomplished by providing each heat sink  14  with a dedicated subcircuit  92 ,  94 ,  96 ,  98 , or  100 , in the depiction of  FIG. 9 , which shows five representative heat sinks  14 , which will be understood to include LEDs  12  mounted on printed circuit boards  28 , as described hereinbefore. This arrangement assures that failure of electric supply to at least one of the LEDs  12  of any one heat sink  14  does not impact operability of LEDs  12  of other heat sinks  14 . Because of the overlapping pattern of light projection from the LEDs  12 , loss of one LED  12  or even of all of the LEDs  12  of any one heat sink  14  will not result in an unlit area within the original area of full illumination of a modular luminaire such as the modular luminaire  10 . 
         [0048]    Circuitry will be understood to comprise the number of conductors, and specific connection schemes necessary to carry out the described functions, as well as supporting apparatus such as switches, relays, transducers, circuit breakers, transformers, and voltage dividers, among others, regardless of whether such features are specifically shown. Circuitry and any of its individual components may vary in size, number, location, and logic from that specifically shown or described herein. However, it should be noted that a current regulator  33  (see  FIG. 3 ) may be provided for each heat sink  14 , as shown at the left in  FIG. 3 . Circuitry may have characteristics of conventional LED lights for example, apart from the internal distribution scheme set forth above. For these reasons, circuitry is not specifically called out by reference numerals. 
         [0049]      FIG. 10  shows a clamp feature which may be provided as part of the modular luminaire  10 . A projection  102  is formed integrally with the proximal end piece  16 . This projection  102  (see  FIG. 2 ) may be configured as a trough which presents a generally semi-cylindrical recess  104  to access for receiving a pole (not shown). The pole may be any generally circular pole of the type ordinary used to support street lights, for example. A complementing clamp member  106  bearing a corresponding semi-cylindrical recess  108  may be provided as a separate component, which may be fixed to the projection  102  by fasteners  108 . The fasteners  108  may pass through holes  110  formed in a flange  112 , and engage holes  114  formed in a corresponding flange  116  of the projection  102 . The clamp member  106  may be then tightened over an end of the pole using the fasteners  108 . The holes  110 ,  114  and fasteners  108  may have counterparts on the other side of the projection  102  and the clamp member  106  (these components are called out by reference numeral only on one side of the modular luminaire  10 ). 
         [0050]      FIG. 11  shows a further advantage of the module luminaire  10 , which in  FIG. 11  is mounted above the ground  2  on a pole  4 , as is enabled by the clamp arrangement described above. An arcuate array of heat sinks, which may be the heat sinks  14 A,  14 B,  14 C,  14 D, and  14 E of  FIG. 5  for example, each have associated LEDs such as the LED  12 A which is mounted on the heat sink  14 A. Light projecting from the LED  12 A through a lens such as the lens  30 A projects in directions represented as rays shown as the arrows D, E, F, G, H, and I. This representation of light emanating as discrete rays is of course only symbolic as the projected light beam is a continuum. 
         [0051]    It will be seen that the rays represented as D and E are obstructed by the heat sink  14 E, whereas those represented as F, G, H, and I are unobstructed. 
         [0052]      FIG. 12  shows why partial obstruction of light is advantageous. With the modular luminaire  10  mounted above a roadway  6 , light projecting from the modular luminaire  10 , which would otherwise shine into the eyes of a driver (not shown) of a motor vehicle  8  traveling towards the pole  4 , as indicated by the arrow J, is limited. Rays such as that represented in broken lines as E have been obstructed. Light more directly angled towards the roadway  6  are unobstructed. This greatly limits light impinging upon the driver from great distances, which light would otherwise be seen as glare. This is because at greater distances, light projecting from the modular luminaire  10  is oriented more closely to parallel to the roadway  6 . However, such nearly parallel rays are obstructed, with only the more angled light being able to escape the modular luminaire  10 . As the driver approaches the modular luminaire  10 , his or her view diverges from direct viewing of the light from the modular luminaire  10 , the latter now becoming more overhead relative to the driver&#39;s eyes. The net effect is that annoying long distance glare is minimized by the arrangement described with respect to  FIG. 11 . 
         [0053]    The LEDs  12  of the present invention may be of any desired hue or color, including white light LEDs. 
         [0054]    The circuitry of the modular luminaire  10  may include a photovoltaic charging system if desired. 
         [0055]    The present invention is susceptible to modifications and variations which may be introduced thereto without departing from the inventive concepts. For example, although the invention has been described with respect to individual LEDs, it would be possible to provide LEDs in pluralities or clusters (not shown), with each cluster being treated as described priorly with regard to individual LEDs. Also, LEDs need not be arrayed in perfect linear rows as illustrated, provided that a plurality of LEDs is provided along the length of each heat sink, such as the heat sink  14 . 
         [0056]    While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is to be understood that the present invention is not to be limited to the disclosed arrangements, but is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible.