Patent Abstract:
A lighting system utilizing light-emitting diodes (LEDs) and methods for configuring lanterns thereof are disclosed. The lantern includes a roof or canopy that includes fans that span directly between the electronics and LEDs for improved heat dissipation, the fans preferably formed integral with the canopy. The LEDs are mounted on easily mounted and removed modular printed circuit boards, in at least two different sizes and numbers of LEDs, and optical lenses of at least two different lighting patterns are provided, so that the lantern may be assembled or retrofit according to a desired application including candlepower and lighting pattern for cast light. The optical lenses are individually provided, utilize refraction to diminish reflection, and, in one form, incorporate an integral reflector to assist in defining a lighting pattern. In some forms, a securement may be provided for individual securement of lenses with the PCB.

Full Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a lighting system utilizing light-emitting diodes (LEDs) and, in particular, to a LED-based lamp or lantern with removable circuit boards, with improved heat-dissipation, and with novel light-directing lenses. 
       BACKGROUND 
       [0002]    Specialized diodes as light-emitting devices have slowly been incorporated into more and more applications. In virtually every application, particularized technical issues have presented themselves, issues that arise both from starting with older designs and from the inherent characteristics of light-emitting diodes, or LEDs. 
         [0003]    LEDs have several major benefits in comparison to non-LED lighting. If properly installed and treated, an LED has a longer life span than many comparable light elements. Thus, LEDs have been or work is being undertaken to devise manners to incorporate LEDs into applications where it is costly and/or difficult to replace the light elements. Relative to size, an LED can produce a greater amount of light, measured in lumens, than a comparatively sized non-LED light. For this reason, LEDs have been incorporated into many applications requiring small-sized light elements. Related to the greater light is the ability of LEDs to provide more light relative to power consumption than other lighting. 
         [0004]    As an LED provides more light, the obvious corollary of greater light with respect to power consumption is that an LED wastes less power in the form of heat. While this is true, a large portion of generated heat is lost not on the light-emitting side of the diode, but instead at its base. The diode, which would be recognized as an electrical circuit component, is typically mounted on a printed wiring or printed circuit board, referred to herein as a PCB. The heat generated by the diode is initially transferred to the PCB, and the PCB is often heat-sinked in some manner. An 8-watt LED that has been properly installed and has proper heat dissipation may have a ten-year life span of daily 8-hour usage, while the same LED may fail in approximately twenty minutes without a heat sink. 
         [0005]    Some efforts have been made to incorporate LEDs into pole or stanchion-type lights, such as what would typically viewed as an outdoor lamp or lantern and may be referred to as a streetlight. Traditional streetlights require bulb replacement and exhibit a heavy electrical cost burden for municipalities, shopping centers, retail establishments, and commercial zones, for example. In line with traditional approaches to construction, LED-based streetlights have an internal assembly that is mounted inside of an outer shell. The internal assembly is hardwired with the LEDs and, often times, each individual LED is separately mounted with the internal assembly. Beyond the labor required, each LED must be ensured of proper mounting so that the heat dissipation is proper, and the LEDs and connecting wires are susceptible to damage during handling and manufacture. Moreover, these designs are difficult or impossible to reconfigure or retrofit (such as altering the lighting elements) or replace/repair. 
         [0006]    This internal assembly typically includes a main body formed of cast aluminum for the heat dissipation or heat sinking properties. The body often includes a top surface or area that includes fans to increase the surface area with the atmosphere. However, when the internal assembly is mounted within its outer shell, the fans are exposed to a cavity of air within the shell, and the air acts as an insulator. The result is that this type of prior art LED light has poor heat dissipation beyond the heat sink. 
         [0007]    An LED is not unlike a traditional light-emitting element in that the element itself does little to control the direction of cast light. For many applications, and most outdoor applications, established patterns of cast light are usually specified. These patterns are often referred to by definitions provided by the Illuminating Engineering Society (IES). For instance, a Type III pattern is an oval or elliptical pattern wherein the light is cast in lateral directions from the lantern, while Type IV is similar to Type III, but the former casts the oval in a forward direction relative to the lateral directions. Both Type III and Type IV patterns may be specified for streetlighting in a residential area so that a lantern mounted proximate to but out of the roadway casts its light principally downward and into the street, and does not cast appreciable light towards the residences along the roadway. A Type V pattern is a generally symmetrical distribution. 
         [0008]    In some applications, there is also a “cutoff” specification for determining how much light may be cast upwards from the lantern, demonstrating a concern for “light pollution” and light nuisance in urban areas. The IES defines a “full cutoff” as zero lumens at 90 degrees from vertical plumb or nadir. “Cutoff” requires 2.5% or less of total candlepower (i.e., measured lumens) at 90 degrees from nadir, while “semicutoff” requires 5% or less at 90 degrees from nadir. 
         [0009]    The construction of the lantern itself creates issues for satisfying the pattern and cutoff specifications. In one prior art LED-based lantern, the LEDs are individually mounted in a ring around a circular internal assembly. The internal assembly includes a central support for positioning the ring to have the LEDs direct light downward in a generally circular pattern, and the central support includes a reflective surface formed on a concave cylinder. While the reflective surface serves to distribute light outward, the lower portion flares outwardly so that downward rays are reflected laterally, the concomitant result being that light is also reflected upwardly. 
         [0010]    The principal manner used to control the throw or cast of light is reflective lenses. In a typical lantern, the outer shell includes a top portion or canopy, and light is emitted outward from the lantern below the canopy. In order to promote the low cutoff properties, the canopy also extends outwardly (horizontally) beyond any lens and is solid and opaque. A first style of lens is generally a translucent body or series of panels extending from the lower skirt of the canopy to a top of a lantern base, the base also being solid and opaque and providing structure support between the lantern and the stanchion upon which it is mounted. This style of lens may be clear, may be frosted, may have a pattern formed on the surface of the lens to reflect the light in a specific direction, or a combination of both. These lenses are heavy, and they can be expensive to manufacture and replace (such as when struck by vandals) or change (such as when the light Type pattern is to be changed). 
         [0011]    Another style of lens is sometimes referred to as an “optic” or to as “optics.” This style utilizes a separate lens dedicated to a singular light-emitting element, though a plurality of lenses may be formed as a sheet. The individual lenses are placed close to the LEDs to generally capture most of the light from the LED and may be used to reduce the overall size requirements for the assembly. 
         [0012]    A common drawback of the above-described prior art lanterns is the use of reflection to direct the light rays. As is know, reflection is the physical principal of a light ray hitting a reflective barrier, broadly treated herein as an internal or external surface or boundary for which a light ray strikes at an angle of incidence, the light then being turned away from the boundary at an angle of reflection. Reflection of light results in certain portion of the rays being lost to diffusion, for a variety of reasons. At a minimum, the lost rays are wasteful; at a maximum, they can be reflected at greater than 90 degrees to the nadir. 
         [0013]    Accordingly, there has been a need for an improved light assembly and, in particular, an improved LED-based lantern assembly. 
       SUMMARY 
       [0014]    In accordance with an aspect, a lantern is disclosed including a canopy having an outer surface externally exposed to atmosphere for heat dissipation thereto and heat sink structure integrally formed with the outer surface, heat-producing lighting elements, and a mounting substrate from mounting the lighting elements, wherein the canopy is adapted for securing the mounting substrate to the heat sink structure for dissipation of heat from the lighting elements. 
         [0015]    In some forms, the lighting elements are light emitting diodes (LEDs). The mounting substrate may include a printed circuit board (PCB) upon which the LEDs are mounted. The lantern may include a fixture plate mounted between and in physical contact with both the PCB and the heat sink structure. 
         [0016]    In another aspect, a method of configuring a light emitting diode (LED)-based lantern is disclosed including the steps of selecting a lighting application including a lighting pattern and candlepower, selecting two or more lighting element assemblies in accordance with the lighting application, mounting each selected lighting element assembly within a lantern, and wiring each selected lighting element with the lantern. 
         [0017]    In some forms, the step of mounting each selected lighting element assembly includes mounting each selected lighting element assembly with a fixture plate, and mounting said fixture plate within said lantern. The step of mounting said fixture plate may include mounting the fixture plate in physical contact with a canopy of the lantern. The step of mounting said fixture plate may include mounting the fixture plate in physical contact with a heat sink structure integrally formed with the canopy and mounting the fixture plate in physical contact with each selected lighting element assembly. 
         [0018]    In some forms, the step of selecting one or more lighting element assemblies includes providing lighting assemblies having at least two different configurations. The step of providing the configurations may include providing each configuration with a shape for a printed circuit board (PCB) on which lighting elements are mounted, and providing each configuration with a number of lighting elements producing a predetermined candlepower. The step of providing the configurations may include providing each configuration with a lighting pattern for light cast from the lantern, wherein at least two of the lighting assembly configurations have different lighting patterns. The step of providing each configuration with a lighting pattern may include providing a lens over each lighting element, and the step of selecting one or more lighting assembles includes selecting the lighting pattern provided by the lens thereof. 
         [0019]    In some forms, the method includes the steps of providing a plurality of lenses, the lenses providing at least two different lighting patterns, selecting lenses based on a selected lighting pattern, and mounting the selected lenses with each of the selected lighting element assemblies. The method may include the step of removing previously mounted lighting assemblies. The method may include the step of removing previously mounted lenses. 
         [0020]    In some forms, the method includes the step of initially providing a previously assembled lantern. 
         [0021]    In a further aspect, a method of constructing a light emitting diode (LED)-based lantern is disclosed including the steps of providing an individual lens for each LED, providing an individual lens securement for each lens and each LED, mounting each securement proximate the LED, and securing each lens with a respective LED. 
         [0022]    In some forms, the method further includes the steps of providing a solder pad for connecting the LED, providing a solder pad for mounting each securement, and solder-reflowing the LED and securement solder pads simultaneously. 
         [0023]    In some forms, the step of securing each lens includes snapping the lens into the securement. 
         [0024]    In still a further aspect, an optical lens for a light emitting diode (LED) is disclosed comprising a base, a cavity formed in the base, the cavity having an inner surface proximate an LED when mounted in a lighting assembly, and a first portion of the lens including a structure for casting light therefrom in a radial and annular pattern, wherein the optical lens at least partially refracts light therethrough. 
         [0025]    In some forms, the first portion has a radial extent no greater than half of the base, the optical lens further including a second portion for refracting light away from a radial direction. The optical lens may be used in directing light away from an undesired direction, wherein light emitted from the LED at least partially towards the undesired direction is refracted by and emitted from the second portion less towards the undesired direction and more towards a lateral direction to the undesired direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    In the Figures, 
           [0027]      FIG. 1  is a side elevation view of a representative lantern for mounting on a support or stanchion, such as for an outdoor lighting application; 
           [0028]      FIG. 2  is a perspective view of a canopy of the lantern of  FIG. 1  showing an internal assembly including a fixture plate and a plurality of printed circuit boards mounted to the fixture plate, each of the printed circuit boards including a plurality of light-emitting diodes (LEDs) mounted thereon; 
           [0029]      FIG. 3  is a perspective view of the fixture plate of  FIG. 2 ; 
           [0030]      FIG. 4  is a top plan view of a semi-circular one of the printed circuit boards of  FIG. 2 ; 
           [0031]      FIG. 5  is a top plan view of a circular one of the printed circuit boards of  FIG. 2 ; 
           [0032]      FIG. 6  is a perspective view of the fixture plate, a semi-circular one of the printed circuit boards mounted thereon, a second semi-circular one of the printed circuit boards in an assembly step with the fixture plate, and a circular one of the printed circuit boards in a second assembly step with the fixture plate; 
           [0033]      FIG. 7  is a perspective view of LEDs mounted on one of the printed circuit hoards showing optical gel applied to the LED; 
           [0034]      FIG. 8  is a perspective view of LEDs mounted on one of the printed circuit boards showing assembly steps for disposing optic lenses on the LEDs; 
           [0035]      FIG. 9  is a perspective view of the fixture plate and printed circuit boards of  FIG. 2  with cover plates mounted over the LEDs, printed circuit boards, and optic lenses; 
           [0036]      FIG. 10  is a perspective view of a portion of the fixture plate and printed circuit boards with LEDs mounted thereon of  FIG. 8  showing a cover plate of  FIG. 9  being mounted thereon; 
           [0037]      FIG. 11  is a first perspective view of an outer side of a semi-circular one of the cover plates of  FIG. 9 ; 
           [0038]      FIG. 12  is a second perspective view of an inner side of the semi-circular cover plate of  FIG. 11 ; 
           [0039]      FIG. 13  is a perspective view of an inner side of the circular cover plate of  FIG. 11 ; 
           [0040]      FIG. 14  is a top perspective view of the optic lens of  FIG. 8 ; 
           [0041]      FIG. 15  is a cross-sectional view of the optic lens of  FIG. 8 ; 
           [0042]      FIG. 16  is a detail of the view of  FIG. 15  showing angles along various points of an external surface for distributing light from an LED; 
           [0043]      FIG. 17  is a bottom perspective view of the lens of  FIG. 8 ; 
           [0044]      FIG. 18  is a side elevational view of the optic lens of  FIG. 8  showing lines representing paths of light rays for a light ray emission pattern from an LED through the optic lens; 
           [0045]      FIG. 19  is a perspective view of an alternative embodiment of an optic lens; 
           [0046]      FIG. 20  is a second perspective view of the optic lens of  FIG. 19 ; 
           [0047]      FIG. 21  is a third perspective view of the optic lens of  FIG. 19 ; 
           [0048]      FIG. 22  is a side elevational view of the optic lens of  FIG. 19 ; 
           [0049]      FIG. 23  is a top plan view of the optic lens of  FIG. 19 ; 
           [0050]      FIG. 24  is a perspective view of the canopy of  FIG. 2 ; 
           [0051]      FIG. 25  is a cross-sectional view of the canopy of  FIG. 24 ; 
           [0052]      FIG. 26  is an alternative form of a lantern having an alternative form of a canopy; 
           [0053]      FIG. 27  is a perspective view of the canopy of  FIG. 26 ; 
           [0054]      FIG. 28  is a second alternative form of a lantern having an alternative form of a canopy wherein the lantern depends from and the canopy is mounted with a support; 
           [0055]      FIG. 29  is a perspective view of a securement for retaining and mounting a lens within the assemblies described herein; 
           [0056]      FIG. 30  is a cross-sectional view of the securement of  FIG. 29  showing a shoulder for retaining the lens therein; 
           [0057]      FIG. 31  is a bottom plan view of the securement of  FIG. 29  showing a plurality of tabs for a solder joint with a PCB; 
           [0058]      FIG. 32  is a perspective view of second embodiment of a securement for retaining and mounting a lens within the assemblies described herein; 
           [0059]      FIG. 33  is a perspective view of a second embodiment of an Optic lens for providing a Type 5 lighting pattern; 
           [0060]      FIG. 34  is a top plan view of the optic lens of  FIG. 33  showing securing structure for cooperating with a securement; 
           [0061]      FIG. 35  is a side elevational view of the optic lens of  FIG. 33 ; 
           [0062]      FIG. 36  is a cross-sectional view of the optic lens of  FIG. 33  showing lines representing paths of light rays for a light ray emission pattern from an LED through the optic lens; 
           [0063]      FIG. 37  is a partial fragmentary cross-sectional view of the optic lens of  FIG. 33  and the securement of  FIG. 30  showing the securing structure of the lens cooperating with the securement to retain the lens therewith; 
           [0064]      FIG. 38  is a perspective view of a second embodiment of an optic lens for providing a Type 3 lighting pattern; 
           [0065]      FIG. 39  is a top plan view of the optic lens of  FIG. 38 ; 
           [0066]      FIG. 40  is a side elevational view of the optic lens of  FIG. 38 ; 
           [0067]      FIG. 41  is a front elevational view of the optic lens of  FIG. 38 ; 
           [0068]      FIG. 42  is a cross-sectional view of the optic lens of  FIG. 38 ; and 
           [0069]      FIG. 43  is a plot of light emitted from the optic lens of  FIG. 38 . 
       
    
    
     DETAILED DESCRIPTION 
       [0070]    Referring initially to  FIG. 1 , the exterior of a first form of a lantern  10  is illustrated with a visual appearance and construction consistent with prior art lanterns and non-LED-based lanterns such as would commonly be installed in outdoor applications. The lantern  10  includes a base portion  12  for securing the lantern  10  with a stanchion or support or lamppost at a desired height for distributing light from the lantern  10 . The base portion  12  also provides an internal path and housing for some electrical components (not shown), and the base portion  12  supports (either directly or indirectly) the other components of the lantern  10 . The other components of the lantern  10  include an external lens or globe  14  and a canopy  16 . 
         [0071]    Turning now to  FIG. 2 , the canopy  16  is shown with several lighting element assemblies  18  secured therein. In the present embodiment, the lighting element assemblies  18  are each secured to a plate fixture  20 , as are other components discussed below. As can be seen, the lighting element assemblies  18  are secured above and recessed from a lower edge  22  of the canopy  16  so that the canopy  16  and lighting element assemblies  18  are suitable for full cutoff applications. However, in the event the illustrated globe  14  is a diffuser, the globe  14  extending laterally beyond the edge  22  of the canopy  16  likely renders the globe  14  unsuitable for such. 
         [0072]    The lighting element assemblies  18  are secured with a fixture plate  30  depicted in  FIG. 3 . In the illustrated form, the fixture plate  30  is a relatively thin disc with a high thermal conductivity. The fixture plate  30  may be metal such as aluminum or another material that easily conducts heat. For each of the lighting element assemblies  18 , a plurality of mounting posts  32  and at least a single wiring hole  34  are provided. As can be seen by comparing  FIGS. 3 and 6 , a single lighting element assembly  18   a  is provided with a pair of mounting posts  32   a  and a wiring hole  34   a . The fixture plate  30  also includes mounting holes  36  for securing the fixture plate  30  with the interior  24  of the canopy  16 , such as by receiving a screw (not shown) therein. 
         [0073]      FIG. 2  illustrates a plurality of the lighting element assemblies  18  having different configurations and, specifically, illustrates four individual arc or semi-circular or partial-circular lighting element assemblies  40  and a single circular lighting element assembly  42 . The lighting elements assemblies  40  and  42  each hold a set of lighting elements in the form of light emitting diodes or LEDs  44  so that each of the lighting element assemblies  18  may include a subset of the total LEDs installed in a particular lantern  10 . In this manner, the amount of candlepower or lumens provided by the lantern  10  is scalable based on the number and arrangement of the lighting element assemblies  18  installed. For instance,  FIG. 5  illustrates the circular lighting element assembly  42  as having twenty-six LEDs  44 , and such may be installed in a lantern  10  as the only lighting element assembly  18 . Alternatively, a lantern  10  may include fewer, such as two or three, of the illustrated arc lighting element assemblies  40 , and the lantern  10  may be constructed with or without the central circular lighting element assembly  42 , so that the number of LEDs and, hence, the amount of candlepower provided by the lantern  10  is easily selected without other components of the lantern  10  being affected. In a further alternative, a lighting element assembly (not shown) may simply have a configuration of a different number of LEDs, such as a circular lighting element assembly similar to that of  FIG. 5  but having only one of the inner or outer illustrated circles  44   a ,  44   b  of LEDs  44 . The lighting element assembly  40  of  FIG. 4  may similarly be modified. In contrast, prior art LED lanterns utilize a single lighting element assembly, rendering the lantern non-scalable. 
         [0074]    Focusing on  FIG. 4 , each of the lighting element assemblies  18  includes a printed wiring or printed circuit board (PCB)  50 . In a preferred form, the PCB  50  is formed of FR4, a well known substrate material, or another material that promotes heat dissipation from the LEDs  44  mounted thereon. The PCB  50  includes a trace wiring layer (not shown) connected to input/output wires  52  for receiving power and forming an electrical circuit with the lantern. In a preferred form, the array of LEDs  44  is wired with pairs of LEDs  44  in parallel, and each pair then wired in series with the other pairs. 
         [0075]    Notably, the lantern  10  locates the other electronic circuitry elsewhere and not on the PCB  50 . For instance, a secondary board (not shown) may be located above the fixture plate  30 , or may be located in the base. In any event, regardless of the selection of one or more lighting element assemblies  18 , the control electronics are not redundant and can easily be connected with the lighting element assemblies  18 . This also reduces waste should one of the lighting element assemblies be replaced. 
         [0076]    Preferably, each wire  52  passes through two bores  54  before being soldered into connection and with the PCB  50 , a structural feature that diminishes the susceptibility of the lighting element assembly  18  to damage by handling or transit, for instance. For each LED  44 , solder pads are formed on the PCB  50  for electrical connection and mounting of the LED  44  on a front side  50   a  of the PCB  50 . In a preferred form, the PCB  50  includes a back side  50   b  ( FIG. 6 ) provided with a foil layer (not shown), preferably of aluminum, for promoting heat dissipation. The PCB  50  includes mounting holes  56  for securing the PCB  50  with the mounting posts  32  of the fixture plate  30 , such as via screws (not shown). Mounting of the lighting element assemblies  18  with the fixture plate  30 , and the fixture plate  30  with the canopy  16 , are relatively simple steps that allow a technician to assembly the lighting element assemblies  18  and fixture plate  30  within the lantern  10  according to a customized selection, including retrofitting or changing the components in a field-installed application. This feature is further promoted by the lighting element assemblies  18  being robust and self-contained, without requiring a technician to individually mount the LEDs  44 , as is the case with most prior art applications. 
         [0077]    Turning now to  FIGS. 7 and 8 , LEDs  44  mounted to a PCB  50  are shown. As is known, an LED  44  includes a clear, vitriform covering  46  through which emitted light passes. In one form, the lantern  10  utilizes refraction to direct emitted light from the LEDs, as opposed to the reflection employed by prior art lanterns. In some forms, this is promoted by providing each LED covering  46  with an amount of optical gel  60  and a lens  64  that least partially refracts light. The optical gel  60  is applied as a gel drop  62  to the covering  46  ( FIG. 7 ). A commercially-available optical gel marketed as ______ by the ______ (company) ______ of ______ (location of company) ______ may be used, as an example. As best seen in  FIG. 8 , individual lenses  64  are then disposed over the LEDs  44 , mounting with light pressure (as the LED covering is relatively susceptible to damage by focused pressure) and a rotating motion (arrow R) in order to distribute the optical gel  60  within a cavity (discussed below) formed on the bottom side  64   a  of the lens  64 . Preferably, the optical gel  60  fills any interstitial volume that light may pass between the LED covering  46  and the lens  64 . The optical gel  60  reduces or eliminates boundary deflection, reflection, and diffusion that would normally occur without the optical gel  60  at the boundary between the covering  46  and air and between the air and the lens  64 . During manufacturing and assembly of the components, the optical gel  60  also provides a retention force to retain the lens  64 , at least temporarily, with the light element assemblies  18 . It should be noted that, while a preferred embodiment utilizes the plurality of lenses  64 , it is within the scope of forms of the inventions described herein to utilize a single lens (not shown) for multiple LEDs  44 . It should be noted that in another form discussed below the optical gel  60  may be obviated. 
         [0078]    With reference to  FIGS. 9-13 , the next step in assembly is providing one or more cover plates  70  for each lighting element assembly  18 . With initial reference to  FIG. 9 , each of the lighting element assemblies  18  has an individually sized and mounted cover plate  70  such that arc cover plates  72  are provided for the arc light element assemblies  40  and a circular cover plate  74  is provided for the circular light element assembly  42 . 
         [0079]    The cover plates  70  include openings  76  for the LEDs  44 . More specifically, the openings  76  allow the light emitted from the LEDs  44  to pass through and, in the preferred form, at least a portion of the lens  64  is disposed within the openings  76 . In the present form, a single opening  76  is provided for each lens  64  and LED  44 . 
         [0080]    Each opening  76  and the cover plate  70  are designed to minimize interference with light being emitted, while also providing a degree of weather element protection. Towards this end, each cover plate  70  is larger than that PCB  50  of the lighting element assembly  18  for which the cover plate  70  is provided, and an outer gasket  80  is secured at the peripheral edge  78  of the cover plate  70  for sealing with the fixture plate  30 . The cover plate  70  also includes lens gaskets  82  ( FIG. 10 ) positioned around each opening  76  for sealing with the lens  64  received within the opening  76 . In  FIGS. 12 and 13 , the rear sides  70   a  of the cover plates  70  include a rim  84  on which the peripheral edge  78  is formed, the rim  84  and outer gasket  80  providing a stand-off for a top surface  70   b  of the cover plate  70  from the fixture plate  30 , thereby allowing the cover plate  70  to receive the light element assembly  18  within a slight cavity  70   c  formed within the rear side  70   a  of the cover plate  70 . 
         [0081]    The size of the rim  84  also provides for the lens gaskets  82  mounted on the cover plate rear side  70   a  around the openings  76 . That is, the stand-off provided by the rim  84  positions the cover plate  70  over the lenses  64  with the lens gaskets  82  therebetween. 
         [0082]    The cover plate  70  is secured with the light emitting assembly  18  and with the fixture plate using posts  90  formed in the cover plate  70 . As can be seen in the Figs., the posts  90  extend from the cover plate top surface  70   b ; while not shown, in the present form the posts  90  have an internally threaded blind bore  92  at the rear side  70   a  so that a threaded member (not shown) passes through the fixture plate  30 , through the PCB  50 , and into the posts  90 . The threaded members can be tightened to compress the gaskets  80 ,  82  against the lenses  64  and fixture plate to seal the light element assembly  18  from weather elements at those interfaces. 
         [0083]    As best seen in  FIGS. 10 and 11 , the cover plate  70  includes a bevel  96  surrounding each opening  76 . Recognizing the top surface  70   b  of the cover plate  70  is positioned away from the LED  44  itself (due to the lens  64 , and the gasket  82  thereat, e.g.), the bevel  96  reduces any interference the cover plate  70  has on the emission of light from the LED  44  and lens  64 . 
         [0084]    In preferred forms, each lens  64  is molded of optically clear and UV stabilized acrylic, the acrylic having a 1.49 refractive index. Turning now to  FIGS. 14-18 , a lens  64  in the form of a symmetrical lens  100  is illustrated, the symmetrical lens  100  providing a generally circular light pattern and being known as a Type V lens under the IES pattern standard. The lens  100  includes a base  102  including a bottom side  102   a . The base  102  includes a flange portion  104  extending radially outwardly and having a top surface  104   a . When the cover plate  7  is secured over the lines  100 , the lens gasket  82  is pressed against the flange top surface  104   a . The base  102  is placed on and against the PCB  50  around an LED  44  mounted to the PCB  50 . To enable this, the base  102  includes a central cavity  106  into which the LED  44  and the optical gel  60  is disposed. As can be seen in  FIG. 15 , the symmetrical lens  100  is designed to locate a photometric center  110  of the LED  44  along a center axial line X just below the plane P of the bottom side  102   a.    
         [0085]    The symmetrical lens  100  includes a light emitting portion  120  through which light from the LED  44  passes, best illustrated in  FIG. 18  in which rays of light are represented as arrows  122 . In the present form, there is little ability to control the direction of a center arrow  122   a  that passes orthogonally from the LED covering  46  and from the photometric center  110  thereof to and through the light emitting portion  120 . A portion of the rays represented by arrow  122   b  immediately radially outward from the center arrow  122   a  are bent while passing from the LED  44  to the lens  100  and while exiting the lens  100  to the surrounding air. As can be seen, a central portion  124  of the lens  100  has a least a first and preferably a first and a second angle surface  124   a ,  124   b  that cause the rays  122   b  to be distributed somewhat evenly in emission from the central portion  124  surfaces  124   a ,  124   b.    
         [0086]    The combination of the refracting of the light  122  as it enters and leaves the lens  100  results in a large portion of the overall light  122  being directed outwardly, to some degree. That is, a portion of the light represented by arrows  122   c  is directed outwardly from the central axis defined by arrow  122   a  such that it is emitted from a surface  126  formed radially outwardly on the central portion  124 . An arced profile is provided on a medial portion  128  to define an arced surface  128   a , again resulting in light represented by arrow  122   d  being partially distributed radially outwardly. A emission base portion  130  includes a substantially vertical portion  130   a  that bends light forward so rays  122   e  converges somewhat with the rays  122   c  and  122   d.    
         [0087]    In this manner, the light pattern cast from the lens  100  forms a Type 5 light pattern. More specifically, each lens  100  provides a bright ring of rays  122 , somewhat annular, with a center of the ring also somewhat illuminated due to rays  122   b  and  122   a , for instance. The combination of plurality of lenses  100  provides a pattern of overlapping rings that, together, form the Type 5 light pattern, as can readily be understood from the array of LEDs  44  illustrated in FIG.  2 , for instance. It can also be understood that, due to the angle for the rays  122   c - e , that the light is cast on a surface with a radius; the farther the surface (such as a street or ground level surface surrounding a lantern  10 ) from the LEDs  44 , the larger the radius for that light. Accordingly, LEDs  44  located in the center of the lantern  10  (such as that of  FIG. 26 ) will nonetheless cast the vast majority of their light outwardly and not simply directly into the support located therebelow. 
         [0088]      FIGS. 19-22  illustrate a lens  64  in the form of an asymmetrical lens  150  which may be designed to satisfy the IES standard Type III pattern. The asymmetrical lens  150  has a base  152  similar to that of the symmetrical lens  100 , described above, and having a bottom side  152   a  ( FIG. 22 ) and a flange  154  with a top surface  154   a . However, while the symmetrical lens cavity  106  has an interior surface  106   a  that is generally hemispherical and concave (see  FIG. 15 ), the asymmetrical lens  150  includes a central cavity  156  that with an interior surface  156   a  (see  FIG. 22 ) that is conically shaped and extends into the cavity  156 . 
         [0089]    The lens  150  includes a light emitting portion  160  formed on the base  152 . For prior art lanterns attempting to satisfy the Type III pattern, a metal structure such as a central pole is usually provided, some distance from the LED, to reflect light away from undesired directions, the pole providing little to no effective control over the direction of light and undesirably dispersing a significant portion of the light. For the present asymmetrical lens  150 , a novel reflective shield portion  162  is provided as part of the lens  150  itself. The shield  162  is formed a short radial distance from the cavity  156  and extends axially. In a preferred embodiment, the shield  162  is frosted on front and rear surfaces  162   a ,  162   b , and such surface treatment is provided during formation such as molding. The shield  162  serves to direct light from the LED  44  disposed in the cavity  156  minimally away from the undesired directions (generally in the directions of representative arrows U in  FIGS. 22 and 23 ) and preferably towards the desired directions (generally in the directions of representative arrows D in  FIGS. 22 and 23 ) 
         [0090]    The light emitting portion  160  may generally be bisected into a semi-symmetrical half  170  and a non-symmetrical half  172 , of which the shield  162  is a part. The semi-symmetrical half  170  has an outer shape generally like that of the symmetrical lens  100 . What should be recognized from the above discussion of rays  122  for the lens  100  is that the rays  122  are refracted toward the normal when entering the lens  64  and are refracted away from the normal when exiting the lens  64 , and the lens  150  behaves in the same manner. Rays  122  passing through the semi-symmetrical half  170  are refracted in the same manner as illustrated in  FIG. 18 , discussed above. 
         [0091]    Each lens  64  discussed herein attempts to minimize the rays  122  that simply pass straight through the lens  64 , such as rays  122   a  and  122   b  in  FIG. 18 , because such rays  122  are generally not responsible for defining the light pattern such as Type 3 or Type 5. Two manners for promoting this goal is by maximizing overall height of the lens  64  from the photometric center  110  and by reducing the radial extent of the central portion such as central portion  124  of the lens  100  as shown in  FIG. 18 . The non-symmetrical half  170  of lens  150  is further designed to minimize light being cast in the undesired direction U, preferably casting the light either laterally to directions D and U or towards direction D. 
         [0092]    The non-symmetrical half  170  may be viewed as being in three portions, the shield  162 , a “wing” section  174 , and a “boat” section  176 . Each section  162 ,  174 ,  176  is symmetrical about an axis B ( FIG. 23 ). The boat section  176  has outer surfaces  178  that are angled radially downwardly at a much greater angle (from vertical axis C,  FIG. 22 ) than the angle of medial portion  128  ( FIG. 22 ); in addition, the outer surfaces  178  angle inwardly (toward axis B,  FIG. 23 ) much more sharply than the semi-circular shape of medial portion  128  ( FIG. 23 ). Thus, rays  122  from the photometric center  110  ( FIG. 22 ) are emitted from the boat outer surfaces  178 , and the rays  122  therethrough are refracted both towards the axis C ( FIG. 22 ) and towards axis A ( FIG. 23 ). The boat section  176  also has inner surfaces  180 ; as can be seen in  FIG. 23 , the inner surfaces  180  extend radially to a shorter extent than surfaces  124   a ,  124   b , which reduces the number of rays  122  (amount of light) that pass orthogonally (substantially in the direction of axis C) from the lens  150 . Additionally, the inner surfaces  180  are somewhat V-shaped across the axis B and are substantially flat; in this manner, the inner surfaces  180  tend to refract light in the lateral direction of axis A, thereby minimizing or reducing the number of rays  122  through the inner surfaces  180  that are directed toward the undesirable direction U. 
         [0093]    The wing section  174  is somewhat similar to the boat section  176 , as can be seen in  FIG. 23 , so that rays  122  are refracted towards the axes A and C, towards desired direction D, and away from undesired direction U. The wing section  174  has shield surfaces  182  which receive rays  122  from the other sections, principally from the boat section  176 , and reflect (or disperse) the light forward in the desired direction D or in the direction of axis C. The wing section  174  has outer surfaces  184  and inner surfaces  186  that each refract the light towards the axes A and C. A more detailed viewing of the light passing through the lens  150  is apparent through a comparison of the lens  150  with lens  600 , discussed below. 
         [0094]    The light emitting portion  160  is orientation specific. Accordingly, each of the lenses  150  may be individually adjusted for the light cast therefrom. As the lenses  150  are not heat-staked or otherwise fixedly mounted with the light element assembly  18  or the cover plate  70 , a technician can adjust the position of the lenses  150  after assembly. L 2 Optics LTD, United Kingdom, utilizes an “adhesive pad” to retain lenses over the LEDs; again, this does not allow a user to change the position of the lens unless it is first released (separated) from the adhesive pad. 
         [0095]    It should be noted that, as the lantern  10  has been discussed as scalable, lenses  64  with different light patterns may be used in a single lantern  10 , or lenses with different lighting effects (such as diffusion, or colors, or level of opacity) may be retrofitted, replaced, or combined in a single lantern  10 . 
         [0096]    As discussed in the background, LED-based lanterns tend to generate a significant amount of heat on the back side of the LED  44 , that is, between the LED  44  and its PCB  50 . A number of features described herein are designed to accommodate heat dissipation, such as the foil layer on the back of the PCB  50  and the use of thermally conductive material for the PCB  50  and the fixture plate  30 . 
         [0097]    Also discussed in the background is the prior art approach of building an internal unit that is installed within a shell, the internal unit including a heat sink. The internal unit may include approximately eight pounds of aluminum for the heat sink, and this unit is what is handled by a technician in assembling or installing the lantern. The prior art has an insulating air space between the heat sink and the outer shell of the lantern. 
         [0098]    Turning to  FIGS. 24 and 25 , the canopy  16  is illustrated. In contrast to the prior art, the present canopy  16  includes integrally formed heat sink fans  200 . The fixture plate  30  with the lighting element assemblies  18  thereon is mounted directly to the fans  200 , eliminating the insulating air of the prior art lanterns. The fans  200  are integral with the canopy  16  (specifically, a canopy housing  208 ) so that heat passing from the LEDs  44 , to the PCB  50 , to the fixture plate  30 , to the fans  200  easily passes to the exterior surface  202  of the canopy housing  208 . 
         [0099]    As discussed above in the background, a prior art lantern typically has the LEDs mounted directly to the heat sink. Accordingly, alteration of the LEDs is usually less costly when the entire unit is simply thrown away, as the labor required to remove the LEDs and associated wiring and then re-mounting a new LED assembly and circuit is more costly than the materials waste. For forms of the present invention, as discussed above, the only portion that need be replaced is the comparatively inexpensive lighting element assembly  18 , which often carries only a subset of the total LEDs  44 . 
         [0100]      FIG. 26  shows an alternative form of the lantern  10  as lantern  300 . In contrast to the lantern  10 , lantern  300  includes support arms  302  for connecting a canopy support  304  to a base  306 . The canopy support  304  supports and connects a canopy  308  to the rest of the lantern  300 . In  FIG. 26 , a latch  310  is shown for connecting one side  312  of the canopy  308  to the canopy support  304 , while  FIG. 27  shows hinge connections  314  for hingedly connecting a second side  316  of the canopy  308  to the canopy support  304 . In the illustrated form, the lantern  300  includes four individual arc light element assemblies  40  and a single circular light element assembly  42 . Like the canopy  16 , the canopy  308  includes fans  320  integrally formed with an outer housing  322 , which has an outer surface  324 . Like the lantern  10 , the lighting element assemblies  40 ,  42  pass heat through their PCBs  50 , to the fixture plate  30 , to the fans  320 , and, ultimately, to the outer surface  324  for dissipation therefrom. 
         [0101]      FIG. 28  shows a further alternative form of the lantern  10  as a pendant lantern  400 . The lantern  400  includes a canopy  402  that is securable at a top point  402   a  thereof to a support (not shown). The canopy  402  includes fans (not shown) formed integrally therewith for each dissipation, the illustrated lighting elements  18  being secured directly or operatively with the fans for heat dissipation therethrough. A light cover or globe  410 , such as a diffuser, is illustrated as would be mounted to an outer hood 420 portion of the canopy  402 . 
         [0102]    The above discussion regarding lenses  64  described two embodiments of lenses  64  as lens  100  and lens  150  as producing Type 5 and Type 3 lighting patterns, respectively. The lenses  100  and  150  are maintained or secured by the cover plates  70 , and generally utilized optical gel. Alternative forms of lenses  64  are described below. 
         [0103]    Turning to FIGS.  29 -**, lenses  500  are mechanically securable to a PCB  50  via a securement device  510 . In the present forms, the securement  510  is ring-shaped and includes board-mounting features  512 . 
         [0104]    Turning specifically to  FIGS. 29-31 , a first embodiment of a securement  510  is shown as ring  520 . The board-mounting features  512  are in the form of tabs  522  extending radially outwardly from a body  524 . In the preferred form, the ring  520  is formed of metal and, more preferably, of tin plated copper. To assembly the ring  520  with the PCB  50 , solder pads (not shown) are provided on the PCB  50  surrounding or proximate to the connection points for the LEDs  44 . The metal rings  520  and LEDs  44  are placed on their respective connection points (solder pads), and the solder reflow step for connecting the LEDs  44  also joins the tabs  522  with the PCB  50 . 
         [0105]    The securements  510  serve to mount and position the lenses  500  on the PCB  50 . Turning to  FIGS. 31 and 32 , it can be seen that the body  524  includes lens-retaining features  525  a lip or shoulder  530  formed thereon and facing towards the PCB  50  when mounted therewith. As will be discussed below, the lenses  500  snap into the ring  520  by snapping into the shoulder  530 . Additionally, the ring  520  includes tabs  531  extending axially downwardly that assist in positioning the ring  520  on the PCB  50 . In the present form, the shoulder  530  is discontinuous having a plurality of gaps  532 ; in some forms, the gaps  532  may be used to receive securing structure  550  ( FIG. 33 , e.g.) on the lens  500  received within the ring  520 , the lens  500  then being rotated so that the structure  540  is received underneath the shoulder  530 . 
         [0106]    In the present form, three stand-off tabs  531  and three solder tabs  522  are provided, though the number may be varied. In some forms, the stand-off tabs  531  may alternatively be radially inwardly extending from the body  524  so as to restrict the rotation of the lens  500 . 
         [0107]    In another alternative, a securement  510  may be provided in the form of ring  540 , illustrated in  FIG. 32 . The ring  540  has a generally annular body  542  with board-mounting features  512  in the form of posts  544 . In the preferred form, the ring  540  is formed of thermoplastic and, thus, the posts  544  may be inserted into openings of the PCB  50  and heat-staked thereto. The ring  540  includes lens-retaining features  525  in the form of retaining blocks  546  having downwardly-facing shoulders  547  formed thereon. An inner surface  546   a  of the block  546  is beveled or chamfered for assisting in receiving the lens securing structure  550  ( FIG. 33 . e.g.) therein. The ring  540  further includes retention gaps  548  for receiving the lens securing structure  550  therewithin to prevent rotation of the lens  550  once received by the ring  540 . 
         [0108]    Turning to  FIG. 33 , et seq., lenses  500  are provided with the above-mentioned lens securing structure  550 . A representative lens  500  for use with the securements  510  is illustrated in  FIGS. 33-36  as a lens  560  producing a Type 5 lighting pattern. As can be seen, lens  560  has securing structure  550  in the form of a plurality of barbs  562  having a leading chamfer  564  for assisting in snapping the lens  560  into the securement  510  and a trailing shoulder  566  that is generally horizontal or parallel with the PCB  50  when secured therewith. As can be seen in  FIG. 37 , force applied to the lens  560  to direct the lens  560  within the securement  510  causes a combination of compression on the lens  560  and expansion of the securement  510  as the chamfer  564  is driven against the interior edge  524   a  of the body  524 . Once the chamfer  564  clears the body shoulder  530 , each of the lens  560  and securement  510  are able to return to their natural state. The shoulders  530  and  566  then cooperate to retain the lens  560  within the securement  510 . 
         [0109]    It should also be noted that the geometry of the lens  560  varies from that of lens  500 , as can be seen by comparing  FIGS. 33-35  with  FIGS. 14-18 . The lens  560  has a base  570  from which the securing structure  550  radially extends. The base  570  includes a cavity  572  for receiving the LED  44  therein, and the photometric center  110  of the LED  44  is shown in  FIG. 36 . The top  574  of the cavity  572  is convex, in contrast to that of the lens  500  ( FIG. 18 ). 
         [0110]    Rays  122  pass from the LED  44 , generally from the photometric center  110 , through the lens  560  and, predominantly, through a central emission portion  580  thereof, as illustrated in  FIG. 36 . As discussed above, rays  582  are refracted towards normal when entering the lens  560  and away from normal when leaving the lens  560 . Ray  582   a  exits straight from the photometric center  110  through the central emission portion  580  along axis C and through a center conical portion  584  of the central emission portion  580 . Light ray  582   b , radially outward from ray  582   a , also passes through the center conical portion  548 . Light rays  582   c  pass through a first outer section  586  of the central emission portion  580 , while light rays  582   d  and  582   e  pass through a second outer section  588  of the central emission portion  580 . As can be seen, the lens  560  thus casts the light rays  582  outwardly to form a halo pattern, with an illuminated center of lower intensity, a plurality of the lenses  560  being arrayed to produce the Type 5 lighting pattern. 
         [0111]    Turning to  FIGS. 38-42 , a lens  500  for securing with a securement  510  is illustrated as a lens  600  that produces a Type 3 lighting pattern, as best viewed in  FIG. 43 . As can be seen, the lens  600  includes the securing structure  550  in a substantially identical manner as the securing structure  550  of lens  560  and, thus, the lens  600  is secured with and retained the securement  510  as illustrated in  FIG. 37 . That is, the securing structure  550  of the lens  600  is the form of a plurality of barbs  562  having a leading chamfer  564  ( FIG. 40 ) for assisting in snapping the lens  560  into the securement  510  and a trailing shoulder  566  ( FIG. 40 ) that is generally horizontal or parallel with the PCB  50  when secured therewith, the chamfer  564  and shoulder  566  engaging and cooperating with the interior edge  524   a  of the body  524  to snap the lens  600  within the securement  510 , each of the lens  560  and securement  510  are able to return to their natural state once the chamfer  564  clears the body shoulder  530 . 
         [0112]    Like lens  150 , lens  600  includes a base  601 , a semi-symmetrical portion  602  and a non-symmetrical portion  604 . The semi-symmetrical portion  602  is substantially identical to the central emission portion  580  of lens  560 , discussed above, and forms approximately half of the lens  600 , other than the base  601 . The non-symmetrical portion  604  includes a shield  610  similar to the shield  162  of lens  150 , a wing section  620  similar to the wing section  174  of lens  150 , and a boat section  640  similar to the boat section  176  of the lens  150 . 
         [0113]    In the same pursuit of lens  150 , lens  600  seeks to cast light from the non-symmetrical portion  604  towards the desired direction D and away from the undesired direction U ( FIG. 39 ). More specifically, the lens  600  redirects light from the undesired direction U towards the axes A and C, as well as towards the desired direction D. As the semi-symmetrical portion  602  allows light to pass in the same manner as discussed above for lens  560 , it is not repeated here in detail. 
         [0114]    The shield  610  is preferably frosted so as to disperse light and/or to reflect any light towards desired direction D and/or axis C. 
         [0115]    The boat section  640  extends slightly beyond, radially, a portion of the semi-symmetrical portion  602 . In this manner, small shield surfaces  642  are provided for interfering with errant light rays that may be emitted from the semi-symmetrical portion  602 . These surfaces  642  are principally provided, though, so that other surfaces of the boat section  640  may extend to a greater degree. 
         [0116]    More specifically, the boat section  640  includes forward and rearward  644   a  and  644   b  and upper and lower inner surfaces  646   a  and  646   b . As a theoretical matter, light rays are emitted from the photometric center  110  of the LED  44 , shown in  FIGS. 39 and 42 . As discussed above, the lens  600  refracts the light rays entering towards normal and refracts the light rays exiting away from the normal. The convex surface  606  on the interior of a cavity  608  provided for the LED  44  located therein tends to focus more rays from the photometric center  110  through the general center of the lens  600 . As can be visualized, a portion of the rays from the LED  44  through the non-symmetrical portion  604  are emitted close to the axis C (see  FIGS. 39 and 42 ) and, thus, pass through the inner surfaces  646   a  and  646   b  of the boat section  640 . As an example, light is radially emitted from the photometric center  110  and enter the lens  600  at the convex surface  606 , which would refract the light towards the normal which is also towards axis C ( FIG. 2 ); as such light exits the lens  600 , it is refracted away from the normal at the inner surfaces  646   a ,  646   b , which are severely angled so that the light is directed laterally towards axis A (as well as axis C). 
         [0117]    The same principal guides light passing through the forward and rearward surfaces  644   a ,  644   b  of the boat section  640 . That is, light emitted from the photometric center  110  (see  FIG. 39 ) to be refracted away from the normal when exiting; as can be seen in  FIG. 39 , the forward and rearward surfaces  644   a ,  644   b  are angled with respect to the photometric center  110  such that the radial distance of a point on the forward and rearward surfaces  644   a ,  644   b  increases from the rearward-most area to the forward-most (rearward being in the undesirable direction U). Thus, normal direction is angled rearwardly, and the light emitted from these surfaces (refracted away from the normal) is bent towards the axis A. 
         [0118]    A comparatively small portion of light reaches inner and outer surfaces  660 ,  662  of the wing section  620 . Generally speaking, light emitted through the wing section  620  is at a severe angle from the normal. The outer surfaces  662  are curved to produce severe angles with respect to normal for light emitting from the outer surfaces  662 , the result being that light emitted therefrom is bent towards the lateral direction of axis A and the vertical direction of axis C. The inner surfaces  660  attempt to generally redirect light towards the axis C; however, comparatively little light reaches these surfaces, and a significant portion is simply allowed to be dispersed by the shield  610 . 
         [0119]    Turning to  FIG. 43 , a plot  690  of light emitted from the lens  600  is illustrated. The lens  600  positioned 1000 mm from a surface produces the plot  690 . The outer dark gray region  692  indicates absence or minimal light; lighter areas progressing inwardly as  693  correlate to greater intensity of light; finally, dark regions  694  within the lighter areas correspond with the greatest intensity of light on the surface. The axis A corresponds to the axis A of the lens  600  shown in  FIG. 39 . 
         [0120]    As can be seen, a region  4  corresponds to light received generally from the shield  610 . Thus, it can be seen that the shield  610  is responsible for very little or no light reaching the surface. A region  1  corresponds to light received from the semi-symmetrical portion  602 . The region labeled  2  &amp;  3  indicates light received from the wing section  620  and the boat section  640 . As can be seen, light from the semi-symmetrical portion  602  overlaps with light received from the wing section  620  and the boat section  640 , the latter of which heavily overlap as well. 
         [0121]    While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.

Technology Classification (CPC): 5