Abstract:
A method and apparatus for installing an LED lamp module into a light such as a traffic signal light. The LED lamp module includes a plurality of LEDs for producing light. The traffic signal light includes a housing, a door assembly removably or movably attached to the housing and having an aperture for passing the light, and a securing bracket having a first end secured to the door assembly and a second end secured to the LED lamp module, for maintaining an alignment between the door assembly and the LED lamp module.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/752,944, filed Dec. 21, 2005. 

   FIELD OF THE INVENTION 
   The present invention relates to the design and the use of light emitting diode (LED) lamps for various traffic signal light applications, and more particularly to an improved LED traffic signal lamp design that better facilitates the removal and replacement of one LED based light engine with another LED based light engine as needed. 
   BACKGROUND OF THE INVENTION 
   Light emitting diode (LED) lamps have been developed to replace conventional incandescent or fluorescent lamps for reducing electrical and maintenance costs, and for increasing reliability. LED lamps consume less electrical energy than conventional lamps while exhibiting much longer lifetimes. Such LED lamps typically include a power supply and a plurality of LEDs mounted on a flat or curved surface. 
   One growing use of LED lamps is the replacement of incandescent light bulbs in traffic signal lamps. A common conventional traffic signal lamp is illustrated in  FIGS. 1A and 1B , and includes a housing  1 , a front door plate  2 , a lens  3 , a reflector  4  and an incandescent light bulb  5 . Retainers  6  affix the lens  3  to the front door plate  2 , which opens via hinges  7  to allow access to the interior of the housing  1 . Light bulb  5  screws into electrical socket  8 , which is electrically attached to a terminal strip  9 , which in turn receives its power from the traffic signal controller. 
   It is known to replace the incandescent light bulb  5  with an LED lamp, along with the lens  3  since it is designed for the output of an incandescent light bulb. In a conventional traffic signal lamp retrofit procedure, the lens  3 , light bulb  5 , reflector  4  and socket  8  are all removed, and an LED lamp module  10  is installed to the front door plate  2  to replace lens  3 , as illustrated in  FIG. 2 . Wires  11  from the LED lamp module are connected to the terminal strip  9 . 
   The above mentioned retrofit method has several drawbacks. First, it is time consuming and labor intensive to remove the reflector  4  and socket  8 , and access the terminal strip  9  with new wiring. Because traffic is usually blocked in order to access traffic lights, time is of the essence. Second, in order to safely disconnect the socket connector wires from the terminal strip, and connect new wires from the LED lamp module  10  to the terminal strip, the power to the traffic signal must be temporarily turned off, which disrupts traffic flow through the intersection. Finally, once the retrofit is complete, it is not possible to put the original incandescent lamp back in the traffic signal lamp, for example in case a spare LED lamp is not available. 
   One solution is to insert an LED lamp that utilizes the reflector  4  and socket  8 , thus negating the need for their removal, as taught by U.S. Pat. No. 6,796,698. Here, a specially designed LED light source screws directly into the socket connector. The drawbacks to this solution are that the reflector can introduce light loss (especially when contaminated by dirt or deteriorated with age), reflectors can vary among manufacturers necessitating varying LED light source designs, and the LED light source design is complicated and expensive. 
   Another solution is to utilize a lamp module that mounts to the front door plate of the signal light housing, with a threaded electrical connector compatible with the socket connector, as taught in U.S. Pat. Nos. 6,268,801 and 6,905,227. This solution involves removing the conventional lens and light bulb source, mounting the lamp module to the front door plate, and connecting the threaded electrical connector to the socket connector, which avoids the use of the reflector (and any associated light loss therefrom) while also avoiding the removal of the reflector and socket electrical connector. However, it still requires lens removal and module mounting to the door. 
   An even simpler solution is the use of an LED lamp with a threaded electrical connector compatible with the socket connector, where the socket connector not only supplies the electrical power, but also provides the sole mechanical support for the LED lamp in the traffic signal housing, as taught in U.S. Pat. No. 6,911,915. Here, the conventional lamp is simply replaced with the LED lamp having the same electrical connection, and a Fresnel lens is mounted to the door that collimates the light so that it just fills and illuminates the outer lens of the traffic signal lamp. The use of the reflector (and any associated light loss) is avoided. Subsequent lamp changes simply involve swapping one LED lamp with another. However, even here there are possible complications. Alignment between the LED lamp and Fresnel lens is important because of the directionality of the light output of the LED lamp (and the avoidance of using the reflector). For traffic signal lamps where the socket connector does not adequately align the LED lamp with the Fresnel lens, light can be wasted (by missing the Fresnel lens), and even illumination of the outer lens may not achieved. Improper socket connector alignment can be a function of inadequate initial alignment or quality control, fatigue with age, extreme shaking (e.g. from wind), or even inadequate mechanical support of the socket connector for supporting the weight of the LED lamp (e.g. the LED lamp sags downwardly after installation and/or with time). 
   There is a need for a lamp design that reliably aligns and secures an LED lamp to the associated lens(es) while still providing easy removal and installation of the LED lamp. 
   SUMMARY OF THE INVENTION 
   The present invention solves the aforementioned problems by providing a securing bracket that positions and secures the LED lamp module to lens(es) and/or front door which it illuminates. 
   A lamp assembly includes a housing, an LED lamp module disposed in the housing and including a plurality of LEDs for producing light, a door assembly removably or movably attached to the housing and having an aperture for passing the light, and a securing bracket having a first end secured to the door assembly and a second end secured to the LED lamp module for maintaining an alignment between the door assembly and the LED lamp module. 
   A method of retro-fitting a traffic signal lamp with an LED lamp, where the traffic signal lamp has a housing, a door assembly attached to the housing, a lens attached to the door assembly, a reflector in the housing, a threaded electrical socket connector in the housing, and a threaded light source connected into the socket connector, includes: removing the threaded light source from the threaded socket connector, connecting a threaded LED lamp module into the threaded socket connector, wherein the LED lamp module includes a plurality of LEDs, and securing a first end of a securing bracket to the door assembly and securing a second end of the securing bracket to the LED lamp module for maintaining an alignment between the door assembly and the LED lamp module. 
   In addition, a method of retro-fitting a traffic signal lamp with an LED lamp, where the traffic signal lamp has a housing, a door assembly attached to the housing, a lens attached to the door assembly, an electrical connector in the housing, and a light source connected to the electrical connector, includes: disconnecting the light source from the electrical connector, connecting an LED lamp module to the electrical connector, wherein the LED lamp module includes a plurality of LEDs, securing a first end of a securing bracket to the door assembly and securing a second end of the securing bracket to the LED lamp module for maintaining an alignment between the door assembly and the LED lamp module. 
   Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a side cross-sectional view of a conventional traffic signal lamp. 
       FIG. 1B  is a back view of a front door from a conventional traffic signal lamp. 
       FIG. 2  is a side cross-sectional view of a conventional traffic signal lamp containing a conventional LED lamp module. 
       FIG. 3  is a side cross-sectional view of a traffic signal lamp assembly with a secured LED lamp module, with the front door open. 
       FIG. 4  is a side cross-sectional view of the traffic signal lamp assembly with the secured LED lamp module, with the front door closed. 
       FIG. 5A  is a back view of the LED lamp module secured by the securing bracket utilizing a solid conical shaped member. 
       FIG. 5B  is a back view of the LED lamp module secured by the securing bracket utilizing a plurality of support arms. 
       FIG. 6  is a side cross-sectional view of a first alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 7  is a back view of the first alternate embodiment of the LED lamp module secured by the securing bracket. 
       FIG. 8A  is a side cross-sectional view of a second alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 8B  is a side cross-sectional view of a third alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 8C  is a side cross-sectional view of a fourth alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 8D  is a side cross-sectional view of a fifth alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 8E  is a rear view of the fifth alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 8F  is a side cross-sectional view taken along the line A-A in  FIG. 8E , of the fifth alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 8G  is a side cross-sectional view of a sixth alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 9  is a side cross-sectional view of a seventh alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
       FIG. 10  is a side cross-sectional view of an eighth alternate embodiment of the traffic signal lamp assembly with the secured LED lamp module. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention is traffic signal lamp utilizing an LED lamp that is secured in place relative to the lens(es) that it illuminates. This improved design makes replacement of traffic signal lights quick and highly cost effective compared to the existing LED retrofit signal lamps presently available. 
     FIGS. 3-4  illustrate a first embodiment of the traffic signal lamp assembly  16 , which includes a front door assembly  18  and a housing  20 , which together include a front door  22  (with an aperture  22   a  through which light will pass), an LED lamp module  24 , a reflector  26 , a threaded socket connector  28 , wires  30  (for supplying power to socket connector  28 ), inner and outer lenses  32 / 34  (in the front door aperture  22   a ), and securing bracket  36 . The front door assembly  18  (which includes the front door  22 , lenses  32 / 34 , and securing bracket  36 ) removably or movably attaches to the housing  20  (via securing retainers, hinge(s), etc.—not shown), which allows easy access to the interior of the housing  20 . LED lamp module  24  includes a plurality of light emitting diodes (LEDs)  38  powered by an internal power supply  40  that receives power from a threaded electrical connector  42  (that screws into socket connector  28 ). The LEDs  38  can be exposed, or can be covered by a lens  44  as shown that can be clear, translucent, and/or have optical focusing power. Inner lens  32  can be a focusing lens such as a Fresnel lens, that directs the light from the LEDs  38  to illuminate outer lens  34  (which can be a colored lens with or without focusing power) in the desired manner. 
     FIG. 3  illustrates the traffic signal lamp assembly  16  with front door assembly  18  in its open configuration, in which the interior of the housing  20  can be accessed.  FIG. 4  illustrates the front door assembly  18  in its closed position (to secure and possibly seal the housing  20 ). In the closed position, the securing bracket  36  secures the LED lamp module  24  in proper position relative to the front door assembly  18 , assuring proper alignment thereto. More specifically, securing bracket  36  has a first end  36   a  which is secured to the front door assembly  18  via a retaining member, adhesive, etc. Securing bracket  36  has a second end  36   b  that engages with the LED lamp module  24  when the front door assembly  18  is closed over housing  20 , thus securing the LED lamp module  24  in proper position (vertically, horizontally, and in distance) relative to the front door assembly  18  (and more particularly to lenses  32 / 34 ). 
   In the illustrated embodiment, first and second ends  36   a  and  36   b  are shaped as annular rings, joined together by either a solid conical shaped member  45  (as shown in  FIG. 5A ) or by individual arms  46  (as shown in  FIG. 5B ). Ring shaped first end  36   a  is affixed to the circumference of the front door  22  and/or lenses  32  or  34 . Ring shaped second end  36   b  engages the circular side surface  24   a  of the LED lamp module  24 , and preferably, but not necessarily, an annular flange  48  extending from the LED lamp module side surface  24   a , as best illustrated in  FIGS. 3-4 . With this configuration, the interior of the housing  20  can be conveniently accessed when the front door  22  is open (allowing for the LED lamp module  24  to be conveniently installed or replaced), and the LED lamp module  24  is held in proper alignment to lenses  32 / 34  (vertically, horizontally, and in distance) when the front door  22  is closed (where displacement of the LED lamp module  24  caused by lamp weight, mounting fatigue, housing vibration, etc. is avoided). Rotational orientation of the LED lamp module  24  and/or lenses  32  or  34  may be required depending on the optical design and the required light output pattern. 
   Although two lenses  32 / 34  are shown, any number of lenses (with or without focusing power) can be utilized depending on the application. In fact, even no housing lens need be used. The traffic signal lamp assembly  16  can not only be a standard sized 12 inch or 8 inch traffic signal light, but it can also be used in pedestrian signs, arrow signs, commercial signs, non-standard sized traffic lights, etc. The LED lamp module  24  need not include power supply  40 , which can either be external or absent should the power from wires  30  be of the required voltage. Other quick disconnect electrical connectors can be used instead of threaded electrical connectors  28 / 42 . For example, such connectors could be push and twist type, with one or more pins of one connector engaging a shaped channel of the other connector. 
     FIGS. 6-7  illustrate another embodiment similar to that above, but without a fixed socket connector  28  (i.e. reflector  26  not present or previously removed). In this embodiment, the LED lamp module  24  is affixed to the securing bracket  36  (e.g. while the front door  22  is open) using one or more retainer members  50 . The socket connector  28 , at the free ends of wires  30 , is connected to threaded connector  42  either before or after the LED light module  24  is affixed to the securing bracket  36 . Here, the alignment of the LED lamp module  24  to the lenses  32 / 34  can be created, confirmed, and/or adjusted before the front door  22  is closed. An optional seal member  56  (e.g. gasket, rubber o-ring, etc.) can be engaged between the securing bracket  36  and LED lamp module  24  as shown to seal the cavity formed by these elements and lens  32 . This seal cavity keeps the lens  44  clean, and even allows lens  44  to be omitted to expose the LEDs  38 . 
     FIG. 8A  illustrates yet another embodiment, where the LED lamp module  24  has no lens over the LEDs  38 , and no threaded electrical connector. Instead, the wires  30  enter the LED lamp module housing, and the LEDs  36  are exposed. With this configuration, it may be preferable for the securing bracket  36  to form an air tight seal between inner lens  32  and LED lamp module  24  (i.e. either being formed integrally, sealed or bonded with glue or other adhesive, using seal members  56 , etc.), in order to protect the LEDs  38  and associated circuitry from moisture. The embodiment shown in  FIG. 8B  is essentially the same as that in  FIG. 8A , except the retaining member  50  consists simply of a screw or bolt securing the flange  48  to the securing bracket  36 . 
     FIG. 8C  illustrates yet another embodiment, where the power supply  40  is housed in a separate housing  40   a  that removably attaches to the main portion of LED lamp module  24  via retainer members  50  (and optionally seal member  56 ). Power supply  40  is connected to the LEDs  38  via a quick disconnect electrical connector  52 . With this embodiment, if the power supply  40  fails, just it can be easily accessed, removed and replaced, without having to remove and replace the rest of the LED module  24   
     FIGS. 8D-8F  illustrate yet another embodiment similar to that of  FIG. 8C , but where a locking mechanism  58  is used to secure the power supply housing  40   a  to the rest of the LED lamp module  24 . The locking mechanism includes tabs  60  extending from the power supply housing  40   a , and slot members  62  on the LED lamp module  24  main housing for receiving the tabs  60 . To secure the power supply housing  40   a , it is placed over the LED lamp module  24  main housing and then rotated until the tabs  60  enter into the slots formed by slot members  62 . An optional tab  60   a , having a hole  64 , can be included that is disposed over a hole  66  in the LED lamp module  24  main housing when the rotation is complete. A screw or bolt can then be used to prevent any undesired counter-rotation that would result in inadvertent disengagement. 
     FIG. 8G  illustrates another embodiment similar to that of  FIGS. 8D-8F , but with a second locking mechanism  58  to secure the LED lamp module  24  main housing to the securing bracket  36 . 
     FIG. 9  illustrates still another alternate embodiment, which differs from that of  FIG. 8G  by mounting the power supply  40  inside the housing  20  (e.g. on the securing bracket  36  as shown) instead of inside the LED lamp module  24  itself. In this manner, the power supply  40  or LED lamp module  24  can be individually replaced should only one of them fail. A quick disconnect electrical connector  52  can be utilized on the wires  54  between the power supply  40  and LED lamp module  24  to facilitate removal of just one of these elements. 
     FIG. 10  illustrates one additional alternate embodiment, which differs from that of  FIG. 6  in that LED lamp module  24  does not include the threaded electrical connector. Instead, the wires  30  enter the LED lamp module housing directly. 
   It is to be understood that the present invention is not limited to the embodiment(s) described above and illustrated herein, but encompasses any and all variations falling within the scope of the appended claims. One skilled in the art will appreciate that the methods described herein and/or claimed need not necessarily be performed in the order described/claimed.