Patent Publication Number: US-2006013000-A1

Title: Flat mount for light emitting diode source

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims priority from Provisional Patent Application No. 60/588,627, filed Jul. 16, 2004. 
    
    
     TECHNICAL FIELD  
      This invention relates to electric lamps and particularly to electric lamps utilizing a single light emitting diode (hereafter LED or LEDs) light source. More particularly the invention is concerned with an electric lamp with an LED light source for providing a lamp assembly having a low profile.  
     BACKGROUND ART  
      In the past, most automotive light sources have involved the use of incandescent bulbs. While working well and being inexpensive, these bulbs have a relatively short life and, of course, the thin filament employed was always subject to breakage due to vibration.  
      Recently some of the automotive uses, particularly the stoplight, have been replaced by LEDs. These solid-state light sources have incredible life times, in the area of 100,000 hours, and are not as subject to vibration failures. However, these LED sources have been hard-wired into their appropriate location, which increases the cost of installation. Additionally, the light sources have employed multiple LEDs, which increased the cost. It would therefore be an advance in the art if an LED light source could be provided that had the ease of installation of the incandescent light sources. Additionally, it would be advantageous to have a light source that could be permanently mounted without the need for any specific orientation. Still further, it would even more advantageous to have a lamp assembly utilizing a single LED, with said lamp assembly having a low profile.  
     BRIEF SUMMARY OF THE INVENTION  
      It is, therefore, an object of the invention to obviate the disadvantages of the prior art. It is another object of the invention to enhance to provide a lamp assembly that is convenient and useful. Still another object of the invention is the provision of lamp assembly using a single LED and having a low profile. These objects are accomplished, in one aspect of the invention, by a lamp assembly comprising: an LED light source; a planar substrate having a first side and a second side, the LED being mounted in a center region of the first side, leaving an edge region of the first side extending circumferentially around the LED, the substrate having portions of high thermal conductivity in thermal contact with the LED; a reflector having a reflective surface defining a concave cavity open in a direction toward a field to be illuminated, the reflector being formed with a through passage extending to the cavity; the LED being extended through the passage to face the reflective surface, the edge region circumferentially sealed to the reflector, the substrate otherwise being mechanically coupled to the reflector; and electrical connections extending through the substrate connecting to the LED to supply electrical power to the LED. The use of the single LED centrally mounted upon a planar substrate with the substrate itself being mechanically coupled to the reflector allows for the provision of a lamp assembly having a low profile. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a diagrammatic view of an embodiment of the invention;  
       FIG. 2  is diagrammatic view of an alternate embodiment;  
       FIG. 3  is a diagrammatic view of yet another embodiment; and  
       FIG. 4  is a diagrammatic view of the size relationships of the elements of the lamp assembly  
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims taken in conjunction with the above-described drawings.  
      Referring now to the drawings with greater particularity, there is shown in  FIG. 1 a  lamp assembly  10  that comprises a side-emitting LED light source  12 , mounted upon a planar substrate  14  that has a first side  16  and a second side  18 . The LED light source  12  is mounted in a center region  20  of the first side  16 , leaving an edge region  22  of the first side  16  extending circumferentially around the LED light source  12 . The substrate  14  has at least a portion  24  of high thermal conductivity in thermal contact with the LED light source  12 .  
      A reflector  26  has a reflective surface  28  defining a concave cavity  29  with an opening  30  in a direction toward a field to be illuminated and has a through passage  32  extending into the cavity  29 . While not shown in the drawing, it will be apparent to those skilled in the art that any type of suitable covering, such as a lens, can be used to seal the opening  30 .  
      The LED light source  12  extends through the passage  32  and has a light emitting surfaces  34  facing the reflective surface  28 . The edge region  22  is circumferentially sealed to the reflector  26  in any of numerous ways, as will be detailed hereafter, and electrical connections  36  extend through the planar substrate  14  and connect the LED light source  12  to a supply of electrical power  38 , which can be the battery or power source of a motor vehicle.  
      As mentioned above, the planar substrate  14  can be glued to the reflector  26  at the edge region  22  of the substrate. Alternatively, as shown in  FIG. 2 , the planar substrate  14  can be provided with a screw thread, as is known, and screwed into the reflector  26 .  
      Another convenient structure can be a press-fit to a circumferential lip  40  formed on the reflector cooperating with a groove  41  formed on a boss  43  on the planar substrate  14  as shown in  FIG. 3 .  
      Preferably, the planar substrate  14  further supports a circuit  42  that provides controlled power to the LED source  12 . In a preferred embodiment a cover  44  encloses the circuitry.  
      At least a portion  46  of the second side  18  of the planar substrate is exposed to the exterior of the lamp assembly  10  for heat dissipation from the planar substrate  14  and, if necessary because of the power requirements of the LED, additional heat sinking can be provided in that area.  
      To utilize the capabilities of the single LED, the reflector  26 , as shown in  FIG. 4 , is shallow, having an internal face diameter D at least two times as large as the axial depth D 1  from the front opening  30  to an interior passage plane  48 .  
      Thus there is provided a lamp assembly that avoids the problems of the prior art. It is convenient to use and uses little depth, a decided advantage in automotive applications where space is always at a premium.  
      While there have been shown and described what are present considered to be the preferred embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the invention as defined by the appended claims.