Abstract:
An exterior lighting device based on a light emitting diode in conjunction with an optic fiber is disclosed. The device has a cylindrical housing having a closed end and an open end. The light emitting diode is placed on the interior of the on the closed end of the cylindrical housing. A clear lens having one end in proximity with the light emitting diode and an opposite end with a flat surface is provided. A top cap is installed over the open end of the cylindrical housing. The top cap forms a water tight seal with the cylindrical housing using O-rings. A retaining plate is held in place between the top cap and the cylindrical housing. The retaining plate is locked with the flat surface of the lens thus holding the lens in place over the light emitting diode. An optic fiber has a receiving end held by the retaining plate in proximity to the light emitting diode and an opposite emitting end extending from a socket in the top cap. A coupling assembly sits in the socket in the top cap and holds the optic fiber in relation to the top cap.

Description:
FIELD OF INVENTION  
       [0001]     The present invention relates generally to the field of light emitting diode driven optic fiber lighting devices. More specifically, the present invention is directed to a water resistant optic fiber light emitting diode device which may be used in outdoor lighting applications.  
       BACKGROUND OF INVENTION  
       [0002]     Light emitting diodes (LEDs) are well known solid state light sources. LEDs have many advantages over traditional lighting sources such as incandescent bulbs as they are cheaper to produce, more robust, and require less power. LEDs are especially desirable as they emit light with high power efficiency over specific colors in the spectrum. However, LEDs are not a focused light source and suffer from relatively low light output. The lack of focused light and low light output prevents application of LEDs to uses where high light intensity is desired. Further LEDs cannot be fabricated in different shapes for decorative purposes. Finally, the light output of LEDs cannot be intensified without an optical device to focus the light.  
         [0003]     There are many commercial applications requiring high light output. For example, there is a great demand for outdoor and indoor decorative or architectural lighting. Neon lighting is presently used for such applications. Neon or fluorescent lighting uses a glass tube which is filled with neon gas which is then electrified. Such devices may be used for lighting but also for advertising and signs as the tubes may be fabricated into different shapes. Such tubes may have different colors or generate simple white light. The light intensity of a neon tube depends on the color generated.  
         [0004]     However neon lighting suffers from a number of problems. Neon lights require a relatively large amount of electricity resulting in greater costs for applications requiring long term use such as outdoor signs. Also, neon lights require periodic replacement and maintenance because such lights experience a significant drop off in output after continual use. Further, the maximum length of a neon tube is around seven feet which necessitates more units for large scale uses. All of these factors may create cost issues. Neon lights require a high voltage transformer which may create safety issues. Finally, neon lights must be installed with care in outdoor situations as the electrical components require considerable shielding in order to remain resistant to water.  
         [0005]     Thus, there is a need for a light emitting diode based optic fiber lighting source which has high reliability. There is a further need for an LED based lighting system which may be used for outdoor applications and is therefore durable and water resistant. There is also a need for a LED based lighting system which may be used for applications requiring water tight housings such as underwater lighting. There is also a need for a LED based lighting system which may be used for commercial applications for attractive and signage based lighting.  
       SUMMARY OF THE INVENTION  
       [0006]     These needs and others may be met by the present invention, one example of which is a commercial lighting device having a housing having a closed end and an open end. A top cap installable over the open end of the housing is provided. A light emitting diode is contained in the closed end of the housing. An optic fiber coupler having an aperture is fixed to the top cap. An optic fiber is held by the aperture of the coupler and has a light receiving end in proximity to the light emitting diode.  
         [0007]     A second example is an exterior lighting device having a cylindrical housing having a closed end and an open end. A light emitting diode is placed on the interior of the on the closed end of the cylindrical housing. A lens having one end in proximity with the light emitting diode and an opposite end with a flat surface is provided. A top cap is installed over the open end of the cylindrical housing, the top cap forming a water tight seal with the cylindrical housing, the top cap having a socket. A retaining plate is held in place between the top cap and the cylindrical housing. The retaining plate is locked with the flat surface of the lens. An optic fiber having a receiving end held by the retaining plate is located in proximity to the light emitting diode and an opposite emitting end extending from the top cap. A coupling assembly which sits in the socket in the top cap holds the optic fiber in relation to the top cap.  
         [0008]     It is to be understood that both the foregoing general description and the following detailed description are not limiting but are intended to provide further explanation of the invention claimed. The accompanying drawings, which are incorporated in and constitute part of this specification, are included to illustrate and provide a further understanding of the method and system of the invention. Together with the description, the drawings serve to explain the principles of the invention. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]     These and further aspects and advantages of the invention will be discussed more in detail hereinafter with reference to the disclosure of preferred embodiments, and in particular with reference to the appended Figures wherein:  
         [0010]      FIG. 1  is a perspective view of a light emitting diode optic fiber based lighting device for external applications according to one example of the present invention;  
         [0011]      FIG. 2  is an exploded perspective view of the components of the lighting device in  FIG. 1 ;  
         [0012]      FIG. 3  is a cutaway view of the lighting device in  FIG. 1 ;  
         [0013]      FIG. 4  is a perspective view of an alternative light emitting diode based lighting device for external applications according to another example of the present invention;  
         [0014]      FIG. 5  is an exploded perspective view of the components of the lighting device in  FIG. 4 ;  
         [0015]      FIG. 6  is a cutaway view of the lighting device in  FIG. 4 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     While the present invention is capable of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiment illustrated.  
         [0017]      FIGS. 1-3  show a lighting device  10  which is one example of the present invention. The lighting device  10  is a high output lighting device which is designed for decorative outdoor lighting applications such as signs or architectural highlights. Of course the lighting device  10  may be used for other lighting applications.  
         [0018]     The lighting device  10  has a housing  12 , an optic fiber bracket assembly  14  and an optic fiber  16 . The housing  12  encloses a lighting assembly  18  which is holds a light emitting diode (LED) as will be explained below. The housing  12  has a closed end with a back plate  20 , a circular side wall  22 , and an open end with a shoulder  24 . A top cap  26  fits over the shoulder  24  to enclose the housing  12 . The top cap  26  has a mounting socket  28  which holds the optic fiber bracket assembly  14 . The housing  12  is preferably cylindrically shaped and constructed from a durable material preferably metal or thermally conductive high strength plastic in order to be weather or water resistant or in the case of this example water tight. Of course other shapes may be used for the housing depending on the application required.  
         [0019]     The top cap  26  has a front surface  30 , a circular side wall  32  and a shoulder surface  34 . The shoulder  24  of the housing  12  is in contact with the shoulder surface  34  of the top cap  26 . The shoulder surface  34  of the top cap  26  is wider than the shoulder surface  24  of the housing  12 . The shoulder  24  has a series of threaded mounting holes  36 . The front surface  30  has a series of threaded mounting holes  38  which correspond to the threaded mounting holes  36  on the shoulder  24 . A series of bolts  40  are screwed into the threaded mounting holes  36  and  38  in order to join the top cap  26  with the shoulder  24 .  
         [0020]     An inner notch  42  is formed on the shoulder  24  of the housing  12 . A retaining plate  44  is inserted on the inner notch  42  and held in place by the shoulder surface  34  of the top cap  26 . The retaining plate  44  has a top surface  46  which has a circular groove  48  and a bottom surface  50 . An O-ring  52  is placed in the circular groove  48  to create a seal between the top surface  46  of the retaining plate  44  and the shoulder surface  34  of the top cap  26 . The bottom surface  50  of the retaining plate  44  is placed on an O-ring  54  to create another seal between the bottom surface  50  and the notch  42 . The housing  12  is thus water proof allowing the device  10  to be used for underwater applications such as pool lighting. It is to be understood for many outdoor applications, the housing  12  need only be water resistant in which case the O-rings  52  and  54  and sealing arrangements may not be needed. The top surface  46  has a socket  56  which holds one end of the optic fiber  16 . The top surface  46  has a circular window  58  which allows light transmission to the optic fiber  16 . Alternatively, the entire retaining plate  44  may be fabricated from clear plastic.  
         [0021]     The lighting assembly  18  includes an LED  60  which is any semi-conductor, solid state light source such as a flat LED. The LED  60  will preferably have a lambertian distribution for the widest angle distribution of light. The LED  60  is mounted on a substrate plate  62  which may be coupled to a power source via two electrical pins  64  and  66 . In addition to the LED  60 , the housing  12  may contain a power supply for powering the LED  60 . Such a power supply is enclosed in housing  12  and sealed with a water tight fitting. This power supply could be of various types with the final stage being a constant current stage for driving the LED  60 . The stages before the constant current supply could include an AC/DC converter or a DC/DC converter. Such power supplies are connected to an external low voltage transformer which can be located remotely to convert 120VAC to low voltage to reduce installation cost. Of course the entire power supply may be located external to the housing  12  if desired.  
         [0022]     The substrate plate  62  has a series of edge notches  68 . A series of pins  70  extend from the back plate  20  of the housing  12 . The pins  70  lock in the notches  68  and hold the LED  60  and the substrate  62  in place. Heat from the LED  60  may be thermally dissipated through the substrate  62  to the housing  12 .  
         [0023]     A reflector  72  is installed over the LED  60  to focus the light emitted from the LED  60 . The reflector  72  is fabricated from a clear material such as PMMA/plexiglass, glass or plastic. The reflector  72  has a front flat circular surface  74  which is mounted on a conical body  76 . The reflector  72  has a rear end  78  which creates a socket fitting over the LED  60 . Other types of materials and shapes such as a metallic cone may be used for the reflector  72 . The conical body  76  is shaped to reflect light rays from the LED  60  out through the front surface  74 . A reflective surface  80  on the border of the conical body  76  reflects incident light from the LED  60 , through the front surface  74  to the fiber optic  16 . The basic shape of the conical body  76  is an ellipse according to the equation of x 2 /A+y 2 /B=1. The ellipse shape has two foci which enables light collection. The reflector  76  may also be a compound elliptical concentrator that also has two foci.  
         [0024]     Three arms  82 ,  84  and  86  extend from the front surface  74  for fitting the reflector  72  in relation to the top cap  26  and the retaining plate  44 . The bottom surface  50  of the retaining plate  44  has a collar  88  which forms three slots  90 ,  92  and  94 . The arms  82 ,  84  and  86  are inserted in the slots  90 ,  92  and  94  in order to hold the reflector  72  in place in relation to the retaining plate  44 .  
         [0025]     The mounting bracket assembly  14  has a guiding sleeve  100  which is placed around the optic fiber  16  and through the mounting socket  28  of the top cap  26 . The guiding sleeve  100  is preferably a flexible material such as plastic and has a first open end  102  and a second open end  104  which is inserted around the socket  56  on the retaining plate  44 . The exterior of the guiding sleeve  100  is threaded to allow the placement of the other components of the mounting bracket assembly  14 . An inner collar  106  is rotated on the sleeve  100  to be positioned under the top cap  26 . The top cap  26  is then placed in position to rest on the inner collar  106  and the shoulder  24  of the housing  12 . An outer collar  108  is then rotated in place on the sleeve  100  to rest on the front surface  30  of the top cap  26 . The inner and outer collars  106  and  108  thus hold the sleeve  100  in place relative to the top cap  26 . A locking screw  110  is then threaded over the open end  102  of the sleeve  100  to lock the fiber optic  16  in place. The locking screw  110  has a slight taper at one end. When the locking screw  110  is screwed on the guide sleeve  100 , the guiding sleeve  100  flexes and compresses the open end  102  to create a water tight seal along the interface with the optic fiber  16 .  
         [0026]     The optic fiber  16  is shown in  FIGS. 1-3  as a linear rod shape. However, the optic fiber  16  may be formed or twisted in any variety of non-linear shapes. For example, the optic fiber  16  may be bent into the shape of a letter for a commercial application. In this example, the optic fiber  16  is manufactured by 3M, although other optic fibers which allow for side or end light effects may be used. The optic fiber  16  is preferably plastic to be flexible and resistant to fatigue, elongation and vibration. The optic fiber  16  has a core material which is preferably polymethacrylate and a cladding material which has a lower refractive index than the core material. When light enters the optic fiber  16 , it is transported down the length of the fiber by total internal reflection between the core and cladding layers.  
         [0027]     The optic fiber  16  has a body  120  and a light receiving end  122  which is in proximity to the LED  60  and receives the light from the LED  60 . The optic fiber  16  also has an emitting end  124 . The optic fiber  16  allows end light emission from the emitting end  124  or preferably a side light effect from the perimeter of the body  120 . In this case, the cladding material of the optic fiber  16  is translucent.  
         [0028]     Light from the LED  60  is focused on the receiving end  122  of the optic fiber  16  via position of the LED  60  and any incident light is directed by the reflector  72  through the window  58  to the receiving end  122 . When the light from the LED  60  is focused on receiving end  122 , it is scattered at the core/cladding interface and leaves the body  120  along the perimeter of the optic fiber  16 . The light emission appears visually uniform along the length of the optic fiber  16 . Since the light is directed by the optic fiber  16 , any shape may be formed by the body  120  and corresponding light will be emitted throughout the body  120 . The optic fiber  16  in this example is a core rod, however, a bundle of smaller diameter fibers may be bundled and used in place of the optic fiber  16 . In addition, the color of the LED  60  may be changed or the cladding of the optic fiber  16  may have different colors for further decorative effect.  
         [0029]      FIGS. 4-6  show a second lighting device  200  which is another example of the present invention. The lighting device  200  is a high output lighting device which is designed for decorative indoor or outdoor lighting applications. As will be explained below the lighting device  200  is water tight using interlocking components, making device  200  easier to assemble than the bolts  40  needed for the lighting device  100  described in  FIGS. 1-3 .  
         [0030]     The lighting device  200  has a housing  202 , a top cap  204 , an optic fiber bracket assembly  206  and an optic fiber  208 . The housing  202  has a closed end which encloses a base substrate  210  which holds a light emitting diode (LED)  212 . The housing  202  has an outer surface  214  and an open end  216 . The outer surface  214  has a threaded area  218  which is near the open end  216 . The cap  204  has a mounting socket  220  which holds the optic fiber bracket assembly  206 . The housing  202  is constructed from a durable material preferably metal or thermally conductive high strength plastic in order to be weather or water resistant or in the case of this example water tight.  
         [0031]     The top cap  204  has a front surface  222  and an interior threaded surface  224  which allows the top cap  204  to be screwed on the housing  202 . An inner notch  226  is formed on the interior of the open end  216  of the housing  202 . A retaining plate  228  is inserted on the inner notch  226  and held in place by the top cap  204 . The retaining plate  228  has a top surface  230  which has a circular groove  232  and a bottom surface  234 . An O-ring  236  is placed in the circular groove  232  to create a seal between the top surface  230  of the retaining plate  228  and the top cap  204 . The bottom surface  234  of the retaining plate  228  is placed on an O-ring  238  to create another seal between the bottom surface  234  and the notch  226 . The housing  202  is thus water proof allowing the lighting device  200  to be used for underwater applications such as pool lighting. For other applications, the housing  202  and cap  204  may be simply water resistant without the O-ring arrangements described above.  
         [0032]     The top surface  230  has a socket  240  which holds one end of the optic fiber  208 . The top surface  230  has a circular window  242  which allows light transmission to the optic fiber  208 . A reflector  244  is installed over the LED  212  to focus the light emitted from the LED  212 . The reflector  244  is fabricated from a clear material and has a front flat circular surface  246  which is mounted on a conical body  248 . The reflector  244  has a rear end  250  which creates a socket fitting over the LED  210 . The conical body  248  is shaped to reflect light rays from the LED  212  out through the front surface  246 .  
         [0033]     A series of arms extend from the front surface  246  for fixing the reflector  244  in relation to the top cap  204  and the retaining plate  228 . The bottom surface  234  of the retaining plate  228  has a collar  252  which forms slots which interlock with the arms of the front surface  246 .  
         [0034]     The mounting bracket assembly  206  has a guiding sleeve  260  which is placed around the fiber optic  208  and through the mounting socket  220  of the top cap  204 . The guiding sleeve  260  has one end which is inserted around the socket  240  on the retaining plate  228 . The exterior of the guiding sleeve  260  is threaded allowing an inner collar  262  to be rotated into place on the guiding sleeve  260  on the interior of the top cap  204 . An outer collar  264  is rotated in place on the guiding sleeve  260  to rest flush on the front surface  222  of the top cap  204 . The inner and outer collars  262  and  264  thus hold the guiding sleeve  260  in place relative to the top cap  204 . A locking screw  266  is threaded over the open end of the sleeve  260  to lock the fiber optic  208  in place.  
         [0035]     The optic fiber  208  is similar to the optic fiber  16  shown in  FIGS. 1-3 . The optic fiber  208  receives the light from the LED  212  and allows light emission from the perimeter of the optic fiber  208 . Light from the LED  212  is focused on the optic fiber  208  via the position of the LED  212 . Incident light is directed by the reflector  244  through the window  242  to optic fiber  208 .  
         [0036]     It will be apparent to those skilled in the art that various modifications and variations can be made in the method and system of the present invention without departing from the spirit or scope of the invention. Thus, the present invention is not limited by the foregoing descriptions but is intended to cover all modifications and variations that come within the scope of the spirit of the invention and the claims that follow.