Abstract:
An apparatus and method that improves the usable life and reliability of detachable stem lights for boats. It replaces electrical energy coupling by light energy coupling, thereby eliminating electrical contact corrosion problems.

Description:
[0001]    This application claims priority of provisional application 60/950,650 filed on 19 Jul. 2007. 
       REFERENCES SITED  
       [0002]      
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 US Patent Documents 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 4,389,085 
                 June 1983 
                 Mori 
               
               
                   
                 4,740,870 
                 April 1988 
                 Moore 
               
               
                   
                 5,161,874 
                 November 1992 
                 Benes 
               
               
                   
                 5,339,225 
                 August 1994 
                 Wiggerman 
               
               
                   
                 6,155,195 
                 December 2000 
                 Nirenberg 
               
               
                   
                 6,742.916 B1 
                 June 2004 
                 Dunn 
               
               
                   
                   
               
             
          
         
       
     
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to boat stern lights for anchor and navigational purposes. Specifically, to detachable (stowable) stem lights, which allow the light to be stored out of the way, an advantage for many daytime activities and boat storage. 
         [0005]    2. Background 
         [0006]    Detachable (sometimes called stowable) stem lights typically consist of a base which is mounted to the boat structure and a pole which mechanically couples to the base. The pole has a light emitting device (typically an incandescent bulb) at the distal end. Power to energize the bulb is coupled via electrical contacts at the base and the proximal end of the pole. 
         [0007]    Electrical contacts are composed primarily of copper and copper alloys. Although weather covers are typically provided to cover the base electrical contacts, water intrusion almost always occurs. Copper electrical contacts exposed to moisture leads to corrosion and eventual electrical failure of the contacts. The problem is particularly acute in marine environments. 
         [0008]    Several U.S. patents describe prior art systems which are related but differ from the invention. 
         [0009]    U.S. Pat. No. 4,389,085 to Mori describes a fiber optic system which collects and distributes sunlight. 
         [0010]    U.S. Pat. No. 4,740,870 to Moore discloses a central light source which is transmitted to different areas of a boat via fiber optic cabling. 
         [0011]    U.S. Pat. No. 5,161,874 to Benes describes a remote illumination system that utilizes a single light source and a light pipe to transmit the light to some remote locations from the source. 
         [0012]    U.S. Pat. No. 5,339,225 to Wiggerman is a boat stern light design that illuminates the length of the pole, as opposed to just having a light at the distal end. 
         [0013]    U.S. Pat. No. 6,155,195 to Nirenberg discloses a telescoping stern light that can be retracted out of the way when not in use. 
         [0014]    U.S. Pat. No. 6,742,916 B1 to Dunn describes a fiber optic cabling system for the sides of boats which is intended illuminate said side for safety or enjoyment purposes. 
       SUMMARY OF THE INVENTION 
       [0015]    Previous detachable stern light designs utilize electrical contacts between the base and detachable pole. The contacts connect the electrical power present in the base component to wires within the pole, which in turn transmit the electrical power to a distal end mounted light bulb. 
         [0016]    The invention eliminates the electrical contacts corrosion problem of previous designs by transmitting light instead of electrical current across the coupling of the base and pole. It further replaces the combined pole and light bulb assembly into a single light conduit (pole). 
         [0017]    In the broadest form, the invention consists of a boat, a base mounted to the boat, a external electrical power connection, a electrical power conditioning device, an optical source, a detachable optical conduit (pole) that mounts to the base, and a mechanism to redirect and emit the transmitted light out of the optical conduit. 
         [0018]    The boat is any vessel that is required to have or desires to have a detachable stern light. 
         [0019]    The base is essentially a boat mounted socket for the pole. The socket provides mechanical mounting and light (not electrical) coupling between the base and light conduit (pole). In various embodiments, the base may have the optical source incorporated into it or the optical source may be externally mounted to it. 
         [0020]    The optical source may be formed by a multitude of visible light emitting devices, in one embodiment being a high intensity LED or LEDs. 
         [0021]    The electrical power may be from any suitable source which can energize the optical source. In one embodiment, the source is the boat&#39;s electrical power system. 
         [0022]    The electrical power conditioning circuit can consists of any device capable of converting the incoming electrical power to a form required by the optical source. Examples of such devices range from a simple power resistor to switching power topology circuits. 
         [0023]    The optical conduit may also take a multitude of embodiments, one being an acrylic rod. A key characteristic of the optical conduit is the efficient conduction of light. The diameter and length of the optical conduit is determined by the application. The rod may or may not have an external opaque covering. 
         [0024]    The redirection mechanism for the light traveling within the light conduit may also take multiple forms. A fundamental characteristic of the mechanism is reflection of the conduit light to a direction which causes it to be emitted in essentially perpendicular (or nearly so) directions to the light conduit (pole). This emission may be in a 360 degree pattern or some lesser or subset(s) of 360 degrees around the boat. 
         [0025]    In the following section, one embodiment of the invention is explained in detail. The invention is not intended to be limited in its application to the details of construction and to the arrangements of the components described in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. 
         [0026]    Also, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
         [0027]    It is the intention of the invention to provide a new detachable marine anchor and navigational stern light system which overcomes the disadvantages of previous systems which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art boat light systems, either alone or in any combination. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The following drawings illustrate the best modes presently contemplated for carrying out the present invention (Preferred Embodiment): 
           [0029]      FIG. 1  Perspective component view of the invention and how they interface. 
           [0030]      FIG. 2  Cross Section View of Invention with detail 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0031]    Principle of Operation 
         [0032]    The basic principle is that a light conduit (pole) couples the light source contained in the base to an apparatus at the top of the light conduit that disperses the light so as to meet the requirements of boat stem lights determined by the USCG and/or other regulatory agencies. 
         [0033]    Refer to  FIGS. 1 and 2  for the following description. 
         [0034]    The Components: 
         [0035]    The preferred embodiment consists of two primary components: base  4  mounted to the boat structure  5  and an acrylic light conduit  2  (shown detached), which plugs into the base light conduit socket  3 . 
         [0036]    The base contains an encapsulated LED light source  12  and LED drive device  9  where said LED light is directed upward into the optical conduit socket  3 . The encapsulated LED is located at the bottom end of the light conduit socket  3  so as to minimize physical separation between the LED and the installed optical conduit. 
         [0037]    The optical conduit socket  3  diameter is such as to provide a slip fit to the optical conduit, thus providing secure attachment of the optical conduit, yet still allowing it to be easily removed. 
         [0038]    Electrical wires are provided on the lower side of the base to connect to the boat electrical power system or separate electrical power source. 
         [0039]    The base  4  may be constructed of any material suitable for the marine environment. Examples include aluminum, stainless steel and a variety of plastics and composites. This preferred embodiment utilizes aluminum. 
         [0040]    The optical conduit  2  is constructed from a clear acrylic rod. The diameter is not critical and is primarily determined by the proximal end surface area needed to couple the optical source light radiation pattern. Another diameter consideration is structural integrity, larger diameters being sturdier. This preferred embodiment uses a one inch diameter acrylic rod. 
         [0041]    The length of the optical conduit  2  is likewise not critical, and can be varied to meet the height requirements of the application. The primary limitation on length is light intensity loss, however that can be offset by higher optical source intensity as needed. The preferred embodiment uses a length of thirty six inches. The dimensions chosen for the preferred embodiment are not intended to be a limitation in any sense, since the length and diameter of the acrylic rod can be of nearly arbitrary length, as needed by the application. 
         [0042]    The acrylic optical conduit has a cone  1  machined into the distal end to form a light redirection surface. The maximum diameter of the cone is sized so as to nearly match the diameter of the acrylic rod, tapering down to a point at the center of the acrylic rod. The cone angle of the preferred embodiment is sixty degrees. 
         [0043]    Description of Operation 
         [0044]    Electrical Section 
         [0045]    The base  4 , on its lower side, provides wires or terminals  6  for connection to the boat electrical power system. Alternatively, a battery or other electrical power source separate from the boat electrical system may be used. The base  4  contains the LED light source  12  that is directed upward inside the base socket so as to project light into the mating optical conduit. The LED light source is a state-of-the-art high intensity white LED available from multiple semiconductor manufacturers. The invention anticipates continuing advancements in LED technology which will provide more light output for less power consumption, hence improving overall efficiency and enabling longer optical conduit lengths. 
         [0046]    The LED is driven by the LED drive device  9  which conditions the voltage presented via the electrical connection  6  to the drive requirements of the LED. The LED drive device can take the form of a simple voltage dropping power resistor or a switching power supply design for lower power dissipation and more accurate LED current control. Multiple semiconductor manufactures provide LED driver circuits which are switching power supply topology based designs. For most application the switching power supply design is preferred due to its low power dissipation and more accurate LED current control. The voltage dropping resistor is suitable to applications were the input voltage will not result in excessive power dissipation. 
         [0047]    The LED light source  12  and the LED drive device  9  are epoxy encapsulated within the base to prevent water damage. 
         [0048]    Optical Section 
         [0049]    The light emerging from the LED light source  12  is optically coupled into the removable light conduit installed into the base socket. The light conduit  2  in this preferred embodiment is constructed from an acrylic rod which has excellent light transmission properties. The light inside the conduit experiences nearly total internal reflection, maximizing optical power transmission. 
         [0050]    An optional opaque outer covering  11  further increases the internal reflection and blocks light from emerging along the periphery of the light conduit. 
         [0051]    The distal end of the rod has a cone machined into it forming a reflective surface  7 , due to the optical discontinuity. The light traveling within the light conduit  8  is reflected by the cone&#39;s reflective surface  7  and is emitted  10  at angles largely perpendicular to the light conduit. Since light impinges essentially the entire reflective surface  7  of the cone, the light is emitted in a three hundred sixty degree pattern around the light conduit. 
         [0052]    The emitted light pattern can be reduced or segmented via opaque coverings over the sections where light is not desired to be emitted.