Abstract:
Waterproof miniature LED device including a cylinder having a first housing part with an internal thread and a second housing part with an external thread and rotatably coupled to the first housing part via engagement of the threads, an LED light assembly mounted to the cylinder and a dome connected to the cylinder and covering the LED light assembly. The cylinder defines a chamber for receiving batteries. Each housing part is conductive to enable formation of an electrical circuit including the batteries, LED light assembly and conductive portions of the housing parts. Illumination provided by the LED light assembly is controlled by rotating the housing parts relative to one another causing formation or interruption of the electrical circuit. An elastic ring covers a space between the housing parts alongside the threads to prevent water from entering between the threads into the interior of the cylinder and interrupting the electrical circuit.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to a miniature light-emitting diode (LED) device and more specifically to a miniature LED-light emitting device which is waterproof and therefore can be used in environments in which it will be exposed to water. 
   BACKGROUND OF THE INVENTION 
   A typical miniature LED device includes a metal cylinder in which an LED and batteries for providing power thereto are received. The cylinder includes opposite axial parts whereby one axial part has a tubular part with an internal thread while the other axial part has a smaller diameter tubular part with an external thread engageable with the internal thread, with the cooperating threads allowing relative rotation between the axial parts. Illumination of the LED is controlled by rotating one axial part of the metal cylinder relative to the other axial part which regulates the formation or interruption of a circuit between the LED and the batteries. 
   To enable the relative rotation of one axial part of the metal cylinder relative to the other, a space must be maintained between opposed edges of the axial parts. This space is defined between edges of the axial parts which are substantially perpendicular to and alongside the threads. As the axial parts are rotated relative to one another, the dimensions of this space vary. 
   A particular problem with such miniature LED devices is that when the LED devices are exposed to water, the water can enter into the space between the opposed edges of the axial parts. From this space, the water can seep between the threads into the interior of the LED device and interrupt the circuit between the LED and the batteries, i.e., cause a short-circuit. Once this happens, the LED device is rendered useless. In view of this problem, such miniature LED devices are often not used in environments in which water is likely to be present. 
   Another problem with such miniature LED devices is that one of the axial parts might be inadvertently rotated relative to the other thereby turning the LED on or off when set in either position, i.e., the inadvertent rotation might turn the LED off when the device is set in the on position or turn the LED on when the device is set in the off position. 
   It would therefore be desirable to have an LED device which is waterproof and can be used in all environments including those in which it will be exposed to water, and also an LED device which can be maintained in its set position without allowing inadvertent rotation of the axial parts relative to one another. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a new and improved miniature LED device which is waterproof. 
   It is another object of the present invention to provide a new and improved miniature LED device which allows for two axial parts to be rotatable relative to one another to enable control of illumination of the LED via such rotation while preventing entry of water into a space between the axial parts necessary to allow such rotation. 
   It is yet another object of the present invention to provide a new and improved miniature LED device which can be maintained in its set position without allowing inadvertent rotation of the axial parts relative to one another to cause the set position to change. 
   In order to achieve these objects and others, a miniature light-emitting diode (LED) device in accordance with the invention includes a cylinder including a first housing part having an internal thread and a second housing part having an external thread and rotatably coupled to the first housing part via engagement of the threads, an LED light assembly arranged in connection with the cylinder and a dome connected to the cylinder in a position covering the LED light assembly. The cylinder defines a chamber in which one or more batteries are received. At least a portion of each housing part is conductive to enable formation of an electrical circuit including the battery or batteries, the LED light assembly and the conductive portions of the housing parts. Illumination provided by the LED light assembly is controlled by rotating the housing parts relative to one another causing formation or interruption of the electrical circuit. 
   The device also includes an elastic ring or similar structure which covers a space between the housing parts and alongside the threads to prevent water from entering between the threads into the interior of the cylinder and interrupting the electrical circuit. The device is thereby rendered waterproof and can be used in environments where water is present. 
   Furthermore, in view of a friction fit of the elastic ring to both housing parts, it prevents inadvertent movement of the housing parts relative to one another to thereby prevent inadvertent changing of the on or off status of the device. The device&#39;s status can therefore be reliably maintained. 
   In one embodiment, the dome is faceted to provide better light distribution and a distinctive illumination when the LED light assembly is operative. A faceted dome can be used independent of the elastic ring or other structure which prevents water from entering between the threads, i.e., the invention contemplates an embodiment wherein the device includes a faceted dome but does not include the elastic ring. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals identify like elements, and wherein: 
       FIG. 1  is a perspective view showing a miniature LED device in accordance with the invention. 
       FIG. 2  is a front elevational view of the miniature LED device in accordance with the invention. 
       FIG. 3  is an end view of a faceted dome of the miniature LED device in accordance with the invention. 
       FIG. 4  is a cross-sectional side view taken along the line  4 - 4  of  FIG. 2 . 
       FIG. 5  is an exploded perspective view of the miniature LED device in accordance with the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the accompanying drawings wherein like reference numerals refer to the same or similar elements, a miniature LED device  10  in accordance with the invention includes a cylinder  12  having a bottom housing part  14  and a top housing  16 , a faceted dome  18  coupled to the top housing part  16 , an elastic ring  20  arranged around the cylinder  12 , batteries  22  housed in a chamber defined in the cylinder  12  and an LED light assembly  24  arranged in connection with the cylinder  12 . In the convention used herein, the bottom of the device  10  is considered the leftmost part of the device  10  as shown in the drawings whereas the top of the device  10  is considered the rightmost part of the device  10  as shown in the drawings. 
   Both bottom and top housing parts  14 ,  16  are made at least partially of an electrically conductive material such as metal to enable completion of an electric circuit including the batteries  22  and the LED light assembly  24 . Additional details of the formation of this circuit are described below. 
   Bottom housing part  14  includes a circular base  26 , a tubular part  28  extending upward from the periphery of the base  26 , an internal thread  30  formed on an inner surface of the tubular part  28 , a contact button  32  arranged on the base  26  inside of the tubular part  28  and a through ring  34  extending downward from the base  26 . Through ring  34  enables the device  10  to connect to holding means such as a hook, string or wire for hanging the device  10 . 
   Top housing part  16  includes a first tubular part  36 , a second, smaller diameter tubular part  38  extending downward from the first tubular part  36 , an external thread  40  formed on the second tubular part  38  and a cylindrical recess  42  at an upper region. The faceted dome  18  is secured to the first tubular part  36  and extends partially into the cylindrical recess  42 . Top housing part  16  also includes an inner flange  44 . 
   As shown in  FIG. 4 , there is an annular space  46  between a bottom-facing surface  48  of the top housing part  16  at the edge of the first tubular part  36  and a top-facing surface  50  of the tubular part  28  of the bottom housing part  14 . Space  46  is alongside the threads  30 ,  40  and its size varies upon rotation of the bottom and top housing parts  14 ,  16  relative to one another. The bottom-facing surface  48  is part of an annular step between the first and second tubular parts  36 ,  38  which is formed in view of the different diameters of the first and second tubular parts  36 ,  38 . The presence of this space  46  enables relative rotation of the bottom and top housing parts  14 ,  16  to control power supply to the LED light assembly  24 , explained in detail below. 
   To prevent water from entering into the interior of the LED device  10  through space  46  and between the cooperating threads  30 ,  40 , elastic ring  20  is slid onto the cylinder  12  to a position in which it covers or surrounds the space  46  and extends a small distance below the space  46  and a small distance above the space  46  (see  FIG. 4 ). Elastic ring  20  has a substantially tubular form and maybe made of rubber. 
   The diameter of the elastic ring  20  is selected to provide a friction fit against the outer surfaces of the bottom and top housing parts  14 ,  16  and thereby form a water-tight seal which prevents water from entering into the space  46 . However, the diameter of the elastic ring  20  is also dimensioned so that it is not overly tight against the bottom and top housing parts  14 ,  16  because it is necessary to maintain the ability to rotate the bottom and top housing parts  14 ,  16  relative to one another. Nevertheless, if the elastic ring  20  is designed to provide a very tight seal which hinders rotation of the bottom and top housing parts  14 ,  16  relative to one another, the elastic ring  20  could be slid up or down to a position entirely on one of the housing parts  14 ,  16  so that the housing parts  14 ,  16  can then be rotated relative to one another. 
   Another advantage obtained by the presence of elastic ring  20  in contact with both bottom and top housing parts  14 ,  16  is that inadvertent rotation of the housing parts  14 ,  16  relative to one another is prevented in view of the friction fit between the elastic ring  20  and the bottom and top housings parts  14 ,  16 . As such, the LED device  10  can be reliably maintained in an on or off position without concern that inadvertent rotation will change this status. 
   To ensure a water-tight environment in the cylinder  12 , the tubular part  28  of the bottom housing part  14  and the first tubular part  36  of the top housing part  16  do not include any uncovered openings on their outer surfaces. For example, there is no uncovered opening in either tubular part for an activation strip which is often provided in prior art miniature LED devices to separate the batteries from an electrical contact in order to prolong battery life by initiating operation only after the activation strip is removed. The presence of an uncovered opening for an activation strip would allow water to enter into the interior of the cylinder. If it is desired to provide such an activation strip in the LED device in accordance with the invention and an opening therefor is required, the opening for the activation strip can be formed in close proximity to the space  46  between the bottom and top housings parts  14 ,  16  so that the opening is covered by the elastic ring  20 . 
   Additional protection against water seeping into the interior of the cylinder  12  is provided by securing the faceted dome  18  to the first tubular part  36  of the top housing part  16  in a water-tight matter. As such, water cannot seep into the interior of the cylinder  12  between the top housing part  16  and the faceted dome  18 . 
   LED light assembly  24  includes a substantially planar printed circuit board  52  having a first electrical contact  54  on a lower surface which engages with the positive terminal of the uppermost one of the batteries  22  and a second electrical contact  56  on an upper surface which engages with the flange  44  of the top housing part  16 . A light-emitting diode (LED)  58  is mounted to the upper surface of the printed circuit board  52  via a pair of electrical contacts  60  (see  FIG. 5 ). When arranged in the top housing part  16 , the printed circuit board  52  of the LED light assembly  24  is below the flange  44 , the LED  58  is above the flange  44  and the contacts  60  extend through an opening defined by the flange  44  (see  FIG. 4 ). 
   When the bottom and top housing parts  14 ,  16  are engaged with one another via the cooperating threads  30 ,  40 , they can be rotated in one direction relative to one another to cause the contact button  32  to contact the negative terminal of the lowermost one of the batteries  22  and urge the positive terminal of the uppermost one of the batteries  22  against the first electrical contact  54 . At the same time, the second electrical contact  56  is urged against the flange  44 . In this state, shown in  FIG. 4 , an electrical circuit is completed from the negative terminal of the lowermost one of the batteries  22 , through the contact button  32  on the bottom housing part  14 , through the bottom and top housing parts  14 ,  16  to the second electrical contact  56  of the printed circuit board  52 , through wiring on the printed circuit board  52  and one electrical contact  60  to the LED  58 , through the other electrical contact  60  connected to the LED  58  to the printed circuit board  52  and through wiring on the printed circuit board  52  to the first electrical contact  54  in contact with the positive terminal of the uppermost one of the batteries  22 . As such, rotation of the bottom and top housing parts  14 ,  16  relative to one another controls illumination of the LED  58  in that it selectively brings the contact button  32  into or out of contact with the negative terminal of the lowermost one of the batteries  22  to form or interrupt the electrical circuit between the batteries  22  and the LED light assembly  24 . 
   Bottom and top housings parts  14 ,  16  may be made entirely of a conductive material or only partly of conductive material. It will suffice that only a portion of the bottom and top housing parts  14 ,  16  which establishes a conductive path from the contact button  32  to the surface of the top housing part  16  being contacted by the second electrical contact  56  is made of conductive material. 
   LED device  10  also includes a sleeve  62 , preferably made of plastic or another non-conductive material, which surrounds the batteries  22 , i.e., the sleeve  62  is positioned substantially between the circumferential edges of the batteries  22  and an inner cylindrical surface of the top housing part  16 . Sleeve  62  electrically isolates the batteries from the top housing part  16 . 
   LED device  10  also includes a resilient washer  64  made of, for example, rubber which surrounds the positive terminal of the uppermost one of the batteries  22  (see  FIG. 5 ). 
   The faceted dome  18  has a plurality of flat surfaces  66  so that light emitted from the LED  58  is better distributed and also includes with a distinctive illumination pattern. 
   Instead of the elastic ring  20 , it is possible to use an O-ring which is placed into the space  46  between the bottom-facing surface  48  of the top housing part  16  and the top-facing surface  50  of the tubular part  28  of the bottom housing part  14 . Such an O-ring would prevent water from entering into the interior of the device  10  between the threads  30 ,  40 . 
   As another alternative to the elastic ring  20 , any member which is arranged to cover the space  46  and/or in the space  46  and prevents water from entering between the threads  30 ,  40  can be used in the invention. 
   While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. For example, although the illustrated embodiment includes three batteries, it is possible to use any number of batteries including only a single battery.