Patent Document

PRIORITY CLAIM TO EARLIER FILED APPLICATION 
     This application is a continuation in part of and claims priority from U.S. patent application Ser. No. 10/080,164, filed Feb. 12, 2002 now U.S. Pat. No. 6,626,556 and Provisional Patent Application No. 60/270,657, filed Feb. 22, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     The instant invention relates to a method of manufacturing a sealed, waterproof head assembly for a ruggedized LED flashlight. More specifically, this invention relates to a method of creating an internal sealing assembly that provides an integral and complete seal between the outer casing, lighting elements, and circuitry of the flashlight head. The flowable characteristics of the sealant and the manner in which the parts interfit create a unique structure not seen in the prior art. 
     Heretofore, the majority of flashlights utilized incandescent bulbs as a light source. The incandescent bulb was typically positioned within a cup reflector, which in turn was concentrically received within a threaded head ring. The outer end of the threaded ring included a clear acrylic cover to protect the incandescent bulb from damage while also allowing light from the bulb to project outwardly. The inner end of the head ring was inwardly threaded for receipt onto a complementary outward thread on the barrel of the flashlight housing. When waterproofing of the head was required, the manufacturers typically utilized compressible o-ring gaskets between the acrylic cover and the head ring, and also concentrically within the threaded connection. Threaded mounting of the head ring onto the barrel sufficiently compressed the cup reflector and acrylic cover against the head ring to provide waterproofing of the head assembly. 
     With the recent price reductions of super bright white light LED&#39;s, there has been a push to incorporate these new LED&#39;s into flashlight assemblies. In many cases, manufacturers are simply creating new bulb assemblies using a single LED or multiple LED&#39;s. These assemblies are known as based LED&#39;s. They include appropriate circuitry for voltage control and can be threaded into the same sockets as a conventional incandescent bulb. The manufacturer simply installs the based LED assembly into the old flashlight assembly. In this manner, no modifications of the flashlight head or housing are required. 
     However, the light emitted from these based LED assemblies is not ideal because LED&#39;s have a different light emission pattern that does not reflect correctly off of the cup reflector. While retrofit based LED&#39;s have bridged the gap in introduction of LED&#39;s into flashlights, there are drawbacks to this retrofit approach as noted above. Accordingly, there is perceived to be a need in the art for an entirely new head assembly specifically engineered for the physical constraints of the LED package as well as the optical needs of LED semiconductor light source. 
     SUMMARY OF THE INVENTION 
     In this regard, and in furtherance of the above stated objectives, the present invention provides a novel method of manufacturing a waterproof head assembly specifically designed for LED light sources. The method is necessitated by several novel conditions that arise with LED flashlight devices. The first novel design aspect of the head assembly is that the LED&#39;s are not enclosed behind an acrylic cover. LED&#39;s are ruggedly packaged and not susceptible to the same type of damage, as would an incandescent bulb. Accordingly, the rounded end surface of the LED package need not be protected within an enclosure. The rounded end surfaces of the LED are thus exposed to the outside environment through apertures formed in a solid end wall of the head assembly. In this regard, the apertures in the end wall now provide an entry point for unwanted fluid contaminants, i.e. water, into the interior of the flashlight. The second novel design aspect of the present head assembly comes from a need to compensate for this new entry point. To prevent water from entering into the interior of the flashlight through the apertures, the applicant has filled the interior cavity of the head with a sealant which substantially entirely fills all of the gaps between the outside surfaces of the LED&#39;s, the inside surfaces of the apertures, and the inside surfaces of the open end of the head assembly. 
     More specifically, the sealed head assembly comprises a tubular enclosure including a tubular sidewall, and an end wall, wherein the inner surfaces of the end wall and the sidewall cooperate to define an open end of said enclosure. The end wall includes a plurality of inwardly extending apertures for receiving the LED&#39;s therein. The head assembly further comprised a circuit board (mounting board), which is snugly received in intermitting engagement within the inner sidewalls of the open end of the enclosure. In this regard, the inner or upper surface of circuit board and the inner surfaces of the sidewall and the end wall cooperate to define a substantially enclosed interior cavity within the tubular enclosure. A plurality of LED&#39;s are mounted on the inner surface of the circuit board in electrical communication with contact leads on the circuit board. When the circuit board is received in interfitting engagement within the sidewalls of the enclosure, the LED&#39;s are in turn slideably received within the corresponding plurality of apertures in the end wall. Finally, to prevent water or such other fluid contaminant from entering into the flashlight through the open apertures, a sealant is injected into the enclosed interior cavity through a hole in the circuit board so as to substantially entirely fill the enclosed interior cavity. 
     It is therefore an object of the present invention to provide a method of manufacturing a sealed head assembly for an LED light wherein the LED lighting elements are exposed to the outside environment. It is another object of the invention to provide a method whereby a sealed head assembly for an LED light, which includes a minimal number of parts that is simple to assemble for mass production. It is a further object of the present invention to provide a method of sealing a flashlight head that has improved performance characteristics, such an internally formed and protected seal that is not exposed to normal wear. It is yet another object of the present invention to provide method of sealing an in-line flashlight assembly that is completely enclosed within the body of a flashlight thereby eliminating the possibility of contamination and damage from external forces. 
     Other objects, features, operational details and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate the best mode presently contemplated for carrying out the present invention: 
     FIG. 1 is a perspective view of a flashlight containing the reverse operating switch mechanism of the present invention; 
     FIG. 2 is an exploded perspective view thereof; 
     FIG. 3 is a cross-sectional view of the flashlight of the present invention in FIG. 1 along the section line  3 — 3  in the normally open, off position; and 
     FIG. 3 a  is a cross-sectional view of the flashlight of the present invention in FIG. 1 along the section line  3 — 3  in the closed, on position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, a completed flashlight assembly incorporating the reverse-acting switch mechanism and sealed flashlight head of the present invention is generally indicated at  12  in FIGS. 1-3 a . While the sealing assembly is shown incorporated into a flashlight in the description of the preferred embodiment, the present disclosure provides that the sealing assembly as described can be incorporated into a variety of other devices that require a sealed lighting assembly having the same or similar operational characteristics. As will hereinafter be more fully described, the present invention provides a fully contained waterproof inline flashlight assembly that provides improved operating features, higher durability and easier assembly as compared to similar flashlights in the prior art. The entire assembly is contained in a simple housing to provide a useful, novel and improved light source. 
     The flashlight  12  generally includes an elongated housing  14 , batteries  16  disposed in the housing  14 , and a flashlight head portion  10 . 
     The flashlight head  10  has an outer enclosure  18  that at least partially encloses at least one light emitting diode (LED)  20 , and a circuit component  22 , as well as the reverse switch assembly. 
     The reverse switch assembly is best shown in FIG. 2, and includes a spring  24 , an insulator disk  26 , a contact spring  28 , a plunger  30 , a contact tube  32 , and a switch housing  34 . The flashlight head  10  further includes a lower enclosure  36  assembled in a permanent fashion to the outer enclosure  18  to enclose both the switching assembly and light source  20  of the flashlight  12  inside the flashlight head  10 . 
     Turning to FIG. 1 an assembled view of the flashlight  12  of the present invention is shown. The outer shape of the flashlight  12  is formed by the battery housing  14  and the outer enclosure  18  of the flashlight head  10  where the battery housing  14  also serves as the handle for the flashlight  12 . Both the battery housing  14  and the outer enclosure  18  are formed of a metallic material such as milled aluminum or stainless steel. This allows both of these components to be electrically conductive and employed as components of the overall circuitry of the flashlight  12  as will be further described below. 
     FIG. 2 shows the flashlight  12  and the flashlight head  10  of the present invention in an exploded perspective view, illustrating the general relationship between all of the components in the overall device. The battery housing  14  is generally tubular in shape having a closed bottom and an open top. The battery housing  14  is generally hollow with an opening  38  that is of a diameter particularly suited to receive batteries  16 . In the preferred embodiment, the battery housing  14  is shown of a dimension to accept two batteries  16 , however, the present invention will operate equally well using one, three, four or more batteries  16  and the length of the battery housing  14  will be adjusted accordingly to accommodate the number of batteries  16  used. The inner surface of the open end  38  of the battery housing  14  has female threads  40  that are designed to engage corresponding male threads  42  on the lower enclosure  36  thereby maintaining the flashlight  12  in an assembled condition and allowing the head portion  10  to be rotated relative to the battery housing  14 . Rotation of the head  10  relative to the housing  14  selectively adjusts the relative positions to one another. When the batteries  16  are installed into the battery housing  14  one contact of the battery  16  is in electrical communication with the bottom of the battery housing  14 . Since the battery housing  14  is metallic, electricity is therefore conducted from the battery  16  contact, through the bottom of the battery housing  14  and up through the battery housing  14  into the flashlight head  10  as will be further described below. 
     The head  10  portion of the flashlight  12  has an outer enclosure  18  that receives and houses all of the switching components and the light source of the flashlight. The outer enclosure  18  is also formed of a machined metallic material that is electrically conductive, such as machined aluminum or stainless steel. The outer enclosure  18  is cylindrically shaped, having an opening at one end into which all of the remaining components are installed and several smaller openings  44  at the other end through which the installed LED lamps  20  protrude. Circuit assembly  22  is typically a printed circuit board onto which the LED lamps  20  are mounted. The circuit assembly  22  has circuit traces connecting one pole of each LED  20  to a metal connection tab  46  and the other pole of each LED  20  to a central connection point  52  on the bottom surface of the circuit assembly  22 . Once the LED lamps  20  are installed onto the circuit assembly  22 , it is slid into the opening in the outer enclosure  18 , so that the LED lamps  20  protrude through the openings  44  in the outer enclosure  18 . The connection tab  46  is in electrical communication with the wall of the outer enclosure  18 , thereby completing a path of electrical conductivity from the first contact of battery  16 , through the battery housing  14  up into the outer enclosure  18  of the head and into the circuit assembly  22  through connection tab  46 . The remaining portion of the electrical circuit is completed through the switch components as will be discussed below. In addition to providing paths of conductivity to each of the LED lamps  20 , the circuit assembly  22  may also include additional circuitry for controlling the flow of current through the LED lamps  20  or to provide additional functionality, such as flashing, to the flashlight  12 . 
     As can be seen, the circuit board  22  is inserted into the rear opening in the outer enclosure  18  with the LED lamps  20  extending through the openings  44  in the front thereof. In this manner, the circuit board  22  and outer enclosure  18  cooperate to form interior cavity. Once the circuit board  22  is fixed in place the sealant  60  is injected into the interior cavity to substantially fill the cavity and provides a monolithic seal between the circuit board  22 , the outer enclosure  18 , the LED lamps  20  and the openings  44  in the front of the outer enclosure  18 . As can be best seen in FIG. 2, an opening  21  is provided in the circuit board  22  to provide a location where the sealant  60  can be injected into the interior cavity. While the opening  21  is shown as being provided in the circuit board  22 , the opening may also be provided in the side or front walls of the outer enclosure  18  as well. 
     In accordance with the objectives of the method of the present invention, the critical steps reciting method of assembly of the flashlight head  10  are further provided in detail below. The method includes the following steps that are necessary to provide a sealed LED flashlight head  10  assembly. First, an outer enclosure  18  is provided. The outer enclosure  18  includes a tubular outer wall and a front wall with apertures  44  provided therein for receiving the LEDs  20 . Second, a circuit board  22  is provided with LEDs  20  mounted thereon. The circuit board  22  may further include an opening  21  therein to facilitate injection of the sealant  60  as will be further described in a later assembly step. The circuit board  22  with the LEDs  20  mounted thereon is then placed into the outer enclosure  18  through the open end opposite the front wall. The circuit board  22  is slid into the outer enclosure  18  until the LEDs  20  extend through the apertures  44  provided within the front wall of the outer enclosure  18 . Finally, a sealant material  60  is placed into the interior cavity formed between the outer enclosure  18  and the circuit board  22  to substantially fill the cavity and seal the space between the LEDs  20 , the apertures  44  in the front wall and the outer walls of the outer enclosure  18 . Further, the aperture  21  in the circuit board  22  may also be provided in the front or side wall of the outer enclosure  18  as required by the manufacturing process used. 
     The principal component of the switch mechanism is plunger  30 . The plunger  30  is substantially cylindrical and formed from a metallic material such as machined brass. One end of the plunger  30  is in contact with the second contact end of the battery  16  when the flashlight  12  is fully assembled. The opposite end of the plunger has a raised shoulder  48 . The raised shoulder  48  serves to retain contact spring  28  in an operative position on the plunger  30 . During assembly, the contact spring  28  is slid onto the plunger  30  and is pressed onto the raised shoulder  48  so that the spring is frictionally retained and in firm electrical communication with the plunger  30 . Further, insulator disk  26  is attached to the end of the plunger  30  opposite the battery  16  contact. This sub-assembly (plunger  30 , contact spring  28  and insulator disk  26 ) is then slid into contact tube  32 . 
     Contact tube  32  is a cylindrically shaped tube that is open on the top end and has a bottom wall. The bottom wall has an opening  54  that has a diameter slightly greater than the diameter of the plunger  30 . The remaining portion of the bottom wall forms switch contact  50 . The plunger  30 , contact spring  28  and insulator disk  26  are slid into the open end of the contact tube allowing the contact end of the plunger to protrude through the opening  54  in the bottom wall of the contact tube  32  without making physical or electrical contact with switch contact  50 . In this regard, the insulator disk  26  is sized to have a diameter that is only slightly smaller than the diameter of the contact tube  32 . This allows the insulator disk  26  to slide freely up and down inside the contact tube  32  while supporting the plunger  30  in the center of the contact tube  32  and preventing the plunger  30  from contacting the sides of the contact tube  32 . The insulator disk  26  is formed from a non-conductive material and is preferably a plastic material. Biasing spring  24  is then installed into the contact tube  32  behind the insulator disk  26 . The biasing spring  24  has a diameter that is also only slightly smaller than the inner diameter of the contact tube  32  and is in electrical communication with the inner walls of contact tube  32  and with the central connection point  52  on the circuit assembly  22  when the entire flashlight head  10  is assembled. The contact tube  32  including the switch components described above is installed into the switch housing  34 , which consists of cylindrical support housing that is electrically insulative and designed to isolate contact tube  32  from the rest of the flashlight head assembly  10 . 
     The switch housing  34 , after the above-described assembly, is then placed into the lower enclosure  36 . The lower enclosure  36  is a metallic component having an opening in its center into which the entire switching assembly is placed. The lower enclosure has an opening in its center to allow the plunger  30  to protrude and contact the battery  16  in an assembled position. The lower enclosure  36  also has male threads  42  that correspond to the female threads  40  on the interior of the battery housing  14 . To complete the assembly of the head  10 , the lower enclosure  36  containing all of the switching components, is pressed into the outer enclosure  18  using a hydraulic press (not shown) or similar method known in the art. This provides a completed flashlight head  10  that is sealed, having no parts that are accessible by the user. The head  10  is then threaded into the battery housing  14 , which already contains batteries  16  to complete the assembly of the flashlight  12 . To further seal the flashlight assembly  12  and prevent water infiltration, an O-ring gasket  56  is provided in a groove  58  in the side of lower enclosure  36 . The O-ring gasket  56  serves to seal the operable junction between the flashlight head  10  and the battery housing  14  prevent infiltration of water or other contaminants. Additionally, sealant  60  in the preferred embodiment is a UV curable potting compound, but may be any suitable sealant such as silicone, epoxy, rubber or any other sealant well known in the relevant art, is installed in the gap between the LED lamps  20  and the openings  44  in the outer enclosure  18  to further prevent infiltration to the interior of the flashlight  12 . 
     As can be seen, the circuit board  22  is inserted into the rear opening in the outer enclosure  18  with the LED lamps  20  extending through the openings  44  in the front thereof. In this manner, the circuit board  22  and outer enclosure  18  cooperate to form interior cavity. Once the circuit board  22  is fixed in place the sealant  60  is injected into the interior cavity to substantially fill the cavity and provides a monolithic seal between the circuit board  22 , the outer enclosure  18 , the LED lamps  20  and the openings  44  in the front of the outer enclosure  18 . As can be best seen in FIG. 2, an opening  21  is provided in the circuit board  22  to provide a location where the sealant  60  can be injected into the interior cavity. While the opening  21  is shown as being provided in the circuit board  22 , the opening may also be provided in the side or front walls of the outer enclosure  18  as well. 
     Turning to FIGS. 3 and 3 a  a section is shown of the flashlight  12  of the present invention in the operational state. FIG. 3 shows the flashlight  12  in the normally open, off state, and FIG. 3 a  shows the flashlight  12  in the closed, on state. In FIG. 3 the flashlight head  10  is shown threaded completely into the battery housing  14 . In this state, as can be seen, there is a gap between contact spring  28  and the bottom surface of the switch contact  50 . This gap is a break in the electrical circuit of the flashlight  12  and prevents the batteries  16  from energizing the LED lamps  20 . While plunger  30  is spring biased by the force of spring  24  in the direction of the batteries  16 , it is not allowed to move in the direction of the batteries  16  because of the proximity of the batteries  16  to the flashlight head  10 . In other words, when the flashlight head  10  is screwed entirely onto the battery housing  14 , the batteries  16  force the plunger upwardly against spring  24 . Because the spring  28  is connected to the top of the plunger, the contact spring  28  is moved out of electrical contact with the bottom of the contact tube  50 . 
     In FIG. 3 a , the battery housing  14  is shown as being slightly unscrewed from the flashlight head  10  as indicated by the arrow  62 , or vice versa, the head  10  is unthreaded from the body  14 . This displacement of the battery housing  14  results in displacement of the batteries  16  from the flashlight head  10  by the same distance. Since the plunger  30  is spring biased in the direction of the batteries  16  by spring  24 , this linear displacement of the batteries  16  allows the spring  24  to expand and thus displace the plunger  30  rearwardly by the same distance as the battery housing  14  and the batteries  16 . Once the distance of displacement of the plunger  30  is sufficient, the contact spring  28  comes into contact with switch contact  50 . When this contact is made it can be seen that a complete electrical circuit is provided starting at the top battery  16  contact through the plunger  30 , the contact spring  24 , switch contact  50 , contact tube  32 , secondary spring  24 , central contact  52 , into the circuit assembly  22  and the LED lamps  20 , through contact tab  46 , back into the outer housing  18 , through the lower housing  36 , into the battery housing  14  and finally to the bottom contact of battery  16 . Therefore, by translating the battery housing  14  in a rearward direction  62  from the flashlight head  10  an electrical circuit is completed thereby energizing the flashlight  12 . 
     It can also be seen in FIG. 3 a  that at the point where contact spring  28  initially contacts switch contact  50 , the contact spring  28  is not compressed. Since the spring force in the secondary spring  24  is greater than the spring force in the contact spring  28 , further displacement of the battery housing  14  and batteries  16  in the rearward direction  62  allows the plunger  30  to also be further displaced in the rearward direction  62 . As the plunger  30  is further displaces by secondary spring  24 , contact spring  28  is further compressed allowing the plunger  30  to remain in contact with the battery  16  until the contact spring  28  is completely compressed. The use of the contact spring  28  and secondary spring  24  in this manner provide for the extended operational range provided for under the present invention. 
     It can therefore be seen that the instant invention provides a compact inline flashlight switching mechanism that is fully enclosed and sealed against infiltration of water of other contaminants. It can be further seen that the present invention provides a novel reverse acting switch design that provides for smooth operation and an extended operational range through the use of spring contacts. For these reasons, the instant invention is believed to represent a significant advancement in the art, which has substantial commercial merit. 
     While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.

Technology Category: 2