Abstract:
A flashlight has front and rear interconnected housing portions which define an interior waterproof chamber. The waterproof chamber carries an illumination source, an electronic drive for the illumination source and a power source. A switch system includes an electronic switch component for switching the relatively high current required for the electronic drive while a mechanical switch (e.g. a magnetic reed switch) activates the electronic switch component, therefore maintaining integrity of the waterproof seal about the chamber. A commutator assembly is provided to maintain electrical contact between the switch and other components. The power supply may be in the form of a plurality of battery stacks batteries aligned in the housing in a manner to provide a compact unit, while electrical components may be mounted to circuit boards positioned transversely to the length of the flashlight.

Description:
The present invention relates to a flashlight or illumination device and in particular to such a device which is of a waterproof construction and thus of applicability for use by scuba divers and the like. 
   BACKGROUND OF THE INVENTION 
   The use of flashlights and related illumination equipment to provide underwater lighting is well known. With the inclusion of a portable power supply, such as a battery pack, a diver is able to carry with him a safe, stable illumination source to provide visibility in the dark and murky depths. Conventional underwater lighting has long utilized incandescent bulbs as a light source. Such bulbs can be driven directly by a battery pack and thus provide minimal difficulties in being installed in a watertight housing. 
   Incandescent bulbs, however, have shortcomings. The light normally generated is of a yellow, rather than white, character, and is often of relatively poor intensity. In addition, such bulbs are inefficient light generators. To combat such deficiencies, miniature high-intensity discharge (HID) bulbs are replacing incandescent bulbs for use in underwater flashlights. The use of such HID devices, however, is not without its own shortcomings. In particular, while such bulbs have improved light output and energy efficiency, they require a ballast and drive circuitry to properly condition and regulate the voltage source. 
   Many HID underwater lights are of a two-piece construction, having the lamp and drive circuitry in a first, hand-held housing, and a battery power supply in a second housing. Electrical connections between the two housings and the enclosed components are through a cable. While such two-piece construction allows the lamp heads to be of relatively small dimensions, the presence of a connecting cable can be an impediment to use. In addition, the diver must still tether the battery pack in some manner. 
   It is accordingly a purpose of the present invention to provide a new and improved waterproof flashlight construction utilizing HID lighting in which the light source and power supply are in a single unit. 
   It is a further purpose of the present invention to provide such a flashlight which is of a compact construction. 
   Yet a further purpose of the present invention is to provide such a portable flashlight having the capability of convenient battery exchange and replacement. 
   SUMMARY OF THE INVENTION 
   In accordance with the foregoing and other objects and purposes, an underwater flashlight of the present invention comprises a main housing portion having an inner compartment or cavity. An illumination source located at a first end of the cavity with a clear lens forming a waterproof first end seal thereat, while the drive cavity and a replaceable battery power supply are located behind the illumination source. The rear end of the cavity is sealed by a removable rear cap which provides access to the batteries and contains a main electrical switch for the flashlight. When the cover is in place, the switch is electrically connected to the batteries and drive circuitry. 
   To maintain the waterproof nature of the flashlight, the switch is preferably of the type in which external mechanical switching action is transferred in a non-contact manner to the switch&#39;s electrical contacts. In a particularly preferred embodiment the switch comprises a magnet, an electrical reed switch, and an electronic switch element capable of carrying the relatively high currents required by the drive circuitry while keeping the current flow through the reed switch, which is a low current capacity device, to acceptable levels. 
   To provide a compact construction for the flashlight, the battery power supply may comprise a plurality of individual batteries arranged in co-linear adjacent stacks within the body cavity. Continuity between the battery stacks is accomplished through a commutator assembly, which allows electrical contact to be developed and maintained between switch circuitry and the batteries irrespective of the precise orientation of the rear cap with respect to the main body. Transversely-mounted circuit boards both carry electrical components and provide interconnections between the components and the batteries. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A fuller understanding of the present invention will be obtained upon review of the following, detailed description of a preferred but nonetheless illustrative embodiment thereof, when reviewed in conjunction with a the annexed drawings, wherein: 
       FIG. 1  is a schematic representation of the flashlight&#39;s electrical system; 
       FIG. 2A  is a cross-sectional view of a flashlight constructed in accordance with the invention; 
       FIG. 2B  is a side elevation view of the commutator assembly; 
       FIG. 3  is an end view of the flashlight depicting the power switch; and 
       FIG. 4  is a plan view of the commutator ring portion of the commutator assembly 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With initial reference to  FIG. 2A , flashlight  10  includes a main, generally cylindrical housing  12  defining an interior space or cavity in which illumination source  14 , ballast  16 , drive electronics board  18 , and batteries  20  are located. The housing  12  is preferably constructed of an appropriate durable metal, such as an anodized aluminum alloy, which allows it to serve as a circuit element, while providing both corrosion resistance and heat dissipation. The front end of the housing carries lens  22 , which is held to the front of the housing by retaining ring  26  which is affixed to the front of the housing by bolts  28 . A gasket assembly  24  seals the lens from water entry. The housing may be preferably milled out of a solid piece of stock with a forward cavity portion  30  for the bulb ballast and drive electronics board; three parallel cavity portions  32 , each dimensioned to receive a stack of batteries  20 ; and a rear, open-ended cavity portion  34 , which accepts the rear cap  36 . Each of the battery cavity portions  32  connects with forward cavity portion  30  and rear cavity portion  34 . Drive electronics board  18  bearing the drive circuitry for the bulb and ballast is mounted transversely to the length of the flashlight and is mounted at the rear end of the first cavity. It is maintained in a flush position against the rear wall surface  38  of the first cavity by a C-ring  40 . Bolt  44  provides electrical contact between a trace on the printed circuit board and main body portion  12 , as will be explained infra, as well as providing additional retention for the board. The rearwardly-facing surface of the printed circuit board also bears spring contacts  42  to establish electrical connection with the battery stacks in each of the battery cavity portions  32 . 
   Rear cap  36 , which may similarly be of anodized aluminum, includes externally-threaded, generally cylindrical side wall  46  which threadedly engages a complimentary threaded inner surface portion  48  of the housing  12  which defines the rear cavity  34 . A pair of O-rings  50  mounted on the cap side wall  46  establish a watertight seal between the rear cap and the housing. The rear cap  36  carries the main power switch for the flashlight while maintaining a watertight seal for the housing interior cavity. As shown, rotatable main switch  52 , which includes rearwardly-extending operating knob  54 , is rotatively mounted on the exterior of the rear cap about central hub  56 . The switch is rotatable about an arc of approximately 50 degrees, as shown in  FIG. 3 , the end points of rotation defining “on” and “off” positions. The switch carries with it magnet  58 , affixed in an inner recess in the switch, which rotates into and out of proximity to magnetic reed switch  62 , which is mounted by clamp  64  to the inner surface of the transverse wall portion  66  of the rear cap. With the magnet  58  positioned adjacent the reed switch, the reed switch contacts close, creating electrical continuity though the switch, while when the magnet is rotated away from proximity to the switch, the switch contacts open. Accordingly, electrical switching can be performed without physical contact or access to the sealed interior of the flashlight. 
   With reference to  FIG. 1 , illumination source  14  is a miniature HID bulb, such as that sold under the SOLARC trademark by Welch Allyn. As known in the art, ballast  16  provides a controlled drive current for the lamp, including the generation of an initial higher voltage spike required to “strike” the arc in the bulb. The ballast may be, for example, the Welch Allyn B10N003 unit. 
   Electrical power for the ballast and bulb is derived from batteries  20   a - f . Three stacks of two cells each are wired in a series arrangement. The batteries are preferably 2.5-volt rechargeable nickel-cadmium cell units, providing a total nominal output voltage of 15 volts. Voltage regulator  68  is used to provide a stable input voltage to the ballast and bulb. The voltage regulator may be, for example, a 14.5 volt output unit. Input and output side capacitors  70  and  72 , respectively and bias resistors  74  and  76  are chosen as known in the art. Thermal cut-out switch  78 , in series with the positive voltage input to the regulator, is provided to cut power in the event of overheating. It may, for example, be of bimetallic design having a cut-out temperature of approximately 40° C., thereby assuring that the body of the light remains safe to touch. In this regard, it is to be noted that the exterior surface  80  of the forward end of housing  12  may be of a ribbed or fin-like configuration to provide increased surface area and thus improve heat transfer and dissipation to the surrounding atmosphere. The voltage regulator  68  and the associated components are mounted upon drive electronics board  18 . 
   The three stacks of the batteries  20  are positioned between drive electronics board  18  and rear contact board  82 . Electrical continuity between the negative or ground end of the full battery stack and the drive circuitry is established by line  86 , while continuity between the positive end and the drive circuitry is established through the flashlight housing. Bolt  44  provides the link to the housing from main board  18 , while a spring-loaded contact  88 , inserted into a mating bore in the body and contacting a corresponding circuit trace on rear board  82 , couples the high end of the batteries to the body. The contact  88  is retained in the bore by bolt  90  overlying a peripheral flange of the contact. 
   As magnetic reed switch  62  must of necessity be of small physical size, its contacts are unable to withstand the total current drawn by the regulator  68  and supplied to the ballast and bulb. Accordingly, the present invention includes a semiconductor switch or relay that operates in conjunction with the reed switch to perform main switching of the batteries and control in the load current. As may be seen in  FIG. 1 , P channel field effect transistor  92  has its main source-drain junction in series with the battery supply, and in particular between the anode of battery  20 B and the cathode of battery  20 C. Thus, when transistor  92  is in the open or non-conducting state, a high resistance appears in series with the battery stack, effectively depriving the drive circuit load of power. The operative condition of transistor  92 , however, is controlled by reed switch  62 . With reed switch  62  closed, the potential applied to the gate is from the anode of battery  20 F at the top of the battery stack, and is higher than the potential applied to the transistor&#39;s source, due to the presence of pull down resistor  94 . Accordingly, transistor  92  is turned on, and appears as a virtual short between its source and drain electrodes. Full battery voltage is thus applied to the drive circuit and the flashlight is “on”. Because of the high impedance of the transistor&#39;s gate-drain junction and the parallel resistance of pull-down resistor  94 , which is a high value, the current flowing through reed switch  62  is minimal. With reed switch  62  open, the potential applied to the source and gate is that of the left or cathode end of battery  20 C, and the transistor&#39;s gate is lower than that of its source by virtue of resistor  94 . The transistor is thus maintained in the off state, with a high resistance path between source and drain to interrupt the battery circuit. 
   Because reed switch  62 , transistor  92  and pull-down resistor  94  are mounted to the transverse wall portion  66  of the rear cap, and the rear cap is threadedly mounted to the housing, it is necessary to provide means to establish and maintain electrical contact between the switch circuitry and the battery stacks, irrespective of the final radial orientation of the rear cap with respect to the body when the rear cap is installed. This is performed by the commutator assembly detailed in  FIGS. 2B and 4 . 
   With reference to  FIGS. 2B ,  2 A and  4 , board  96  is mounted to the forward end of the rear cap, transversely to the length of the flashlight, by bolts  98 . The board supports two sets of three spring-loaded contact pins  100   a - c  which bear against concentric conductive paths or traces  102  on the rear face of contact board  82 , also mounted transversely to the length of the flashlight. Each of the traces on board  82  is in electrical continuity with a battery stack through either a spring contact  42  or a contact trace  104 . One pin of each set is connected to the reed switch, transistor source, and transistor gate as shown in  FIG. 1 . The two sets of pins may preferably be oriented in a diametrically-opposed manner, as shown in  FIG. 4 . For clarity only one pin set is depicted in  FIG. 2B . 
   To afford convenient access to the batteries  20  when the rear cap is removed, contact board  82  is not permanently mounted to the main body. Rather, it is provided with a central orientation bore  106  and peripheral orientation bores  108 , as seen in  FIGS. 2B and 4 . Guide pins  110  (only one of which is shown in  FIG. 2A ) are installed on the housing and support the contact board in the required transverse alignment. When the rear cap is screwed down, the spring action of the contacts  100  provide a forwardly-directed bias against the contact board, urging the battery contacts into continuity with the respective batteries and maintaining the necessary electrical contact between the board and body spring-loaded contact  88 . The placement of the individual contact pins  100  about the circumference of the board insures that consistent and equal force is applied across the board to maintain alignment and prevent skewing. 
   With the batteries installed and contact board  82  placed on the guide pins  110 , rear cap  36  is screwed into the housing, the O-rings  50  maintaining a waterproof seal between the body and cap. The precise angular orientation of the cap with respect to the housing is not critical, as the contacts  100  create electrical continuity between the switch circuitry in the cap and the contact board and batteries, irrespective of their relative orientations. With the rear cap in place, operation of the flashlight is controlled by the angular position of switch piece  52 . 
   The rotating action of the switch piece  52  allows the flashlight to be operated, even if a diver is encumbered with diving gloves. Yet, as HID lamps are capable of generating a fair amount of heat, it is important that safeguards be provided to prevent inadvertent activation of the light, such as when it is packed away for storage. Thus, in addition to the use of thermal overload switch  78 , the flashlight may include a mechanical locking mechanism to maintain the power switch in the “off” orientation as desired. With reference to  FIG. 3 , switch piece  52  may be provided with shoulder portion  118  carrying locking pin  112 . Elastic band  114  is retained on the cap  36  by bolt  116  and can be manually stretched over the pin  112  to apply a counterclockwise bias to the switch piece  52  and thereby maintaining the switch in the “off” position. The elastic band is simply lifted off the pin  112  to allow normal switch operation to occur. 
   Modifications and adaptations of the invention as specifically described herein will be apparent to those skilled in the art. Accordingly, the scope of the present invention is to be determined upon reference to the claims appended hereto.