Abstract:
A guide plate on the head of the flashlight provides an alignment feature which aligns a pair of flashlight charging contacts with a pair of terminals in charging unit for releasably holding the flashlight in its charging receptacle. The flashlight is held within the charging receptacle in a consistent orientation, so that the flashlight switch may be easily found when the flashlight is grasped. The charging receptacle grips the head portion of the flashlight with a pair of spring-loaded jaws. A battery assembly is provided which presents both positive and negative terminals at the forward end of the battery unit. Connections are made from the forward end of the battery to an interconnection module within the flashlight head assembly.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a rechargeable flashlight and recharging unit. More specifically, the invention relates to a compact recharging unit having an alignment feature and a rechargeable flashlight which employs a custom battery assembly and a recharging fixture. 
     BACKGROUND 
     Metal flashlights, such as machined aluminum flashlights, are commonly finished, such as by surface anodization or bright dipping, to protect the surface of the flashlight and to impart an aesthetic quality to the flashlight. The body of such flashlights commonly includes a threaded tail cap for providing access to the battery compartment and which also serves as a battery terminal contact. Since the body of such flashlights usually provides part of the electrical circuit between the batteries and the light bulb, it is necessary for such electrically and physically mating surfaces as the body and the tail cap to be machined subsequent to surface finishing, such as anodizing, so that the electrical path through the body will have a low resistance. Machining the mating surfaces of the flashlight after surface finishing increases the cost of fabricating the flashlight due to the expense of a further machining step after anodizing and occasional damage to the finished surface of the flashlight during such further machining. To avoid further machining, it would be desirable to provide a battery assembly which presents both positive and negative contacts at the forward end of the flashlight so that the body of the flashlight would not need to be used as part of the electrical circuit. Hence, all machining of parts could be achieved before anodization. 
     It is known in the art to provide flashlights with rechargeable batteries. In prior art arrangements, when the flashlight is in the charger unit, the switch may be covered and inaccessible or the flashlight may be oriented (i.e. about the roll axis) in a wide variety of orientations. Hence the switch for operating the flashlight may be in a wide variety of orientations with respect to the charger unit. However, flashlights are often needed when it is dark in the vicinity of the flashlight in the charger unit. Hence, it would be desirable to provide a recharging system for a rechargeable flashlight which consistently presents the flashlight to the user with a known orientation of the operating switch on the flashlight in order to minimize fumbling for the switch on the flashlight in a dark environment. 
     It is recognized that a flashlight that is tightly held within a recharging unit in order to withstand vibration may be difficult to remove from the charging unit. This latter problem is increased if the flashlight is of compact size. Hence, it would be desirable to provide a rechargeable flashlight which is tightly held within a recharging unit while being easily removable to remove from the charging unit when needed. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention an elongated, tubular battery assembly has both positive and negative terminals located at the same end of the assembly. The battery assembly is composed of stacked cells of the sub-C NiCd rechargeable type. The stack of cells is preferably surrounded or wrapped in a first layer of shrink wrap tubing, which leaves exposed the positive contact of the top cell and the negative contact of the bottom cell. A conductive terminal extension member is preferably attached to the negative contact of the stack. An elongated conductor electrically connects the conductive extension member to an annular collar which forms the negative contact of the battery assembly and holds the elongated conductor in place. Preferably, a further layer of shrink wrap tubing holds the elongated conductor in place and covers the conductor along the side of the assembly. 
     According to another aspect of the invention, an interconnection module located in the head of the flashlight provides interconnection of the battery assembly, the lamp, and a pair of charging contacts. The interconnection module is a three-dimensional “circuit boardp” formed of a single piece of selectively-plated plastic. Contact is made between the interconnection module and the battery assembly by suitable conductors. The interconnection module mates with a switch module inside the head of the flashlight. 
     According to another aspect of the invention, the rechargeable flashlight is provided a guide means in the form of a guide plate which mates with alignment surfaces of the charging unit. The mating action of the guide plate and the alignment surfaces provides mating of the charging contacts on the head of the flashlight with the charging terminals of the charging unit. The charging contacts on the flashlight have concave surfaces which mate with convex surfaces of the charging terminals to assure the charging conditions. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     The foregoing summary, as well as the following detailed description of preferred embodiments of the present invention, will be better understood when read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is an elevational view of the flashlight and a perspective view of its charging unit in accordance with the present invention; 
     FIG. 2 is a sectional view of the charging unit of FIG. 1 taken along the line  2 — 2  of FIG. 1; 
     FIG. 3 is a sectional view of the flashlight of FIG. 1 taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is another sectional view of a battery assembly of FIG. 3 with the electrical connections for the assembly enlarged for clarity; 
     FIG. 5 is a perspective view of the conductive connection member of the battery assembly of FIG. 4; 
     FIG. 6 is a bottom view of the interconnection module taken along line  6 — 6  of FIG. 3; 
     FIG. 7 is an elevational view of the interconnection module taken along line  7 — 7  of FIG. 3; 
     FIG. 8 is a plan view of the interconnection module taken along line  8 — 8  of FIG. 3; 
     FIG. 9 is an elevational view of the interconnection module taken along line  9 — 9  of FIG. 3; and 
     FIG. 10 is a schematic circuit diagram illustrating the electrical connections of physical components of the flashlight shown in FIGS. 1,  3 , and  6 - 10 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, there is shown a flashlight  20  and a charging unit  40 . The flashlight  20  includes a head assembly  28 , a barrel  26 , and a tail cap  24 . A guide means, such as triangular guide plate  32 , is mounted on the side of the head  28 . A pair of charging contacts such as concave contacts  34  and  36  are located in the guide plate  32 . The guide plate mates with an alignment recess  50  of the charging unit  40 , when the flashlight  20  is placed into the charging unit  40 . The charging unit  40  includes a pair of jaws  46 , a receptacle generally designated  38  which includes the alignment recess  50 , and a pair of convex charging terminals  52  and  54  in the alignment recess  50 . The recess  50  is shaped to receive and align the guide plate  32 , so that the charging terminals  52  and  54  of the charging unit  40  mate with respective charging contacts  34  and  36 , when the flashlight is received or mounted in the charging unit  40 . The jaws  46  snugly grip the head  28  of the flashlight  20  with a gripping action described in greater detail hereinafter. The gripping action of the jaws  46  is adapted to securely hold the flashlight  20  and to allow the charging unit  40  be mounted in any desired orientation without the flashlight separating from the charging unit. The gripping action of the jaws  46  further allows the charging unit  40  to be mounted upon surfaces subject to vibration such as occurs within an automobile or other vehicle, and urges the contacts  34  and  36  securely against charging terminals  52  and  54 . 
     The charging unit  40  further includes an LED  42  for indicating when the flashlight  20  is being charged, a power plug (not shown) for connecting the charging unit to a source of electrical energy such as an automotive electrical system, and a pair of screw holes  48  which extend through the charging unit  40 . The screw holes  48  receive elongated screws which facilitate the charging unit being conveniently mounted upon a surface, such as a kick plate of an automobile passenger compartment. A charging circuit (not shown) is contained within the charging unit  40 . The charging circuit may provide a trickle current to maintain the charge of the batteries, or it may include other features of battery charging circuits which are well-known to those skilled in the art. 
     Although the guide plate  32  and the recess  50  are shown in FIG. 1 with mating V-shaped surfaces, it should be appreciated that various other interlocking geometries may be employed within the scope of the invention to guide and align the flashlight in the charging unit for mating the charging contacts  34  and  36  of the flashlight with terminals  52  and  54  of the charging unit  40 . As an alternative, a projecting member upon the charging unit may be formed to mate with a recessed surface of the flashlight in order to provide the functionality of the guide plate  32  and alignment recess  50 . It is likewise noted that the concave and convex mating surfaces of the respective charging contacts and terminals may be of other configurations than that shown in FIG.  1 . 
     It should be apparent that the flashlight is preferably inserted in charging unit  40  by pressing the barrel  26  between the jaws  46  and moving the head of the flashlight axially to mate the head within the jaws and the guide plate  32  into the alignment recess  50 . The flashlight  20  may be removed from the charging unit  40  by gripping the barrel  26  and applying a levering action to the barrel  26  using the head  28  as the fulcrum. Since the flashlight  20  is preferably of compact size, such as from 5 inches to 8 inches in length, the location of the guide plate  32  upon the head of the flashlight  20  provides greater leverage for removing the flashlight from the charging unit  40  than would otherwise be available if the charging contacts  34  and  36  and the guide plate  32  were located at a lower position on the flashlight, such as on the taper  22  or the barrel  26 . Alternatively, the flashlight  20  may be removed from the charging unit  40  by sliding the flashlight upward within the receptacle  38  and then moving the barrel  26  out of the receptacle thus reversing the action of inserting the flashlight into the charging unit  40 . 
     The gripping mechanism of the jaws  46  of the charging unit  40  is best seen in FIG.  2 . Each of the jaws  46  includes a protruding curved portion  46   a  and an integral elongated portion  46   b  which extends into the interior of the charging unit  40 . The jaws  46  are mounted about pivots  56  at the junction between the curved portions  46   a  and the elongated portions  46   b . The elongated portion  46   b  of each jaw  46  is provided with a retaining groove  66  for holding one end of a compression spring  64  which extends between the two elongated portions  46   b . The compression spring  64  biases the jaws  46  against the exterior walls  74  of the charger unit  40 . The gap  47  between the jaws  46  is of sufficient size to accommodate the barrel  26  as the flashlight  20  is placed into the charger. As the flashlight  20  is placed into the charging unit  40 , guide plate  32  is lowered into the alignment recess  50  and the curved portions  46   a  of the jaws  46  are pushed apart by the taper portion  22  of the flashlight. When the guide plate  32  has been completely lowered into the alignment recess  50 , the jaws  46  snugly grip only the head portion  28   a  of the flashlight. In alternative embodiments, the jaws  46  may be maintained in the position shown by inward pressure of the curved portions  46   a  against lips  76  rather than by outward pressure of the elongated portions  46   b  against exterior walls  74 . The use of a single compression spring between the two jaws  46  provides a balanced gripping action of the jaws so that the flashlight is not biased to one side as it is removed from the charging unit  40 . In alternative embodiments, a single pivoting jaw may be used or each of the jaws may be provided with a separate spring. 
     The configuration of the charging terminals  52  and  54  is exemplified by the view of the charging terminal  52  seen in FIG.  2 . The charging terminal  52  has a rounded end attached to a shaft  60 . The shaft  60  extends through the anterior wall of the guide recess  50  and is secured by a retaining ring  62 . A compression spring  58  positioned behind the rounded head of the charging terminal  52  urges the rounded end to extend into the guide recess  50 . Such spring-loaded mounting of the charging terminals  52  and  54  allows the charging terminals to retract into the charging unit  40  as the guide plate  32  is lowered into the charging position. As the charging terminals  52  and  54  are aligned with the charging contacts  34  and  36  of the flashlight  20 , the charging terminals  52  and  54  are biased into mating arrangement with the charging contacts  34  and  36 . 
     Turning now to FIG. 3, it is shown that the charging contacts  34  and  36  are preferably formed of screws which are threaded or pressed into the head  28  and secure the guide plate  32  thereto. Before being threaded or pressed into the head  28 , the slotted surfaces of the screws may be machined, if necessary, to form the concave depressions of the charging contacts  34  and  32 . 
     The head assembly  28  of the flashlight  20  includes a lens cap  30  with a knurled outer surface for ease of turning the lens cap  30 . The head assembly  28  houses a socket assembly made of a switch module  95 , which is interlocked with an interconnection module  90 . The interconnection module  90  provides one form of connecting means for electrical interconnection between the battery assembly  100 , the switch module  95 , the charging contacts  34  and  36 , and a lamp  82 . The lamp  82 , preferably a bi-pin halogen lamp, is plugged into the socket assembly and extends through an opening in a parabolic reflector  82 . The parabolic reflector  82  is press-fitted into the lens cap  30 . The portion of the parabolic reflector  82  which mates with the interior surface of the head  28  is threaded so that as the lens cap  30  is turned, the parabolic reflector  82  is axially translated relative to the lamp  81 , thus projecting a beam having a variable angle of divergence. The parabolic reflector  82  and the lamp  81  are protected by a lens  80 , which is preferably made an acrylate polymer such as LEXAN. The lens  80  may be transparent or selectively transparent to some portion of the light produced by the lamp  81 , such as by tinting or polarization. The lens cap or ring  30 , includes a sleeve  30   a  which surrounds the forward end of the head portion  28   a . An o-ring  78  is mounted within a groove in the head portion  28   a  between the sleeve  30   a  and the head portion  28   a . The o-ring  78  provides a water-tight seal between the head portion  28   a  and the sleeve of the lens cap  30 . The o-ring  78  also stiffens the joint between the head and the lens cap sleeve  30   a  to prevent vibration and to frictionally maintain the focus of the beam. The lens cap and the parabolic reflector may be completely unscrewed from the forward end of the flashlight to provide access to the lamp  81 . 
     The switch module  95  is preferably molded of a polymer material, such as an ABS plastic. The switch module  95  includes a “press-on/press-off” switch mechanism of a well-known type having a plunger cap  86  and ratchet  155 , which applies downward pressure upon a spring  156  and, in turn, a plunger contact  88  when the switch is actuated. The plunger  88  rides upon another spring  157  which rests against a plated conductive plunger shaft  150 . When pressed down onto the shaft  150 , the plunger  88  locks into an “on” or “off” position according to the original state of the switch. The bottom portion of the plunger  88  provides a conductive surface which completes an electrical connection between two segments or traces that may be plated into the switch well  214  as described in greater detail hereinafter. The switch module  95  is protected from moisture by a flanged rubber seal  84  which is secured over the cap  86  between the switch module  95  and the interior surface of the head  28 . The flanged rubber seal  84  is located on the opposite side of the flashlight  20  with respect to the charging contacts  34  and  36  for ease of finding the switch when the flashlight is removed from the charging unit  40 . 
     The barrel  26  of the flashlight  20  is hollow and contains a tubular battery assembly or unit  100 . The battery assembly  100  includes a center battery terminal  104  at the forward or head end of the assembly. The center battery terminal  104  is surrounded by an annular battery terminal  102  as shown in FIG.  4 . The center battery terminal  104  is preferably the positive terminal and the annular battery terminal  102  is preferably the negative terminal. Electrical connection between terminal  104  and the interconnection module  90  is established by contact spring  108 , which is retained by the interconnection module  90  within a contact spring recess  110 . Electrical connection between terminal  102  and the interconnection module  90  is established by contact spring  106  which is retained by the interconnection module  90  upon a contact spring retainer  112 . 
     The tailcap  24  is threaded onto the distal or rear end of the barrel  26 , so that the tailcap  24  may be unscrewed for removal of the battery assembly or for retrieval of a spare lamp  83  stored within a hollow compartment  85  in the tailcap  24 . The threaded connection between the rear end of the barrel  26  and the tailcap  24  need not be machined after the metal surfaces of the flashlight have been finished as has commonly been the practice heretofore. Since both terminals of the battery assembly  100  are made at the forward or head end of the battery assembly  100 , the threaded connection between the barrel  26  and the tailcap  24  is not employed to complete any electrical circuit between the battery assembly  100  and the lamp  81 . It is noted, however, that such use of a tailcap as part of the electrical circuit may be practiced in alternate embodiments employing other aspects of the invention. 
     The battery assembly  100  is shown in greater detail in FIG.  4 . The battery assembly includes a stack of cells generally designated  118  forming a battery of electrochemical voltaic cells  114 ,  115 , and  116 . The cells  114 ,  115 , and  116  are preferably secondary, or rechargeable cells of the Nickel-Cadmium type, although other electrochemical materials, such as Nickel-Metal Hydride, Lithium, or other types of cells may be employed. The cells are most preferably three sub-C size NiCd cells. Sub-C NiCd cells are widely available, sufficiently compact, and exhibit a superior energy density. The stack typically operates at a capacity of 1 Ah to 2 Ah at 3 V to 4 V. The cells  114 ,  115 , and  116  have respective top contacts  104 ,  101 , and  103 , and respective bottom contacts  120 ,  121 , and  122 . The cells are stacked in series so that the top contact  104  of the top cell  114  provides the contact to one pole of the stack  118 , while the bottom contact  122  of the bottom cell  115  provides contact to the other pole of the stack  118 . The top contact  104  is oriented toward the forward or head end of the flashlight  20  when the battery assembly  100  is inserted in use into the barrel with the tail cap removed. 
     The stack  118  is surrounded by a sheath  130  which insulates the stack  118  and provides mechanical support or holds the cells together. The sheath  130  is preferably formed of shrink-wrap tubing. The sheath  130  tightly surrounds the stack  118 , leaving at least portions of the top cell contact  104  and the bottom cell contact  122  exposed. 
     In order to provide both terminals of the battery assembly  100  at the forward or head end of barrel  26 , a terminal extension member or piece  128  provides a conduction path from the bottom cell contact  122  to the annular battery terminal  102 . The terminal extension piece includes a conductive tab  126  which is attached to the bottom cell contact  122 , an elongated conductor  125  attached to the conductive tab  126 , and a terminal end  124  adjacent to and surrounding but spaced and insulated from the top contact  104  of the battery assembly  100 . The top surface of the terminal end  124  serves as the forward or negative terminal  102  of the battery assembly  100 . As may be seen in FIG. 5, the terminal end  124  of the terminal extension piece  128  is preferably is in the form of an annular collar. The elongated conductor  125  may be of a single piece with the terminal end  124  or may alternatively be formed of a separate strap which is suitably attached, such as by spot welding, to the terminal end. In other embodiments, a plurality of elongated conductors may be employed. The conductive tab  126  may be formed by bending the lower end of the elongated conductor  125 . 
     Returning to FIG. 4, the annular collar of the terminal end  124  is fitted over the annular shoulder  134  at the top of the stack  118 . The conductive tab  126  is attached to the portion of the bottom contact  122 , which was left exposed by sheath  130 . The conductive tab  126  is attached to the bottom contact  122  by a suitable attachment procedure which maintains electrical continuity such as spot welding or soldering. 
     After the terminal extension piece  128  is fitted to the stack, the battery assembly  100  is wrapped in a second sheath  132  surrounding both the stack and the terminal extension piece  125 . The second sheath  132  is preferably formed of shrink-wrap tubing, which is of sufficient length to leave the terminal  102  of the terminal extension piece  128  exposed. The second sheath provides further insulation and mechanical support to the battery assembly and also serves to protect the terminal extension piece  128  from damage due to impact against the interior surface of the barrel  26  or during shipment. The second sheath is preferably of sufficient thickness to provide a snug fit of the battery assembly  100  within the barrel  26  so that the battery assembly  100  does not vibrate within the barrel  26  and detract from the solid “feel” of the flashlight. 
     Returning to FIG. 3, it is seen that the battery assembly  100  is constrained from axial translation within the barrel  26  by the contact springs  108  and  106  which are respectively attached to the interconnection module within contact spring recess or retainer  110  and upon respective contact spring retainer  112  as previously mentioned. The interconnection module  90  is preferably made of a platable engineering resin, such as RYTON. The interconnection module  90  preferably provides a unitary three-dimensional circuit board for connecting the battery assembly with the lamp  81  and with the charging contacts  34  and  36 . Conductors are preferably selectively plated upon the surface of interconnection module  90  and through openings therein. As shown in FIG. 6, electrical contact from the battery assembly  100  to the interconnection module  90  is made by the contact springs  108  and  106  to respective spring contact pads  200  and  202  which are plated upon the bottom of the interconnection module  90 . The central contact pad  202  has a retainer  110  thereon for for contacting the spring  108  and hence battery terminal  104 . Tabs  206  extend outward from the periphery of the interconnection module  90  in order to secure the module  90  into grooves (not shown) cut into the interior surface of the head  28 . 
     The contact pad  202  is connected to trace  208  which extends to the leftward edge of the bottom of the module  90 . Turning to FIG. 7, it may be seen that conductor  210  contacts trace  208  at the leftward edge of the bottom of the module  90 . The trace  210  connects, at one end, to trace  211  and, at the other end, to trace  224 . Trace  211  connects to trace  213  which leads into the switch well  214  and then connects to plunger shaft  150 . When the switch contact plunger  88  is depressed into the switch well  214 , electrical connection is made from trace  213  to trace  218  through post  150 , spring  157 , and plunger  88 . Trace  218  is raised above the floor of switch well  214 , and consequently is raised above trace  213  and extends partially around the periphery of the switch well  214  and connects to trace  218   a . As best seen in FIG. 8, trace  218   a  connects to trace  219  which extends toward the base of spring housing  220 . Returning to FIG. 7, it is shown that the interior of spring housing  220  contains a spring clip  221 . The interior of spring housing  220  is metal plated to provide a socket for one prong of the bi-pin lamp which is secured into position by spring clip  221 . Thus it may be seen that one side of the lamp circuit is completed from contact pad  202  via trace  208 ; to traces  210 ,  211 , and  213 ; to post  150  and spring  157  to contact plunger  88  and across the switch well  214  to traces  218  and  218   a ; and then to the spring housing  220  via trace  219 . In the preferred embodiment, the branch of the lamp circuit just described is the branch of positive polarity. 
     The trace  210  also provides connection to trace  224  which extends to a plated hole or opening  225  in which one lead of a blocking diode  216  is soldered. The blocking diode  216  prevents the battery voltage from being present at the charging terminals when the flashlight is not being charged. The blocking diode  216  extends from plated hole or opening  225  to plated hole or opening  222 . Plated hole  222  extends through the module  90  into a recess  227  as seen best in FIG.  9 . Within recess  227 , contact is made from plated hole  222  to trace  224 . Trace  224 , in turn, leads to trace  228 . Trace  228  is connected to trace  229  which extends outward from the bottom of the recess  227 . Trace  229  connects to trace  231  which leads to plated hole or opening  230 . Plated hole  230  is the hole or opening which receives the screw that forms charging contact  36 . The other charging contact  34 , which is preferably the negative contact, is screwed into plated hole  232 . Turning to FIG. 7, it is seen that the interior side of plated hole  232  is surrounded by trace  234 . Trace  234 , as seen in FIG. 8, contacts forked trace  236 . One fork of forked trace  236  completes one side of the negative circuit to recess  238  in which is contained spring clip  239 . Plated spring recess  238  forms the negative socket for one of the pins of the bi-pin lamp. The other fork of forked trace  236  extends toward the shelf  223  of the module  90 . Referring again to FIG. 7, it can be seen that forked trace  236  connects to trace  240  which extends to the top surface of the shelf  223 . At the surface of the shelf, trace  240  joins with trace  242 , as shown in FIG. 8, and extends across the shelf  223 . At the edge of the module  90 , trace  242  joins with trace  244 . Turning again to FIG. 7, trace  244  extends toward the rear surface of the module  90  and connects to trace  245 . Trace  245  extends to the edge of the module  90  and connects with trace  247 . Finally, trace  247  connects to the contact pad  200 , thus completing the negative branch of the lamp circuit. 
     To further clarify the configuration of the lamp and charging circuit, the diagram of FIG. 10 illustrates the schematic arrangement of the traces described in connection with the preceding figures. Each trace of the circuit shown in FIG. 10 is drawn as an individual conductive element with the appropriate trace indicated thereon. Indeed, the module  90  may be alternatively constructed using interconnected conductive elements or segments, rather than plated traces to complete the circuit. 
     From the foregoing disclosure and the accompanying drawings, it can be seen that the present invention provides certain novel and useful features that will be apparent to those skilled in the pertinent art. In particular, there has been described a compact rechargeable flashlight employing a unitary molded electrical interconnection module; a battery assembly which simplifies the fabrication of the flashlight; and a charging unit which provides ease of insertion and removal of a compact flashlight. It should also be apparent that the flashlight oriented in the charger unit by the guide plate and alignment recess, orients the switch of the flashlight in the same, accessible position when charging the flashlight. Accordingly, if the flashlight is grasped in a dark environment, the person removing the flashlight from the charger unit can easily know where the switch is located and find it for ready use upon removing the flashlight from the charger unit, as used by police officers in their vehicles in emergencies. 
     The terms and expressions which have been employed are used as terms of description and not of limitation and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described, or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.