Patent Publication Number: US-8523376-B2

Title: Self-defense walking aid

Description:
FIELD OF THE INVENTION 
     The present invention relates to self-defense devices that employ an electrical deterrent to discourage attackers, and relates particularly to a device that also provides support for individuals to aid in walking. 
     BACKGROUND OF THE INVENTION 
     Security against attack is a concern for many individuals, and is of particular concern for those who need assistance walking; such individuals may be more likely to be targeted by attackers due to their impaired physical ability. 
     One approach to deterring and countering attacks is to employ a device that generates a high electrical voltage. Such devices may be able to deter an attack by presenting a threatening electrical discharge display, and if the attack continues, electrodes of the device can be applied to the body of the attacker to interrupt the attack. Two such devices are taught in U.S. Pat. Nos. 5,041,951 and 6,439,432, each of which also incorporates a flashlight and a chemical spray for use when an attacker is at a distance. Including a chemical spray for use against attackers at longer range may restrict the locations where the device may be legally carried. 
     Electrical deterrent devices may be elongated so as to extend the reach of the user to allow the electrodes to contact the attacker before the attacker can get close enough to grasp the user. One elongated electrical device is taught in U.S. Pat. No. 3,885,733, which teaches an electric prod for animals which also incorporates a flashlight. Elongated devices intended for use against attackers are taught in U.S. Pat. Nos. 4,093,969 and 5,388,603, both of which teach electric deterrent devices that are incorporated into collapsible umbrellas to disguise the device. These two devices can employ configurations of electrodes having both electrodes on the tip of the device, for pushing into contact against an attacker, and electrodes extending on the side of the device to prevent an attacker from grasping the device to disarm the user. While these devices may be effective in deterring attacks, the ability to disguise the device is limited; if the device is carried in dry weather when rain is not expected, the disguise may be ineffective. 
     Furthermore, none of the above devices serve to provide support for the user when walking, which is frequently desirable for elderly or otherwise physically impaired persons. One cane which appears to incorporate electrodes along the shaft is illustrated in U.S. Pat. Des. 325,297. However, the device is not disguised, and thus a potential attacker may be alerted to the presence of the defensive device and be able to take precautions before attacking. It has been suggested that retractable electrodes might be employed to extend from the tip of a cane, but it is unknown whether such a device has been effectively implemented. 
     As noted above, some electrical devices incorporate a flashlight. While flashlights such as taught in the &#39;951 and &#39;432 patents may be useful to identify a potential attacker, if such a light is employed with an elongated device such as taught in the &#39;951 patent, the distribution of light will be limited by shadowing, since the light is only provided on one side of the device. Devices have been developed to provide lighting for a shaft-mounted tool while avoiding shadows caused by the shaft. Such devices employ an array of 2 or more LED lamps on a device attached to a shaft of the tool, with the LED lamps positioned in a radial array about the longitudinal axis of the shaft, as taught in U.S. Pat. Nos. 5,845,986 and 7,575,334. These devices are designed to provide light only a short distance to illuminate the tip of the tool to facilitate its use in darkened environments, and thus the intensity and distribution of the light provided can be very limited compared to the intensity and distribution of light that would be desirable to identify a potential attacker in a darkened environment. 
     SUMMARY OF THE INVENTION 
     The present invention is for a cane or walking stick (hereinafter referred to simply as a cane) for assisting a user in traversing ground and floor surfaces and which incorporates an electrical self-defense device that is concealed and does not affect the primary function of providing support when the cane is in normal use. The electrical self-defense device has electrodes located at the tip region of the cane so as to extend the reach of the user when attempting to parry or fend off an attacker. The cane may also incorporate a light source to aid the user in identifying a potential aggressor in darkened environments. Such a light source also has utility by itself in that it can illuminate the ground surface so as to avoid obstacles and aid the user in planting the cane tip on a suitable location on the underlying surface for providing stable support. 
     The cane of the present invention has a grip which is attached to a support shaft which in turn terminates in a tip region. A cane tip fabricated of an elastic material is mounted on the tip region of the support shaft. The cane tip terminates in a support surface which is designed to grippably engage the underlying surface on which it rests when a downward force is applied to the cane tip by a user when supplemental support is being sought. 
     A pair of tip electrodes are embedded in the cane tip and preferably are positioned with respect to the tip such they are exposed in the support surface, so as to be exposed with respect to a surface or object advancing toward the support surface. Preferably, these tip electrodes reside at or in close proximity to the support surface, and can be slightly protruding or recessed with respect to the support surface. An energizing circuit creates a high-voltage potential between the tip electrodes. When so energized, a discharge of these electrodes onto an aggressor will stun the aggressor and forestall the aggressor&#39;s advance. It is further preferred that the pair of electrodes provided in the cane tip be nested and aligned with the support shaft. 
     It is preferred that the tip electrodes be fabricated from a conductive elastomer so as to provide a fully flexible cane tip that can interact with the ground or floor surface with which it is engaged without scratching or marring the surface, as well as providing resistance to slipping so as to enable the cane to provide support when needed by the user. This is particularly desirable when the tip electrodes protrude from the support surface to help assure that they make contact with the body of an attacker when the cane tip is pushed against the attacker. When such a elastomer conductors are used, they can be backed with metal disks or washer elements so that the elastomer conductors are at a constant potential and can be readily connected to wiring leading to the energizing circuit. These metal elements also tend to distribute the load in the elastic tip and provide the same function as the metal element typically employed in medical supply quality cane tips. 
     Means for energizing the electrodes are provided by the energizing circuit in combination with an energy source such as one or more batteries. Such batteries and energizing circuitry are known in the art, and typically employ an oscillator to convert the battery power to an AC current which is then provided to a series of step-up transformers to increase the voltage, with the secondary winding of the last transformer being connected to the electrodes. The energizing circuit may be housed in the grip or in the shaft, and are typically arranged so as to provide a desirable distribution of the cane&#39;s weight for balance purposes. The location of the batteries will frequently be selected to provide ready access to allow replacing the batteries if necessary. To serve as additional deterrence, the electrodes can be spaced apart such that, when an activating voltage is applied by the energizing circuit, the resulting potential is sufficient to cause arcing between the electrodes to provide a readily apparent audible and visible warning display. 
     In some embodiments, the cane has at least one pair of side electrodes that are located in the tip region, and positioned along the exterior surface of the support shaft. These side electrodes are also connected to the energizing circuitry and their separation can be adjusted such that, when the electrodes are energized, the potential between the electrodes causes visible arcing therebetween. Furthermore, when contact is made with the aggressor, the electrodes will discharge through the aggressor and stun the aggressor. These side electrodes are intended for use when the aggressor is too close to allow the end of the cane to be used for discharging the potential therebetween, or in the event that the aggressor grasps the tip region of the support shaft while attempting to take the cane from the user. These electrodes can be configured to appear as a decorative element of the cane. 
     When elastomer conductors are employed for the tip electrodes, it is preferred that the gap between the side electrodes be adjusted such that discharge in air will occur first between the side electrodes. This can extend the useful life of the elastomer tip electrodes by avoiding air discharge between the elastomer conductors, which would otherwise tend to volatilize the arcing surfaces of the tip electrodes over time. Arcing on the sides may also provide a sufficiently alarming visual and audible display to deter an aggressor from advancing or from attempting to disarm the user. If not, then once the tip electrodes or the side electrodes are placed against the body of the aggressor, the contacting electrodes will stun the aggressor by passing a current through the body of the aggressor. 
     The cane can be designed to provide an additional benefit when provided with an annular light source directed along the support shaft towards the cane tip. This light source can aid the user in identifying an individual to assess whether the individual presents a threat, as well as to illuminate the ground surface over which the user traverses. If sufficiently bright, the light may also serve as a dazzling and confusion-causing deterrence by making it difficult for the attacker to see clearly. 
     When an annular light is incorporated into the support shaft of the cane, in some embodiments the support shaft has a stepped cross-section, with a lower shaft extension section that terminates in the cane tip being smaller than an upper base section attaching to the grip. A coupling unit is provided between the two sections, and a means for illuminating the tip of the cane and an annular region thereabout is provided. 
     In one embodiment, the coupling unit has a tubular element having an inner cross section configured to grippably engage the shaft extension section. An extension section stop is provided to limit the depth to which the shaft extension section penetrates the tubular element. The outer cross section of the tubular element is configured such it will grippably engage a passage in the shaft base section of the support shaft. Again, a base section stop is provided to limit the depth of penetration of the tubular element into the shaft base section. 
     The tubular element of the coupling unit is fabricated from a light-transmitting material. The means for illuminating the cane tip and an annular region thereabout employs an LED lamp to generate light, the LED lamp being housed in a light receptor. Means are provided for transmitting the light from the light receptor and redirecting it so as to pass down the tubular element. Such can be provided by connecting the tubular element to the LED receptor with a series of light pipes or, alternatively, by an annular lens configured to have reflection surfaces that redirect the light so that it passes down the tubular element; in this latter case, the annular lens and the tubular element could be fabricated as an integral coupling unit. 
     While this annular light has been described as a complementary feature of the cane, it should be appreciated that annular light source would have utility in and of itself when integrated into a cane. 
    
    
     
       BRIEF DESCRIPTIONS OF THE FIGURES 
         FIG. 1  is an isometric view of one embodiment of a cane of the present invention. The cane has a cane tip that incorporates a pair of tip electrodes that are provided with an electrical potential therebetween by an energizing circuit housed within a support shaft of the cane. The energizing circuit in turn is provided electrical power from batteries housed in a grip via a switch that is also mounted on the grip. 
         FIGS. 2 and 3  are sectioned isometric views of the cane tip of the cane shown in  FIG. 1 , showing further details of the electrodes. The electrodes are formed as rings fabricated from a conductive elastomer, each of the rings contacting a metal electrode support element to which a power lead from the energizing circuit is connected. The elastomer rings are embedded in an elastomer tip element (shown in Phantom in  FIG. 2 ) so as to reside behind a support surface of the cane tip. The metal electrode support elements are configured to have overlapping footprints to avoid creating shear planes in the cane tip, and to provide more consistent support across the cane tip whenever the cane is employed to support the weight of the user. 
         FIG. 4  is an isometric view of a cane that forms another embodiment of the present invention, which again has a pair of energized elastomer tip electrodes located on a cane tip; however, in this embodiment the electrodes protrude slightly beyond the support surface of the cane tip. In this embodiment, the support shaft is stepped in cross section with a shaft extension section that terminates in the tip being smaller than a shaft base section attaching to the grip. A coupling unit is provided with a means for illuminating the tip of the cane and an annular region thereabout. In this embodiment, the tip electrodes are formed from conductive elastomer and again are recessed with respect to a support surface of the cane tip. To extend the useful life of the conductive elastomer material of the tip electrodes, this embodiment is provided with a pair of side electrodes that are spaced apart such that, when the energizing circuit is activated, an arc is preferentially provided between the side electrodes. With such spacing, the arcing occurs between the side electrodes until such time as the cane tip is in sufficiently close proximity to an aggressor for the arc to jump, via the tip electrodes, to the body of the aggressor. The electrodes of this embodiment are formed by cutting diagonally through a length of conductor sized to slidably engage the support shaft. This embodiment also includes an annular light source on the shaft to aid the user in traversing uneven ground and in identifying an approaching individual to aid in determining whether or not the individual poses a threat. 
         FIG. 5  is a view of the section  5 - 5  of  FIG. 4 , showing further details of the side electrodes. Because the electrodes are milled by a diagonal cut, the profile of the electrode edge that is opposed to the other side electrode has an obtuse inner corner residing against the support shaft and an acute outer corner that is raised above the surface of the support shaft. Electrical arcing tends to occur where the angle is sharpest, and thus occurs at the upper corner, reducing any effect of moisture which may collect on the shaft, since such moisture tends to collect against the support shaft at the lower corner. 
         FIG. 6  is an exploded partial section view of the support shaft of the cane shown in  FIGS. 4 and 5 , illustrating details of the coupling unit and its means for illuminating the tip of the cane and an annular region thereabout. In this embodiment, the coupling unit is a lens having a central cavity configured to grippably engage the shaft extension section while the larger shaft base section has a shaft passage configured to grippably engage the external surface of the coupling unit.  FIG. 6  shows the elements of the support shaft when exploded, while  FIG. 4  shows the shaft when assembled. 
         FIG. 7  is a partial isometric view of an embodiment similar to that shown in  FIGS. 4-6 , but which has a grip configured to shield the switch to prevent inadvertent activation of the electrodes. 
         FIGS. 8 and 9  illustrate an alternative coupling unit which enhances the structural integrity of the support shaft and offers improved optical performance. The coupling unit serves as a lens configured to act as a light guide to redirect the light from an LED lamp from an axial direction first to a radial direction and then back to an axial direction, but at a greater radius from a central axis of the lens. In this embodiment, the shaft extension section of the support shaft, the lens, and the shaft base section of the support shaft have a pin passing therethrough to eliminate any shearing forces on the coupling unit resulting from loading of the support shaft. 
         FIGS. 10-13  illustrate some possible alternative configurations of side electrodes that can be employed to protect the tip electrodes from deterioration, as well as to provide a desired decorative appearance. 
         FIG. 14  is a partial isometric view showing a portion of a support shaft that employs an array of optical fibers to receive and redirect light from an LED lamp. A lens is also employed, to adjust the distribution of the emitted light as well as to serve as part of a coupling unit between the sections of the shaft. 
         FIGS. 15 and 16  are partial isometric views illustrating another embodiment of the present invention, which provides a handle that can be readily replaced to conform to the hand of the user, and which employs an alternate position for switches used to selectively activate an LED lamp and a set of electrodes. 
         FIG. 17  is an isometric view of another embodiment, which employs a switch that allows the tip electrodes to be deactivated while retaining activation of the side electrodes, so as to preserve an uncompromised electrical deterrent whenever the cane is employed in conditions where the cane tip is likely to become damp. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1-3  illustrate a cane  100  which forms one embodiment of the present invention. The cane  100  has a grip  102  which is attached to a support shaft  104  terminating in a tip region  106 . A cane tip  108  fabricated from an elastic material is mounted to the tip region  106  of the support shaft  104 . The cane tip  108  in turn terminates in a support surface  110  (better shown in  FIG. 3 ) which is designed to grippably engage an underlying surface on which it rests when a downward force is applied to the cane tip  108  by a user who is employing the cane  100  to provide balance or ambulatory support. 
     The cane  100  has a pair of tip electrodes ( 112 ,  114 ) embedded in the cane tip  108 , which can be discharged into an aggressor to stop the aggressor&#39;s advance. A high-voltage potential is created across the electrodes ( 112 ,  114 ) by an energizing circuit  116  housed within the support shaft  104  and connected to the electrodes ( 112 ,  114 ) by wiring  118 . The energizing circuit  116  in turn is provided electrical power from batteries  120  housed in the grip  102 , via a switch  122  that is mounted on the surface of the grip  102 . Such energizing circuits for electrical deterrents are known in the art, and typically employ an oscillator to convert the battery power to an AC current which is then provided to a series of step-up transformers to increase the voltage, with the secondary winding of the last transformer being connected to the electrodes. 
     The switch  122  is preferably a momentary-on switch that only supplies electrical power while depressed by the user, thereby preventing the user from inadvertently setting the cane  100  down while activated. The energizing circuit  116  can be designed to automatically pulse the electrical power supplied to the electrodes to conserve battery power. The grip  102  has a screw-off cap  124  to allow access to replace the batteries  120 . If rechargeable batteries such as lithium iron phosphate batteries are to be employed, the grip  102  should be configured to allow recharging the batteries  120  without requiring them to be removed; suitable techniques for recharging batteries while they remain inside a housing are well known in the art. 
       FIGS. 2 and 3  are partial section views showing further details of the tip electrodes ( 112 ,  114 ) of the cane  100 ;  FIG. 2  shows the structure with the elastomer material of the cane tip  108  shown in phantom, while  FIG. 3  shows this material sectioned. The electrodes ( 112 ,  114 ) are formed as rings fabricated from a conductive elastomer, each of the rings contacting a metal electrode support element ( 126 ,  128 ) to which the wiring  118  is connected. The electrodes ( 112 ,  114 ) and the metal electrode support elements ( 126 ,  128 ) are in turn embedded in an elastomer material that forms the cane tip  108  (shown in  FIG. 3 ), with the electrodes ( 112 ,  114 ) positioned such that their exposed surfaces are slightly recessed from the support surface  110 . Recessing the electrodes ( 112 ,  114 ) should reduce premature wear in the event that the conductive elastomer material employed is significantly softer than the surrounding material of the cane tip  108 , as well as reducing susceptibility to separating from the surrounding material due to flexing as the cane tip  108  is employed to provide functional support for the user. Further resistance to separation can be provided by adhering the electrodes ( 112 ,  114 ) to the surrounding material of the cane tip  108  with a suitable adhesive. Recessing the electrodes ( 112 ,  114 ) may also aid in keeping them dry when the cane  100  is employed on a damp surface. The use of a conductive elastomer for the electrodes ( 112 ,  114 ) maintains a high degree of flexibility and resilience for the support surface  110 , providing enhanced engagement with a ground or floor surface to resist slipping when the cane  100  is employed to support the user. 
     One example of conductive elastomer material which could be employed for the electrodes ( 112 ,  114 ) is the silver-bearing elastomer material employed for making RFI shielding gaskets used to prevent electromagnetic signals from being emitted from electronic equipment. One source of such RFI shielding elastomer material is Chomerics North America of Woburn, Mass. Alternative materials, such as elastomers bearing copper, graphite, or other conductive substances, might be employed, and might be developed to provide superior resistance to degradation due to arcing. 
     The metal electrode support elements ( 126 ,  128 ) are axially spaced apart but are configured to overlap, such that an axial projection of either is partly superimposed on the other. This overlap prevents the creation of sheer planes within the elastomer material of the cane tip  108 , and helps to distribute forces on the elastomer material caused by weight applied to the support shaft  104 , which is frictionally received in a tip recess  130  in the cane tip  108  (shown in  FIG. 3 ). The elastomer material of the cane tip  108  must be an electrically insulating material to isolate the axially-separated metal electrode support elements ( 126 ,  128 ) from each other to prevent arcing within the cane tip  108  when voltage is applied to the metal electrode support elements ( 126 ,  128 ). 
     The metal electrode support elements ( 126 ,  128 ) also provide a material to which the wiring  118  can be readily connected by conventional techniques such as soldering. In turn, electrical connectivity with the electrodes ( 112 ,  114 ) can be provided by simple contact; however, more positive continuity can be provided by employing a conductive adhesive such as a graphite-filled epoxy to secure each of the electrodes ( 112 ,  114 ) to its corresponding metal electrode support element ( 126 ,  128 ). In the cane  100  illustrated, the metal electrode support element  128  is formed as a washer, allowing the wiring  118  to pass through to connect to the metal electrode support element  126 , which is formed as a solid disk. 
       FIGS. 4-6  illustrate a cane  200  that forms another embodiment of the present invention, which includes additional electrodes as well as a means for illuminating the tip of the cane and an annular region adjacent thereto. The cane  200  again has a grip  202  and a support shaft  204 , with a cane tip  206  mounted to the support shaft and having two tip electrodes  208  mounted therein. In this embodiment, the tip electrodes  208  protrude slightly beyond a support surface  210  of the cane tip  206  to positively assure that, when the cane tip  206  is pushed against an attacker, the tip electrodes  208  are brought into contact with the body of the attacker. When the tip electrodes  208  protrude in this manner, it is important that they be made from a compliant material such as a conductive elastomer to provide traction and to prevent marring floor surfaces. 
     In addition to the tip electrodes  208 , the cane  200  has two side electrodes  212  that are mounted on a tip region  214  of the support shaft  204 , the tip region  214  being formed from an electrically-insulating material or having an insulating surface material. The side electrodes  212  are formed from tubular stock of a conductive material such as aluminum, and are formed with a side electrode base portion  216  that forms a complete cylinder about the support shaft  204  and a side electrode tapered portion  218  that extends along the support shaft  204  in opposition to the side electrode tapered portion  218  of the other side electrode  212 . The tapered portions  218  can be formed by milling the tubular stock at an angle so as to produce parallel opposed faces  220  of the side electrodes  212 , as shown in  FIG. 5 . A milling angle of about 5-10° relative to the length of the support shaft  204  is felt to provide an effective tapered profile. Since the cut edges form a curve, the consistency of the separation between the opposed faces  220  increases as the angle at which they are cut decreases, employing a relatively shallow angle of cut results in the spacing of the opposed faces  220  being sufficiently consistent along the length of the tapered portions  218  that an electrical arc caused by electrical potential therebetween can move freely along the length. 
     As shown in the section view of  FIG. 5 , cutting the tapered portions  218  at an angle results in the opposed faces  220  being parallel. Each of the opposed faces  220  is bounded by a lower corner  222 , which resides against the tip region  214  of the support shaft  204 , and an upper corner  224 . Because the upper corners  224  are acute angles where electrical charge concentrates, arcing will tend to occur between the upper corners  224 , reducing untoward effects caused by moisture that collects on the cane  200  when employed in damp environs such as dewy grass or slush-covered walkways, since such moisture will tend to collect at the juncture of the lower corner  222  and the support shaft  204 .  FIG. 5  also shows two wiring passages  226  that are provided through the tip region  214  to allow wiring  228  to connect to the side electrodes  212 . 
     To assure that arcing occurs preferentially between the side electrodes  212  rather than between the tip electrodes  208 , the separation between the opposed faces  220  can be adjusted by adjusting the relative axial positions of the side electrodes  212  along the tip region  214  of the support shaft  204 . An appropriate separation can be set to assure arcing initially occurs between the side electrodes  212  and is only readily transferred to the tip electrodes  208  when they are brought into close proximity or contact with an aggressor. Having arcing occur on the side electrodes  212  can not only extend the useful life of the cane tip  206  by avoiding premature deterioration of the conductive elastomer material of the tip electrodes  208  caused by prolonged arcing therebetween, but also tends to deter an attacker from attempting to grasp the support shaft  204 . In a prototype, it was found that even when the tip was sufficiently damp as to cause weak sparking at the tip rather than on the sides, the electrical arc would still transfer effectively to a simulated attacker when prodded by the cane tip. An alternative embodiment that may provide improved performance in damp conditions is discussed below in the description of  FIG. 17 . 
     Referring again to  FIG. 4 , the support shaft  204  is formed with a shaft base section  230 , which attaches to the grip  202 , and a shaft extension section  232 , on which the tip region  214  is provided; this stepped configuration provides an enlarged cross section in the shaft base section  230  to more readily house electronic components. These sections are connected together by an annular lens  234  which serves as a coupling unit; as better illustrated in  FIG. 6 , the annular lens  234  also serving as means for distributing light generated by an LED lamp  236  about the shaft extension section  232 . The light can allow a user to illuminate an approaching individual to evaluate the threat posed by the individual, and can also provide a benefit when the cane is used as a support device, by illuminating the ground or floor surface without substantial shadowed areas to enable the user to discern obstacles. This latter function could provide a benefit even for canes which do not include an electrical deterrent. 
     The annular lens  234  has a lens base end  238  and a lens emitting end  240 , and is symmetrically disposed about a lens axis  242 . The lens base end  238  resides within a base section terminal end region  244  of the shaft base section  230  and is configured to receive light from the LED lamp  236 . A clear optical gel could be employed between the LED lamp  236  and the lens base end  238  to improve light transmission from the LED lamp  236  into the annular lens  234 . A high-output white LED lamp can be selected to provide a desirable degree of brightness, and may serve to disorient or deter an aggressor when the resulting light is directed into the eyes of the aggressor. The light received from the LED lamp  236  is directed into the annular lens  234  to a conical reflector  246  of the annular lens  234 . The annular lens  234  also has a lens base reflecting surface  248 , a lens inner cylindrical surface  250 , and a lens outer cylindrical surface  252 . The conical reflector  246  and the base reflecting surface  248  serve to redirect the light so that it exits through the lens emitting end  240 , as discussed below. To reduce light loss, the conical reflector  246  and the base reflecting surface  248  should be surfaces of rotation defined by parallel line segments rotated about the lens axis  242  such that they have the same angle of inclination with respect to the lens axis  242 . 
     The annular lens  234  serves both to redirect the light and to provide a mounting element to stabilize and support the shaft extension section  232  with respect to the shaft base section  230 . The base section terminal end region  244  has a base terminal end inner surface  254  that is configured to slidably engage the lens outer cylindrical surface  252 . The base terminal end inner surface  254  is polished to serve as a reflecting surface to reflect back any light that exits through the lens outer cylindrical surface  252 . The annular lens  234  also has a lens outer ledge  256  that is adjacent to the lens outer cylindrical surface  252  so as to supportably engage against a base section terminal surface  258  of the base section terminal end region  244 . The shaft extension section  232  has an extension base end region  260  with an extension base end outer surface  262  that is configured to slidably engage the lens inner cylindrical surface  250 , and which is polished to reflect back any light that exits from the lens inner cylindrical surface  250 . A lens inner ledge  264  is positioned adjacent to the lens inner cylindrical surface  250  and the conical reflector  246  so as to supportably engage an extension terminal surface  266  of the extension base end region  260 . 
     The conical reflector  246 , the lens base reflecting surface  248 , the base terminal end inner surface  254 , and the extension base end outer surface  262  are configured to direct the light received through the lens base end  238  such that substantially all the light is directed out from the lens emitting end  240 . The light from the LED lamp  236  is directed predominantly to the conical reflector  246 , which in turn reflects this light such that most of the light strikes the base reflecting surface  248 . The base reflecting surface  248  then reflects this light to the lens emitting end  240 . Stray light that passes through one of the lens cylindrical surfaces ( 250 ,  252 ) is reflected by either the base terminal end inner surface  254  or the extension base end outer surface  262  back into the lens  234 , such that substantially all of the light is eventually directed out the lens emitting end  240 . The lens emitting end  240  is configured to direct the emitted light substantially parallel to the lens axis  242 , with a slight outward divergence so as to create a distribution of light substantially parallel to and surrounding the shaft extension section  232 . Because the light is emitted around the circumference of the shaft extension section  232 , the shaft extension section  232  will not cast shadows, providing complete illumination to show obstacles on the surrounding ground surface. 
     To allow access for the wiring  228  extending from a power supply (not shown) to the electrodes ( 208 ,  212 ) provided on the shaft extension section  232 , the annular lens  234  is provided with one or more wire passages  268  that extend from the lens base reflecting surface  248  to the conical reflector  246 . 
     Referring again to  FIG. 4 , the cane  200  is provided with separate switches ( 270 ,  272 ) located on the grip  202  for selectively activating the electrodes ( 208 ,  212 ) and the LED lamp  236  (shown in  FIG. 6 ). The switch  270  that serves to cause energizing of the electrodes ( 208 ,  212 ) is a momentary-on push-button switch that is conveniently located so as to be readily depressed by the fingers of the user when grasping the grip  202 , while the switch  272  for activating the LED lamp  236  is a sliding switch, allowing the user to maintain the LED lamp  236  activated without having to maintain a grasp on the grip  202 . 
       FIG. 7  is a partial view of a cane  200 ′ that is similar to the cane  200  shown in  FIG. 4 , but which has a grip  202 ′ that is contoured to provide a guard  274  that serves to prevent the fingers of the user from inadvertently depressing the switch  270 . The guard  274  thus prevents activation of the electrodes (not shown) unless the user takes deliberate action to place their finger over the switch  270  to depress it. One example of an alternate switch configuration that avoids inadvertent activation is discussed below with regard to  FIGS. 15 and 16 . 
       FIGS. 8 and 9  illustrate an alternative annular lens  300  that can be employed in a support shaft  302  as part of a coupling structure that connects together a shaft base section  304  and a shaft extension section  306 . Again, the annular lens  300  also serves to distribute light generated by an LED lamp  308  about the shaft extension section  306 . The annular lens  300  is designed to provide improved optical performance and reduced cost compared to the lens  234  shown in  FIG. 6 . 
     The annular lens  300  is slidably insertable into a base section terminal end region  310  of the shaft base section  304  and is configured to slidably accept an extension base end region  312  of the shaft extension section  306 . Again, the annular lens  300  is provided with a lens outer ledge surface  314  that supportably engages the base section terminal end region  310  and a lens inner ledge surface  316  that supportably engages the extension base end region  312 . 
     The lens  300  is formed generally as a cylindrical cup, having a lens base section  318  extending normal to a lens cylindrical section  320  that terminates at a lens emitting end  322 ; the lens  300  is symmetrically disposed about a lens axis  324 . A light receptor  326  attaches to the lens base section  318  and directs light emitted by the LED lamp  308  to a conical reflector  328  that is formed in the lens base section  318  and centered on the lens axis  324 . The conical reflector  328  is formed as a 45° cone with a height H that is about equal to a thickness T of the lens base section  318 , such that essentially all the light from the LED lamp  308  hitting the conical reflector  328  is directed radially outward in the lens base section  318 . The lens base section  318  terminates in a base beveled surface  330  that is a section of a 45° cone, and which reflects essentially all the light it receives into the lens cylindrical section  320 , directed parallel to the lens axis  324  so as to be directed to the lens emitting end  322 . To enhance the reflective properties of the conical reflector  328  and the base beveled surface  330 , it is preferred for the exterior of these surfaces to have a reflective coating applied thereon. In fact, all surfaces of the lens  300  other than the light-receiving surfaces of the light receptor  326  and the lens-like surface of the lens emitting end  322  can have a reflective coating applied to help maximize the amount of light that is eventually emitted from the lens emitting end  322 . The lens emitting end  322  is again configured to direct the emitted light substantially parallel to the lens axis  324 , with a slight outward divergence to distribute the emitted light around the shaft extension section  306 . 
     Because the lens  300  has an overall thinner structure than the lens  234  shown in  FIG. 6 , and has a particularly thin structure at the base beveled surface  330 , it may be desirable to provide additional structure to transfer a load applied in service between the shaft extension section  306  and the shaft base section  304  to assure that the support shaft  302  is able to support the weight of the user. In the support shaft  302 , a transfer pin  332  is provided, which passes through pin passages  334  in the shaft extension section  306 , the lens  300 , and the shaft base section  304  in order to transfer forces directly between the shaft base section  304  and the shaft extension section  306  without relying on the structural integrity of the lens  300 . The pin passages  334 ′ that extend through the lens cylindrical section  320  may cause minor shadowing in the emitted light, but the distribution is typically sufficient that such shadows do not significantly impede the ability of the emitted light to illuminate a potential aggressor or a ground surface. 
     To allow access for the wiring (not shown) to pass through the lens  300 , one or more wire passages  336  are provided through the lens base section  318 , which again may result in some minor shadowing. The shadowing can be reduced when it is desired to provide a more widely distributed pattern of emitted light by frosting or otherwise treating the emitting surface of the lens to cause the emitted light to radiate from the lens surface rather than being directed by the lens. 
       FIGS. 10-13  illustrate various alternative configurations of side electrodes that can be employed on a support shaft to provide a desired decorative appearance.  FIG. 10  shows three electrodes ( 400 ,  402 , and  404 ), where a voltage is created between the center electrode  402  and the bracketing electrodes ( 400 ,  404 ). The center electrode  402  in this embodiment is preferably provided at least a limited degree of rotation on a support shaft  406 , allowing simultaneous adjustment of the gap G′ between the center electrode  402  and the first bracketing electrode  400  and the gap G″ between the center electrode  402  and the second bracketing electrode  404 . It is further preferred for the bracketing electrodes  400  and  404  to be longitudinally adjustable so that the gaps G′″ and G″″ can also be adjusted. Adjusting the size of the gap between adjacent electrodes varies the voltage required to generate an arcing spark therebetween, and can determine whether sparks are generated on the support shaft  406  or on a cane tip  408 . It is preferred for the sparks to be displayed along the support shaft  406 , to distract an aggressor from the tip  408  and to prevent undue degradation of concentric tip electrodes  410  embedded in the cane tip  408  when these tip electrodes  410  are formed from a conductive elastomer. 
       FIG. 11  illustrates another side electrode configuration which can be employed. In this configuration, a pair of side electrodes ( 450  and  452 ) are substituted for the three electrode configuration ( 400 ,  402 , and  404 ) shown in  FIG. 10 . This configuration is felt to be less functionally practical than the configuration shown in  FIG. 4 , as adjustment of the gap between the side electrodes ( 450 ,  452 ) cannot be made consistent on both sides of a support shaft  454  (shown in phantom) by longitudinally sliding the side electrodes ( 450 ,  452 ) relative to each other; in this embodiment, adjustment is made by rotating one of the side electrodes ( 450 ,  452 ), with the result that as the gap on one side is reduced, the gap on the other side increases, so arcing will occur preferentially on just one side of the support shaft  454 . 
       FIG. 12  shows a configuration where alternating ring-shaped electrodes ( 500 ,  502 ) encircle a support shaft  504 . In this embodiment, adjustment of the gaps G between adjacent electrodes ( 500 ,  502 ) can be adjusted if the positions of the electrodes ( 500 ,  502 ) are longitudinally adjustable along the shaft  504 ; such could be accomplished by threadably mounting the electrodes ( 500 ,  502 ) on the shaft  504 . 
       FIG. 13  shows an alternative embodiment where the separation between two side electrodes  550  is not adjustable, and must be carefully preset. The electrodes  550  are helically-positioned on a support shaft  552 , having a fixed gap G therebetween. Again, the gap G should be selected such that arcing sparks are generated preferentially along the support shaft  552  rather than across tip electrodes  554 . The electrodes  550  of this embodiment can be flush with the surrounding surface of the support shaft  552  to provide a more finished appearance. 
       FIG. 14  illustrates a section of a support shaft  600  that employs an alternative means for receiving light generated by an LED lamp  602 , which is housed in a shaft base section  604 , and redirecting the light so as to emit the light about a shaft extension section  606  in a direction substantially parallel to a shaft axis  608 . In this embodiment, such means is provided by an array  610  of optical fibers  612  in combination with an annular lens  614 . 
     Each of the optical fibers  612  terminates in a fiber receiving end  616  and a fiber emitting end  618 . The fiber receiving ends  616  are bundled side by side in a collar  620  and are positioned to receive the light generated by the LED lamp  602 . To reduce light loss, an optical gel (not shown) can be placed between the LED lamp  602  and the fiber receiving ends  616 . The optical fibers  612  are arranged such that they spread out and surround an extension section base end region  622  of the shaft extension section  606 , and are positioned such that the fiber emitting ends  618  are evenly distributed about the extension section base end region  622  and oriented to direct the light emitted from the fiber emitting ends  618  in a direction substantially parallel to the shaft axis  608 . In this manner, the array  610  serves to receive and redirect the light to emit it in a distribution about and substantially parallel to the shaft extension section  606 . 
     While the array  610  should serve to adequately redirect the light generated by the LED lamp  602 , the distribution of the emitted light can be further adjusted by the annular lens  614 . The annular lens  614  also provides a solid spacing element between the shaft base section  604  and the shaft extension section  606  to maintain these sections ( 604 ,  606 ) concentric. Since the light is distributed about the extension section base end region  622  by the array  610 , the annular lens  614  can be much simpler in structure than the annular lenses ( 234 ,  300 ) discussed above. The annular lens  614  of this embodiment is substantially cylindrical, having a lens base end  624  that contacts the fiber emitting ends  618  of the optical fibers  612  to receive the light emitted therefrom. To reduce loss of light, the fiber emitting ends  618  can be attached to the lens base end  624  by an optical adhesive or the fiber emitting ends  618  can be placed against the lens base end  624  with an optical gel interposed therebetween. The lens  614  also has a lens emitting end  626  that circumscribes the extension section base end region  622  to provide the desired distribution of emitted light. 
     While the embodiments discussed above employ a single LED light source combined with means for distributing the light around the shaft, alternative structures for providing an annular distribution of light could be employed, such as an annular array of LED&#39;s or an annular luminescent screen surrounding the extension section base end region of the shaft. 
       FIG. 15  is an isometric view of a portion of a cane  700  that forms another embodiment of the present invention. The cane  700  again has a grip  702  and a support shaft  704 , the support shaft  704  having a cane tip region (not shown) with electrodes for providing an electrical deterrent. The grip  702  of this embodiment is readily replaceable to allow adapting the cane  700  to be comfortably gripped by the hand of an individual user. 
     The grip  702  has a base portion  706  with a grip passage  708  therethrough, the grip passage  708  being sized to slidably engage the support shaft  704 . The grip  702  also has a contoured handle portion  710  that is ergonomically configured to be comfortably grasped by a user. Since the grip  702  is replaceable, the contoured handle portion  710  can be sized to match the hand of the intended user. 
     The support shaft  704  of this embodiment again incorporates an annular light source  712  to illuminate the surface over which the user traverses as well as to illuminate the environs and/or potential aggressors. The support shaft  704  has a light switch  714  that is conveniently positioned near the grip  702  so as to be readily activated by the user. The light switch  714  can be provided by a conventional momentary-on push-button switch, and in such cases can be readily activated by the index finger of the user while maintaining a grasp on the contoured handle portion  710  of the grip  702 . In the cane  700 , the electrodes and annular light source  712  are powered by batteries (not shown) housed within the support shaft  704 , so as to facilitate exchanging grips  702  and for leveraged distribution of weight. 
     The support shaft  704  also has an arming switch  716  that serves to allow the light switch  714  to also activate the electrical deterrent and energize the electrodes located at the cane tip. The arming switch  716  illustrated is located in a base end  718  of the support shaft  704 , where it can be readily operated by the thumb of the user while grasping the contoured handle portion  710 . The arming switch  716  shown is a toggling pushbutton switch that, when toggled to its “on” position, causes the momentary switch  714  to activate both the light source  712  and to energize the electrodes when depressed. When the arming switch  716  is in its “off” position, depressing the momentary switch  714  only activates the light source  712 , allowing the arming switch  716  to provide a safety against accidental activation of the electrodes. Inadvertent activation of the electrodes is further avoided by the position of the arming switch  716 , where it requires the user to move their thumb to operate the switch  716 . In some cases, it may be desirable to reverse the position of these switches so that the cane  700  at all times requires the user&#39;s thumb to be moved in order to activate the electrodes. 
     To notify the user when the arming switch  716  is in its “on” position, a status indicator LED  720  can be provided that is illuminated when the arming switch  716  is on. The status indicator LED  720  can also provide an indication of the battery status, such as by blinking to indicate when the battery voltage is below a specified minimum value. 
       FIG. 16  is a partial exploded view showing the structure for retaining the grip  702  on the support shaft  704 . The support shaft  704  has a shaft reduced section  722  sized to slidably engage the grip passage  708 , and terminating at a shaft ledge surface  724 ; the shaft reduced section  722  can be readily provided by an insert affixed in the remainder of the support shaft  704 . A retaining ring  726  threadably engages the shaft reduced section  722  and, when tightened thereon, clamps the base portion  706  of the grip  702  against the shaft ledge surface  724  to secure the grip  702  onto the support shaft  704 . The retaining ring  726  has a ring central opening  728  to allow access to the arming switch  716 , which is recessed to further prevent inadvertent activation of the electrodes. 
       FIG. 17  illustrates a cane  800  which forms another embodiment of the present invention; the cane  800  employs a three-position arming switch  802  that may provide improved performance in damp conditions. The cane  800  again has a support shaft  804  and a grip  806 . The support shaft  804  has a light  808  incorporated therein, and has side electrodes  810  positioned thereon. The support shaft  804  terminates at an elastomer cane tip  812  that incorporates a pair of tip electrodes  814  that are formed of a conductive elastomer. 
     The arming switch  802  operates in conjunction with an activation switch  816 , which is a momentary-on pushbutton switch. The arming switch  802  determines which components are activated when the activation switch  816  is depressed by the user. 
     When the arming switch  802  is in a first position, illustrated in  FIG. 17 , depressing the activation switch  816  only causes activation of the light  808 . In this position, the cane  800  is safe from inadvertent activation of the electrodes ( 810 ,  814 ). 
     When the arming switch  802  is placed in a second position, depressing the activation switch  816  causes activation of the light  808  in addition to the side electrodes  810 , but not the tip electrodes  814 . This position is intended to enhance the performance of the cane  800  when used in damp conditions where the cane tip  812  may become wet, reducing the effective insulating gap between the tip electrodes  814 . A second position indicator light  818  blinks to indicate that the arming switch  802  is in this position, providing notice to the user that the cane  800  is in an armed condition. 
     When the arming switch  802  is moved to a third position, indicated by a third position indicator light  820 , depressing the activation switch  816  causes activation of the light  808  in addition to both the side electrodes  810  and the tip electrodes  814 . However, while both sets of electrodes ( 810 ,  814 ) are activated, the spacing is set such that arcing initially occurs only between the side electrodes  810 , and is only transferred to the tip electrodes  814  when the cane tip  812  is in close proximity to or in contact with an aggressor. Again, the third position indicator light  820  blinks to advise the user that the cane  800  is in an armed condition. 
     While the novel features of the present invention have been described in terms of particular embodiments and preferred applications, it should be appreciated by one skilled in the art that substitution of materials and modification of details obviously can be made without departing from the spirit of the invention.