Patent Publication Number: US-6707659-B2

Title: Heel grounder

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     (Not Applicable) 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     (Not Applicable) 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to heel grounders, and more particularly to an improved heel grounding device which allows its wearer to visually check for proper dissipation of electrical voltages to ground simply by observing the fasteners such as rivets holding the assembly of parts together remain intact. 
     In the assembly of electronic components, a major threat to the quality of such assemblies is the electrical potential difference existing between the electrical part assembly and the operator which may cause the part to be damaged. The typical solution to this electrostatic discharge problem in the work place has been to provide an environment which is substantially at a zero electrical potential. Electrostatic-free environments are typically created by providing workers and work stations with anti-static carpets, conductive or dissipative grounded desk top work surfaces, and/or hot air ion generators which emit ions to neutralize static charges. 
     Although such environments have proved to be generally useful in alleviating the electrostatic discharge problem, they do not typically have the degree of effectiveness that is desired by the manufacturers. Specifically, electrostatic-free environments fail to directly ground the workers themselves to a zero electrical potential. In this regard, electrically conductive bracelets have been implemented within such environments to sustain the workers at the zero electrical potential. However, these bracelets suffer from the disadvantage of limiting worker movement between work stations. 
     As such, various footwear grounding devices have been developed which can conduct electrical charges to ground while allowing the workers substantially unlimited mobility throughout the work place. A typical footwear is a heel grounder which is generally formed of a conductive rubber band and an elastic counter band or garter band. The prior art heel grounder further includes a fabric grounding tab generally of a woven polyester material coated with a conductive elastomer (such as neoprene loaded with 30% carbon), or alternatively metallic thread (such as silver yarn) is interwoven into the fabric of the grounding tab. It also includes a plastic fastening strap typically having a hoop and loop fastener, as well as a one-meg ohm chip resistor for providing additional safety of the worker against electric shock. 
     Though such currently known and available heel grounders may achieve their primary objective of properly grounding the workers, they possess certain deficiencies which detract from their overall utility. Perhaps the greatest deficiency of the prior art heel grounders lies in the method of their construction. 
     In the existing construction, the biggest problem is that all parts such as conductive rubber band and garter band are integrated and sewn together. In other words, all the parts forming the heel grounder are sewn and hidden among each other. However, if the sewing thread becomes loose and broken during use, then electrical continuity between the parts also become broken. Such occurrence inevitably leads to the undesired effect of destroying the conduction of electrical charges between the worker and earth ground. 
     The parts of the heel grounder need not come apart fully in order to destroy the charge conduction as loosening of the threads is generally sufficient to break continuity. This is where most of the electronic components are damaged. If the parts do not fall apart from each other, there is no way for the worker to know there is a problem unless the heel grounder is checked using a heel grounder tester. This is not practical and generally not done especially when the worker is in the middle of assembly. Hence, various electronic components become unintentionally damaged no matter how much effort was expended in providing a electrostatic-free environment. 
     Thus, there exists a substantial need in the industry, and in the microelectronics business in particular, for a heel grounding device that enables workers to quickly and accurately check for proper dissipation of electrical voltages irrespective of the work stage they are in. More specifically, there exists a need for a visually apparent heel grounding device which allows the workers to easily and rapidly visually check for proper electrical condition in a user-friendly manner. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention specifically addresses and alleviates the above-referenced deficiencies associated with the use of the heel grounders of the prior art. More particularly, the present invention comprises an improved heel grounding device which allows its wearer to quickly, visually check for proper dissipation of electrical voltages to the earth ground. As will become more apparent below, this is accomplished by visually verifying that the assembly of parts forming the present heel grounding device through the use of fasteners such as rivets remains intact. 
     In accordance with a preferred embodiment of the present invention, there is provided a grounding device which can be worn around a shoe in order to dissipate electrical voltages from the wearer to the earth ground. The heel grounding device of the present invention preferably utilizes two plastic anchor plates which are adapted to be maintained on opposing side portions of the wearer&#39;s shoe. An elongate electrically conductive strap preferably fabricated from rubber is formed between the anchor plates and is designed to extend around the heel portion of the wearer&#39;s shoe. Such conductive strap is preferably riveted to the plastic anchor plates. 
     In the preferred embodiment of the present invention, the heel grounding device also features an elongate garter strap or band which is formed between the two plastic anchor plates. The garter strap helps to secure the grounding device to the wearer&#39;s shoe by extending around its rear portion. Preferably, the garter strap is fabricated from an elastic material. 
     An attachable/detachable hook-and-loop (Velcro.TM.) system is further defined between the two anchor plates to provide adjustable fastening of the grounding device to the wearer&#39;s shoe. Such system is comprised of a hook strip and a loop strip which extend outwardly from their respective anchor plates and are releasibly connected to each other around the upper portion of the wearer&#39;s shoe. As is well known, the hook strip&#39;s inner surface may be connected at any location along the outer surface of the loop strip in order to provide adjustable fastening. 
     In the preferred embodiment, a grounding tab is riveted to any one of the two plastic anchor plates and extends freely (i.e. dangles) therefrom. The exposed end of this tab maybe tucked inside the wearer&#39;s sock so as to touch his or her skin. The grounding tab is preferably made from fabric such as polyester which includes either are electrically conductive elastomer or metallic thread. 
     A chip resistor which is preferably used for preventing electric shocks which preferably is provided on the same plastic anchor plate that the grounding tab extends from. This chip resistor is formed between the points of rivet attachment of the conductive strap and the grounding tab as the same rivets are used to mount the resistor on the anchor plate. The chip resistor preferably comprises a one-meg ohm chip resistor. 
     In operation, the heel grounding device of the present invention is worn around the wearer&#39;s shoe by first placing the shoe&#39;s heel portion upon the elongate conductive strap. Thereafter, the shoe&#39;s rear portion should be closely abutted against the garter strap or band so that tensioning fit develops once the grounding device is fastened. The hook and loop strips are then extended around the shoe&#39;s upper portion and fastened, after which the grounding tab&#39;s exposed end is tucked inside the wearer&#39;s sock so as to touch his or her skin. Of course, the strips may be adjusted to accommodate differing sizes and styles of the shoes. 
     With the heel grounding device on, the wearer is effectively grounded to zero electrical potential. Hence, the wearer may stand or freely walk on the grounded conductive surface while performing his or her electronics assembling duties. Thus, there is no unintentional static discharge to the electronic components to cause damage. 
     Due to all of the electrical connections to the heal grounder being facilitated by the conductive rivets attached to the anchor plates which can be easily visually observed by a user during use the user can easily check for proper dissipation of electrical voltages simply by observing the rivets holding the assembly together remain intact. As such the present invention comprises a visually apparent/evident heel grounder which insures proper electrical grounding merely by quick visual observation of the rivets and on anchor plates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These as well as other features of the present invention will become more apparent upon reference to the drawings wherein: 
     FIG. 1 is, a perspective view of a heel grounding device constructed in accordance with a preferred embodiment of the present invention and illustrating its first anchor plate which attaches a conductive strap, a grounding tab and a chip resistor through the use of rivets; 
     FIG. 2 is a perspective view of the heel grounding device of FIG. 1 illustrating its second anchor plate which attaches the conductive strap through the use of rivets; and 
     FIG. 3 is a side view of the heel grounding device of FIG. 1 which is worn around its wearer&#39;s shoe with the grounding tab&#39;s exposed end being tucked inside the wearer&#39;s sock. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same, FIG. 1 perspectively illustrates a heel grounding device  10  constructed in accordance with a preferred embodiment of the present invention. As indicated above, the present heel grounding device  10  allows its wearer to quickly visually check for proper dissipation of electrical voltages to the ground simply by observing that the fasteners such as rivets holding the assembly of parts together remain intact. As will be demonstrated below, this simple visually evident/apparent method of checking for proper voltage dissipation due to the unique construction of the heel grounding device  10  significantly mitigates unintentional static discharges to the electronic components to cause damage. 
     Referring more particularly to FIGS. 1 and 2, the heel grounding device  10  of the present invention is comprised of a first anchor plate  12  and a second anchor plate  14 . Although the first and second anchor plates  12 ,  14  may be fabricated from any rigid or semi-rigid material, a polymer/plastic is the preferred material of choice. The anchor plates  12 ,  14  are adapted to be maintained on opposing side portions  16  of the wearer&#39;s shoe  18 . In this configuration, the first and second anchor plates  12 ,  14  respectively define a first inner plate surface  20  and a second inner plate surface  22  which face toward their respective side portions  16  of the wearer&#39;s shoe  18 . 
     An elongate conductive strap  24  is provided between the first and second anchor plates  12 ,  14 . The conductive strap  24  is configured to tightly wrap around the heel portion  25  of the wearer&#39;s shoe  18  so that it effectively dissipates electrical voltages from the wearer. The elongate conductive strap  24  is preferably fabricated from an electrically conductive elastomeric material such as an electrically conductive rubber. Such material should provide a texture and thickness which would possess sufficient abrasion resistance and tear strength to withstand continued contact and sliding over the conductive flooring. 
     The conductive strap  24  is attached to the first and second anchor plates  12 ,  14  via a plurality of fasteners. More specifically, the conductive strap  24  defines a first conductive end  26  and a second conductive end  28 . The first conductive end  26  is positioned against the first outer plate surface  30  of the first anchor plate  12  whereat the first fasteners  32  are then driven therethrough towards the first inner plate surface  20 . Likewise, the second conductive end  28  is placed against the second outer plate surface  34  of the second anchor plate  14  so that second fasteners  36  are then inserted therethrough towards the second inner plate surface  22 . Although any types of fasteners such as screws or pins may be used for this purpose, rivets are the preferred fasteners. Moreover, the number of fasteners to be used is irreverent, but preferably two on each anchor plate  12  or  14  has been found to be adequate to sturdily attach the conductive strap  24 . 
     An elongate garter strap  38  is also provided between the first and second anchor plates  12 ,  14 . As will be better illustrated below, the garter strap  38  helps in securing the heel grounding device  10  to the wearer&#39;s shoe  18  by extending around its rear portion  40 . Preferably, the garter strap  38  is made from an elastic material so that it yields some degree of stretching when wrapped around the shoe&#39;s rear portion  40 . 
     The garter strap  38  has a first garter end  42  and a second garter end  44 . The first garter end  42  is first inserted through the first garter opening  46  defined on the first anchor plate  12  in which such end  42  attaches itself to the garter strap  38 . Similarly, the second garter end  44  is inserted through the second garter opening  48  defined on the second anchor plate  14  and is then attached to the garter strap  38 . The attachment of the first and second garter ends  42 ,  44  to their respective locations of the garter strap  38  may be accomplished in any manner. However, it is preferred that they are either sewn or ultrasonically welded to the garter strap  38 . 
     The present heel grounding device  10  is further provided with an attachable/detachable system. preferably a hook-and-loop (Velcro.TM.) system  50  between the first and second anchor plates  12 ,  14 . Such system  50  is designed to provide adjustable fastening of the grounding device  10  to the wearer&#39;s shoe  18 . The hook-and-loop system  50  first comprises a loop strip  52  in which its first loop end  54  is inserted through the loop opening  56  defined on the first anchor plate  12 . The first loop end  54  is then attached to any given location on the loop strip  52 . The system  50  also includes a hook strip  58 , the first hook end  60  of which is inserted through the hook opening  62  defined on the second anchor plate and thereafter attached to any location on the hook strip  58 . Like the first and second garter ends  42 ,  44 , the first loop and hook ends  54 ,  60  are attached via sewing or ultrasonic welding. 
     The loop and hook strips  52 ,  58  are designed to extend outwardly from their respective anchor plates  12 ,  14  and releasibly connect with each other around the upper portion  64  of the wearer&#39;s shoe  18 . As is common with every hook-and-loop systems, the inner hook surface  66  of the hook strip.  58  may be connected at any location along the outer loop surface  68  of the loop strip  52  in order to provide adjustable fastening. Hence, the present heel grounding device  10  may fit well on nearly any conventional shoe, regardless of style or size. Although the hook and loop fastener system is preferred, those having ordinary skill in the art will recognize that alternative adjustable strap systems, such as buckle or button systems are contemplated herein. 
     The heel grounding device  10  of the present invention includes an elongate grounding tab  70  either at the first or second anchor plates  12  or  14 . Choosing the first anchor plate  12  as its location, a tab fastener  72  preferably a rivet attaches the first grounding end  74  of the grounding tab  70  to the first anchor plate  12 . By this sole attachment, the grounding tab  70  is left to extend freely (i.e. dangle). The exposed second grounding end  76  of the grounding tab  70  may be tucked inside the wearer&#39;s sock  78  so as to be placed in abutting electrical contact with the wearer&#39;s skin. The grounding tab  70  is preferably constructed from a fabric material such as polyester which includes either a conductive elastomer or metallic thread. 
     A chip resistor  80  which is used for preventing electric shocks to the wearer is provided on the same anchor plate  12  or  14  that the grounding tab  70 . The chip resistor  80  is preferably positioned between the points of rivet attachment of the conductive strap  24  and the grounding tab  70  as the same rivets are used to mount the resistor  80  on the anchor plate  12  or  14 . More particularly, the first resistor end  82  of the chip resistor  80  is disposed over the first conductive end  26  whereas its second resistor end  84  is positioned over the first grounding end  74 . Preferably, the chip resistor  80  is a one-meg ohm chip resistor. 
     FIG. 3 shows the operation of the heel grounding device  10  of the present invention. As illustrated, the heel grounding device  10  is worn around the wearer&#39;s shoe  18  by first placing the shoe&#39;s heel portion  25  upon the elongate conductive strap  24 . Thereafter, the shoe&#39;s rear portion  40  should be closely abutted against the garter strap  38  so that tensioning fit develops once the grounding device  10  is fastened. The loop and hook strips  52 ,  58  are then extended around the shoe&#39;s upper portion  64  and fastened, after which the exposed second grounding end  76  is tucked inside the wearer&#39;s sock  78  so as to touch his or her skin. Of course, the strips  52 ,  58  may be adjusted to accommodate differing sizes and styles of the shoes. 
     With the heel grounding device  10  on, the wearer is effectively grounded to zero electrical potential. Hence, the wearer may stand or freely walk on the grounded conductive surface while performing his or her electronics assembling duties. Thus, there is no unintentional static discharge to the electronic components to cause damage. To ensure that such electrical grounded condition is constantly maintained, the wearer can easily visually check for proper dissipation of electrical voltages simply by visually observing that the fasteners  32 ,  36 ,  72 , namely, rivets holding the assembly together remain intact. As such the present invention comprises a visually evident i.e. apparent heel grounder which allows the user to quickly and reliably visually verify proper heel grounder function while maintaining the heel grounder disposed upon the users shoe. 
     Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of parts describe and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative device within the spirit and scope of the invention.