US 2710366 A
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June '7, 1955 J, s. STERN, JR., ETAL 2,710,366
STATIC DISCHARGING SHOE Filed D60. 8, 1952 INVENTOR WPA/JR /V/Vm/V `$77X BY M Y 7% ATTORNEYS United States Patent O T STATIC DISCHARGING SHOE Joseph S. Stern, Jr., and Nathan Stix, Cincinnati, Ohio Application December 8, 1952, Serial No. 324,636
7 Claims (Cl. 317-2) This invention relates to static discharging shoes and aims generally to improve and simplify the construction thereof.
Shoes affording electrically conductive paths between the foot of the wearer and the earth for various purposes have been known for many years. to Royer No. 497,822, issued May 23, 1893, and Cooper No. 871,479, issued November 19, 1907, employed such a construction for its alleged therapuetic effect, and patents to Olmstead No. 1,728,167, September 10, 1929, and Temple No. 2,023,346, December 3, 1935, employed similar constructions for earthing static electrical charges that might be collected by the body of the wearer.
Also for many years it has been known that by employing a conductive rubber, and more specifically a relatively high resistance conductive rubber, a leakage path for earthing static charges without danger of sparking could be provided. See McKesson Patent No. 2,047,216, July 14, 1936; Crawford Patent No. 2,084,523, June 22, 1937; Thacher Patent No. 2,318,340, May 4, 1943, and Bulgin Patent No. 2,341,360, February 8, 1944, for example.
Applying such known effects, several patents have recently been issued on particular arrangements of conductive rubber soles and insoles with conductive rubber interconections therebetween for the slow, non-sparking earthing of static charges accumulated on the body of the wearer, but such constructions in general have been difficult to assemble, complicated, relatively expensive, and, like other rubber soled shoes, have involved danger of slipping on wet oors. Examples are Monahan Patent No. 2,261,072, issue of October 28, 1941, and Taber et al. Patent No. 2,407,189, issued September 3, 1946.
The present invention is based on the same generally old principles, and aims to provide a simpler and less expensive, but highly effective combination in which the need for conductive insolves and outsoles is eliminated, and in which ordinary leather soles, less apt to slip on wet surfaces, may be employed. These and other objects and advantages of the new construction forming the subject of this invention, will be clearly apparent from the following description of a preferred embodiment thereof. The invention resides in the novel structural features and new combinations thereof hereinafter disclosed and claimed.
In the accompanying drawing of the illustrative embodiment Fig. 1 is a partial longitudinal cross-section of a staticdischarging shoe embodying the invention, and
Fig. 2 is a bottom view thereof.
As shown in the drawings, the shoe of the present invention eliminates the need for conductive insoles and conductive outsoles entirely, and instead employs a novel stitched upper assembly and a novel shoe bottom assembly so combined that an adequate leakage path is provided for the earthing of static charges without danger of sparking, with a minimum of special or difficult construction, a complete absence of elements apt to render The patents Patented June 7, 1955 ICC the shoe uncomfortable to wear, and elimination of the danger of slipping on wet floors.
As best shown in Fig. 1, is this construction the shoe includes a shoe bottom comprising a wedge heel 1, that in the form shown consists of a wooden heel and shank member rabbeted at its shank end 1a to receive and support the shank end 2a of a cork or composition insole 2 that has secured to its upper face in spaced relation to its edges a sole filler 3 of resilient material, preferably sponge rubber, that is somewhat smaller in area than the area of the insole, to leave a rabbet 3a above the edge of the latter.
A suitable heel filler 4, preferably of cork or composition, is also provided, this element being skived at its shank end 4a to overlie the joint between the insole and filler 2, 3 and the heel member 1, and being somewhat smaller in area than the top surface of the heel 1 and insole 2 and marginally spaced therefrom to form a rabbet 4b overlying the peripheral edges of the heel and shank member 1.
The upper assembly 5 in the form shown comprises a welt-strip 5a, a shoe upper 5b of conventional construction that may include a heel stay Sc, and a sock lining I 5d that may have its heel portion reinforced with a thin leather lamination Se on its underside, the sock lining preferably being made of cotton fabric similar to a light canvas or duck, and being dip-coated or impregnated with an electrically conductive composition. Pepperells No. 28 Black VulcateX with U. S. Rubber Code #4506 impregnation both sides is a suitable conductive fabric, as it has firmness and body and is non-tacky, while the conductive carbon content of the coating in known manner is capable of affording a leakage path for static charges. The turned down inner edge of the welt strip 5a, and the down-turned edges of the upper 5b, Se, sock lining 5d and sock liner heel reinforcement Se are stitched together to forni a depending welt-seam 6, which welt seam lies in the rabbet 3a, 4b about the edges of the sponge rubber filler 3 and cork or composition heel filler 4 and contacts the top margins of the insole 2 and wedge heel 1.
In assembling the shoe, the upper assembly 5 6 is first fabricated and welt seamed as above described. The heel filler 4 is then cemented to the sock lining 5d or sock liner reinforcer 5e inside the heel embracing part of the welt seam 6. The insole 2 and sole filler 3 is then assembled with the latter lying within the sole embracing part of the welt seam 6 and preferably marginally cemented thereto. The wooden wedge heel 1 is then placed t0 align with the edges of the heel embracing portion of the Welt seam 6 and its rabbeted shank edge 1a is cemented to the shank edge 2a of the cork insole 2 whereever it falls. Thus any variations in length necessary to align the toe portion of the insole 2 and the rear face of the heel 1 with the faces of the welt seam 6, is accommodated by the overlap of these elements at the supporting rabbet 1a, as shown.
The upper assembly, soleand heel-fillers, insole and heel having thus been assembled, the welt strip 5a is turned downwardly and stretched smoothly about the outer faces of the insole and heel member 2 and 1, and its inturned edges are cemented to the marginal portions of the undersides of these members. A suitable ller '7, say of cotton or the like, is placed to support the center of the cork insole 2 that is not covered by the inturned portions of the welt strip 5a, and the outsole 8 of leather or any other suitable material is cemented in place. The top lift 9, preferably of leather, though composition or like top lifts may be used, is then cemented and secured in place against the outsole, as by brass nails 10 penetrating the wooden heel 1.
By the procedure just described there is created a wedge heel shoe especially well adapted for nurses when made with a white leather upper and a white leather welt strip.
Thenextstep in the production of the new shoe is to bore a hole 1l, say 3%; of an inch in diameter, vertically through the top liftrg, wooden heel l, cork heel ller 4 and ysocle-lining 3i.` This hole is preferably outwardly` Crawford, Bulgin or Thatcher', may be employed for this j.
plug, or the commercially available 3/4" extruded cord conductive rubber, U. S. Rubber Company Compound S8752, may be used.
Following the insertion of plug l2 a conductive patch or heel pad layer i3 of material similar to that of the sock lining 5a, is cemented in overlying relation to the plug and the adjacent portions ofthe sock lining, using a commercially available conductive cement, and a somewhat larger decorative patch or heel pad layer i4 of thin leatheror fabric is cemented in overlying7 relation to the conductive heel pad i3.
The edgesand bottoms of the leather or like outsole and top lift being suitably finished there is produced a Vstatic discharging shoe hardlyv different in .appearance from-a standard shoe, fully as comfortablerto wear, but very slightly greater'in cost, and which provides an ade; quateleakage path from the forepart of the foot of the wearer through the thin conductive sock lining 5a, the conductive heel pad i3 and the conductive rubber plug 12 to the oor or ground. As will be clear to those skilled in the art the materials above'designated to constitute and connect the plug l2, impregnated sock lining 3 and impregnated heel patch 1.3 are selected to impart to the shoe a conductivity conforming to the current standards of therNational Fire Protection Association. Further when the sole becomes worn the new construction permits half-s'oling of the shoe with leather or any other standard material Without loss of its static discharging etiiciency. The offset location of the plug i2 places it where the weight of the heel rests directly on top of the plug the bottomiof. which is in direct Contact with the ground or floor. With the long bearing surface afforded between the wooden heel andplug the latter is securely positioned without need for anges or other anchors, contributing to thesimplicity of the assembly. The use of a single plug l2 is preferred, though a plurality thereof may be cmployed if desired, and the resiliency ot the rubber causes it to abrade lessquickly than the leather or composition top lift and thus to protrude very slightly when the top lift has beenv buffed initially, or in subsequent-replacements of the top lift rendered possible by the fact that the rubber is better resistant to abrasive than the -top lift, and also largely protected from all but rolling contact with the ground thereby.
While there has been described herein what is at pres ent considered a preferred embodiment of the invention, it Will be obvious to those skilled in the art that minor modifications and changes may be .made therein without departing from the essence of the invention. fore tobe understood that the exemplary embodiment is illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that Vcome within the meaning and range of equivalency of the claims are intended to be included therein.
l. A static discharging shoe comprising anupper -having `a conductivesock lining stitched thereto along a welt it is therellt) seam, a non-conductive insole and soleA liller .underlyingVA the, florepart ofvsaidlsock liningandwelt seam, a Wooden heelfand shankmember underlyingthe heel, part of. said sock lining and welt seam, and supporting the shank end ofisaid insole'and filler, Va non-conductive heel filler interposed between said heel and ,sock lining and extending across the junction of said heel and insole, a welt strip extending from said welt seam into underlying relation to said insole and said heel and shank portion and secured thereunder to form an assembly, an outsole and top Vlift secured to said assembly, a plug of conductive rubber extending throughsaidtop lift, wooden heel, heel filler and sock lining, and a conductive patch overlying the upper end of said plugfand in electrical contact therewith andwith said sock lining.
2. A static discharging'shoe comprising an upperhaving a conductive sock lining stitched thereto along a welt seam, a non-conductive insole and sole ller underlying the forepart of said sock lining and welt seam, a wooden heel and shank member underlying the heel part of said sock lining and welt seam, and supporting the shank end of said insole and ller, a nonconductive heel filler interposed between said heel and sock lining and extending across the junction of said heel and insole, a welt strip extending from .said welt seam into underlying relation to said insole and said heeland shank portion and secured thereund-erto form an assembly,l an outsole and top lift secured to said assembly, a plug of conductive rubber extending through said top lift, wooden heel, heel ller and sock lining, a conductive patch overlying the upper end of said plug andv in electrical contact therewith and with said socklining, and a decorative patch overlying said conductive patch.-
3. A static discharging shoe comprising an upper having a conductive sock lining stitched thereto along a welt seam, said sock lining comprising an underlying nonconductive heel area reinforcement,` a non-conductive insoleand sole ller underlying the forepart of said sock lining-and -welt seam,.a wooden heel and shank-member underlying the heel part of said sock lining and welt seam, and supporting the shank endl of said insole and filler, a
non-conductive heel Afiller interposed between Ysaid heelV and sock lining and extending across the junction of said heel and insole, a welt strip extending from said welt seam into underlying relation to said insole and said heel and shank portion and secured. thereunder to forman assembly, an outsole and top lift secured to said assembly, a plug of conductive rubberrextending through said top lift, wooden heel, heel ller reinforcement and sock lining,
and a conductive patch overlying the upper end ofsaidy plug and in electrical contact therewith and with said sock lining. v
4. A method of constructing a static discharging shoe that comprises: assembling a shoe upper with an external welt strip and a sock-liningof fabric impregnated with.
electrically conductive material by edge sewing the same together to form .a downwardly extending welt seam, cementing a heel `liller to the assembly inside the heel embracing part of the ,welt seam,.assembling an insole and sole iiller within thelsole embracing part of the welt seam, aligning a wooden heel wedge'with the edges of the heel lembracing portionV ofthe vwelt seam and cementing its shank portion to the'shank portion of said insole, turning downl the welt strip and stretching it smoothly about the outer faces of the insole and heel member and turning its edges in under said insole land heel vmember and cementing them thereto, positioning a ller within .the sole framing portionsof said inturned edges, cementing a non-conductive outsoleandtop lift to the resulting assembly, drilling a Vertical lhole of substantial diameter completely through said top lift, wooden heel, heel filler and sock lining, forcing into said hole flush `with the inside of said sock lining and slightly projecting from said top lift a plug ofvconductive rubber, andcementing a conductive patch to the upper side of said conductive sock sock lining through-said heel plug.` v
5. A methodaccording lto claim- 4, in ,-whieh'theto amd-36a lift and conductive rubber plug are buled off simultaneously, the resiliency of the plug causing it to abrade less quickly than the top lift and thus to protrude slightly below the plane thus produced on the top lift.
6. A method according to claim 4, in which said hole is drilled in a position outwardly and rearwardly offset from the center of the heel of the shoe to a position in which the weight of the heel of a wearer will rest directly on top of the plug that in use falls into direct contact with the ground or floor during standing or walking.
7. A method according to claim 4, further comprising the step of cementing a decorative non-conductive heel pad in overlying relation to said conductive patch.
References Cited in the le of this patent UNITED STATES PATENTS Olmstead Sept. l0, 1929 Temple Dec. 3, 1935 Monahan Oct. 28, 1941 Siers Apr. 7, 1942 Maskowitz June 5, 1945 Maling Oct. 16, 1945 Taber Sept. 3, 1946