BACKGROUND OF THE INVENTION The present invention relates to an insole containing a magnet and reflexology nodules. Both the magnet and the nodules provide a therapeutic effect for the wearer based upon the stimulus provided to the foot during the wearing of the insole.

Magnets have been used in a variety of ways including in insoles. U. S. Patent No. 5,233,768 describes the use of a magnatherapy insole. In this insole, there are lengthwise magnetic strips which alternate between a north pole and a south pole orientation. In other cases, circular magnets have been affixed to the bottom of insoles.

At the present, there are no insoles available which are believed to provide a therapeutic effect to the wearer. Available magnetic insoles do not contain magnets of sufficient strength to confer a benefit to the wearer. For a magnet placed in an insole to be effective, it must emit a magnetic field of a sufficient strength. Manufacturing methods for magnetic insoles reported in the art do not result in placement of the magnet sufficiently near the foot to allow the magnets to exert an effect on the foot. In addition, the placement of the magnet in the insoles in the art places magnets in areas where foot pressure is the greatest, thus resulting in reduction of the strength of the magnetic field, and the effectiveness of the magnetic force being minimized.

SUMMARY OF THE INVENTION Accordingly, the present invention provides an insole with a magnet and a method of manufacture for such an insole. The strength and placement of the magnet are such to allow the magnetic force to render a therapeutic effect on the wearer.

Without being bound to a theory of operation, the therapeutic effect on the wearer is believed to be a result of the effect of the magnetic force upon the individual red blood cells found in the blood of the wearer of the insole. Because human red blood cells carry heme, which is a charged molecule, red blood cells can be affected by a magnetic field. The effect of a magnetic field of sufficient strength is to cause the red blood cells to organize themselves in a linear formation such that passage through blood vessels is facilitated. In addition, the composition of the insole is such that the magnet is thin and flexible and unable to separate from the insole. The method of manufacture permits close proximity of the magnet to the foot in the finished product.

The present invention also contains flexible nodules which stimulate reflexology zones in the body.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top overlay view of the invention, showing the magnet and the top fabric layer.

FIG. 2 is side cutaway view of the invention showing the magnet embedded in the polyurethane foam with the fabric layer.

FIG. 3 is a perspective view of the insole in the shoe of a wearer.

FIG. 4 is a top overlay view of the invention with the reflexology nodules.

FIG. 5 is a side cutaway view of the invention with the reflexology nodules.

FIG. 6 is a perspective view of the molding turntable.

FIG. 7 is a view of the mold design.

FIG. 8 is view of the molding process as the fabric is being placed in the mold.

FIG. 9 is a view of the placement of the magnet on the fabric in the mold.

FIG. 10 is a view of the shooter dispensing foam into the mold.

FIG. 11 is a view of the closed mold.

FIG. 12 is a view of the cured material being removed from the mold.

FIG. 13 is a graph showing the correlation between the distance from the magnet and the correlative magnetic field strength at that distance.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic insole the preferred embodiment of which is shown in FIGS. 1 and 2 and is generally designated by the numeral 100. The magnetic insole is designed to provide a therapeutic effect to the wearer via the magnetic field. A top fabric layer 10 is for the comfort of the user and is in contact with the foot of the user. A magnet 12 is positioned within the body of the insole 14 and just beneath the top fabric layer 10. The magnet 12 must be of a sufficient magnetic field strength such that the magnetic field permeates the foot of the wearer.

It is preferred that the magnet be of such a strength such that there is a Gauss reading of 500 at a distance of about two inches (about 5 cm) from the magnet, such as a magnet charged to a strength of 2450 Gauss. See FIG. 13. The fabric top layer 10 is preferably constructed from a stretchable material such as nylon or polyester. FIG. 2 is a side view of the insole, and depicts insole magnet 12, and top fabric layer 10.

The insole 100 is manufactured by first placing a layer of nylon or polyester fabric which will form top fabric layer 10 into a mold. A magnet is placed on the fabric and positioned so that the magnet will be in the area of the finished insole which receives the least amount of foot pressure during use by a wearer. After the magnet is properly positioned on the fabric, a polyurethane foam mixture is shot into the mold which is cured. After curing, the fabric/foam composition is removed and allowed to post-cure. The fabric/foam composition is then cut to the desired insole shape and size. The method results in an insole having the magnet close to the foot as shown in FIG. 3. FIG. 3 demonstrates that the magnet 12 is preferably located directly beneath the arch 13 of the foot of the wearer allowing for maximum penetration of the magnetic force 15 into the foot of the wearer. Optionally, a special type of mold which has the indentations built into the mold is used which results in the formation of the reflexology nodules 16 after the polyurethane foam mixture is shot into the mold.

See FIGS. 4 and 5.

In use, the insole is placed in the shoe either as a replacement for the shoe insole or on top of the existing insole adjacent to the foot. The magnet is positioned to align with the area of the foot which receives the least of amount of pressure during a

standard walking step. As shown in FIG. 3, the most preferred position of the magnet 12 is alignment with the arch 13 of the foot of the wearer. Slight adjustment is possible as long as the ability of the magnet to provide the beneficial field effects is not hampered more than fifty percent.

EXAMPLE A top cloth layer of 100% polyester jersey with four-way stretch and 2.70 oz. per sq. yd. (0.009 g per sq. cm), supplied by Adele Knits of Salem, N. C., is shipped to Shawmut Mills where a 1 mil. polyurethane film is laminated to the backside of the fabric using an acrylic spray-on adhesive. It is anticipated that any fabric providing sufficient stretch may be used. A molding turntable 18 is turned on and allowed to heat to the required 140 °F temperature. The turntable, designed and built by Spenco Medical Corporation, holds 36 individual molds 20 and is about 11 foot (about 335 cm) in diameter. The turntable 18 has a variety of areas at which specific steps in manufacturing are sequentially performed as the table turns: area A, insert fabric; area B, position magnet; area C, shoot foam; area D, close mold; area E, cure foam (area is heated to provide a curing temperature for the foam); and area F, pull molded insole from mold. See FIG. 6. The turntable has an adjustable speed controller that is set to a specified rotation speed. The speed that the turntable rotates matches the cure time that the foam requires. As depicted in FIG. 7, molds 20 are made of aluminum and have a bottom 22 and a hinged top 24, using methodology for mold making known in the art. Preferably, the bottom 22 and top 24 have a latching mechanism as illustrated by latch 51 and latch hook 50. The bottom 22 is hollowed out to make an outer wall frame 26. A design pattern 28 is suspended in the bottom frame at the specified height that will control the finished part's thickness. A sylastic liquid rubber compound is poured into the mold base frame. An exact negative impression is formed as the rubber hardens. The reflexology nodule indentations 30 are recessed into the mold from the positive pattern. A locator magnet 32 is also molded into the base surface at this time. This magnet will attract and locate the like magnet that will be placed in the insole. A recessed area is also molded into the rubber base that will allow exact placement of the fabric"blocker"38 (not shown). The design prototype was milled on

a 1 angle forward to the toe to aid the stance and distribute the body's load to the foot.

The lid 34 of the mold, which also controls the finished insole's thickness, is milled flat. A polyethylene liner 36 is attached to the lid. This liner is vacuum formed out of 0.020 inch (0.05 cm) polyethylene sheet. The polyethylene liner material prevents the polymeric liquid from sticking to the lid of the mold.

The rectangular shaped piece of polyester fabric 38 known as the"blocker"is placed in the recessed fabric area of the rubber mold base fabric side down (FIG. 8).

Next, a die punched magnet 12 is placed on the laminated side of the fabric"blocker" 38 in a specific location such that the magnet is located with the south pole just under the surface of the fabric next to the foot (FIG. 9). The magnet is preferably a Plastiform flexible permanent magnet with energy product 1.4 x 106 gauss-oersteds.

The magnet has a sulfur cured (vulcanized) nitrile rubber binder containing oriented barium ferrite magnetic particles, and is about 0.060 inch (about 0.2 cm) thick x 2 inches (5 cm) wide x 2 1/2 inches (6.4 cm) long with a Gauss reading of 2450. The magnetic material is produced by Arnold Engineering of Norfolk, NE., and die punched to the shape as described above. The magnet is produced with the south pole running the length of the top surface and the north pole running the length of the bottom surface. Six 3/8 inch (1 cm) diameter holes are punched at the same time the outside shape is formed. The 3/8 inch (1 cm) holes have two design purposes-one is to project circular force fields up into the foot. The other design purpose is to secure the magnet to the foam and fabric by allowing the liquid polymeric to expand up and through the magnet and bond to the polyurethane film side of the fabric. The south pole is the strongest pole in a magnet.

The preheated mold 20 passes in front of the shooter 42 which dispenses a mixed shot of the two part polyurethane chemicals through the mixing equipment and on top of the magnet and fabric in the rubber base part of the mold (FIG. 10). The foam consists of two parts. The"A"part is the Diisocyanate or ISO 44 and the"B" part is the Poyloyl or resin 46. These polymeric chemicals have specifications that will yield a finished mixed foam that is 54 shore on the"oo"hardness scale which maintains the specified 48% energy return and the 22-26 Peak-G cushioning rating.

The polymeric chemicals are stored in a heated room that is controlled at 90 °F.

The two part polymeric foam (BASF, Carrollton TX) is mixed and dispensed through a Kymofoam machine. A drum of the part"A"and a drum of the part"B" that have been internally mixed and maintained at 90° F are placed beside the Kymofoam machine and hooked up to heaters, static mixers and air pumps. The pumps are turned on to fill a ten gallon day tank (37.9 liters) located on the machine for each chemical. The ISO or"A"tank is filled with nitrogen that prevents moisture building inside the tank. Another set of pumps are used to pump the day tank chemicals up and into the metering head with the ISO part entering through line 44 and the B part entering through line 46. Pump RPMs determine the amount of volume of chemical that is available at the metering head. Needle valves in the metering head provide precision adjustment to obtain the specified ratio of part"A"and part"B"that reach the foam machine part 48 and the mixing/dispersing head 49. The ratio determines the outcome and properties of the foam. The ratio for the BASF foam is 21.3: 1 with part"A"being the 1. The total shot weight is 63.71 grams for the 1-2 size, 71.76 grams for the 3-4 and 78.13 grams for the 5-6 size. Part"A"pump speed is 101 RPMs and part"B"pump speed is 128 RPM. The mixing head temperature is 62-72 °F, and the mixer speed is 3600 RPM. A water line 47 is used to regulate the temperature of the mixing head and to purge the mixing head after dispensing the foam.

The molding table is set at 2 minutes and 30 seconds per revolution. This speed gives 4.2 seconds per mold. The foam 39 has to be dispensed in this 4.2 second interval. All other operations such as closing, pulling, and inserting the fabric and magnet must be done in the same 4.2 seconds. This speed will yield 850 parts per hour. The heated molds expedite the chemical reaction taking place as the mixed chemicals react and produce the solid foam. The reaction process of the chemicals also produces heat in the molds. Mold temperatures are monitored by infrared thermometers and the heaters are adjusted as required. The turntable is rotated via a motor and gearbox with a friction tire contacting the bottom side of the turntable and adjusted with a speed controller.

After the foam 39 has been dispensed into the mold 20, the lid 34 of the aluminum mold is closed and latched via latch 51 and latch hook 50 as the foam

begins to rise (FIG. 11). The polyurethane mixture undergoes a chemical reaction and expands to the internal shape of the mold. The part cures in the heated area E of the turntable (FIG. 6) for a specific time before it can be removed. The mold is opened and the cured part 60, having a polymeric foam side 62 and a fabric side 64 encasing magnet 12, is removed from the mold, inspected and stored for a post cure period of time (FIG. 12). After a twenty-four hour post cure, the part is cut to the finished shape, final inspection is done and the pair of insoles is packaged.