Patent Publication Number: US-11039653-B2

Title: Football helmet

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/452,577 filed Jan. 31, 2017, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to helmets and, in particular, to football helmets. 
     BACKGROUND OF THE INVENTION 
     In recent years, there has been a significant amount of research into the health risks associated with repetitive head trauma. In the game of American football (“football”), players are subjected to player-to-player contact and it is not uncommon for a player&#39;s head to strike the ground or another player. To prevent injuries to the head and face, football players wear a helmet with a hard shell, internal padding and a wire face guard. While the football helmets in the prior art generally protect players from broken bones and abrasions in their head and face, they are inadequate at protecting players from internal injuries, specifically injuries to the brain. 
     Studies have indicated that football players are susceptible to developing chronic traumatic encephalopathy (“CTE”), which is a degenerative disease that has been attributed to repetitive concussions or subconcussive impacts to the brain. Instead of preventing the concussions and subconcussive impacts that are theorized to cause CTE, the football helmets in the prior art can exacerbate trauma to the brain in certain impacts. For instance, when football players have head-to-head contact, the hard shell of prior art football helmets create a nearly elastic collision where the kinetic energy of the two helmets before the collision is nearly equal to their kinetic energy after the collision. This effect is similar to a first moving pool ball hitting a second stationary pool ball—after the impact, the first ball becomes stationary and the second ball begins to move at approximately the same rate as the first ball originally was moving. When football players experience head-to-head contact, the force of the impact is not absorbed by the prior art helmets, but rather, like a pool ball, the force is conserved and exerted on one or more player&#39;s head. 
     By not absorbing the energy of impacts, but instead conserving the energy, the football helmets in the prior art do not adequately protect the brain from concussions and subconcussive impacts. The nearly elastic collisions that are characteristic of the prior art football helmets also amplify the magnitude of force exerted on the neck and brain stem of players, potentially causing neck injuries or other brain injuries that are not yet known. 
     While prior art football helmets have a layer of padding inside the hard shell, the design of the padding is not adequate to support the head in an impact. The internal padding of a helmet is most effective when there is no gap between a player&#39;s head and the padding. In the prior art helmets, the padding often has gaps between the padding and a player&#39;s head unless the helmets are custom designed for that player&#39;s head. As most players are unable to purchase a helmet with padding custom designed for their head, most players have gaps between the padding and their head, reducing the effectiveness of the prior art helmet systems. 
     Therefore, there is a need for a football helmet that is better able to prevent the brain from receiving concussions and subconcussive impacts. There is also a need for a helmet that reduces the prevalence of gaps between a player&#39;s head and the internal padding of the helmet. Accordingly, it is the object of the present invention to provide a football helmet that prevents the brain from receiving concussions and reduces the magnitude of subconcussive impacts and that reduces the prevalence of gaps between a player&#39;s head. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a football helmet that reduces the occurrence of concussions and the severity of subconcussive impacts to the brain when worn by football players. Football is not the only sport where CTE is a problem and other sports and activities would also benefit from the invention disclosed herein. The invention uses multiple materials and configurations that are novel to helmet applications and reduce the magnitude of impacts to the head, brain and neck. 
     The present invention is comprised of materials that are new to the field of football helmets. The materials used in the present invention can be grouped into the rigid core or frame of the helmet (hereinafter “rigid core”), the exterior impact absorbing system (hereinafter “EIAS”) and the interior impact absorbing system (hereinafter “IIAS”). To reduce the prevalence of elastic collisions, the present invention uses an EIAS comprised of one or more durable, yet easily compressible materials fixed to the exterior surface of the rigid core. The EIAS is are capable of dissipating some or all of the energy from an impact. The present invention uses a rigid core to provide structure to the helmet and protect against head injuries during high pressure impacts. Fixed to the inside surface of the rigid core of the helmet is an IIAS comprised of one or more compressible materials that conform to a player&#39;s head, eliminating gaps between the IIAS and the player&#39;s head and absorbing some or all of the force of an impact. Because the IIAS also absorbs the force of an impact, impacts are absorbed by both the EIAS and IIAS. 
     The exemplary embodiments presented in this application are optimized for use in a football helmet, however, it is appreciated that the invention could be used in other types of helmets within the inventive concept expressed herein. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of the preferred embodiment of the invention. 
         FIG. 2  is a front view of the preferred embodiment of the invention 
         FIG. 3  is a rear view of the preferred embodiment of the invention. 
         FIG. 4  is a side view of the preferred embodiment of the invention. The left side and right side are substantially mirror images of each other. 
         FIG. 5  is a top view of the preferred embodiment of the invention. 
         FIG. 6  is a bottom view of the preferred embodiment of the invention. 
         FIG. 7  is a bottom exploded isometric view of the preferred embodiment of the invention. 
         FIG. 8 a    is a side sectioned view of a portion of the preferred embodiment of the helmet, showing the EIAS, rigid core and IIAS. 
         FIG. 8 b    is a side sectioned view of a portion of an alternative embodiment of the helmet, showing the EIAS, rigid core and IIAS. 
         FIG. 9  is an exploded perspective view of a first portion of the interior of the preferred embodiment of the invention. 
         FIG. 10  is an exploded perspective view of a second portion of the interior of the preferred embodiment of the invention. 
         FIG. 11  is an exploded perspective view of a third portion of the interior of the preferred embodiment of the invention. 
         FIG. 12  is an exploded perspective view of a cylindrical component used in the IIAS. 
         FIG. 13  is a top view of a cylindrical component used in the IIAS. 
         FIG. 14  is an exploded perspective view of the forehead component used in the IIAS. 
         FIG. 15  is a top view of the forehead component used in the IIAS. 
         FIG. 16  is an exploded perspective view of an elongate component used in the IIAS. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1  is a perspective view of the preferred embodiment of the invention, a football helmet  10 , comprised of an EIAS  30 , rigid core  40 , an IIAS  50  and a facemask  14 . The rigid core  40  does not need to be completely rigid in all embodiments. In some embodiments, the rigid core  40  is more rigid than the EIAS  30  or IIAS  50 . In some embodiments, the rigid core  40  has a higher stiffness than the EIAS  30  or IIAS  50 . In some embodiments, the rigid core  40  has a higher hardness than the EIAS  30  or IIAS  50 . The rigid core  40  can also be referred to as the core layer. In this view, a facemask  11  is attached to the helmet  10  using facemask mounted snaps  12 . 
     Visible in  FIG. 1  is the exterior of the EIAS  30 , which is comprised of multiple layers of materials in the preferred embodiment. While the preferred embodiment uses a two layer EIAS  30 , it is appreciated that the number of layers may be added or subtracted within the inventive concept expressed herein. Depending on the particular conditions expected for the helmet, it may be desirable to increase or decrease the number of layers used in the EIAS, the materials used in the EIAS or the thickness of the layers used in the EIAS. For instance, a heavier player may require an EIAS  30  that is capable of dissipating a larger amount of impact energy than a lighter player. 
     A portion of the IIAS  50 , fixed to the inside of the rigid core  40 , is visible in  FIG. 1 . The IIAS  50  in the preferred embodiment uses four layers, however, it is appreciated that the number of layers may be added or subtracted within the inventive concept expressed herein. Depending on the particular conditions expected for the helmet  10 , it may be desirable to increase or decrease the number of layers used in the IIAS, the materials used in the IIAS or the thickness of the layers used in the IIAS. For instance, a heavier player may require an IIAS that is capable of dissipating a larger amount of impact energy than a lighter player. 
     The facemask  11  is attached to the helmet using snaps  12  and is comprised of a novel material with respect to helmets. In one embodiment, the facemask  11  is comprised of a fiber reinforced polymer that has been modified to withstand the impact forces expected on the facemask without failure. In another embodiment, the facemask is comprised of a carbon fiber reinforced polymer. Carbon fiber reinforced polymer is generally defined as carbon fiber filaments combined with a resin to create a solid material. Carbon fiber reinforced polymers (hereinafter “carbon fiber”) have a relatively high stiffness and high tensile strength for its weight, however, much of its strength is directional. Because the strength of carbon fiber is dependent on the orientation of the individual filaments, it can be very strong in a first direction and very brittle in a second direction. 
     In one embodiment of the facemask  11 , it is comprised of carbon fiber, where most of carbon fiber filaments are oriented along the axes of the elongate bars  13  that comprise the facemask  11 . This configuration optimizes the strength of the facemask  11  in impacts that load the elongate bars  13  in the axial direction. However, carbon fiber filaments can be weak and/or brittle when impacted in a direction normal to its elongate axis, making a conventional carbon fiber compound prone to cracking in this application. In one embodiment, the facemask  11  is modified with a rubberizing compound to increase the flexibility of the facemask  11  in impacts that are normal to the axial direction of the elongate bars. Many types of rubberizing compounds and flexibility promoters are known in the art and could be used in the construction of the facemask  11 . In another embodiment, the resin used to bond the carbon fiber filaments of the facemask  11  is comprised of 30-50% epoxy laminating resin and 50-70% rubberizing compound. In another embodiment, the resin used to bond the carbon fiber filaments of the facemask  11  is comprised of 40% epoxy laminating resin and 60% rubberizing compound. In another embodiment, the resin used to bond the carbon fiber filaments of the facemask  11  is comprised of 35% epoxy laminating resin and 65% rubberizing compound. In another embodiment, the resin used to bond the carbon fiber filaments of the facemask has a hardness of approximately 6.50 on a 0 to 10 scale. The term “approximately” as used herein denotes the stated value along with a variation of 10% in the positive or negative direction. 
     In  FIGS. 2-5  are alternative views of the helmet  10 .  FIG. 2  is a front view of the helmet  10  with the facemask  11  attached.  FIG. 3  is a rear view and  FIG. 5  is a top view of the helmet  10 . 
       FIG. 4  is a side view of the helmet  11 , where the right side and left side views are mirror images of one another. Visible in this view are the EIAS  30  and the IIAS  50 . The rigid core  40  is sandwiched between the EIAS  30  and IIAS  50  and hidden in this view. Towards the edges of the helmet or in the vicinity of the ear holes, the EIAS reduces in thickness so that it has a rounded convex cross section if viewed from the side. The rounded cross sections protect players from the edge of the rigid core  40  and prevent articles from placing a tangential load on the EIAS  30  in those areas. 
     In  FIG. 6  is a bottom view of the helmet  10  with components removed to expose the IIAS  50 . Towards the top of the helmet  10 , the IIAS  50  is comprised of cylindrical impact absorbing components  51  (hereinafter “foam cylinders”). While the components of the IIAS  50  are referred to as foam, they may be comprised of any material with adequate impact absorbing properties and/or contouring properties. Other materials that may be appropriate for use in the IIAS  50  include, but are not limited to, bladders containing a fluid (including gas, liquid, semifluid, semisolid), vinyl encased impact absorbing members or mechanical shock absorbing apparatuses. 
     In one embodiment, the foam cylinders  51  are further comprised of a cylindrical hole  52  oriented along the same axis as the foam cylinder  51 . The cylindrical hole  52  is preferably oriented along the same axis of the foam cylinder  51 , but there are situations where it may be preferable to offset the axes. Offsetting the axes would change the compressive properties of the foam cylinders  51  without having to change their material, diameter or height. The cylindrical holes  52  may be configured as through holes that extend from one end of the foam cylinder  51  to the other. The cylindrical holes  52  may also be configured as countersunk holes where their depth is less than the height of the foam cylinder  51 . The cylindrical holes  52  may also be countersunk from either direction. In some embodiments, the foam cylinders  51  have more than one cylindrical hole  52  to reduce the weight of the foam cylinder and to change its impact absorption properties. In some embodiments, the foam cylinders  51  have a centrally located cylindrical hole  52  and a plurality of smaller holes located in the radial direction from the centrally located cylindrical hole. While the hole has been described as cylindrical for ease of manufacture, holes or voids of other shapes could be substituted. In some embodiments, the cylindrical hole  52  does not extend to either end of the foam cylinders  51  and, instead, is an internal void. 
     In the area of the helmet  10  that contacts a player&#39;s forehead is a forehead pad  54  comprised of an impact absorbing material with one or more holes  55 . The forehead pad  54  is shaped to sit against the inside of the rigid core  40  and between the foam cylinders  51  and elongate strips  57 . The elongate strips  57  are comprised of an impact absorbing material with one or more holes  58 . The area below a player&#39;s ears and between the rigid core  40  and the player&#39;s head are further comprised of ear strips  60  that are comprised of an impact absorbing material, optionally comprised of one or more holes  61 . Similar to the cylindrical holes  52  in the foam cylinders  51 , the holes  55 ,  58  and  61  may be configured as through holes, countersunk from either direction or merely voids internal to the forehead pad  54 . 
     In  FIG. 7  is an exploded perspective view of the helmet  10  with components of the IIAS  50  removed for clarity. The helmet  10  is optionally further comprised of a liner  70  removably fixed to the inner surface. The removable liner  70  can be comprised of a material that provides a wicking effect, anti-bacterial or anti-microbial effect or a moisture barrier effect, among others. Each individual impact absorbing component in the IIAS  50  has an air impermeable layer fixed to the end furthest from the rigid core  40 . 
     For example, the foam cylinders  51  are fixed to the rigid core  40  on one end and a circular air impermeable layer  53  is fixed to the distal end. Similarly, the forehead pad  54 , elongate strips  57  and ear strips  60  are fixed to the rigid core  40  on one end and an air impermeable layer  56 ,  59  and  62  is fixed to their respective distal end. 
     In one embodiment, the air impermeable layers  53 ,  56 ,  59  &amp;  62  (hereinafter collectively “barrier”  63 ) are comprised of vinyl and fixed to the underlying portion of the IIAS  50  with an adhesive. In another embodiment, the barrier  63  is comprised of a plastic sheet adhered to the impact absorbing material. In another embodiment, the barrier  63  is a unitary article fixed to each foam section of the underlying IIAS  50 . In another embodiment, the barrier  63  is not air impermeable, but rather is partially air permeable, allowing an amount of air to pass through the barrier  63 . 
     The barrier  63  greatly increases the effectiveness of the IIAS  50  by utilizing the air trapped in the holes  52 ,  55 ,  58  &amp;  61  to absorb impact energy. In one embodiment, the impact absorbing members  51 ,  54 ,  57  &amp;  60  of the IIAS  50  are comprised of an open cell foam and the barrier  63  is comprised of an air impermeable material. When the impact absorbing members  51 ,  54 ,  57  &amp;  60  are comprised of an open cell foam, the air contained in the holes  52 ,  55 ,  58  &amp;  61  can only enter or exit the hole through the open cell structure of the foam, providing an impact absorbing benefit. The impact absorbing members  51 ,  54 ,  57  &amp;  60  effectively become shock absorbers, where the air flow is regulated by the properties of the open cell foam. While particular shapes are disclosed herein for the impact absorbing members  51 ,  54 ,  57  &amp;  60 , many other shapes could easily be substituted. 
     In one embodiment, the impact absorbing members  51 ,  54 ,  57  &amp;  60  are comprised of an open cell foam and the barrier  63  is comprised of a partially air permeable layer. When the barrier  63  is comprised of a partially or semi-permeable material with respect to air, the shock absorbing effect of the IIAS  50  is reduced. When the barrier  63  is partially permeable, the air contained in the holes  52 ,  55 ,  58  &amp;  61  can exit through the open cell structure of the foam or the permeable structure of the barrier  63 , allowing the air to escape at a greater rate. 
     The shock absorbing effect of the IIAS  50  may also be modified by changing the materials used in the IIAS  50  and the relationship between the size of holes  52 ,  55 ,  58  &amp;  61  relative to their respective impact absorbing members  51 ,  54 ,  57  &amp;  60 . For example, increasing the diameter of the holes  52 ,  55 ,  58  &amp;  61  relative to the size of their respective impact absorbing member  51 ,  54 ,  57  &amp;  60  reduces the lateral distance that the air contained in the holes  52 ,  55 ,  58  &amp;  61  must travel through the impact absorbing member  51 ,  54 ,  57  &amp;  60  before escaping. By reducing the lateral distance, the air contained in the holes  52 ,  55 ,  58  &amp;  61  can escape more easily, therefore reducing the impact absorbing capacity of the IIAS  50 . 
     The shock absorbing effect of the IIAS  50  may also be modified by changing the lateral width of the impact absorbing members  51 ,  54 ,  57  &amp;  60  relative to the diameter of the holes  52 ,  55 ,  58  &amp;  61 , changing the property of the materials used in the IIAS  50  and changing the thickness of the materials used in the IIAS  50 . The shock absorbing effect of the IIAS  50  may also be changed in other ways that are known in the art. 
     In  FIG. 8 a    is a side sectioned view of a portion of the helmet  10 , showing the layering of materials that comprise the EIAS, rigid core  40  and the IIAS. The view in  FIG. 8 a    is not necessarily to scale and is provided to show the positional relationship between the layers of materials. In the preferred embodiment disclosed herein, the EIAS is comprised of two layers and the IIAS is comprised of four layers, however, the number of layers, the thickness of the layers or the material used in the layers can be changed or optimized within the inventive concept expressed herein. 
     In the preferred embodiment, the IIAS  50  is comprised of one or more layers of viscoelastic polyurethane foam (“viscoelastic foam”). This material is also known as low-resilience polyurethane foam, memory foam or temper foam, along with other names. Viscoelastic foam is pressure and temperature sensitive and quickly molds to the contour of an object pressed against it. Viscoelastic foam&#39;s ability to mold around the contour of an object makes it an ideal material for the interior of a helmet. It&#39;s use inside a helmet allows the same helmet to contour to multiple players and eliminate gaps between the IIAS  50  and a player&#39;s head without resorting to an expensive helmet customization process. 
     Viscoelastic foam also provides effective impact cushioning and temperature control. Viscoelastic foam is excellent at absorbing impact and when used in the IIAS  50  and provides impact absorption between a player&#39;s head and the rigid core  40 . Viscoelastic foam also stabilizes the temperature of objects placed against it. It tends to absorb and release heat slowly, allowing the material to stabilize the temperature of a player&#39;s skin. 
     In the preferred embodiment, the IIAS  50  is comprised of three layers of foam, each with different properties, fixed on one end to the inside of the rigid core  40  and sealed on its distal end by the barrier  63 . In this embodiment, a first layer of foam  64  is fixed to the inner surface of the rigid core  40 . Fixed to the first layer is a second layer of foam  65  and fixed to the second layer of foam  65  is a third layer of foam  66 . 
     In some embodiments, the first layer of foam  64  is a soft to medium lightweight viscoelastic foam and the second layer of foam  65  is a firm lightweight viscoelastic foam. The terms soft, medium and firm refer to the relative difficulty to compress an area of foam, otherwise known as the firmness of the foam. A lightweight viscoelastic foam is capable of absorbing the energy of sudden impacts. A material that is particularly well suited for this purpose is an elastomeric, polyurethane viscoelastic open cell foam with a density between one quarter and 15 pounds per cubic foot. In this embodiment, the first layer  64  is comprised of a medium-soft lightweight viscoelastic foam with a density of one half to one pound per cubic foot and the second layer  65  is comprised of a firm lightweight viscoelastic foam with a density of one to one and a half pounds per cubic foot. 
     In this embodiment, the third layer of foam  66  fixed to the second layer of foam  65  is a viscoelastic foam with gel-like properties, an open cell structure and a soft dough-like consistency (hereinafter “gel-like foam”). Gel-like foam with a density between 15 and 50 pounds per cubic foot is particularly effective at maintaining its shape when worn by a user and providing effective impact cushioning. In some embodiments, a gel-like foam with a density between 15 and 33 pounds per cubic foot is used to provide effective impact cushioning in the helmet. In another embodiment, a gel-like foam with a density between 30 and 35 pounds per cubic foot is used in the first layer  64 . An important characteristic of the gel-like foam used in this embodiment is that it is capable of easily molding around a player&#39;s head to eliminate gaps. 
     In the preferred embodiment, it is preferable that the first layer  64  and second layer  65  are substantially the same thickness and that the third layer  66  is 50-70% of the thickness of either the first or second layer  64  &amp;  65 . In this instance, substantially the same thickness means a thickness up to and including a 10% variation from one another, so that if the second layer is 1.0 inch thick, the third layer  66  would still be substantially the same with a thickness of 1.1 inches. While the use of viscoelastic foam has been disclosed as the preferred embodiment, it is appreciated that other materials with similar impact absorbing and density properties would also be suitable for this application. 
     In some embodiments, the first layer  64  comprises a medium lightweight viscoelastic foam with a thickness of about 0.3 to 0.75 inches, the second layer  65  comprises a medium soft lightweight viscoelastic foam with a thickness of about 0.30 to 0.75 inches and the third layer  66  comprises a gel-like foam with a thickness of about 0.20 to 0.50 inches and a density of about 15 pounds per cubic foot to 50 pounds per cubic foot. In some embodiments, the first layer  64  comprises a medium lightweight viscoelastic foam with a thickness of about 0.4 to 0.6 inches, the second layer  65  comprises a medium soft lightweight viscoelastic foam with a thickness of about 0.4 to 0.6 inches and the third layer  66  comprises a gel-like foam with a thickness of about 0.25 to 0.35 inches and a density of about 15 pounds per cubic foot to 50 pounds per cubic foot. In some embodiments, the first layer  64  comprises a medium lightweight viscoelastic foam with a thickness of about 0.45 inches to 0.55 inches, the second layer  65  comprises a medium soft lightweight viscoelastic foam with a thickness of about 0.45 to 0.55 inches and the third layer  66  comprises a gel-like foam with a thickness of about 0.25 to 0.32 inches and a density of about 15 pounds per cubic foot to 50 pounds per cubic foot. In some embodiments, the first layer  64  comprises a firm lightweight viscoelastic foam with a thickness of about 0.4 inches to 1.0 inch the second layer  65  comprises a medium lightweight viscoelastic foam with a thickness of about 0.3 to 0.75 inches and the third layer  66  comprises a gel-like foam with a thickness of about 0.2 to 0.5 inches and a density of about 15 pounds per cubic foot to 50 pounds per cubic foot. In some embodiments, the first layer  64  comprises a firm lightweight viscoelastic foam with a thickness of about 0.6 inches to 0.9 inches the second layer  65  comprises a medium lightweight viscoelastic foam with a thickness of about 0.4 to 0.6 inches and the third layer  66  comprises a gel-like foam with a thickness of about 0.25 to 0.35 inches and a density of about 15 pounds per cubic foot to 50 pounds per cubic foot. In some embodiments, the first layer  64  comprises a firm lightweight viscoelastic foam with a thickness of about 0.7 inches to 0.8 inches the second layer  65  comprises a medium lightweight viscoelastic foam with a thickness of about 0.45 to 0.55 inches and the third layer  66  comprises a gel-like foam with a thickness of about 0.25 to 0.32 inches and a density of about 15 pounds per cubic foot to 50 pounds per cubic foot. 
     In the preferred embodiment, the EIAS  30  is comprised of a layer  31  of lightweight viscoelastic foam fixed to the exterior of the rigid core  40  to absorb the impact energy from sudden impacts on the exterior of the helmet  10 . In one embodiment, the layer  31  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one half and 15 pounds per cubic foot. In another embodiment, the layer  31  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one half and eight pounds per cubic foot. In another embodiment, the layer  31  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one and two pounds per cubic foot. In another embodiment, the layer  31  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one and one and a half pounds per cubic foot. While a viscoelastic foam is used in this embodiment, other materials capable of absorbing high impact energy would also be suitable. 
     The EIAS  30  is further comprised of a water-resistant layer  32  fixed to the top of the layer  31 . Various waterproof layers or coatings would be suitable, including, but not limited to, a rubberized coating or room temperature vulcanization silicone. In some embodiments, a two part, flexible polyurethane adhesive is applied as the water-resistant layer  32 . The two part, flexible polyurethane adhesive must be hard enough to resist scuffing and tearing, but also soft enough to remain flexible. Materials with a Shore hardness of A30 to A90 can be appropriate for use in the water-resistant layer  32 . In some embodiments, the water-resistant layer  32  is comprised of a two part, flexible polyurethane adhesive with a Shore hardness between A40 and A70. In other embodiments, the water-resistant layer  32  is comprised of a two part, flexible polyurethane adhesive with a Shore hardness of approximately A50. In one embodiment, the layer  31  is three to six times as thick as the water-resistant layer  32 . In another embodiment, the layer  31  is four to five times as thick as the water-resistant layer  32 . In another embodiment, the water-resistant layer  32  is approximately 1.0 mm thick. To increase the abrasion resistance of the EIAS  30 , the outer surface may optionally be wrapped with a flexible abrasion resistant material, such as a fiber reinforced cloth. Various reinforced materials would be suitable, including, but not limited to, Exotex® Dacron cloth. 
     In some embodiments, the EIAS  30  comprises a single layer of ethylene-vinyl acetate (hereinafter “EVA”). When the EIAS  30  comprises EVA, the material may be applied in sheet form at thicknesses of between and including 0.1 inches to 0.8 inches. When the EIAS  30  comprises EVA, it is preferable for the material to have a thickness of between and including 0.2 inches to 0.3 inches. 
     In the preferred embodiment, the rigid core  40  is a fiber reinforced polymer comprised of carbon fibers, aramid fibers and a resin. In one embodiment, the rigid core  40  is comprised of a layer of carbon fiber reinforced polymer on the exterior and a layer of Kevlar reinforced polymer (hereinafter “Kevlar”) on the interior of the rigid core  40 , where the layer of Kevlar is approximately three times the thickness of the layer of carbon fiber. This thickness ratio of Kevlar to carbon fiber provides an effective balance between strength, weight and durability against impact. In another embodiment, the layer of Kevlar on the interior of the rigid core  40  is about two times the thickness of the layer of carbon fiber on the exterior of the rigid core  40 . A rigid core  40  comprised only of carbon fiber is possible, but rigid core  40  would need to be comparatively thick to be capable of sustaining repetitive impacts normal to the direction of the carbon fiber filaments. The Kevlar layer provides additional strength to the carbon fiber and is more flexible to impacts normal to the direction of the Kevlar fibers, making the rigid core  40  more resistant to cracking. In another embodiment, the rigid core  40  is comprised of a Kevlar layer and carbon fiber layer where the Kevlar layer is one to five times the thickness of the carbon fiber layer. In another embodiment, the rigid core  40  is comprised of a Kevlar layer and carbon fiber layer where the Kevlar layer is approximately 0.6 mm thick and the carbon fiber layer is approximately 0.2 mm thick. In some embodiments, the carbon fiber layer is located on the interior of the rigid core  40  and the Kevlar layer is located on the exterior of the rigid core  40 . 
     In one embodiment, the rigid core  40  is modified with a rubberizing compound to increase the flexibility of the rigid core  40  in impacts that are normal to the axial direction of the carbon fiber filaments. Many types of rubberizing compounds and flexibility promoters are known in the art and could be used in the construction of the rigid core  40 . In another embodiment, the resin used to bond the carbon fiber filaments and the Kevlar fibers of the rigid core  40  is comprised of 30-50% epoxy laminating resin and 50-70% rubberizing compound. In another embodiment, the resin used to bond the carbon fiber filaments and Kevlar fibers of the rigid core  40  is comprised of 40% epoxy laminating resin and 60% rubberizing compound. In another embodiment, the resin used to bond the carbon fiber filaments and Kevlar fibers of the rigid core  40  is comprised of 35% epoxy laminating resin and 65% rubberizing compound. In another embodiment, the resin used to bond the carbon fiber filaments and Kevlar fibers of the rigid core  40  has a hardness of approximately 6.50 on a 0 to 10 scale. 
     In some embodiments, the carbon fiber and Kevlar fibers are oriented to maximize the rigid core&#39;s  40  resistance to frontal and rear impacts. The carbon fiber and Kevlar cloth can be oriented so that the fibers towards the front and rear of the helmet are positioned horizontally and vertically in a woven pattern. 
     While carbon fiber and Kevlar are well suited for use as the rigid core  40 , it is appreciated that there are multiple materials that would be suitable. For instance, Exotex® Dacron has a high strength to weight ratio that exceeds that of carbon fiber and would also be an ideal material for the rigid core  40  when combined with a plastic resin. Other type of basalt fiber based composite materials would have similar high strength and low weight characteristics. The purpose of the rigid core  40  is to provide structure to the helmet  10  and many materials could be suitable based on the desired weight, crush resistance and cost of the helmet. 
     In  FIG. 8 b    is a side sectioned view of a portion of an alternative embodiment of the helmet  100 , showing the layering of materials that comprise the EIAS, rigid core  140  and the IIAS. The view in  FIG. 8 b    is not necessarily to scale and is provided to show the positional relationship between the layers of materials. In the alternative embodiment disclosed herein, the EIAS is comprised of two layers and the IIAS is comprised of four layers, however, the number of layers, the thickness of the layers or the material used in the layers can be changed or optimized within the inventive concept expressed herein. 
     In the alternative embodiment, the IIAS is comprised of three layers of foam, each with different properties, fixed on one end to the inside of the rigid core  140  and sealed on its distal end by the barrier  163 . In the alternative embodiment, the first layer  164  fixed to the inside of the rigid core  140  is a soft to medium firmness lightweight viscoelastic foam is fixed to the inside of the rigid core  140 . A layer of firm hardness lightweight viscoelastic foam, comprising the second layer  165 , is fixed to the bottom of the soft to medium firmness foam. In this embodiment, the first layer  164  is comprised of a medium-soft lightweight viscoelastic foam with a density of one half to one pound per cubic foot and the second layer  165  is comprised of a firm lightweight viscoelastic foam with a density of one to one and a half pounds per cubic foot. In some embodiments, the first layer  164  is comprised of a lightweight viscoelastic foam with a density of one quarter to six pounds per cubic foot and the second layer  165  is comprised of a lightweight viscoelastic foam with a density of one half to six pounds per cubic foot. 
     In the alternative embodiment, the third layer  166  is comprised of a gel-like foam with a density between 30 and 35 pounds per cubic foot. In some embodiments, the third layer  166  is comprised of a gel-like foam with a density between 15 and 50 pounds per cubic foot. 
     In the alternative embodiment, it is preferable that the first layer  164  and third layer  166  are substantially the same thickness and that the second layer  165  is 125-175% of the thickness of either the first or third layer  164  &amp;  166 . In this instance, substantially the same thickness means a thickness up to and including a 10% variation from one another, so that if the second layer is 1.0 inch thick, the third layer  166  would still be substantially the same with a thickness of 1.1 inches. In some embodiments, the first layer  164  is approximately a half inch thick, the second layer  165  is approximately three quarters of an inch thick and the third layer is approximately a half inch thick. In some embodiments, it is preferable for the first layer  164  to be about 1.5 times the thickness of the second layer  165  and for the third layer to be about 0.6 times the thickness of the second layer  165 . In some embodiments, it is preferable for the first layer  164  to be about the same thickness as the second layer  165  and for the third layer to be about 0.6 times the thickness of the second layer  165 . 
     In the alternative embodiment, the EIAS is comprised of a layer  131  of lightweight viscoelastic foam fixed to the exterior of the rigid core  140  to absorb the impact energy from sudden impacts on the exterior of the helmet  100 . In one embodiment, the layer  131  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one half and 15 pounds per cubic foot. In another embodiment, the layer  131  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one half and eight pounds per cubic foot. In another embodiment, the layer  131  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one and two pounds per cubic foot. In another embodiment, the layer  131  is comprised of an elastomeric, polyurethane viscoelastic open cell foam with a density between one and one and a half pounds per cubic foot. While a viscoelastic foam is used in this embodiment, other materials capable of absorbing high impact energy would also be suitable. The EIAS of the alternative embodiment is further comprised of a water-resistant layer  132  fixed to the top of the layer  131 . Various waterproof layers or coatings would be suitable, including, but not limited to, the materials disclosed for the water-resistant layer  32  of the preferred embodiment. The rigid core  140  of the alternative embodiment may be comprised of multiple suitable materials, including, but not limited to, the materials disclosed for the rigid core  40  of the preferred embodiment. 
     In  FIGS. 9-11  are exploded perspective views of the inside of the helmet with components of the IIAS  50  removed for clarity. These figures show the sizing and position of each type of foam used in the preferred embodiment. Foam cylinders  51  are used to protect the top of a player&#39;s head to balance the weight of the IIAS  50  and its impact absorption qualities. The foam cylinders  51  are designed with an air void volume (contained in the cylindrical holes  52 ) to foam volume ratio that optimizes the impact absorption and weight of the IIAS  50 . 
     The top of the helmet experiences high impact hits as well as many lower energy hits. Therefore, the top of the helmet must be soft enough to protect a player from lower energy subconcussive impacts and remain capable of protecting a player from high energy impacts. The IIAS  50  and the foam cylinders  51 , in particular, are designed to deflect when subject to subconcussive impacts and absorb high energy impacts without bottoming out. Bottoming out in this application is when a material has been compressed to its minimum height. Bottoming out is undesirable in a helmet because once the impact absorbing material bottoms out, it cannot provide any substantial impact absorption. 
     The foam cylinders  51  are effective at providing absorption of subconcussive and high energy impacts because of the sealed air void located at their centers. An open cell foam can be readily compressed, however air in a sealed space is much more difficult to compress. The air in the center of the foam cylinders  51  is not completely sealed, in that it can escape through the open cell structure of the foam, but when subject to a high energy impact, the air momentarily acts similarly to air trapped in a sealed container to absorb the high energy impact. As the foam cylinder compresses, the air is pushed through the open cell structure of the foam, absorbing the remainder of the impact. The use of air in a void at the center of the foam cylinders  51  allows the use of a softer foam than would otherwise be appropriate because it reduces the risk of bottoming out in high energy impacts. 
     The forehead pad  54 , elongate pieces  57  and ear pieces  60  use a smaller air void to foam ratio because they are subject to more high impact hits than the top of the helmet. The use of smaller air voids provides a level of protection from bottoming out while also providing shock absorption from the foam itself. 
     In  FIGS. 12-16  are detailed views of three types of foam components used in the IIAS  50 . In  FIGS. 12-13  is an example of a foam cylinder  51  with the vinyl barrier  53  removed. In  FIGS. 14 &amp; 15  is an example of a forehead pad  54  with the vinyl barrier  56  removed. In  FIG. 16  is an example of an elongate pad  57  with the vinyl barrier  59  removed. 
     What has been described is a football helmet designed to reduce the occurrence of concussions and the magnitude of subconcussive impacts to the head. While this disclosure shows the invention as a football helmet, all or part of the invention is capable of being used in other applications. In this disclosure, there is shown and described only the preferred embodiments of the invention, but, as aforementioned, it is to be understood that the invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein.