Patent Publication Number: US-2017367428-A1

Title: Protective Athletic Helmet to Reduce Linear and Rotational Brain Acceleration

Description:
RELATIONSHIP TO PRIOR APPLICATION 
     This patent application is a Continuation-In-Part Patent Application relating to and claiming the benefit of U.S. Non-Provisional patent application Ser. No. 14/504,670, which relates to and claims the benefit of U.S. Provisional Patent Application Ser. No. 61/961,968 filed Oct. 28, 2013 and U.S. Provisional Patent Application Ser. No. 61/995,829 filed Apr. 21, 2014. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to protective helmets, in particular, protective helmets used in sporting events. More particularly, this invention relates to football helmets. 
     It is estimated that there are currently five million football players in the U.S. (200,000 professional, 100,000 college, 1.3 million high school, and 3.5 million youth players). In recent years, it has become quite clear that the most popular sport in America is actually quite dangerous. Estimates vary, but several studies suggest that up to fifteen percent of football players suffer at least a mild traumatic brain injury (MTBI) each season. 
     For decades, football players and other athletes have grappled with the effects, years later, of head injuries, including memory loss, moods swings, irritability, difficulty walking, and depression. These symptoms are potential indications of chronic traumatic encephalopathy, a degenerative disease found in the brains of athletes who have sustained blows to the head. 
     For professional football, it has been found that there is an average of 1.5 to 2.0 concussions each game. The chances for a concussion or other injuries, such as a neck injury, are exacerbated during helmet-to-helmet contact. In high school football in recent years, there are approximately 67,000 diagnosed concussions every year. Additionally, many undiagnosed and unreported concussions are experienced. Experts in the field contend that linear and particularly rotational acceleration of the brain caused by on-field impacts is a major factor leading to MTBI and concussions. While many existing helmets help to attenuate linear acceleration, it is believed that none realistically address reduction of rotational acceleration caused by oblique or angular impacts. Thus, there is a need for safer helmets, particularly football helmets, which reduce the risk of injury to the user and to the other players. This invention is also applicable to other activities in which participants use helmets, such as soccer, lacrosse, hockey, boxing, cycling, skiing, wrestling, auto racing, and military. 
     In May 2013, the Biomedical Engineering Society published a peer-reviewed research report from Virginia Tech that was sponsored by the National Institutes of Health. The report concluded that a helmet that lowers head acceleration predicts a lower incidence of concussion, and that helmets which better manage impact energies result in lower head accelerations and thus a lower risk of head injury. 
     OBJECTS OF THE INVENTION 
     It is one object of this invention to provide an improved athletic helmet to help in reducing the risk of concussions, mild traumatic brain injuries (MTBI), and other head injuries. 
     It is another object of this invention to provide an improved athletic helmet to reduce the effects of both linear and rotational acceleration of the brain upon impact, since lowering head acceleration lowers the risk of concussion. 
     It is another object of this invention to provide a helmet which offers rotational acceleration protection in addition to meeting or exceeding the current NOCSAE (National Operating Committee on Standards for Athletic Equipment) linear acceleration certification specifications and is light weight, has a soft outer surface, and has a smaller profile than current helmets. 
     SUMMARY OF THE INVENTION 
     In accordance with one form of this invention there is provided a protective helmet including an upper section and a lower section, each of the upper and lower sections having an inner facing surface; a gap formed between the upper section and the lower section; at least one resilient member connecting the upper section to the lower section; the upper section being movable with respect to the lower section whereby at least a portion of the force from an impact to the upper section will be absorbed and will not be transmitted to the lower section; an inner shell securable to the inside surface of the lower section; the inner shell having an inner facing surface adapted to receive a portion of the helmet user&#39;s head, whereby the head of the user will be spaced from the inner facing surface of the upper section when the portion of the user&#39;s head is received in the inner shell; at least one foam member attached to the inner shell and contacting the inner facing surface of the lower section; and the inner shell extending into the inside of the upper section; the inner shell substantially preventing the user&#39;s head from making contact with the inner facing surface of the upper section. 
     In accordance with another form of this invention there is provided a protective helmet including an upper section and a lower section; each section having an inside surface and an outside surface; a gap formed between the upper section and the lower section; at least one connection member connecting the upper section to the lower section and maintaining the gap; the upper section being movable with respect to the lower section when an impact force is applied to the outside surface of the upper section; an inner shell securable to the inside surface of the lower section; the inner shell having an inner facing surface adapted to receive a portion of the helmet user&#39;s head, whereby the head of the user will be spaced from the inner facing surface of the upper section when the portion of the user&#39;s head is received in the inner shell; and the inner shell extending into the inside of the upper section; the inner shell substantially preventing the user&#39;s head from making contact with the inner facing surface of the upper section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a frontal view showing one of the preferred embodiments of the invention; for illustration purposes, the face guard, chinstrap, and jaw pads are not shown. 
         FIG. 1A  is a side view of the embodiment of  FIG. 1 . 
         FIG. 2  is a frontal view of a compression strut shown in  FIG. 1 . 
         FIG. 2A  is a side view of the compression strut shown in  FIG. 2 . 
         FIG. 3  is a perspective view of a suspension head harness before insertion in the helmet of  FIG. 1 . 
         FIG. 4  is a top view of the suspension harness of  FIG. 3  received in the lower section of the helmet of  FIG. 1  with the upper section having been removed. 
         FIG. 5  is a side view of the embodiment of  FIG. 1  with a stretchable band covering the gap between the upper and lower sections of the helmet. 
         FIG. 6  shows an alternative embodiment of the invention whereby the helmet of  FIG. 1  is removably attached to a shoulder pad. 
         FIG. 6A  is a side view of one of the attachment clips of  FIG. 6 . 
         FIGS. 7 and 7A  show an alternative embodiment of the invention with the addition of a sliding horizontal continuous band attached to a modified version of the upper and lower sections of the helmet of  FIG. 1 . 
         FIG. 8  is an alternative embodiment of the invention whereby the circumference of the periphery of the outer edge of the upper section of the helmet of  FIG. 1  is greater than the circumference of the periphery of the outer edge of the lower section. 
         FIG. 9A  is a perspective view of an inner shell before insertion in the helmet. 
         FIG. 9B  is a bottom plan view of the inner shell of  FIG. 9A . 
         FIG. 10  is a perspective view of the inner shell of  FIG. 9A . 
         FIG. 11  is a partially exploded view of the inner shell of  FIG. 9A  received in the lower section of the helmet of  FIG. 1  with the upper section having been separated. 
         FIG. 12  is a top plan view of the inner shell of  FIG. 9A  received in the lower section of the helmet of  FIG. 1  with the upper section having been removed. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     Referring now more particularly to  FIGS. 1 and 1A , there is provided helmet  10  having pliant upper soft-shell section  12  and lower hard-shell section  14 . This is a two-piece helmet whereby upper section  12  can move independently of lower section  14  with the wearer&#39;s head being securely anchored to and inside lower section  14 . 
     The wearer&#39;s head thus will extend upward into airspace inside the upper portion  12 . Upon impact to upper section  12 , a reduced amount of energy is transmitted to the head since the head is “floating” in the airspace. Unlike conventional helmets, the head does not contact upper section  12 . 
     To allow the helmet  10  to absorb more of the energy of an impact, there is the need to extend the duration of the impact motion by having helmet upper section  12  that inwardly flexes, and then slowly restores itself. The longer it takes for the helmet shell to bend, the more energy it absorbs. The result is less energy being transferred to the wearer&#39;s head and brain. In order to reduce linear and rotational acceleration of the brain, upper section  12  offers impact protection in two ways. The entire upper section  12  itself will move due to the nature of struts  16 , which are discussed below, upon impact. Also, the pliable “semi-soft” surface of upper section  12  will flex inwardly upon impact. Both actions serve to absorb energy and attenuate dramatic motion of the head, with a resultant decrease in linear and rotational brain acceleration. 
     Upper section  12  preferably is made from semi-flexible polyethylene or polyurethane foam with a urethane coating on the outer surface. It is preferred that upper section have conventional ventilation holes (not shown). The lower section  14  preferably is made from polycarbonate alloy (PCA) or acrylonitrile butadiene styrene plastic (ABS) by injection molding. Lower section  14  has conventional earhole openings  15  and is of conventional shape, approximately 3/16 inch thick. There is a spacing gap  18  between upper section  12  and lower section  14  preferably approximately ½ inch. The bottom of the gap is preferably positioned approximately 1-½ inches above the lowest edge  19  of the front  21  of lower section  14  and continues horizontally around the periphery of the lower section  14 . Compression struts  16  attach to upper section  12  and lower section  14  preferably with bolts and are positioned to provide the ½ inch spacing of gap  18 . Preferably there are four compression struts  16 . In addition to their flexing action, the struts  16  serve to connect upper section  12  and lower section  14 . 
       FIGS. 2 and 2A  show one of the plastic compression struts  16 . Struts  16  are preferably located at the front, rear, and both sides of helmet  10 . Due to the ½ inch spacing of gap  18  between upper section  12  and lower section  14  of the helmet  10 , the compression struts  16  can compress, flex, and slightly rotate in any direction, so that some of the impact energy will be absorbed and thus reduce the harmful effects to the head during an impact on the upper section  12  of helmet  10 . The absorption of this impact energy occurs because of the movement of upper section  12  and the resilient nature of compression struts  16 . This reduces the linear and rotational acceleration of the brain. Since the head harness  20 , described below, is attached to lower section  14 , forced movement of upper section  12  is not directly transmitted to the head, which is firmly held in place inside lower section  14 . Upper section  12  will move slightly in any direction upon impact, but will return to its normal position due to the flexing nature of struts  16 . The struts  16  preferably limit the movement of upper section  12  to approximately ½ inch in any direction. 
     In the embodiment of  FIGS. 1 and 1A , there are four compression struts  16 . Preferably the struts  16  are fabricated from hollow tubing of plastic or rubber so as to retain their curvature when they are cut into curved pieces preferably 1-¼ inches wide by 1-¾ inches high as shown in  FIGS. 2 and 2A . The struts  16  are mounted to upper section  12  and lower section  14  with the concave side  23  of strut  16  facing the inside surfaces of the upper section  12  and lower section  14  of helmet  10 . The curvature retention and the concave mounting add to the ability of the struts  16  to flex and return to their original position. Before cutting a tube to form the struts  16 , the outside diameter of the hollow tubes is preferably between ¾ inch and 1-½ inches, the inside diameter is preferably between ½ inch and ¾ inches, and the wall thickness is preferably between 1/16 inch and ¼ inch thick. In another embodiment, the struts  16  include a uniformly flat surface having a common plane. Also preferably, the Durometer hardness of the material from which the compression struts  16  are made is between 40A and 75A, the tensile strength is between 1800 psi and 2700 psi, and the bend radius is between 1.25 inches and 4 inches. Preferably the compression struts  16  are made from tubular polyvinyl chloride. An example of an appropriate tube is commercially available from McMaster-Carr Supply Company as part #5894K41. The compression struts  16  may be customized for all groups of users. For example, youth helmets may have a softer flex than professional helmets to offer added protection. Alternatively, the struts  16  may be made from plastic, rubber stock, a blend thereof, or any other comparable material having the above-listed characteristics. 
     Upper section  12  may be formed by thermoforming, casting or by injection molding, or a similar process, a semi-flexible polyurethane or cross-linked polyethylene foam to the proper shape. The contour of the upper section  12  outer surface may be rounded more than traditional helmets so as to promote the deflection of a blow by an opponent&#39;s helmet or other surface. With less “flat” surfaces and a more sloped surface area, the striking helmet can more easily “slide off” the subject helmet, and vice versa, thus reducing the energy of the impact. Preferably the foam for upper section  12  is approximately ⅜ inch to ½ inch thick with a density of 4-6 pounds per cubic foot. Other foam materials may be utilized such as TPU, TPR, EPS, LDPE, HDPE, or similar, as well as leather and leather/foam laminates. To impart surface resistance to impact and abrasion, the outer surface of shaped foam upper section  12  may be coated with a polyurethane polyurea hard coating, or a similar coating such as thixotronic plastics. However, the resulting structure should have the ability to inwardly flex and return to its original shape. Four coats are equivalent to approximately  3  mils thickness, which is the preferred thickness. A suitable polyurethane polyurea coating is commercially available from Industrial Polymers of Houston, Tex. 
       FIG. 3  shows suspension head harness  20  which includes a curved plastic band  22 . Head harness  20  further includes foam ring  26  received on the inside of band  22 . The circumference of band  22  and ring  26  are selected to fit an individual user&#39;s head. The foam ring  26  will be described in more detail below. Plastic band  22  is preferably made from polypropylene, ¾ inch wide. Two similar commercially available bands  22  are Lowes item #30246 and Ace Hardware item #554-25. 
     Head harness  20  further includes a pair of crossed 1-½ inches wide head straps  28  and  30  that rest against the top of the user&#39;s head. Head straps  28  and  30  limit how far the user&#39;s head can extend upward into upper section  12 . Preferably the straps are made from nylon or polypropylene webbing. A suitable strap material is commercially available from Tennessee Webbing as item #WP1001-2. 
       FIG. 4  shows a top view of lower section  14  as viewed from above. Head harness  20  is mounted inside lower section  14 . For illustrative purposes, upper section  12  is not shown in  FIG. 4 . Foam pad  27 , approximately 2 inches by 1 inch by ¼ inch thick, may be affixed to the upper surface of strap  28  where it crosses strap  30 . This pad offers additional protection against the top of the wearer&#39;s head from hitting the top inside surface of upper section  12  during a severe impact. 
     The positioning of head harness  20  inside the lower section  14 , and the elimination of conventional interior padding, results in airspace between the user&#39;s head and the inside top and inside side surfaces of upper section  12 . This airspace provides space for the compression struts  16  to flex laterally, inwardly, and downwardly during an impact so that upper section  12  may move without touching the wearer&#39;s head. Head harness  20  is secured to lower section  14  by tee-bolts or “one-way” snaps. 
     Ring  26  is made from foam and may be attached to plastic band  22  using screws, snaps, hook and loop fasteners, or glue. Four foam spacers  24  are attached to the outer surface of band  22  and serve to offset the head harness  20  from the inner surfaces of the lower section  14 . The spacers  24  are positioned in the center of the four quadrants of band  22  and are approximately 2 inches by 1 inch by 1 inch thick. The spacers  24  further add to the impact-absorbing features of the helmet. Foam pads  31  are attached by glue at the inside center front and rear of lower section  14  to offer additional energy absorption upon impact. These two pads  31  are mounted so as to be opposite to ring  26  at approximately the same height. 
     Bolts may be positioned through the thickness of spacers  24  from the inside to the outside of the pad, and through drilled holes in lower section  14 . The bolts are fastened with tee-nuts that, after tightening, are flush to the outside surface of lower section  14 . Head straps  28  and  30  may also be attached with the same bolts used to attach the spacers  24 , by affixing the ends of the head straps  28  and  30  in between band  22  and foam ring  26 . Since the four spacers  24  are attached to band  22 , the entire head harness assembly  20  is thereby affixed to the inner surfaces of lower section  14 . Acceptable foams for ring  26  are foams C-40, C-42, C-45 and C-47 commercially available from 3M Company&#39;s Confor, Durafoam from Monmouth Rubber and Plastics Corp., Poron XRD Foam from Rogers Corp., SunMate Firm and X Firm from Dynamic Systems, Inc. These foams are “slow spring-back” foams. A slow return to the foam&#39;s normal position after impact means that there is less dramatic rebound and more energy absorption. 
     Size adjustability of head harness suspension  20  is accomplished by using replaceable pieces of foam ring  26  having varying thicknesses and degrees of firmness. To aid in this replacement feature, the foam  26  may be attached to band  22  with Velcro, Dual Lock from 3M, or other hook and loop fasteners, or with one-way snaps. The length of head straps  28  and  30  may also be adjusted for varying head sizes. 
     The compression struts  16  and foam rings  26  and pads  24  and  31  may be treated with an anti-microbial material to reduce the transmission of disease and inhibit odor and the growth of mold and mildew. An example is Microban, commercially available from Microban Company. The foam pad  26  may also be covered with an absorbent material to absorb perspiration. Suitable absorbent materials include common nonwoven, woven, or knit materials. 
       FIG. 5  shows helmet  10  with a 7/16 inch to 2 inches wide stretchable band  32  or flexible gasket, around the periphery to cover the ½ inch air space  18  and to keep out debris. The stretchability will further permit the upper section  12  to move independently from lower section  14  upon impact. The band may be attached to upper section  12  and lower section  14  by intermittent lines of adhesive. Examples of suitable materials for band  32  are commercially available from McMaster-Carr as item #8825K68 1 inch poly elastic or Ace Hardware 51270 Vinyl Gasket. The band  32  may also be customized in terms of size and material. For example, band  32  may consist of an EPDM foam rubber “bulb seal” gasket. Attached to the outside lower edge of upper section  12 , the “bulb” may extend outwardly approximately ½ to ¾ inch and the flap section of the gasket would extend downwardly to cover gap  18 . An example of a commercially available gasket is McMaster-Carr&#39;s part #93085K91. 
     If added stiffness is needed for higher levels of football participation, additional struts  16  may be utilized beyond the four shown. For example, sir or eight struts may be used, and stiffer struts may be utilized. 
     There may be mechanisms for attaching a conventional faceguard (not shown) to lower section  14  with bolts on each side of the faceguard. To attenuate energy and to action as a shock absorber, the bolt connectors may include thick compressible washers (not shown) made from foam, rubber, fiber, plastic or similar. The washers may be ¼ inch to ½ inch in thickness and placed between the outer surface of lower section  14  and the inner surface of the faceguard attachment area. To further absorb impact energy, the faceguard may be attached at its side to lower section  14  and not at the top of the faceguard as in conventional constructions. Thus, an impact to the facemask will not be transmitted to upper section  12  and the upper section  12  will be able to rotate/flex without regard to the facemask. The faceguard may also be formed from any material suitable to function as a football helmet faceguard, as is known in the art. Plastic covered metal or plastic are two examples of suitable materials. The faceguard may also be constructed of titanium, for example, to reduce its weight from a typical 1.2 pounds to 0.55 pound. Other lightweight and more compressible materials may also be utilized. 
     An adjustable chinstrap (not shown) may be attached to the outer surface of lower section  14 . The chinstrap may be of conventional design with a chin cup, as is known in the art. Preferably, the chinstrap will contain two straps on each side and will be releasably secured to four outside locations of lower section  14  by male and female snap connectors. 
     Two jaw pads (not shown), one on each side, may be attached to the inner surface of lower section  14 . The pads may be of conventional design and made from resilient material, as is known in the art. Each pad will be preferably connected at three points with lower section  14 , preferably with male and female snaps or hook and loop fasteners. This will result in easy insertion and removal for size adjustability. 
     Helmet  10  has been designed to reduce the overall weight and profile to further attenuate the risk of MTBI and concussion. The preferred embodiment with a soft top would be especially suitable for youth football players, ages 5-13, for several reasons. It is lighter weight and has a smaller profile than conventional helmets. Since the helmet flexes and is “soft” it cannot be used as a “dangerous weapon” against another player, even accidentally. The reduction of weight and profile will help to attenuate the impact forces transmitted to the brain. As an example, the size large youth helmet of the subject invention should weigh approximately 2.70 pounds, compared to 3.80 to 4.20 pounds for leading commercially available large youth helmets. This is a 29 to 36 percent reduction. For a nine year-old football player, this reduces the helmet mass as a percentage of head mass from about 41 percent down to 31 percent, which is critical to the development of young brains. The profile of helmet  10  may be reduced since the subject design does not need to accommodate the thicknesses of foam pads as found in the tops and side of conventional helmets. As part of the smaller profile, the contour of helmet upper section  12  may be more rounded as discussed above. The utilization of a “soft top” design should be considered in the context of all players wearing a similar “soft” helmet. 
     The National Operating Committee on Standards for Athletic Equipment (NOCSAE) is the governing body for certification of football helmets. However, the NOCSAE “Drop Test” measures only linear brain acceleration. Measured is the Severity Index (SI) which rates the protectiveness of a helmet based on the risk of severe skull fracture and the peak linear acceleration measured in Gs. Thus, current certified helmets do a good job of attenuating linear acceleration, which in turn limits catastrophic head injuries such as skull fracture, lacerations, etc. However, research indicates that high values of rotational or angular acceleration of the brain also plays a major role, if not being the major factor, in causing MTBI and concussions. 
     Initial prototypes of helmet  10  (both the soft top, and the hard top version discussed below) were sent to a leading bioengineering laboratory for impact testing. Both subject helmets and a commercially available “control” helmet were subjected to the Linear Impactor Test, which measures both linear and rotational acceleration of the brain at various locations on the helmet. This is a more stringent test than the required NOCSAE Drop Test since the hybrid dummy headform, on which the test helmets are mounted, includes a neck-spring component. 
     Three criteria were used to evaluate the severity of each impact: Head Injury Criteria (HIC), Severity Index (SI), and Peak Angular Acceleration. From the results, values were calculated to correlate these indices to the risk of severe brain injury and to the risk of MTBI or concussion. 
     Initial prototypes of helmet  10  easily surpassed the NOCSAE certification standards for linear acceleration and were comparable to the control helmet. The tests on these helmets  10  and subsequent calculations also indicated that the risks of severe brain injury, MTBI, and concussion were extremely low. Moreover, the subject helmets surpassed the control helmet in lowering rotational acceleration, which is felt to be a major predictor of concussion and other head injuries. As an example, Peak Angular Acceleration of the headform for a rear impact was 1787 rad/s2 for soft top  10 , as compared to 2785 rad/s2 for the control helmet. In these tests, the soft top upper section  12  outperformed the hard top upper section  12  in reducing the peak rotational acceleration values. 
     An alternative embodiment utilizes a “hard top” for upper section  12 . The hard top can utilize the same polycarbonate alloy or acrylonitrile butadiene styrene plastic as lower section  14  and is approximately 3/16 inch thick. The rest of helmet  10  is identical to that described above except that the two struts  16  on the sides of helmet  10  would be constructed from a firmer plastic, such as #5233K71 from McMaster-Carr. The hard top embodiment would be suitable for older high school, collegiate and professional players. As mentioned above, this embodiment may also contain more than four struts and may utilize stiffer struts. The side struts  16  may differ from the front and rear struts in composition/flex. Test results discussed above show that this hard top version of helmet  10  exceeded the NOCSAE certification standards and reduced rotational acceleration compared to the control helmet. Calculations by the testing laboratory showed an extremely low risk of severe brain injury, MTBI, and concussion. Alternatively, to reduce weight and improve strength, a combination of Kevlar (aromatic polyamide) and carbon fibers may be used to mold the helmet  10 . 
       FIGS. 6 and 6A  show an alternative embodiment. Helmet  10  is releasably attached to the wearer&#39;s shoulder pads  40  to stabilize the neck of the user. This attachment would serve to take a portion of the helmet weight off the neck and protect the head from dramatically whipping forward or whipping sideways. Contoured plastic rod  43 , of approximate ½ inch circular diameter, is attached by bolts to the outside rear portion  47  of lower section  14  leaving a space between rod  43  and the outside surface of lower section  14  of preferably approximately 1 inch. Plastic plate  41  is permanently affixed to shoulder pad  40  by bolts and slips into the space between the rod  43  and lower section  14  when the donned helmet  10  is lowered into place on the user&#39;s head. Two brackets  42  are affixed to plate  41 . The brackets  42  are designed to easily accept rod  43  when the helmet  10  is pushed down onto plate  41 . The brackets  42  partially spring closed after rod  43  is pushed down, but allow the helmet to be easily removed by the wearer by pulling up on the helmet to release it from plate  41 . There is sufficient spacing between each bracket  42  and the outer surface of plate  41 , of approximately ⅝ inch, to permit an up or down movement by rod  43  of approximately 3 to 5 inches vertically. Thus, vertical motion of the head is limited to approximately 5 inches. Further, the width of plate  41  is such that horizontal movement is allowed within the space between rod  43  and lower section  14 . The length of rod  43  serves to limit horizontal head movement to about 4 to 6 inches in either direction. This connection will permit the wearer to comfortably move his head vertically and horizontally, but within safe limits. The rod, brackets and plate may be formed may be formed from a durable, low-friction plastic, which permits an easy sliding motion. An example of an appropriate plastic is Delrin made by DuPont. This embodiment may be more relevant to defensive linemen and linebackers to help reduce the risk of brachial plexus injury. 
       FIGS. 7 and 7A  show another embodiment to further aid in the attenuation of rotary acceleration of the brain. Helmet  10  additionally contains slide band  46 . The purpose of the slide band is to move laterally in either direction upon an angular impact, thus absorbing a portion of the energy. The slide band covers gap  18  and straddles the outside bottom of upper section  12  and outside top of lower section  14  of the helmet  10  and can move horizontally in either direction upon impact. The slide band may encompass the entire horizontal periphery of the helmet. The slide band is preferably 3 inches in height, but can range from 2-½ inches to 5 inches. It is a continuous band and it is positioned on the outer surface of the helmet with fifty percent above gap  18  and fifty percent below. It is designed to run in recessed tracks  45  on the outside of the helmet  10 , both in the upper section  12  and in the lower section  14 . It is recessed to the depth whereby the outer surface of the band will be flush with the outer surfaces of upper section  12  and lower section  14 . This embodiment may also include gap filler  32 . 
     The band  46  may be constructed from a durable, puncture-resistant, weather-resistant, think flexible material and one that will easily slide in tracks  45 . Examples include polypropylene or other plastics, or a thin layer of foam, webbing, or rubber, or combinations thereof. The band  46  will have an inner surface that will easily slide in tracks  45 . Band  46  may be built into both the soft top and hard top version of helmet  10 . 
       FIG. 8  shows yet another alternative embodiment of the present invention. In the embodiment of  FIG. 8 , the circumference of the periphery  49  of the lower edge of upper section  12  of helmet  10  is slightly larger than the circumference of the upper edge of the periphery  51  of lower section  14 . Preferably, the major and minor diameters of the periphery  49  of upper section  12  are approximately 1 to 2 inches larger than the major and minor diameters of the upper edge  51  of lower section  14  so that the lower edge of the periphery  49  of upper section  12  overhangs the upper edge  51  of the lower section by approximately ½ to 1 inch. Thus, when there is an impact into gap  18 , the protruding edge of upper section  12  will absorb the initial energy and flex inwardly, which provides additional protection for the user. Alternatively, this may also be accomplished by having a protruding ridge around the outside bottom periphery of upper section  12 . The ridge may be approximately 1 inch high and may protrude outwardly approximately ½ to ¾ inch. Any hit to the gap area will first be contacted by the protruding ridge and will thus transfer the initial energy of the impact to upper section  12 . 
     Helmet  10  may include an attachment method for releasably attaching a conventional known-to-the-art football neck roll to helmet  10 . It will be attached to the rearward lower outside portion of lower section  14  and connected by straps, bolts, glue, hook and loop fasteners, or snaps. The width of the neck roll would be earlobe to earlobe. This feature would help stabilize the neck and head of the wearer upon impacts. 
       FIGS. 9A-12  illustrate another embodiment wherein the helmet  10  includes a semi-rigid inner shell  60  in lieu of suspension head harness  20  and provides an additional barrier to energy transmission. The inner shell  60  attaches to the lower section  14  at a plurality of energy-absorbing attachment points with an energy-absorbing foam member  62  (see  FIGS. 11 and 12 ) at each attachment point. In one non-limiting embodiment of the inner shell  60 , there are six (6) attachment points and a corresponding six (6) foam members  62 , including one at the front and back of the inner shell  60  and opposing pairs on the sides of the inner shell  60 . Other embodiments, of the foam members  62  may be used, as well, including front and rear foam members  62  and four quadrant foam members  62 . Slight movement of the lower section  14  relative to the semi-rigid shell  60  is accomplished through the use of the foam members  62  at the attachment points. The inner shell  60  forms a plurality of cutouts  64  extending between the inner and outer facing surfaces of the inner shell  60 , which permit for reduced weight of the semi-rigid shell  60  and reduced heat buildup within the inner shell  60 . The plurality of cutouts  64  further permit slight flexing of the inner shell  60 . In one embodiment, a plurality of low profile hex nut screws and/or similar variations may be used for securing and removing the inner shell  60  from the lower section  14 , thereby providing for custom fitting of an inner shell  60 . 
     The foam members  62  may be formed from durable impact absorbing foam or a polyethylene type structure or a combination thereof. The positioning of the foam members  62  (beneath the airspace  18 ) permits the inner shell  60  to pivot laterally and undergo inward movement within the airspace  18  upon impact. 
     A plurality of foam pads  66  are attached to the inner facing surface of inner shell  60  and serve to offset the inner shell  60  from the wearer&#39;s head. The pads  66  are positioned throughout the inner facing surface of the inner shell  60  for increased comfort and fit for the wearer. The pads  66  further add to the impact-absorbing features of the helmet  10 . 
     The inner shell  60  provides the rigidity and frame for mounting a hemispheric tensioning system (not pictured) for improved fit of the inner shell  60  about a wearer&#39;s head. The inner shell  60  may include a slot  68  formed along the perimeter of the inner shell  60  to facilitate positioning of the tensioning system control knob  70 . Alternatively, the semi-rigid shell embodiment may be utilized in combination with conventional padded helmets. 
     The positioning of inner shell  60  inside the lower section  14 , and the elimination of conventional interior padding, results in airspace between the user&#39;s head and the inside top and inside side surfaces of upper section  12 . This airspace provides space for the compression struts  16  to flex laterally, inwardly, and downwardly during an impact so that upper section  12  may move independently of the inner shell  60  and, therefore, the wearer&#39;s head. Independent movement of the upper section  12  and the impact resistant foam members  62  in combination permit directional and rotational movement of the inner shell  60  independent of the force undergone by upper shell  12  during impact. 
     Force sensors may be added to the helmet interior to record impacts and acceleration. Examples are: ShockWatch sensors which measure G forces, manufactured by Shockwatch, Inc.; polymer sensors which can transmit impact data to the sidelines, manufactured by Sensortech Corp., for example; battery operated units which measure G forces and transmits to the sidelines, manufactured by Avnet Electronics; MEMS accelerometers manufactured by Analog Devices. 
     NASA developed Phase Change Material may be used to cover the foam  26  to help regulate the user&#39;s temperature. This may be made from a disposable nonwoven fabric and laminated to a perspiration-absorbent nonwoven substrate. Materials other than nonwovens may also be utilized. 
     Soft memory foam, or gel, or a similar compressible material, approximately ¼ inch to ½ inch thick, may be applied to the entire outside surface of the helmet  10  to improve energy dissipation. Since it may degrade after numerous impacts, it may have to be replaced every two to three games. 
     Coatings to the surface of upper section  12  other than polyurethane polyurea or thixotronic plastics may be considered. For example, on the outer surface of the foam a nanodeposited material such as Parylene could be applied using the normal vacuum deposition method for application of nanoparticles. The nanoparticles will impart improved surface characteristics to the foam such as impact resistance, penetration resistance, abrasion resistance, and tear resistance without adding a significant weight. Other nanoparticles besides Parylene may be utilized. The result will be a soft shell to mitigate energy transfer to the head, but with a lightweight protective outer surface to protect against fractures and lacerations. Lower section  14  could be constructed and flexibly attached to upper section  12  as previously described. 
     Struts  16  may be filled with non-Newtonian fluids, or similar. These fluids may be compressed within the struts  16  in their normal state to absorb energy, but will immediately harden upon impact to limit the rotation of the helmet. 
     From the foregoing description of the preferred, additional, and alternative embodiments of the invention, it will be apparent that many modifications may be made therein. 
     It will be understood, however, that the embodiments of the invention are an exemplification of the invention only and that the invention is not limited thereto.