Helmet to minimize directional and localized forces in the brain and other body parts by means of shape preservation

Abstract

A method for protecting the human head during and after an impact. This is accomplished by fabricating a layer of material that fits precisely on each individual wearer's head, and yet is so rigid that upon impact, the head will not be allowed to significantly change shape or volume, even temporarily. The structure and properties of this protective layer can be easily adapted to most helmet designs. The preferred method of forming this protective layer is to map each wearer's head shape with laser scanning, and then form the layer by means of 3D printing. Said fitted and rigid layer in very close and uniform contact with each wearers head is called an SPDI shield. The SPDI label stands for Shape Preservation During Impact.

Claims

1. A helmet for protecting a human head of a wearer from impacts and blows, said helmet comprising: a substantially rigid shell constructed of shape preserving material configured to fit about a head of a wearer so that said rigid shell conforms to said wearer's head and a surface of said wearer's head with no more than 1 mm variation from the surface of said wearer's head over any 5 cm extent between the shell and said wearer's head surface, and whereby incompressibility and inflexibility of the rigid shell when struck by an impact or blow protects a wearer's head and brain therein by substantially preventing a change of the wearer's head shape.

2. The helmet as claimed in claim 1 additionally comprising any of a cushioning layer around an exterior surface of said rigid shell and/or a hard outer layer around the exterior surface off, but separate from the shell.

3. The helmet as claimed in claim 1 additionally comprising a rotation damper located between the exterior surface of the shell and the outer hard layer.

4. The helmet as claimed in claim 1 wherein the rigid shell of shape preserving material comprises at least eight total alternating and stacked layers of fiber glass and epoxy.

5. A helmet for protecting a human wearer's head from impacts and blows, said helmet comprising: a substantially rigid shell configured to fit closely to the wearer's head; said rigid shell configured to fit closely with no more than 1 mm variation from the wearer's head over any 5 cm extent along the surface of the wearer's head; a hard outer layer around an exterior surface of, but separate from, the shell; and a rotation damper located between the exterior of the shell and the hard outer layer; whereby incompressibility, inflexibility and resistance to cracking of the shell when struck protects a brain in the wearer's head by substantially preventing change of a wearer's head shape.

6. The helmet of claim 5 wherein said helmet further includes a cushioning layer around the exterior of said shell.

7. The helmet of claim 5 and further wherein the substantially rigid shell comprises a plurality of fiberglass and epoxy layers.

8. The helmet of claim 6 and further wherein the substantially rigid shell comprises a plurality of fiberglass and epoxy layers.

9. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows, said method comprising: measuring a wearer's head surface geometry for providing said helmet rigid shell with an opening for said helmet wearer's neck, face and ears by any one of: a casting method by constructing a negative plastic cast or by a 3D laser photogrammetry scan; constructing a positive mold head shape of said wearer's head utilizing the plaster cast or said 3D laser scan to thereby construct a positive mold by machining or 3D printing; constructing the rigid shell using said positive mold and forming said SPDI shield inner surface so the inner surface does not deviate more than 1 mm away from the positive mold that represents said wearer's original head shape along any 5 cm long contour line extent along said positive mold head surface forming said SPDI shield inner surface on said positive mold cast; lubricating said positive mold cast; placing at least one layer of a first fiberglass sheet over the cast and covering a said sheet with a layer of epoxy spread liberally over an entire surface of said positive mold cast layer without bubbles between said fiberglass sheet(s) and said epoxy and thereby repeating the layering steps until the number of fiberglass sheet layers and epoxy have been reached; allowing said epoxy to set; after said epoxy is set, the formed rigid shell is trimmed by cutting, filling, filing and sanding said rigid shell with epoxy and sanding said epoxy covered rigid shell when dry.

10. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows as in claim 9, said method further comprising: placing a rotational damper layer on said rigid shell layer and then placing an exterior layer over said rotational dampening layer.

11. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows as in claim 10, said method further comprising: providing holes or channels in said rigid shell layers wherein said holes or channels are less than 1.5 mm wide and are spaced 3 mm or more part.

12. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows as in claim 11, said method further comprising: providing holes or channels in said rigid shell layers wherein said holes or channels are less than 1.5 mm wide and are spaced 3 mm or more part.

13. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows as in claim 10, said method further comprising: wherein the rigid shell of shape preserving material comprises at least eight total alternating and stacked layers of fiber glass and epoxy.

14. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows as in claim 10 and further wherein the substantially rigid shell comprises a plurality of fiberglass and epoxy layers.

15. The helmet as claimed in claim 1 wherein said rigid shell inner surface is configured so as to not deviate more an 1 mm away from said wearer's head shape prior to any said impacts or blows thereon.

16. The helmet as claimed in claim 1 wherein said rigid shell is configured so as to not change shape by more than 1 mm along any 5 cm long contour along the inner surface of said rigid shell prior to any impacts or blows thereon.

17. The helmet as claimed in claim 6 wherein said rigid shell inner surface is configured so as to not deviate more an 1 mm away from said wearer's head shape prior to any said impacts or blows thereon.

18. The helmet as claimed in claim 6 wherein said rigid shell is configured so as to not change shape by more than 1 mm along any 5 cm long contour along the inner surface of said rigid shell prior to any impacts or blows thereon.

19. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows as in claim 10 wherein said rigid shell inner surface is configured so as to not deviate more an 1 mm away from said wearer's head shape prior to any said impacts or blows thereon.

20. A method of constructing a helmet for protecting a human wearer's head from impacts and/or blows as in claim 10 wherein said rigid shell is configured so as to not change shape by more than 1 mm along any 5 cm long contour along the inner surface of said rigid shell prior to any impacts or blows thereon.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS AND DRAWINGS

(1) The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

(2) FIG. 1 illustrates a typical prior art helmet design; showing an inner layer that is placed against the head surface between 14 and 16, and also showing the positioning of typical outer layers and a collapsed cross hatched region where an exterior force 20 is striking the helmet.

(3) FIG. 2 Illustrates an embodiment of a typical helmet design of the present invention that would incorporate the SPDI shield 16 as it would be placed within other features incorporated in typical helmet structures, such as rotation dampers 34 and cushions. Note: Soccer players who make headers may benefit very much from a helmet incorporating only the SPDI shield because they could still maintain the control of the ball.

DETAILED SPECIFICATION DESCRIPTION AND FORMING OF HELMETS USING SPDI

(4) Bighorn sheep are designed by nature to butt heads with all their might, but their skulls are strong enough to withstand the resulting forces without frequently delivering serious damage to their small brains compared to human brains. Their heavy skulls will not change shape very much during impact.

(5) Humans took a different evolutionary path, and did not at first use their heads as weapons. Possibly 500,000 years has been too short a time to develop hard heads. Instead, we have developed large and vulnerable brains. The whole head is quite vulnerable to failure, including the skull which is made up of plates that can be flexed and fractured. These facts provide strong incentives for placing a second skull like layer just outside the one we have inherited.

(6) As discussed above, many current helmet designs rely on materials that compress, crush, or crack or otherwise fail, to cushion and drain energy from impacts to the head. But beyond the point where the cushioning material begins to transmit unbalanced and localized forces that distort the head shape, the protection begins to break down. Example: if a sponge becomes highly compressed, it will transmit the remaining (and potentially very localized) impact forces on toward the head. An example 10 is shown in FIG. 1, with a hard outer layer or shell 12, intermediate collapsible cushion and rotation damper 14, head surface 16, collapse zone 18 and impact forces 20.

(7) The tough inflexible SPDI Shield next to the head surface should be coupled with the typical, and often patented, outer layers now used on some modern helmets, an intermediate layer 34 with appropriate dampers for mitigating linear and rotational forces transmitted from an outer shell. Inside the head the specific responses will very much depend on the geometry and mix of the tissues that act as incompressible and/or compressible materials.

(8) The SPDI shield of the invention described here is compatible with conventional designs for the outer cushioning, rotation damper and outer shell helmet models on the market, and should generally be used with them, except perhaps in soccer.

(9) Rotational forces can still be a problem for helmets with the fitted SPDI shield discussed above. Therefore. if the rotational force mitigation structures recommended by the authors of other patents and other literature turn out to be proven effective in reducing head damage, it will be advantageous to use these technologies outside the SPDI shield of the present invention. In fact, said SPDI shield should improve the performance of any rotation damper by helping to decouple the head from rotational forces. The adaptation of the said SPDI shield should be easily engineered by anyone skilled the design of protective helmets. In this case, skilled implies a basic knowledge of hydrodynamic theory. The objective is to leave the head, the SPDI shield and the inner portion of the rotation damping layer behind in alignment with the head, if the outer layers start rotating about the center of gravity of the head as a result of an exterior impact at an angle. Thereby rotational forces will be reduced before reaching the head, as is well known.

(10) High precision measurements of the head surface geometry and the openings necessary for neck, face and ears must be obtained in three dimensions. This can be accomplished, for example by casting or by scanning. This task must be done for each wearer.

(11) A typical method of casting is to make a negative plaster or plastic cast, and then to make a positive cast upon which said SPDI shield can be built. For example, layers of fiberglass cloth permeated with epoxy or other binders can be built up until the needed strength and rigidity can be obtained. This method has been used to make castings for decades, and, was well described by Hartung, U.S. Pat. No. 4,288,268. But crucially for this helmet application, he did not specify how well his protective layer should fit each wearer's head.

(12) A 3D laser (photogrammetry) scan of the head can be made. Then a positive mold can be made by machining, 3D printing, or other additive manufacturing. 3D scanning together with 3D printing may be the most economical way to manufacture the SPDI shield.

(13) Note that laser scanning of infant heads has become an effective step for skull shape correction helmets. In that case, the helmets utilizing the scanning data are then used to slowly correct the shape of the infant's head as he/she grows. (This head shape modification application is obviously the opposite of shape preservation.)

(14) Fiberglass, layered with epoxy or resin, is light and strong, and in this embodiment can be used for an SPDI shield. However, other materials which may have superior properties, are more adaptive, and are less expensive to fabricate on a custom basis, may be employed. Suitable materials that can be employed in 3D printing, using scanning data, could improve performance overall at a lower cost. Very complex structures can now be made by 3D printing with a variety of materials.

(15) Note that more protection can be provided by extending said SPDI shield over a larger area of the head in a way that makes the helmet more difficult to put on or take offthis complication can be reduced by coupling stepped SPDI shield parts together with latches or other means, compatible with any intermediate layer. This can be done because the SPDI shield is made of a tough, inflexible material.

(16) A detailed example of a viable fabrication procedure, using fiberglass and epoxy, is here provided. Make a mold in plaster of the head to be protected. This cast is called a negative cast. Next, lubricate the inside surface of said negative cast with a substance that will allow separation of the negative and positive casts after the positive cast is set. Pour a new batch of plaster into the negative cast cavity. Before the new plaster sets, put a stake of wood or other material into the plaster. This stake must stick out of the setting plaster far enough to be used as a handle for mounting said positive cast on a fixture. Said fixture can be used to support the positive cast when the SPDI shield is being constructed. Note: It is very important that specifications, as to how the SPDI shield is constructed and will perform in use be designated, i.e. shape preservation during impact. The SPDI shield inner surface should not deviate by more than 1 mm away from the original head shape, preferably, along any 5 cm long contour line along said head surface, when said SPDI shield is in proper position on said wearer's head during the specified limits on impact intensity, time history and geometry. Also, said SPDI shield should not change shape by more than 1 mm along any 5 cm long contour along the inner surface of the original SPDI shield. Current standards do not require these types of specifications. Following these types of specifications will permit testing of the SPDI shield without using a living human head.

(17) Next, remove the negative cast. Mount the positive cast so that said SPDI shield can be formed upon it. In this situation, the positive cast makes it feasible to build said SPDI shield inner surface on the specified shape and size as the head to be protected.

(18) Note: One can add plaster or other materials around the edges of the positive cast so that a flair will be added to said SPDI shield for comfort at its edges.

(19) Prepare the fiberglass sheets required to form said SPDI shield and the needed amount of epoxy for the assembly. Lubricate the positive cast so that it can be separated from said SPDI shield once the setting is complete. Lay a fiberglass sheet over the cast. Cover the said sheet with a layer of epoxy that is spread out liberally over the whole surface and worked into the fabric completely. Leave no bubbles. Lay the next sheet on, and repeat the epoxy application step. Again, leave no bubbles. Continue until the required number of fiberglass-epoxy layers has been reached. (This task is best accomplished before the epoxy hardens and cannot be worked into the sheet layers well.) The fiberglass-epoxy should then be allowed to set before any trimming is done such as cutting, filing, filling gaps with epoxy, and sanding.

(20) Note: The above detailed example in no way limits the manner of fabrication by which said SPDI shield can be constructed, as long as said SPDI shield requirements are met.

(21) FIG. 1 illustrates how a typical inner layer next to the head, for helmets, is preferably placed with respect to any intermediate and outer layers of conventional helmets. FIG. 2 represents a horizontal cross section of a helmet 30 just above the ear line, comprising hard, rigid, outside shell 32, rotational slip boundary 34 and said SPDI shield 16. Again, only the SPDI shield is the core of the invention.

(22) Accordingly, said SPDI shield invention is a device whereby damage from impacts to a helmet wearer's head, can be further reduced from the level of protection provided by conventional shields. The SPDI shield must fit each wearer's head precisely, and not allow the outer surface of said head to change shape, significantly, during and after an impact. This means that any damage that can be caused by a change in head shape during and after an impact will be significantly reduced.

(23) The added protection is likely the best that can be done because, in the case of heads in particular, the head cannot be further protected by somehow adding something to the inside of the head.

(24) The shape and volume preservation of a wearer's head during an impact on the said helmet can only be accomplished if the following characteristics of said SPDI shield, right next to said wearer's head, can be obtained. (1) The material of which said SPDI shield is comprised is shaped precisely to the said wearer's head. (2) The SPDI shield has to be rigid, inflexible and tough enough to meet the requirements determined by the environment for which it will be used. e.g., the maximum force field, and its other characteristics, for which said SPDI shield must not fail to preserve the original head shape and volume during an impact.

(25) Since the head shape and volume are preserved through the impact period by the SPDI shield, and since said head responds primarily like an incompressible fluid, any unbalanced forces (such as local forces and sheer) will not be efficiently delivered to said head, and will only be weakly and uniformly coupled to said head, by any outer layers of the helmet. Instead, the forces and any acceleration will be delivered uniformly to the whole volume almost instantaneously. This means that if there are not serious variations of density or compressibility within the volume of said head, the forces on each component of said head will be approximately equalized everywhere in the head, and the damage will be minimized. Conventional protective helmets do not make adequate use of these hydrostatic phenomena.

(26) The SPDI shield of the invention overcomes the disadvantages of using compressible layers right outside of said head surface in an attempt to protect said head, and make it more comfortable when the initial helmet shape does not provide an adequate fit.

(27) Compressible, flexible, crushable or collapsible substances are not suitable for said SPDI shield, because they will not preserve said head shape and/or volume during impact.

(28) Maintaining the head shape during the impact raises the threshold level for exterior forces that can damage the head and brain.

(29) Makers of conventional helmets often use the word rigid in their descriptions, then place a flexible or collapsible layer next to the head for comfort. But since no substance in nature is perfectly rigid, the term must be accurately defined to be meaningful. However, a precisely fitted SPDI shield, has the potential for being not only very comfortable, because of the good fit, but also to stay in place relative to said head where it can continue to provide enhanced protections. No cushions are needed or required between the SPDI shield and the head.

(30) Low density materials are preferably used in said SPDI shield to help reduce nonuniform accelerations, if these materials are strong and rigid.

(31) Said SPDI shield will not tend to transport an unbalanced or shear force to the head being protected. That is exactly what should be sought. The objective is to minimize the unbalanced, position dependent, energy absorbed and ultimately delivered to said wearer's head. Instead, said SPDI shield will transfer much of the potentially damaging energy back to the outer helmet layers where it will be absorbed. This transfer is made possible by shape preservation through the impact period. Since all parts of said head will tend to move or accelerate together, there will be a much reduced amount of damage done to said head by the impact. In fact, if said SPDI shield is very rigid, much of the force entering said SPDI shield material from the impact side will be diverted around to the opposite side where the back surface will start moving away from any shock forces that can reflect back into said head.

(32) The said SPDI shield can easily be adapted to conventional helmets, with minor modifications, by those skilled in helmet design engineering.

(33) Even if said SPDI shield can only extend over a restricted area of the head, the fact that a portion of the impact area may be spread over a larger area than that provided by collapsing cushions, or other outer layers, will still provide added protection to said head, even if the nature of the impact forces is more limited and omnidirectional.

(34) The SPDI shield can be made quite thin, perhaps about 5 mm. Also, it can be easily be adapted to conventional helmets by those skilled in the art of helmet design and fabrication.

(35) The fact that said SPDI shield can be thin, means that the size of said helmet does not have to be made significantly larger than is typical, in the helmet design field, to accommodate said SPDI shield technology.

(36) When the SPDI shield is in proper position on the wearer's head so that it is in close contact, there should be no significant separation between said head surface and the inner surface of said SPDI shield over any 5 cm long contour line of the head surface, with the following exception. Small holes or channels in said SPDI shield can be added for skin breathing and comfort, provided said holes or channels are less than 1.5 mm wide and are separated by 3 mm or more.

(37) There is no helmet presently on the market that preserves the head shape and/or volume during impact as well is demanded by said SPDI shield. This is because the hydrostatic forces that will dominate the force field in said head are not adequately accounted for in conventional protective helmet designs or in the relevant ASTM or other safety standards.

(38) In the text above, the use of the word helmet may be taken as including a device for protecting body parts other than the head, or vice versa, depending on the context.

(39) Although said SPDI shield invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the helmet design art, and is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patients and publications cited above are hereby incorporated by reference.