Patent attributes
A protective helmet (100) comprises a plurality of layers. A fabric layer (200) conforms to a wearer's head, extending around the head from the top of the head to a point above the ears. A first, conforming hard layer (205) follows and is secured to the fabric layer. A second hard layer (210) conforms to and rests on the previous hard layer, but is not attached to it. A fibrous layer (215) is formed over the second hard layer, and a wet settable friable or frangible material layer, e.g., plaster, (220) is applied over the fibrous layer. The friable or frangible material infiltrates the fiber layer and seals it to the second hard layer. While the friable or frangible material is still wet, a mold (222) or tool (not shown) forms a plurality of lines, e.g., hexagonal trenches (225), in the friable material that extend downward toward the fibrous layer. The mold can optionally be left in place or removed after the plaster hardens. Next, a surface layer (230) of resin is applied over the outside of the layers. The helmet is then trimmed and ready for use and can be worn alone or under another helmet. The friable or frangible layer can break on impact, absorbing energy that would otherwise injure the wearer. The hard layers prevent penetration of objects through the helmet. In an alternative embodiment, accelerometers (105, 110) independently record acceleration of the wearer's skull and the helmet.
