Ordnance – Shields – Body
Reexamination Certificate
2000-03-09
2003-03-04
Johnson, Stephen M. (Department: 3641)
Ordnance
Shields
Body
C089S036020, C002S002500
Reexamination Certificate
active
06526862
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates to ballistic resistant garments, such as soft body armor vests, and a method for constructing the same.
2. Background of the Invention
In the line of duty, law enforcement officers, military personnel, and persons in similarly dangerous occupations require protection against ballistic missiles, such as bullets, shot, shell fragments, knives, and bayonets. Historically, prior art addressing these needs has provided ballistic protection at the expense of mobility, flexibility, and the ability to dissipate heat and moisture. By using heavy and rigid materials, such as steel and plastic, prior art ballistic garments have provided adequate ballistic protection, but with considerable discomfort to the user in terms of weight, thickness, stiffness, and breathability.
Various ballistic performance specifications require different minimum performance requirements to defeat numerous threat types. One example of a ballistic performance specification is National Institute of Justice (NIJ) Standard 0101.03, “Ballistic Resistance of Police Body Armor.” This standard classifies body armor into six specific types, by level of ballistic protection performance. The six types, in increasing levels of protection, are Types I, II-A, II, III-A, III, and IV. The first four of these armor levels, Types I, II-A, II, and III-A, protect against handgun threats and are typically soft armor protective vests worn on a regular basis. Types III and IV, on the other hand, are typically hard armor that protects against the highest threats, 308 Winchester full metal jacketed ammunition and armor piercing ammunition, respectively. For each of the six NIJ threat levels, the armor must not only defeat a specified projectile type and number of shots, but also must limit a depth of deformation in a clay backing behind the armor to 44 mm or less.
The NIJ Type I provides protection, for example, against a 38 Special round nose lead bullet impacting at 850 feet/second, and a 22 long rifle high velocity lead bullet impacting at 1050 feet/second. The NIJ Type II-A provides protection, for example, against a 357 Magnum jacketed soft point bullet impacting at 1250 feet/second, and a 9 mm full metal jacketed bullet impacting at 1090 feet/second. The NIJ Type II standard provides protection, for example, against a 357 Magnum impacting at 1395 feet/second, and a 9 mm full metal jacketed bullet impacting at 1175 feet/second.
The NIJ Type III-A armor standard requires the highest protection level for handgun threats. It provides protection, for example, against 44 Magnum lead semi-wadcutter bullets with gas checks, impacting at a velocity of 1400 feet/second or less, and 9 mm full metal jacketed bullets impacting at a velocity of 1400 feet/second or less. An armor satisfying the Type III-A standard also provides protection against the lesser threat levels, Type I, Type II-A, and Type II.
Types III and IV are for high-powered ball and armor piercing projectiles, respectively, and are typically used during tactical operations where higher protection is required. Type III armor protects against 7.62 mm full metal jacketed bullets (U.S. military designation M80) impacting at a velocity of 2750 feet/second or less, while providing protection against the lesser NIJ armor level threats. Type IV armor protects against 30-06 armor piercing rounds impacting at velocity of 2850 feet/second.
Some prior art ballistic resistant garments, in combination with woven material, use reinforced plastic panels that are thick, cumbersome, and hard to conceal. In addition to hindering mobility, this construction creates a safety hazard because assailants may see the ballistic resistant garment and shoot for the head instead. An example of these types of garments are the vests manufactured by Safari Land under the product name Hyper-Lite™, which incorporate panels made of a reinforced plastic hybrid, Spectra Shield™. The Spectra Shield™ panels are less flexible than woven material and result in a vest that is stiff, thick, and uncomfortable to wear. Further, the impermeable plastic does not ventilate and does not dissipate heat or moisture, causing additional discomfort to the user.
Other prior art ballistic resistant garments avoid the rigid reinforced plastic and instead use woven fabric panels exclusively. For example, U.S. Pat. No. 5,479,659 discloses a ballistic resistant garment made of woven fabric that produces a vest that is more flexible, concealable, and wearable than the vests using reinforced plastic. Although this type of woven fabric vest is light compared to the plastic reinforced vests, the vest still burdens the user with a considerable weight per unit area (referred to as areal density), on the order of 1.0 lbs/ft
2
for an aramid fabric design vest meeting NIJ Level III-A requirements.
To further reduce areal density but maintain performance, manufacturers use stacked woven fabric made of high performance p-phenylene benzobisoxazole (PBO) fiber, e.g., Zylon® by Toyobo, Inc. Currently, the lightest-weight soft body armor is produced by Second Chance Body Armor, Inc. under the product name Ultima™. In meeting the NIJ standards, Ultima™ areal densities are 0.49 lbs/ft
2
for NIJ 0101.03 Type II-A, 0.60 lbs/ft
2
for NIJ 0101.03 Type II, and 0.77 for NIJ 0101.03 Type III-A. Although reduced in areal density when compared to other prior art, the Second Chance Ultima™ is still not optimal.
Overall, a ballistic resistant garment should be comfortable to wear on a continuous basis and should provide ballistic protection meeting the applicable standards for its usage. In providing comfort, the ballistic resistant garment should be flexible, should be thin and concealable, should provide adequate ventilation allowing the user to dissipate heat and moisture, and most importantly, should be lightweight to minimize the overall burden on the user. An emphasis on comfort translates directly into improved protection, since comfortable garments will be worn much more often than burdensome garments.
SUMMARY OF THE INVENTION
The present invention is an improved fabric armor for use in ballistic resistant garments. The fabric armor is constructed of high performance fiber fabric arranged in a quasi-isotropic orientation. This quasi-isotropic orientation is more effective in dispersing the impact energy at a minimal areal density in comparison to the prior art methods that simply stack fabric plies.
The first preferred embodiment uses p-phenylene benzobisoxazole (PBO) fibers, such as commercially available as-spun Zylon®-AS, 500-denier. The PBO fiber also provides cut resistance superior to any other high performance fiber.
The second preferred embodiment uses aramid fibers, e.g., Kevlar™, KM2™, or Twaron™.
A third preferred embodiment uses ultra-high molecular weight polyethylene fibers, e.g., Spectra™ or Dyneema™.
Alternating layers of the high performance fiber fabric are positioned in a quasi-isotropic orientation. This orientation produces a garment that weighs less than any previous soft fabric armor, but still provides equivalent ballistic performance in accordance with the velocity and blunt trauma specifications of NIJ Standard 0101.03. The present invention provides ballistic protection equivalent to prior art NIJ Level III-A garments with a significant reduction in areal density, i.e., a greater than 10% reduction in areal density to less than 0.69 lbs/ft
2
when using the PBO fiber, when compared to the 0.77 lbs/ft
2
Second Chance Ultima™. Along with a reduction in areal density, the improved fabric armor provides the user with a lighter, more flexible, more compact, and more moisture vapor breathable garment.
To achieve the quasi-isotropic orientation, the high performance fiber is woven into a balanced, plain weave fabric, e.g., approximately 25×25 counts/inch and approximately 3.3 oz/yd
2
. Multiple layers of fabric are combined to create the ballistic filler material for a vest. The number of fabric layers is determined by the ballistic requirement, e.g., the NIJ
Johnson Stephen M.
Shaw Pittman LLP
Simula Inc.
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