Abstract:
A gas mask has a facepiece defining an interior chamber and an opening spanning a front portion of facepiece. An optical panel visor is mounted in the opening in the front portion of the facepiece. A hinge joins opposite sides of the visor along a vertical line for relative rotational movement of the opposite sides of the optical panel and the facepiece with respect to each other.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a division a of U.S. patent application Ser. No. 10/257,801, filed Oct. 15, 2002, which is incorporated herein by reference in its entirety and claims priority on International Application No. PCT/US01/12545, filed Apr. 17, 2001, which claims the benefit of U.S. Provisional Application Serial Number 60/198,012, filed Apr. 18, 2000. 
    
    
     BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The invention relates to respirators. In one of its aspects, the invention relates to a respirator that is foldable along a vertical axis for storage. In another of its aspects, the invention relates to a respirator that has an optical visor that spans a face piece and is foldable about a vertical axis. 
     2. Description of the Related Art 
     U.S. Pat. No. 2,737,659, issued Mar. 13, 1956 to Glidden, discloses an optical gas mask with a pair of separate framed lenses that are separated by a longitudinally extending strip of flexible material from the mask for flexing of the mask along a longitudinal line between lenses to adjust the mask to different faces. The rims and flexible material cut down on the field of view for the mask. 
     SUMMARY OF INVENTION 
     A gas mask according to the invention comprises a facepiece defining an interior chamber for filtered air and including at least one inhalation opening for passage of filtered air from the atmosphere to the interior chamber and a filtration canister removably mounted to the facepiece and in fluid communication with the at least one inhalation opening for passage of purified atmospheric air to the facepiece interior chamber and an opening spanning a front portion of facepiece. A visor comprising an optical panel is mounted in the opening in the front portion of the facepiece for user visibility through the facepiece. A hinge joins opposite sides of the visor along a vertical line for relative rotational movement of the opposite sides of the optical panel and the facepiece with respect to each other. 
     In one embodiment, the hinge is integrally formed with the visor. In another embodiment, the hinge is a mechanical hinge. In yet another embodiment, the hinge is formed by welding. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     In the drawings: 
     FIG. 1 is an exploded perspective view of a gas mask and filter assembly according to the invention. 
     FIG. 2 is a partial cross-sectional view of a visor hinge formed by complete encapsulation and taken along lines  2 — 2  of FIG.  1 . 
     FIG. 3 is a partial cross-sectional view, like FIG. 2 of a visor hinge formed by lamination. 
    
    
     DETAILED DESCRIPTION 
     A gas mask and filter assembly  10  according to the invention is shown in the drawings, beginning with FIG.  1 . The assembly  10  comprises a mask housing  12  that fits onto the users face and defines an interior chamber, and a plurality of filter canisters  14 ,  20 . The housing  12  comprises a pair of circular or elliptical canister mounts  13  including an inlet port assembly and self-sealing mechanism  16  and twist-and-lock connector  18  (shown without detail) for affixing circular or elliptical filter canisters  14  to mask housing  12 . 
     Housing  12  further comprises a facepiece  330  and a visor  332 . In a preferred embodiment, facepiece  330  is constructed in multiple sizes of a butyl-rich polymer or other polymer or polymer blend such as butyl/silicone material that will provide the desired level of resistance to penetration of toxic chemicals and will be readily decontaminated. 
     The facepiece  330  further includes a face seal (not shown) that is also injection molded in a separate co-molding process using a silicone-rich polymer or other polymer or polymer blend that is comfortable for the user and forms an effective seal on the face. In this concept, the outer materials would be selected for chemical agent resistance, decontamination, low set, low flammability, mechanical strength and long-term durability. The seal material would be selected for high level of comfort, low skin toxicity, high flexibility at low temperature and the ability to conform closely to facial features. The materials would have to have an acceptable bond strength. In concept, it would be possible to bond polymer to polymer, polymer to blend, or blend to blend as necessary. 
     In an alternative embodiment, the facepiece and seal can be constructed of from the same polymer or polymer blend in a single injection molding operation. The face seal is an in-turned periphery  334  of facepiece  330  and including a built-in chin cup (not shown) for correct location on the user&#39;s face. In another embodiment, face piece  330  is constructed solely of one type of elastomeric material, such as butyl rubber or a blend of silicone and butyl rubber. 
     Visor  332  comprises a panel  336 , constructed for example of polyurethane and configured to give maximum visibility and flexibility to the user, and providing close eye relief. In the depicted embodiment, the visor  332  further includes an elastomeric central hinge  338 , although the visor  332  can be formed without a central hinge. The visor  332  should provide ballistic protection and be configured to receive outserts (not shown) to provide sunlight and laser protection. The visor  332  can further include an anti-scratch surface. 
     The panel  336  must be acceptable for light transmission, haze and reflectivity and must be resistant to the effects of exposure to chemical contaminants and decontaminants. The panel  336  must also have acceptable performance against impact, and be resistant to other challenges such as scratches or abrasions. In general, optical quality materials such as cast or injection-molded polyurethane or polycarbonate are suitable for the visor panel  336 . 
     The hinge  338  should have adequate tensile strength and should be sufficiently flexible to withstand repeated flexing even at low temperatures (−32° C.). Hinge  338  materials must bond to the panel  336  materials, must not take a set during storage, and should preferably be transparent. Polyurethane, styrene butadiene styrene, styrene ethylene butadiene styrene and some vulcanisit or thermoplastic materials are suitable hinge materials. 
     The hinge  338  and panel  336  may be joined together by chemical bonding in a two-part process, or may be adhesively bonded as a post-process operation. The hinge  338  may also be formed as a mechanical hinge, a molded joint, a living hinge or by reduction in the cross-sectional area of the material. The hinge  338  may be formed by complete encapsulation (see FIG. 2) or lamination (see FIG. 3) or the joint between the materials may be made by a form of welding technology using laser, ultrasonic, infra-red or radio frequency (RF) induction. 
     Housing  12  further comprises a primary speech module  342  that combines the functions of speech, drinking system, and outlet valve assembly. The shape of the primary speech module is acoustically formed to eliminate the need for a speech diaphragm. The inlet and outlet valves are interchangeable, reducing the number of unique spare parts required. Housing  12  is held to a user&#39;s face by a plurality of low-profile harness straps  344  defining a flat brow-seal that eliminates hot spots and fits comfortably with a helmet. Harness straps  344  fold over exterior of housing  12  to aid user in rapidly donning mask  10 . The interior chamber of housing  12  further comprises a nose cup (not shown) that is formed of a suitable material such as silicone or polyisoprene and is provided in multiple sizes for comfort and fit on different users. The nose cup also acts as an air guide to eliminate misting of the visor  332 . 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the foregoing description and drawings without departing from the spirit of the invention.