Oro-nasal face mask with improved pneumatic sealing cuff

Claim 1

AN ORAL-NASAL FACE MASK, COMPRISING: A FACE PIECE SHAPED TO COVER THE NOSE AND MOUTH, AND HAVING A FORWARDLY PROJECTING CENTRAL PORTION WITH AN INLET-OUTLET PASSAGE, AND A MARGINAL EDGE PORTION CONFORMING GENERALLY TO THE SURFACE CONTOUR OF THE FACE; AND A SEALING CUFF OF UNITARY CONSTRUCTION EXTENDING AROUND THE PERIMETER OF THE FACE PIECE ALONG SAID MARGINAL EDGE, SAID CUFF INCLUDING ATTACHMENT MEANS FOR SECURING SAID CUFF TO SAID FACE PIECE AND A SUPPORT MEMBER FORMED OF A THIN RESILIENT, FLEXIBLE AND SUBSTANTIALLY NON-STRETCHABLE MATERIAL AND SHAPED TO PROVIDE, IN CROSS SECTION, A REARWARD MOVABLE WALL PORTION WITH REARWARDLY FACING RIDGE MEANS NORMALLY SPACED FROM THE OPPOSITE WALL OF SAID CUFF AND MOVABLE TOWARD AND AWAY FROM THE SAME AND ADAPTED TO MAKE SEALING CONTACT WITH THE FACE AND FORWARDLY FACING RIB MEANS INTEGRAL WITH SAID RIDGE MEANS AND DEFINING A DEPRESSION IN SAID MOVABLE WALL, SAID RIB MEANS BEING ENGAGEABLE WITH THE OPPOSITE WALL OF THE CUFF FOR YIELDABLY RESISTING SUCH MOVEMENT OF SAID RIDGE MEANS TOWARD SAID OPPOSITE WALL AND FLEXING TO PERMIT SAID RIDGE MEANS TO MOVE AWAY FROM SAID OPPOSITE WALL.