US Patent 7677248 Stiffened filter mask

A flat-folding mask includes a filter layer forming a rim. The filter layer has first and second side panels extending from the rim. A substantially centrally located front panel bridges the first and second side panels, the front panel being substantially flat. The filter layer further includes a fused portion that is seamless and spaced from the rim. Triangular pleats may add support to the side walls and increase the effective filtration area of the mask.